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{{Short description|Deliberate and large-scale intervention in Earth's climate system}}
{{Distinguish|Geotechnical engineering}}
{{Redirect|Geoengineering}}


'''Climate engineering''' (or '''geoengineering''', '''climate intervention'''<ref>{{Cite web |title=Research to Inform Decisions about Climate Intervention |url=https://www.wcrp-climate.org/ci-overview |access-date=2024-12-10 |website=www.wcrp-climate.org}}</ref>) is the intentional large-scale alteration of the planetary environment to counteract anthropogenic [[climate change]].<ref>{{Cite book |last=Shepherd |first=John |date=2009 |title=Geoengineering the climate: science, governance and uncertainty |url=https://royalsociety.org/news-resources/publications/2009/geoengineering-climate/ |access-date=2024-10-28 |website=royalsociety.org |publisher=Royal Society of London |page=1 |language=en |isbn=978-0-85403-773-5}}</ref><ref>{{Cite web |last=Union of Concerned Scientists |date=6 November 2017 |year=2017 |title=What is Climate Engineering? |url=https://www.ucsusa.org/resources/what-climate-engineering |access-date=2024-10-28 |website=www.ucsusa.org |language=en}}</ref> The term has been used as an umbrella term for both [[carbon dioxide removal]] and [[solar radiation modification]] when applied at a planetary scale.<ref name="AR6 WGIII Ch 1">IPCC (2022) [https://www.ipcc.ch/report/ar6/wg3/downloads/report/IPCC_AR6_WGIII_Chapter01.pdf Chapter 1: Introduction and Framing] in [https://www.ipcc.ch/report/ar6/wg3/ Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change], Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA</ref>{{rp|168}} However, these two processes have very different characteristics, and are now often discussed separately.<ref name="AR6 WGIII Ch 1" />{{rp|168}}<ref name="IPCC AR6 WGI Glossary">IPCC, 2021: [https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_AnnexVII.pdf Annex VII: Glossary] [Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. Masson-Delmotte, C.&nbsp; Méndez, S. Semenov, A. Reisinger (eds.)]. In [https://www.ipcc.ch/report/ar6/wg1/ Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change] [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 2215–2256, {{doi|10.1017/9781009157896.022}}.</ref> Carbon dioxide removal techniques remove carbon dioxide from the atmosphere, and are part of [[climate change mitigation]]. Solar radiation modification is the reflection of some [[Solar irradiance|sunlight (solar radiation)]] back to space to cool the earth.<ref name=":022">{{Cite book |last=National Academies of Sciences |first=Engineering |url=https://www.nap.edu/catalog/25762/reflecting-sunlight-recommendations-for-solar-geoengineering-research-and-research-governance |title=Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance |date=2021-03-25 |isbn=978-0-309-67605-2 |language=en |doi=10.17226/25762 |access-date=2021-04-17 |archive-url=https://web.archive.org/web/20210417055338/https://www.nap.edu/catalog/25762/reflecting-sunlight-recommendations-for-solar-geoengineering-research-and-research-governance |archive-date=2021-04-17 |url-status=live |s2cid=234327299}}</ref> Some publications include [[Passive daytime radiative cooling|passive radiative cooling]] as a climate engineering technology. The media tends to also use ''climate engineering'' for other technologies such as glacier stabilization, ocean liming, and [[iron fertilization]] of oceans. The latter would modify [[carbon sequestration]] processes that take place in oceans.
[[File:Phytoplankton SoAtlantic 20060215.jpg|right|thumb|An oceanic [[phytoplankton]] bloom in the [[South Atlantic Ocean]], off the coast of [[Argentina]]. Encouraging such blooms with iron fertilization could lock up [[carbon]] on the seabed.]]


Some types of climate engineering are highly controversial due to the large uncertainties around effectiveness, [[side effect]]s and [[unforeseen consequences]].<ref name=":04">{{Cite book |author=Gernot Wagner |url=https://gwagner.com/books/geoengineering-the-gamble/ |title=Geoengineering: the Gamble |year=2021}}</ref> Interventions at large scale run a greater risk of unintended disruptions of natural systems, resulting in a dilemma that such disruptions might be more damaging than the climate damage that they offset.<ref name="perspectives2" /> However, the risks of such interventions must be seen in the context of the trajectory of climate change without them.<ref>{{Cite news|url= |title= Playing God with climate: the EU's geoengineering conundrum|last=Trakimavicius|first=Lukas|work=EUISS|language=en-US}}</ref><ref name="perspectives2">{{cite book |author1=Matthias Honegger |url=https://www.fni.no/doc&pdf/FNI-Climate-Policy-Perspectives-5.pdf |title=Climate Engineering{{Snd}} Avoiding Pandora's Box through Research and Governance. |author2=Axel Michaelowa |author3=Sonja Butzengeiger-Geyer |publisher=Fridtjof Nansen Institute (FNI), Perspectives |year=2012 |series=FNI Climate Policy Perspectives |access-date=2018-10-09 |archive-url=https://web.archive.org/web/20150906055338/https://www.fni.no/doc%26pdf/FNI-Climate-Policy-Perspectives-5.pdf |archive-date=2015-09-06 |url-status=dead}}</ref><ref>{{cite web |author=Zahra Hirji |date=October 6, 2016 |title=Removing CO2 From the Air Only Hope for Fixing Climate Change, New Study Says; Without 'negative emissions' to help return atmospheric {{CO2}} to 350 ppm, future generations could face costs that 'may become too heavy to bear,' paper says. |url=https://insideclimatenews.org/news/04102016/climate-change-removing-carbon-dioxide-air-james-hansen-2-degrees-paris-climate-agreement-global-warming |url-status=live |archive-url=https://web.archive.org/web/20191117214634/https://insideclimatenews.org/news/04102016/climate-change-removing-carbon-dioxide-air-james-hansen-2-degrees-paris-climate-agreement-global-warming |archive-date=November 17, 2019 |access-date=October 7, 2016 |website=insideclimatenews.org |publisher=[[InsideClimate News]]}}</ref>
'''Geoengineering''' is the deliberate and large-scale intervention in the Earth’s climatic system with the aim of reducing [[global warming]].<ref>{{cite report
|url=http://psych.cf.ac.uk/understandingrisk/docs/spice.pdf
| author=United States [[Government Accountability Office]] (GAO)
| year=2011
|month=July
|title=Climate Engineering: Technical Status, Future Directions, and Potential Responses
|number=GAO-11-71
|publisher=Center for Science, Technology, and Engineering
|format=PDF
|page=3
|accessdate=2011-12-01}}</ref><ref name="Royal Society Policy Document">{{cite report
|url=http://royalsociety.org/uploadedFiles/Royal_Society_Content/policy/publications/2009/8693.pdf
| author=Royal Society
| year=2009
|month=September
| title=Geoengineering the Climate: Science, Governance and Uncertainty
|city=London, England
|format=PDF
|ISBN=978-0-85403-773-5
|number=RS Policy document 10/09
|page=1
|accessdate=2011-12-01}}</ref><ref name="nas_policy_implications">[http://books.nap.edu/openbook.php?record_id=1605&page=433 Policy Implications of Greenhouse Warming: Mitigation, Adaptation, and the Science Base] (1992), [[Committee on Science, Engineering, and Public Policy]] (COSEPUP)</ref> The discipline divides broadly into two categories- [[carbon dioxide removal]] and [[solar radiation management]]. Carbon dioxide removal addresses a cause of climate change by removing one of the [[greenhouse gases]] from the [[atmosphere]]. Solar radiation management attempts to offset effects of greenhouse gases by causing the [[Earth]] to absorb less [[solar radiation]].


The [[Union of Concerned Scientists]] warns that solar radiation modification could become an excuse to slow reductions in fossil fuel emissions and stall progress toward a low-carbon economy, as the technology does not address these root causes of climate change.<ref name=":2" />{{TOC limit|3}}
The [[Intergovernmental Panel on Climate Change]] (IPCC) concluded in 2007 that geoengineering options remained largely unproven.<ref name=ipcc>{{cite book
|year=2007
|contribution=C. Mitigation in the short and medium term (until 2030).
|title= Summary for Policymakers.
|series=Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change
|editor=B. Metz ''et al.''
|publisher=Print version: [[Cambridge University Press]], Cambridge, U.K., and New York, N.Y., U.S.A.. This version: IPCC website
|isbn=978-0-521-88011-4
|author=IPCC
|url=http://www.ipcc.ch/publications_and_data/ar4/wg3/en/spmsspm-c.html
|accessdate=2010-05-15}}</ref>


== Terminology ==
Geoengineering has been proposed as a potential third option for tackling [[global warming]], alongside [[mitigation of global warming|mitigation]] and [[adaptation to global warming|adaptation]].<ref>{{cite book
Climate engineering (or geoengineering) has been used as an umbrella term for both carbon dioxide removal and [[Solar radiation modification|solar radiation management]], when applied at a planetary scale.<ref name="AR6 WGIII Ch 1" />{{rp|168}} However, these two methods have very different geophysical characteristics, which is why the [[Intergovernmental Panel on Climate Change]] no longer uses this term.<ref name="AR6 WGIII Ch 1" />{{rp|168}}<ref name="IPCC AR6 WGI Glossary" /> This decision was communicated in around 2018, see for example the [[Special Report on Global Warming of 1.5 °C]].<ref>{{Cite book |url=https://www.cambridge.org/core/product/identifier/9781009157940/type/book |title=Global Warming of 1.5°C: IPCC Special Report on impacts of global warming of 1.5°C above pre-industrial levels in context of strengthening response to climate change, sustainable development, and efforts to eradicate poverty |date=2022 |publisher=Cambridge University Press |isbn=978-1-009-15794-0 |edition=1 |doi=10.1017/9781009157940.008}}</ref>{{rp|550}}
|year=2009 |month=November
|last=Fox |first=T
|title=Climate change have we lost the battle
|url=http://www.imeche.org/Libraries/Key_Themes/IMechE_MAG_Report.sflb.ashx
|format=PDF
|publisher=Institution of Mechanical Engineers
|accessdate=2011-06-14}}</ref> Scientists do not typically suggest geoengineering as an alternative to [[Air pollution|emissions control]], but rather an accompanying strategy.<ref>{{cite doi|10.1126/science.1131728}}</ref> Reviews of geoengineering techniques have emphasised that they are not substitutes for emission controls and have identified potentially stronger and weaker schemes.<ref name="lenton09">{{cite journal | doi=10.5194/acp-9-5539-2009 | last=Lenton | first=T.M. | coauthors=Vaughan, N.E. | year=2009 | title=The radiative forcing potential of different climate geoengineering options | journal=[[Atmospheric Chemistry and Physics]] | volume=9 | issue=15 | pages=5539–5561 | url=http://www.atmos-chem-phys.net/9/5539/2009/acp-9-5539-2009.html }}</ref><ref name="imeche09">{{cite web|url=http://www.imeche.org/Libraries/Key_Themes/IMechEGeoengineeringReport.sflb.ashx|title=Geoengineering – Giving us time to act?|publisher=I Mech E|accessdate=2011-03-12}}</ref><ref name="roysoc09">{{cite web |url=http://royalsociety.org/WorkArea/DownloadAsset.aspx?id=10768
|title=Geoengineering the climate
|publisher=The Royal Society |year=2009
|accessdate=2009-09-02}}</ref>


According to climate economist [[Gernot Wagner]] the term ''geoengineering'' is "largely an artefact and a result of the term's frequent use in popular discourse" and "so vague and all-encompassing as to have lost much meaning".<ref name=":04" />{{Rp|page=14}}
There are no known large-scale geoengineering projects except one conducted outside the scientific mainstream by [[Russ George]]. Almost all research has consisted of computer modelling or laboratory tests, and attempts to move to real-world experimentation has [[Stratospheric Particle Injection for Climate Engineering|proved controversial]]. Some limited [[tree planting]]<ref>{{cite doi|10.1016/S0961-9534(98)00071-3}}</ref> and [[cool roof]]<ref>{{cite web|url=http://www.energy.ca.gov/title24/coolroofs/|title=Cool Roofs and Title 24|publisher=The [[California Energy Commission]] |accessdate=2009-02-25}}</ref> projects are already underway. Ocean [[iron fertilization]] has been given small-scale research trials.<ref>{{cite journal | last=Boyd | first=P.W. | coauthors=''et al.'' | title=Mesoscale Iron Enrichment Experiments 1993–2005: Synthesis and Future Directions | year=2007 | journal=[[Science (journal)|Science]] | volume=315 | pages=612–617 | doi=10.1126/science.1131669 | pmid=17272712 | issue=5812|bibcode = 2007Sci...315..612B }}</ref> [[Field research]] into [[stratospheric sulphur aerosols (geoengineering)|sulfur aerosols]] has also started.<ref>{{cite doi|10.3103/S106837390905001X}}</ref>


<noinclude>Specific technologies that fall into the ''climate engineering'' umbrella term include:<ref name=":13" />{{rp|30}}
Various criticisms have been made of geoengineering and some commentators appear fundamentally opposed. Some have suggested that the concept of geoengineering presents a [[moral hazard]] because it could reduce the political and popular pressure for emissions reduction.<ref>{{cite web | url=http://www.irgc.org/geoengineering | title=Geoengineering | publisher=[[International Risk Governance Council]] | accessdate=2009-10-07 | year=2009 }}</ref>
Groups such as [[ETC Group]]<ref name=ETC>{{cite web|title=ETC website|url=http://www.etcgroup.org/en/issues/geoengineering}}</ref> and individuals such as [[Raymond Pierrehumbert]] have called for a moratorium on deployment and out-of-doors testing of geoengineering techniques.<ref name="worldchanging1">{{cite web|url=http://www.worldchanging.com/archives/008091.html |title=Evaluation + Tools + Best Practices: How Do We Intelligently Discuss Politicized Geoengineering? |publisher=Worldchanging |date= |accessdate=2012-09-06}}</ref><ref name="csmonitor1">[http://features.csmonitor.com/environment/2008/07/16/can-we-engineer-a-cooler-earth/ ''Can we engineer a cooler earth?'']</ref> The full effects of various geoengineering schemes are not well understood.{{verify credibility|date=December 2012}}<ref name="mongabay2007">{{cite web|url=http://news.mongabay.com/2007/0627-planktos.html |title=WWF condemns iron fertilization scheme to fight global warming |publisher=News.mongabay.com |date=2007-06-28 |accessdate=2012-09-06}}</ref>


* [[Carbon dioxide removal]]
==Background==
** [[Biochar]]: Biochar is a high-carbon, fine-grained residue that is produced via [[pyrolysis]]<ref name="DOI10.1038/ncomms1053">{{cite journal |author=Dominic Woolf |author2=James E. Amonette |author3=F. Alayne Street-Perrott |author4=Johannes Lehmann |author5=Stephen Joseph |date=August 2010 |title=Sustainable biochar to mitigate global climate change |journal=Nature Communications |volume=1 |issue=5 |pages=56 |bibcode=2010NatCo...1...56W |doi=10.1038/ncomms1053 |issn=2041-1723 |pmc=2964457 |pmid=20975722}}</ref>
Several notable organizations have investigated geoengineering with a view to evaluating its potential, including the [[US Congress]],<ref name=Bullis>{{cite web|last=Bullis|first=Kevin|title=U.S. Congress Considers Geoengineering|url=http://www.technologyreview.com/view/416187/us-congress-considers-geoengineering/|work=MIT Technology Review|accessdate=26 December 2012}}</ref> [[NASA]],<ref>{{cite web|url=http://event.arc.nasa.gov/main/home/reports/SolarRadiationCP.pdf|title=Workshop on managing solar radiation|date=April 2007|publisher=NASA|accessdate=2009-05-23}}</ref> the [[Royal Society]],<ref>{{cite press release
** [[Bioenergy with carbon capture and storage]] (BECCS): the process of extracting [[bioenergy]] from [[biomass]] and [[Carbon capture and storage|capturing and storing the carbon]], thereby [[Carbon dioxide removal|removing it from the atmosphere]].<ref name="Obersteiner2">{{cite journal |last1=Obersteiner |first1=M. |year=2001 |title=Managing Climate Risk |journal=Science |volume=294 |issue=5543 |pages=786–7 |doi=10.1126/science.294.5543.786b |pmid=11681318 |s2cid=34722068}}</ref>
|title=Stop emitting CO2 or geoengineering could be our only hope
** [[Direct air capture]] and carbon storage: a process of capturing carbon dioxide directly from the ambient air (as opposed to capturing from [[Point source pollution|point sources]], such as a [[cement]] factory or [[biomass]] [[Power station|power plant]]) and generating a concentrated stream of {{CO2}} for [[Carbon sequestration|sequestration]] or [[Carbon capture and utilization|utilization]] or production of [[carbon-neutral fuel]] and [[windgas]].
|url=http://royalsociety.org/Stop-emitting-CO2-or-geoengineering-could-be-our-only-hope/
** [[Enhanced weathering]]: a process that aims to accelerate the natural [[weathering]] by spreading finely ground [[Silicate mineral|silicate]] rock, such as [[basalt]], onto surfaces which speeds up chemical reactions between rocks, water, and air. It also [[Carbon dioxide removal|removes carbon dioxide]] ({{CO2}}) from the atmosphere, permanently storing it in solid [[carbonate mineral]]s or ocean [[alkalinity]].<ref>{{Cite web |date=2018-02-19 |title=Guest post: How 'enhanced weathering' could slow climate change and boost crop yields |url=https://www.carbonbrief.org/guest-post-how-enhanced-weathering-could-slow-climate-change-and-boost-crop-yields |url-status=live |archive-url=https://web.archive.org/web/20210908204350/https://www.carbonbrief.org/guest-post-how-enhanced-weathering-could-slow-climate-change-and-boost-crop-yields |archive-date=2021-09-08 |access-date=2021-11-03 |website=Carbon Brief |language=en}}</ref> The latter also slows [[ocean acidification]].
|date=28 August 2009
* [[Solar geoengineering|Solar Radiation Management]]
|publisher=The Royal Society
** [[Marine cloud brightening]]: a proposed technique that would make [[cloud]]s brighter, reflecting a small fraction of [[Solar irradiance|incoming sunlight]] back into space in order to offset [[Global warming|anthropogenic global warming]].<ref name=":1">{{Cite book |author=Committee on Geoengineering Climate: Technical Evaluation and Discussion of Impacts |url=http://www.nap.edu/catalog.php?record_id=18988 |title=Climate Intervention: Reflecting Sunlight to Cool Earth |author2=Board on Atmospheric Sciences and Climate |author3=Ocean Studies Board |author4=Division on Earth and Life Studies |author5=National Research Council |publisher=National Academies Press |year=2015 |isbn=978-0-309-31482-4 |access-date=2016-10-21 |archive-url=https://web.archive.org/web/20191214192318/http://www.nap.edu/catalog.php?record_id=18988 |archive-date=2019-12-14 |url-status=live}}</ref>
|accessdate=14 June 2011}}</ref> the [[Institute of Mechanical Engineers]],<ref>http://www.imeche.org/Libraries/Key_Themes/IMechEGeoengineeringReport.sflb.ashx</ref><ref>{{cite web|url=http://www.imeche.org/about/keythemes/environment/Climate+Change/Cooling+the+Planet+competition/Geo-engineering+methods.htm|title=Example geoengineering methods|publisher=IMechE|accessdate=2009-05-23}} {{Dead link|date=September 2010|bot=H3llBot}}</ref> and the [[UK Parliament]],.<ref>{{cite web|url=http://www.parliament.uk/documents/upload/postpn327.pdf|title=Geo-engineering research|date=March 2009|work=Postnote|publisher=Parliamentary Office of Science and Technology|accessdate=2009-05-23}}</ref> The [[Asilomar International Conference on Climate Intervention Technologies]] was convened to identify and develop risk reduction guidelines for climate intervention experimentation.<ref>{{cite web|url=http://climateresponsefund.org/index.php?option=com_content&view=article&id=137&Itemid=81 |title=Conference Home |publisher=Climateresponsefund.org |date= |accessdate=2012-09-06}}</ref>
** [[Space mirror (climate engineering)|Mirrors in space]] (MIS): satellites that are designed to change the amount of solar radiation that impacts the Earth as a form of climate engineering. Since the conception of the idea in 1923, 1929, 1957 and 1978 (Hermann Oberth) and also in the 1980s, space mirrors have mainly been theorized as a way to deflect sunlight to counter [[global warming]] and were seriously considered in the 2000s.<ref>{{Cite book |last=Oberth |first=Hermann |date=1984 |orig-date=1923 |title=[[Die Rakete zu den Planetenräumen]] |language=german |publisher=Michaels-Verlag Germany |pages=87–88}}</ref><ref>{{Cite book |last=Oberth |first=Hermann |title=ways to spaceflight |pages=177–506 |url=https://archive.org/details/nasa_techdoc_19720008133 |via=archiv.org |publisher=NASA |access-date=21 December 2017 |language=en |date=1970 |orig-year=1929}}</ref><ref>{{Cite book |last=Oberth |first=Hermann |date=1957 |title=Menschen im Weltraum |language=german |publisher=Econ Duesseldorf Germany |pages=125–182}}</ref><ref>{{Cite book |last=Oberth |first=Hermann |date=1978 |title=Der Weltraumspiegel |language=german |publisher=Kriterion Bucharest}}</ref><ref>{{Cite web |last=Kaufman |first=Rachel |date=August 8, 2012 |title=Could Space Mirrors Stop Global Warming? |url=https://www.livescience.com/22202-space-mirrors-global-warming.html |access-date=2019-11-08 |work=Live Science |language=en}}</ref><ref name=":3">{{Cite journal |last1=Sánchez |first1=Joan-Pau |last2=McInnes |first2=Colin R. |date=2015-08-26 |title=Optimal Sunshade Configurations for Space-Based Geoengineering near the Sun-Earth L1 Point |journal=PLOS ONE |volume=10 |issue=8 |pages=e0136648 |bibcode=2015PLoSO..1036648S |doi=10.1371/journal.pone.0136648 |issn=1932-6203 |pmc=4550401 |pmid=26309047 |doi-access=free}}</ref>
** [[Stratospheric aerosol injection]] (SAI): a proposed method to introduce [[aerosol]]s into the [[stratosphere]] to create a cooling effect via [[global dimming]] and increased [[albedo]], which occurs naturally from [[Volcano|volcanic eruptions]].<ref name="Crutzen062">{{Cite journal |last1=Crutzen |first1=P. J. |year=2006 |title=Albedo Enhancement by Stratospheric Sulfur Injections: A Contribution to Resolve a Policy Dilemma? |journal=Climatic Change |volume=77 |issue=3–4 |pages=211–220 |bibcode=2006ClCh...77..211C |doi=10.1007/s10584-006-9101-y |doi-access=free}}</ref>
The following methods are not termed ''climate engineering'' in the [[IPCC Sixth Assessment Report|latest IPCC assessment report]] in 2022<ref name="AR6 WGIII Ch 1" />{{rp|6–11}} but are included under this umbrella term by other publications on this topic:<ref>{{Cite web |title=Chapter 2 : Land–Climate interactions: Special Report on Climate Change and Land |url=https://www.ipcc.ch/srccl/chapter/chapter-2/ |access-date=2023-10-20}}</ref><ref name=":04" />
* [[Passive daytime radiative cooling]]: this technology increases increases the Earth's solar reflectance and it's [[thermal emittance]] in the [[atmospheric window]].<ref name=":442">{{Cite journal |last1=Zevenhovena |first1=Ron |last2=Fält |first2=Martin |date=June 2018 |title=Radiative cooling through the atmospheric window: A third, less intrusive geoengineering approach |url=https://www.sciencedirect.com/science/article/abs/pii/S0360544218304936 |journal=Energy |volume=152 |page=27 |bibcode=2018Ene...152...27Z |doi=10.1016/j.energy.2018.03.084 |quote=An alternative, third geoengineering approach would be enhanced cooling by thermal radiation from the Earth's surface into space. |via=Elsevier Science Direct}}</ref><ref name=":122222">{{Cite journal |last1=Wang |first1=Tong |last2=Wu |first2=Yi |last3=Shi |first3=Lan |last4=Hu |first4=Xinhua |last5=Chen |first5=Min |last6=Wu |first6=Limin |date=2021 |title=A structural polymer for highly efficient all-day passive radiative cooling |journal=Nature Communications |volume=12 |issue=365 |page=365 |doi=10.1038/s41467-020-20646-7 |pmc=7809060 |pmid=33446648 |quote=One possibly alternative approach is passive radiative cooling—a sky-facing surface on the Earth spontaneously cools by radiating heat to the ultracold outer space through the atmosphere’s longwave infrared (LWIR) transparency window (λ ~ 8–13 μm).}}</ref><ref name=":52">{{Cite journal |last1=Chen |first1=Meijie |last2=Pang |first2=Dan |last3=Chen |first3=Xingyu |last4=Yan |first4=Hongjie |last5=Yang |first5=Yuan |year=2022 |title=Passive daytime radiative cooling: Fundamentals, material designs, and applications |journal=EcoMat |volume=4 |doi=10.1002/eom2.12153 |s2cid=240331557 |quote=Passive daytime radiative cooling dissipates terrestrial heat to the extremely cold outer space without using any energy input or producing pollution. It has the potential to simultaneously alleviate the two major problems of energy crisis and global warming. |doi-access=free}}</ref>
* Ground-level albedo modification: a process of increasing Earth's albedo through the means of altering things on the Earth's surface. Examples include [[Bio-geoengineering|planting light-colored plants]] to help with reflecting sunlight back into space.<ref>{{Cite journal |last1=Wang |first1=Zhuosen |last2=Schaaf |first2=Crystal B. |last3=Sun |first3=Qingsong |last4=Kim |first4=JiHyun |last5=Erb |first5=Angela M. |last6=Gao |first6=Feng |last7=Román |first7=Miguel O. |last8=Yang |first8=Yun |last9=Petroy |first9=Shelley |last10=Taylor |first10=Jeffrey R. |last11=Masek |first11=Jeffrey G. |last12=Morisette |first12=Jeffrey T. |last13=Zhang |first13=Xiaoyang |last14=Papuga |first14=Shirley A. |date=2017-07-01 |title=Monitoring land surface albedo and vegetation dynamics using high spatial and temporal resolution synthetic time series from Landsat and the MODIS BRDF/NBAR/albedo product |journal=International Journal of Applied Earth Observation and Geoinformation |language=en |volume=59 |pages=104–117 |doi=10.1016/j.jag.2017.03.008 |issn=1569-8432 |pmc=7641169 |pmid=33154713|bibcode=2017IJAEO..59..104W }}</ref>
* Glacier stabilization: proposals aiming to slow down or prevent [[sea level rise]] caused by the collapse of notable marine-terminating [[glacier]]s, such as [[Jakobshavn Glacier]] in [[Greenland]] or [[Thwaites Glacier]] and [[Pine Island Glacier]] in [[Antarctica]]. It may be possible to bolster some glaciers directly,<ref name="Wolovick2018">{{Cite journal |last1=Wolovick |first1=Michael J. |last2=Moore |first2=John C. |date=20 September 2018 |title=Stopping the flood: could we use targeted geoengineering to mitigate sea level rise? |url=https://tc.copernicus.org/articles/16/397/2022/ |journal=The Cryosphere |volume=12 |issue=9 |pages=2955–2967 |language=en |doi=10.5194/tc-12-2955-2018 |doi-access=free |bibcode=2018TCry...12.2955W }}</ref> but blocking the flow of [[ocean heat content|ever-warming ocean water]] at a distance, allowing it more time to mix with the cooler water around the glacier, is likely to be far more effective.<ref name="Wolovick2023a">{{Cite journal |last1=Wolovick |first1=Michael |last2=Moore |first2=John |last3=Keefer |first3=Bowie |date=27 March 2023 |title=Feasibility of ice sheet conservation using seabed anchored curtains |url=https://academic.oup.com/pnasnexus/article/2/4/pgad103/7087219 |journal=PNAS Nexus |volume=2 |issue=3 |pages=pgad053 |language=en |doi=10.1093/pnasnexus/pgad053 |pmid=37007716 |pmc=10062297 }}</ref><ref name="Wolovick2023b">{{Cite journal |last1=Wolovick |first1=Michael |last2=Moore |first2=John |last3=Keefer |first3=Bowie |date=27 March 2023 |title=The potential for stabilizing Amundsen Sea glaciers via underwater curtains |url=https://academic.oup.com/pnasnexus/article/2/4/pgad103/7087219 |journal=PNAS Nexus |volume=2 |issue=4 |pages=pgad103 |language=en |doi=10.1093/pnasnexus/pgad103 |pmid=37091546 |pmc=10118300 }}</ref><ref name="MIT2022">{{Cite web|title=The radical intervention that might save the "doomsday" glacier|url=https://www.technologyreview.com/2022/01/14/1043523/save-doomsday-thwaites-glacier-antarctica/|access-date=2022-01-14|website=MIT Technology Review|language=en}}</ref>
* Ocean geoengineering<ref name=":0" /> (adding material such as lime or iron to the ocean to affect its ability to [[Carbon sequestration|sequester carbon dioxide]]).</noinclude>


== Technologies ==
Major environmental organisations such as [[Friends of the Earth]]<ref name="Extreme action guardian">{{cite news |url=http://www.guardian.co.uk/environment/2008/sep/01/climatechange.scienceofclimatechange2 |title=Extreme and risky action the only way to tackle global warming, say scientists |last=Adam |first=David |date= 1 September 2008 |work=Guardian Newspaper |accessdate=2009-05-23 | location=London}}</ref> and [[Greenpeace]]<ref name="Geoengineering no solution">{{cite news|url=http://www.guardian.co.uk/environment/2008/sep/01/climatechange.scienceofclimatechange1|title=Geo-engineering is no solution to climate change|last=Parr|first=Doug|date=1/9/8|work=Guardian Newspaper|accessdate=2009-05-23 | location=London}}</ref> have typically been reluctant to endorse solar radiation management, but are often more supportive of some carbon dioxide removal projects, such as [[afforestation]] and [[peatland restoration]]. Some authors have argued that any public support for geoengineering may weaken the fragile political consensus to reduce [[greenhouse gas]] emissions.<ref>{{cite web|url=http://www.21stcenturychallenges.org/focus/geo-engineering/ |title=Geo-engineering - 21st Century Challenges - Royal Geographical Society with IBG |publisher=21st Century Challenges |date=2010-09-30 |accessdate=2012-09-06}}</ref>


=== Carbon dioxide removal ===
==Proposed strategies==
{{excerpt|carbon dioxide removal|paragraphs=1-2}}
{{See also|List of proposed geoengineering projects}}
Several geoengineering strategies have been proposed. IPCC documents detail several notable proposals.<ref>{{cite web|url=http://www.grida.no/publications/other/ipcc_tar/?src=/CLIMATE/IPCC_TAR/wg3/176.htm |title=IPCC Third Assessment Report - Climate Change 2001 - Complete online versions &#124; UNEP/GRID-Arendal - Publications - Other |publisher=[[UNEP/GRID-Arendal]] |date= |accessdate=2012-09-06}}</ref> These fall into two main categories: [[solar radiation management]] and [[carbon dioxide removal]]. However, [[List of proposed geoengineering projects|other proposals exist]].


===Solar radiation management===
=== Solar radiation modification ===
[[File:SPICE_SRM_overview.jpg|alt=refer to caption and image description|right|thumb|320x320px|Proposed solar radiation modification using a tethered balloon to inject sulfate aerosols into the stratosphere]]
{{Main|Solar radiation management}}
{{See also|Stratospheric sulfur aerosols (geoengineering)|Marine Cloud Brightening}}
{{excerpt|Solar geoengineering|paragraphs=1-2|file=no}}
Solar radiation management (SRM)<ref name="Royal Society Policy Document"/><ref>[http://thehardlook.typepad.com/thehardlook/files/schnare_supplemental_testimony_a_framework_for_geoengineering.pdf Proposed Outline for Solar Radiation Management (Geoengineering) Framework<!-- Bot generated title -->]</ref> projects seek to reduce sunlight absorbed ([[ultra-violet]], near [[infra-red]] and [[visible light|visible]]). This would be achieved by deflecting sunlight away from the Earth, or by increasing the reflectivity ([[albedo]]) of the atmosphere or the Earth's surface. These methods do not reduce [[greenhouse gas]] concentrations in the [[atmosphere]], and thus do not seek to address problems such as the [[ocean acidification]] caused by [[CO2|CO<sub>2</sub>]]. Solar radiation management projects often have the advantage of speedy deployment and effect. While [[greenhouse gas remediation]] offers a more comprehensive possible solution to climate change, it does not give instantaneous results; for that, solar radiation management is required.{{dubious|date=March 2013}}


=== Passive daytime radiative cooling ===
SRM methods<ref name="Royal Society Policy Document"/> may be:
Enhancing the [[Albedo|solar reflectance]] and [[Emissivity|thermal emissivity]] of Earth in the atmospheric window through passive daytime radiative cooling has been proposed as an alternative or "third approach" to climate engineering<ref name=":442"/><ref name=":12222">{{Cite journal |last1=Wang |first1=Tong |last2=Wu |first2=Yi |last3=Shi |first3=Lan |last4=Hu |first4=Xinhua |last5=Chen |first5=Min |last6=Wu |first6=Limin |date=2021 |title=A structural polymer for highly efficient all-day passive radiative cooling |journal=Nature Communications |volume=12 |issue=365 |page=365 |doi=10.1038/s41467-020-20646-7 |pmid=33446648 |pmc=7809060 |quote=One possibly alternative approach is passive radiative cooling—a sky-facing surface on the Earth spontaneously cools by radiating heat to the ultracold outer space through the atmosphere’s longwave infrared (LWIR) transparency window (λ ~ 8–13 μm). }}</ref> that is "less intrusive" and more predictable or reversible than stratospheric aerosol injection.<ref name=":042">{{Cite journal |last=Munday |first=Jeremy |date=2019 |title=Tackling Climate Change through Radiative Cooling |journal=Joule |volume=3 |issue=9 |pages=2057–2060 |doi=10.1016/j.joule.2019.07.010 |quote=A reduction in solar absorption is usually proposed through the injection of reflective aerosols into the atmosphere; however, serious concerns have been raised regarding side effects of these forms of geoengineering and our ability to undo any of the climatic changes we create. |s2cid=201590290|doi-access=free |bibcode=2019Joule...3.2057M }}</ref>
* Surface-based (land or ocean albedo modification); e.g. [[Cool roof]]—using pale-coloured roofing and paving materials.
* Troposphere-based, for example [[cloud whitening]] – using fine [[sea water]] spray to whiten clouds and thus increase cloud reflectivity.
* Upper atmosphere-based (e.g. [[stratospheric sulfur aerosols (geoengineering)|stratospheric aerosols]]). Creating reflective [[aerosols]], such as [[stratospheric sulfur aerosols (geoengineering)|stratospheric sulfur aerosols]], [[aluminum oxide]] particles, even specifically designed [[photophoresis|self-levitating]] aerosols.<ref>{{cite web|url=http://www.pnas.org/content/107/38/16428.full |title=Photophoretic levitation of engineered aerosols for geoengineering |publisher=PNAS |accessdate=2012-05-16}}</ref>
* Space-based: E.g. [[Space sunshade]]—obstructing [[solar radiation]] with space-based mirrors, asteroid dust,<ref>{{cite doi|10.1016/j.asr.2012.07.008}}</ref> etc.


{{excerpt|Passive daytime radiative cooling|paragraphs=1-2}}[[File:A technofix for the climate- Marine geoengineering.webm|thumb|Video to explain some of the marine geoengineering approaches with a focus on their risks, negative impacts and potential side-effects, as well as on the question of governance of these technologies.]]
===Carbon dioxide removal===
{{Unreferenced|date=March 2013}}
{{Main|Carbon dioxide removal|Greenhouse gas remediation|Carbon sequestration}}
Carbon dioxide removal projects seek to remove [[greenhouse gases]] from the [[atmosphere]]. Proposed methods include those that directly remove such gases from the atmosphere, as well as indirect methods that seek to use natural processes(e.g. tree planting). Many projects overlap with [[carbon capture and storage]] and [[carbon sequestration]] projects, and may not be considered to be geoengineering by all commentators. Techniques in this category include:
* Creating [[biochar]] and mixing it with soil to create [[terra preta]]
* [[Bio-energy with carbon capture and storage]] to sequester carbon and simultaneously provide energy
* [[Carbon air capture]] to remove [[carbon dioxide]] from ambient air
* Planting trees to offset carbon emissions
* [[Ocean nourishment]] including [[iron fertilisation]] of the oceans


=== Ocean geoengineering ===
[[File:2007 Arctic Sea Ice.jpg|thumb|250px|right|Significant reduction in ice volume in the Arctic Ocean in the range between 1979 and 2007 years]]
{{Main|Carbon sequestration#Sequestration techniques in oceans}}Ocean geoengineering involves modifying the ocean to reduce the impacts of rising temperature. One approach is to add material such as lime or iron to the ocean to increase its ability to support marine life and/or sequester {{Chem|CO|2}}. In 2021 the US [[National Academies of Sciences, Engineering, and Medicine]] (NASEM) requested $2.5 billion funds for research in the following decade, specifically including field tests.<ref name=":0">{{Cite web |last=Voosen |first=Paul |date=16 December 2022 |title=Ocean geoengineering scheme aces its first field test |url=https://www.science.org/content/article/ocean-geoengineering-scheme-aces-its-first-field-test |access-date=2022-12-19 |website=www.science.org |language=en}}</ref>


Another idea is to reduce [[Sealevel rise|sea level rise]] by installing underwater "curtains" to protect [[Antarctic]] glaciers from warming waters, or by drilling holes in ice to pump out water and heat.<ref>{{Cite news |last=Richter |first=Hannah |date=12 July 2024 |title=To avoid sea level rise, some researchers want to build barriers around the world's most vulnerable glaciers |url=https://www.science.org/content/article/avoid-sea-level-rise-some-researchers-want-build-barriers-around-world-s-most |work=[[Science magazine]]}}</ref>
==Justification==


==== Ocean liming ====
===Tipping points and positive feedback===
{{Main|Carbon sequestration#Adding bases to neutralize acids|Ocean acidification#Carbon removal technologies which add alkalinity}}
[[File:65 Myr Climate Change.png|thumb|300px|right|Climate change during the last 65 million years. The Paleocene–Eocene Thermal Maximum is labelled PETM.]]
Enriching seawater with calcium hydroxide ([[Lime (material)|lime]]) has been reported to lower [[Ocean acidification|ocean acidity]], which reduces pressure on [[marine life]] such as [[oysters]] and absorbs {{Chem|CO|2}}. The added lime raised the water's [[pH]], capturing {{Chem|CO|2}} in the form of [[calcium bicarbonate]] or as [[carbonate]] deposited in [[mollusk]] shells. Lime is produced in volume for the cement industry.<ref name=":0" /> This was assessed in 2022 in an experiment in [[Apalachicola, Florida]] in an attempt to halt declining oyster populations. pH levels increased modestly, as {{Chem|CO|2}} was reduced by 70 ppm.<ref name=":0" />
It is argued that [[climate change]] may cross [[tipping point (climatology)|tipping points]]<ref name="ReferenceA">{{cite doi|10.1073/pnas.0705414105}}</ref> where elements of the climate system may 'tip' from one stable state to another stable state, much like a glass tipping over. When the new state is reached, further warming may be caused by [[positive feedback]] effects,.<ref>{{cite web|url=http://www.energybulletin.net/node/10322 |title=Stopping Runaway Climate Change |publisher=Energy Bulletin |date= |accessdate=2012-09-06}}</ref> An example of a proposed [[causal chain]] leading to [[runaway global warming]] is the collapse of Arctic sea ice triggering subsequent release of [[methane]].<ref>{{cite doi|10.1038/ngeo1452}}</ref>


A 2014 experiment added [[sodium hydroxide]] (lye) to part of Australia's [[Great Barrier Reef]]. It raised pH levels to nearly preindustrial levels.<ref name=":0" />
The precise identity of such "tipping points" is not clear, with scientists taking differing views on whether specific systems are capable of "tipping" and the point at which this "tipping" will occur.<ref>{{cite web|url=http://researchpages.net/ESMG/people/tim-lenton/tipping-points/ |title=Tipping points in the Earth system |publisher=ResearchPages.net |date=2005-10-06 |accessdate=2012-09-06}}</ref> An example of a previous tipping point is that which preceded the rapid warming leading up to the [[Paleocene–Eocene Thermal Maximum]]. Once a tipping point is crossed, cuts in anthropogenic greenhouse gas emissions will not be able to reverse the change. Conservation of resources and reduction of greenhouse emissions, used in conjunction with geoengineering, are therefore considered a viable option by some commentators.<ref>{{cite news| url=http://www.guardian.co.uk/environment/2006/oct/18/bookextracts.books | work=The Guardian | location=London | title=How close is runaway climate change? | first=Paul | last=Brown | date=2006-10-18 | accessdate=2010-03-30}}</ref><ref>http://ipsnews.net/news.asp?idnews=42662</ref><ref>{{cite news| url=http://www.independent.co.uk/news/science/global-warming-now-unstoppable-scientists-warn-702979.html | work= The Independent | location=London | title=Global warming now 'unstoppable', scientists warn | first=Charles | last=Arthur | date=2001-01-23 | accessdate=2010-03-30}}</ref> Geoengineering offers the hope of temporarily reversing some aspects of climate change and allowing the natural climate to be substantially preserved whilst greenhouse gas emissions are brought under control and removed from the [[atmosphere]] by natural or artificial processes.


However, producing alkaline materials typically releases large amounts of {{Chem|CO|2}}, partially offsetting the sequestration. Alkaline additives become diluted and dispersed in one month, without durable effects, such that if necessary, the program could be ended without leaving long-term effects.<ref name=":0" />
===Costs===
Some geoengineering techniques, such as [[cool roof]] techniques, can be achieved at little or no cost, and may even offer a financial payback.<ref>{{cite web|url=http://www.ornl.gov/sci/roofs+walls/facts/CoolCalcEnergy.htm |title=DOE Cool Roof Calculator for Low-Slope or Flat Roofs |publisher=Ornl.gov |date= |accessdate=2012-09-06}}</ref> IPCC (2007) concluded that reliable cost estimates for geoengineering options had not been published.<ref name=ipcc/> More recently, early research into costs of [[solar radiation management]] have been published.<ref>{{cite doi|10.1088/1748-9326/7/3/034019}}</ref> This suggests that "well designed systems" might be available for costs in the order of a few hundred million dollars per year.<ref name = benefits_risks_costs/> These are much lower than costs to achieve comprehensive reductions in CO<sub>2</sub> emissions{{citation needed|date=December 2012}}. Such costs would be within the budget of most nations, and even a handful of rich individuals.<ref>{{cite web|url=http://www.cfr.org/content/thinktank/GeoEng_041209.pdf |title=Unilateral Geoengineering |publisher=CFR |accessdate=2012-05-16}}</ref>


==== Ocean sulfur cycle enhancement ====
In their 2009 report ''Geoengineering the climate'' the [[Royal Society]] adjudged afforestation and stratospheric aerosols as the methods with the "highest affordability" (meaning lowest costs). Furthermore stratospheric aerosol injection, having the highest effectiveness and affordability, would be the nearest approximation to the "ideal method", with the (significant) disadvantage of high uncertainties considering safety and unwanted side effects. While afforestation scored highly for safety, it was found to be of limited effectiveness for treating climate change (see Table 5.1, Figure 5.1., pages 48–49)<ref name="Royal Society Policy Document"/>
{{Main|Ocean fertilization}}


Enhancing the natural marine [[sulfur cycle]] by fertilizing a small portion with [[iron]]—typically considered to be a [[greenhouse gas remediation]] method—may also increase the reflection of sunlight.<ref>{{Cite journal |last1=Wingenter |first1=Oliver W. |last2=Haase |first2=Karl B. |last3=Strutton |first3=Peter |last4=Friederich |first4=Gernot |last5=Meinardi |first5=Simone |last6=Blake |first6=Donald R. |last7=Rowland |first7=F. Sherwood |date=8 June 2004 |title=Changing concentrations of CO, CH<sub>4</sub>, C<sub>5</sub>H<sub>8</sub>, CH<sub>3</sub>Br, CH<sub>3</sub>I, and dimethyl sulfide during the Southern Ocean Iron Enrichment Experiments |journal=Proceedings of the National Academy of Sciences of the United States of America |language=en |volume=101 |issue=23 |pages=8537–8541 |bibcode=2004PNAS..101.8537W |doi=10.1073/pnas.0402744101 |issn=0027-8424 |pmc=423229 |pmid=15173582 |doi-access=free}}</ref><ref>{{cite journal |last1=Wingenter |first1=Oliver W. |last2=Elliot |first2=Scott M. |last3=Blake |first3=Donald R. |date=November 2007 |title=New Directions: Enhancing the natural sulfur cycle to slow global warming |url=https://escholarship.org/uc/item/3t2791f1 |url-status=live |journal=Atmospheric Environment |volume=41 |issue=34 |pages=7373–5 |bibcode=2007AtmEn..41.7373W |doi=10.1016/j.atmosenv.2007.07.021 |s2cid=43279436 |archive-url=https://web.archive.org/web/20200813061020/https://escholarship.org/uc/item/3t2791f1 |archive-date=13 August 2020 |access-date=18 September 2020}}</ref> Such fertilization, especially in the [[Southern Ocean]], would enhance [[dimethyl sulfide]] production and consequently cloud [[reflectivity]]. This could potentially be used as regional SRM, to slow [[Antarctic]] ice from melting.{{Citation needed|date=November 2020}} Such techniques also tend to [[Carbon sequestration|sequester carbon]], but the enhancement of cloud albedo also appears to be a likely effect.
===Ethics and responsibility===
Climate engineering would represent a large-scale, intentional effort to modify the environment, which differ from inadvertent climate change through activities such as burning fossil fuels. Intentional climate change is viewed very differently from a moral standpoint.<ref>Bodansky, D. (1996) May we engineer the climate? [[Climatic Change]] 33: 309–321</ref> This raises questions of whether we as humans have the right to change the climate, and under what conditions this right obtains. Furthermore, ethical arguments often confront larger considerations of worldview, including individual and social religious commitments. For many, religious beliefs are pivotal in defining the role of human beings in the wider world. Some religious communities might claim that humans have no responsibility in managing the climate, instead seeing such world systems as the exclusive domain of a Creator. In contrast, other religious communities might see the human role as one of "stewardship" or benevolent management of the world.<ref>Clingerman, F. (2012) "Between Babel and Pelagius: Religion, Theology and Geoengineering," in Preston, C. (ed.), ''Engineering the Climate: The Ethics of Solar Radiation Management''. Lantham, MD: Lexington, pp. 201-219. </ref> The question of ethics also relates to issues of policy decision-making. For example, the selection of a globally agreed target temperature is a significant problem in any geoengineering [[governance]] regime, as different countries or interest groups may seek different global temperatures.<ref name = geoengineering_option>Victor, D. G., M. G. Morgan, J. Apt, J. Steinbruner, K. Ricke (2009) The Geoengineering Option: A last resort against global warming? [[Foreign Affairs]] March/April 2009</ref>


==== Iron fertilization ====
What most ethicists, policy-makers, and scientists agree on is this: Solar radiation management is an incomplete solution to global warming.<ref>Michaelson, J. (1998) 'Geoengineering: a climate change Manhattan project'. [[Stanford University|Stanford]] Environmental Law Journal, Stanford CA, January 1998</ref> The possible option of geoengineering may reduce incentives to reduce emissions of greenhouse gases. It is argued that geoengineering could be used to 'buy time' before drastic climate change happens, allowing [[Climate change mitigation|mitigation]] and adaptation measures more time to be implemented and work.<ref>Gardiner, S. M. Is "Arming the Future" with geoengineering really the lesser evil? Some doubts about the ethics of intentionally manipulating the climate system in Gardiner, S., S. Caney, D. Jamieson & H. Shue (eds) Climate Ethics: Essential Readings. [[Oxford University Press]], 2010, 284–314</ref> But the opposition points out that the resources spent on geoengineering could be used for mitigation and efforts to reduce emissions of greenhouse gases. Geoengineering also does not resolve other issues related to increasing levels of carbon dioxide.
{{excerpt|Iron fertilization|paragraphs=1|file=no}}


===Political viability===
==== Submarine forest ====
Another 2022 experiment attempted to sequester carbon using [[giant kelp]] planted off the [[Namibia]]n coast.<ref name=":0" /> Whilst this approach has been called ''ocean geoengineering'' by the researchers it is just another form of carbon dioxide removal via sequestration. Another term that is used to describe this process is ''[[blue carbon]] management'' and also ''marine geoengineering''.
It has been argued that regardless of the economic, scientific and technical aspects, the difficulty of achieving concerted political action on climate change requires other approaches.<ref>{{cite news| url=http://www.guardian.co.uk/commentisfree/cifamerica/2008/dec/12/environment-climate-change-poznan | work=The Guardian | location=London | title=Let's get real on the environment | date=2008-12-12 | accessdate=2010-03-30 | first=David | last=Appell}}</ref> Those arguing political expediency say the difficulty of achieving meaningful emissions cuts<ref>{{cite news| url=http://www.nytimes.com/2007/10/24/opinion/24caldiera.html?_r=2&ref=opinion&oref=slogin | work=The New York Times | title=How to Cool the Globe | first=Ken | last=Caldeira | authorlink=Ken Caldeira | date=2007-10-24 | accessdate=2010-03-30}}</ref> and the effective failure of the [[Kyoto Protocol]] demonstrate the practical difficulties of achieving carbon dioxide [[emissions reduction]] by the agreement of the [[international community]].<ref>{{cite news| url=http://www.guardian.co.uk/environment/2008/sep/01/climatechange.scienceofclimatechange2 | work=The Guardian | location=London | title=Extreme and risky action the only way to tackle global warming, say scientists | first=David | last=Adam | date=2008-09-01 | accessdate=2010-03-30}}</ref> However, others point to support for geoengineering proposals among think tanks with a history of climate change skepticism and opposition to emissions reductions as evidence that the prospect of geoengineering is itself already politicized and being promoted as part of an argument against the need for (and viability of) emissions reductions; that, rather than geoengineering being a solution to the difficulties of emissions reductions, the prospect of geoengineering is being used as part of an argument to stall emissions reductions in the first place.<ref>{{cite web|url=http://www.worldchanging.com/archives/009784.html |title=Evaluation + Tools + Best Practices: Geoengineering and the New Climate Denialism |publisher=Worldchanging |date= |accessdate=2012-09-06}}</ref>


=== Glacier stabilization ===
Geoenginering poses several challenges in the context of governance because of issues of power and jurisdiction.<ref name = benefits_risks_costs>[[Alan Robock|Robock, A.]], A. Marquardt, B. Kravitz, and G. Stenchikov (2009). Benefits, Risks, and costs of stratospheric geoengineering, Geophysical Research Letters, 36, D19703, {{doi|10.1029/2009GL039209}}</ref> Geoengineering as a climate change solution differs from other mitigation and adaptation strategies. Unlike a carbon trading system that would be focused on participation from multiple parties along with transparency, monitoring measures and compliance procedures; this is not necessarily required by geoengineering. Bengtsson<ref>Bengtsson, L. (2006) 'Geo-engineering to confine climate change: is it at all feasible?' Climatic Change 77: 229–234</ref> (2006) argues that "the artificial release of sulphate aerosols is a commitment of at least several hundred years". This highlights the importance for a political framework that is sustainable enough to contain a multilateral commitment over such a long period and yet is flexible as the techniques innovate through time. There are many controversies surrounding this topic and hence, geoengineering has been made into a very political issue. Most discussions and debates are not about which geoengineering technique is better than the other, or which one is more economically and socially feasible. Discussions are broadly on who will have control over the deployment of geoengineering and under what governance regime the deployment can be monitored and supervised. This is especially important due to the regional variability of the effects of many geoengineering techniques, benefiting some countries while damaging others. The challenge posed by geoengineering is not how to get countries to do it. It is to address the fundamental question of who should decide whether and how geoengineering should be attempted – a problem of governance.<ref>Barrett, S (2007) Why cooperate? The incentive to supply global public goods. Oxford University Press, Oxford</ref>
[[File:Wolovick2018_Thwaites_sill_timelines.png|thumb|left|A proposed "underwater sill" blocking 50% of warm water flows heading for the glacier could have the potential to delay its collapse and the resultant sea level rise by many centuries.<ref name="Wolovick2018" />]]
{{excerpt|Thwaites Glacier#Engineering options for stabilization|paragraphs=1,2|file=no}}


==Problems==
==Risks and criticisms==
Interventions at large scale run a greater risk of unintended disruptions of natural systems, resulting in a dilemma that such disruptions might be more damaging than the climate damage that they offset.<ref name="perspectives2" />
[[File:WOA05 GLODAP del pH AYool.png|thumb|right|300px|Change in sea surface [[pH]] caused by [[anthropogenic]] [[carbon dioxide|CO<sub>2</sub>]] between the 1700s and the 1990s. This [[ocean acidification]] will still be a major problem unless [[atmosphere|atmospheric]] CO<sub>2</sub> is reduced.]]
=== Ethical aspects ===
Various criticisms have been made of geoengineering,<ref>{{cite web|url=http://www.ametsoc.org/policy/2009geoengineeringclimate_amsstatement.pdf|title=AMS Policy Statement on Geoengineering the Climate System|publisher=[[American Meteorological Society]]|accessdate=2009-07-22}}</ref> particularly Solar Radiaton Management (SRM) methods.<ref>{{cite web|url=http://www.huffingtonpost.co.uk/jon-taylor/geoengineering-climate-change_b_1873231.html|title=Geo-engineering - A Tool in the Fight to Tackle Climate Change, or a Dangerous Distraction? |publisher=[[Huffington Post]]|accessdate=2012-10-02}}</ref> Some commentators appear fundamentally opposed. Groups such as [[ETC Group]]<ref name=ETC /> and individuals such as [[Raymond Pierrehumbert]] have called for a moratorium on geoengineering techniques.<ref name="worldchanging1"/><ref name="csmonitor1"/>
Climate engineering may reduce the urgency of reducing carbon emissions, a form of [[moral hazard]].<ref name="Extreme action guardian2">{{cite news |last=Adam |first=David |date=1 September 2008 |title=Extreme and risky action the only way to tackle global warming, say scientists |work=The Guardian |url=https://www.theguardian.com/environment/2008/sep/01/climatechange.scienceofclimatechange2 |url-status=live |access-date=2009-05-23 |archive-url=https://web.archive.org/web/20190806230902/https://www.theguardian.com/environment/2008/sep/01/climatechange.scienceofclimatechange2 |archive-date=2019-08-06}}</ref> Also, most efforts have only temporary effects, which implies rapid rebound if they are not sustained.<ref name=":4">{{cite web |year=2009 |title=Geoengineering |url=http://www.irgc.org/geoengineering |url-status=dead |archive-url=https://web.archive.org/web/20091203132630/http://www.irgc.org/geoengineering |archive-date=2009-12-03 |access-date=2009-10-07 |publisher=[[International Risk Governance Council]]}}</ref> The [[Union of Concerned Scientists]] points to the danger that the use of climate engineering technology will become an excuse not to address the root causes of climate change, slow our emissions reductions and start moving toward a low-carbon economy.<ref name=":2">{{Cite web |date=Dec 4, 2020 |title=What Is Solar Geoengineering? |url=https://www.ucsusa.org/resources/what-solar-geoengineering |website=The Union of Concerned Scientists}}</ref> However, several public opinion surveys and focus groups reported either a desire to increase emission cuts in the presence of climate engineering, or no effect.<ref>{{Cite journal |last1=Kahan |first1=Dan M. |last2=Jenkins-Smith |first2=Hank |last3=Tarantola |first3=Tor |last4=Silva |first4=Carol L. |last5=Braman |first5=Donald |date=2015-03-01 |title=Geoengineering and Climate Change Polarization Testing a Two-Channel Model of Science Communication |journal=The Annals of the American Academy of Political and Social Science |volume=658 |issue=1 |pages=192–222 |doi=10.1177/0002716214559002 |issn=0002-7162 |s2cid=149147565}}</ref><ref>{{Cite journal |last1=Wibeck |first1=Victoria |last2=Hansson |first2=Anders |last3=Anshelm |first3=Jonas |date=2015-05-01 |title=Questioning the technological fix to climate change{{Snd}} Lay sense-making of geoengineering in Sweden |url=http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-119732 |journal=Energy Research & Social Science |volume=7 |pages=23–30 |doi=10.1016/j.erss.2015.03.001|bibcode=2015ERSS....7...23W }}</ref><ref>{{Cite journal |last1=Merk |first1=Christine |last2=Pönitzsch |first2=Gert |last3=Kniebes |first3=Carola |last4=Rehdanz |first4=Katrin |last5=Schmidt |first5=Ulrich |date=2015-02-10 |title=Exploring public perceptions of stratospheric sulfate injection |journal=Climatic Change |volume=130 |issue=2 |pages=299–312 |bibcode=2015ClCh..130..299M |doi=10.1007/s10584-014-1317-7 |issn=0165-0009 |s2cid=154196324}}</ref> Other modelling work suggests that the prospect of climate engineering may in fact increase the likelihood of emissions reduction.<ref>{{Cite journal |last=Reynolds |first=Jesse |date=2015-08-01 |title=A critical examination of the climate engineering moral hazard and risk compensation concern |journal=The Anthropocene Review |volume=2 |issue=2 |pages=174–191 |doi=10.1177/2053019614554304 |bibcode=2015AntRv...2..174R |issn=2053-0196 |s2cid=59407485}}</ref><ref>{{Cite journal |last=Morrow |first=David R. |date=2014-12-28 |title=Ethical aspects of the mitigation obstruction argument against climate engineering research |journal=Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences |volume=372 |issue=2031 |pages=20140062 |bibcode=2014RSPTA.37240062M |doi=10.1098/rsta.2014.0062 |issn=1364-503X |pmid=25404676 |doi-access=free}}</ref><ref>{{Cite journal |last=Urpelainen |first=Johannes |date=2012-02-10 |title=Geoengineering and global warming: a strategic perspective |journal=International Environmental Agreements: Politics, Law and Economics |volume=12 |issue=4 |pages=375–389 |doi=10.1007/s10784-012-9167-0 |bibcode=2012IEAPL..12..375U |issn=1567-9764 |s2cid=154422202}}</ref><ref>{{Cite journal |last=Moreno-Cruz |first=Juan B. |date=2015-08-01 |title=Mitigation and the geoengineering threat |journal=Resource and Energy Economics |volume=41 |pages=248–263 |doi=10.1016/j.reseneeco.2015.06.001|bibcode=2015REEco..41..248M |hdl=1853/44254 |hdl-access=free }}</ref>


If climate engineering can alter the climate, then this raises questions whether humans have the right to deliberately change the climate, and under what conditions. For example, using climate engineering to stabilize temperatures is not the same as doing so to optimize the climate for some other purpose. Some religious traditions express views on the relationship between humans and their surroundings that encourage (to conduct responsible stewardship) or discourage (to avoid hubris) explicit actions to affect climate.<ref>{{cite journal |last1=Clingerman |first1=F. |last2=O'Brien |first2=K. |year=2014 |title=Playing God: why religion belongs in the climate engineering debate |journal=[[Bulletin of the Atomic Scientists]] |volume=70 |issue=3 |pages=27–37 |bibcode=2014BuAtS..70c..27C |doi=10.1177/0096340214531181 |s2cid=143742343}}</ref>
===Ineffectiveness===
== Society and culture ==
The effectiveness of the schemes proposed may fall short of predictions.<ref>[http://www.scientificamerican.com/article.cfm?id=seeding-atlantic-ocean-with-volcanic-iron-did-little-to-lower-co2 ''Seeding Atlantic Ocean with Volcanic Iron Did Little to Lower CO2''] March 21, 2013 [[Scientific American]]</ref> In ocean [[iron fertilization]], for example, the amount of carbon dioxide removed from the [[atmosphere]] may be much lower than predicted, as carbon taken up by [[plankton]] may be released back into the atmosphere from dead plankton, rather than being carried to the bottom of the sea and sequestered.<ref name="autogenerated1">Seasonal rhythms of net primary production and particulate organic carbon flux to depth describe the efficiency of biological pump in the global ocean", [[Journal of Geophysical Research]], vol. 112, C10011, {{doi|10.1029/2006JC003706}}</ref>


=== Public perception ===
===Incomplete solution to CO<sub>2</sub> emissions===
A large 2018 study used an online survey to investigate public perceptions of six climate engineering methods in the United States, United Kingdom, Australia, and New Zealand.<ref name=":13">{{Cite journal |last1=Carlisle |first1=Daniel P. |last2=Feetham |first2=Pamela M. |last3=Wright |first3=Malcolm J. |last4=Teagle |first4=Damon A. H. |date=2020-04-12 |title=The public remain uninformed and wary of climate engineering |url=https://eprints.soton.ac.uk/440717/1/Thepublic_remain_uninformed.pdf |url-status=live |journal=Climatic Change |language=en |volume=160 |issue=2 |pages=303–322 |bibcode=2020ClCh..160..303C |doi=10.1007/s10584-020-02706-5 |issn=1573-1480 |archive-url=https://web.archive.org/web/20210614062101/https://eprints.soton.ac.uk/440717/1/Thepublic_remain_uninformed.pdf |archive-date=2021-06-14 |access-date=2021-05-18 |s2cid=215731777}}</ref> Public awareness of climate engineering was low; less than a fifth of respondents reported prior knowledge. Perceptions of the six climate engineering methods proposed (three from the carbon dioxide removal group and three from the solar radiation modification group) were largely negative and frequently associated with attributes like 'risky', 'artificial' and 'unknown effects'. Carbon dioxide removal methods were preferred over solar radiation modification. Public perceptions were remarkably stable with only minor differences between the different countries in the surveys.<ref name=":13" /><ref name=":22">{{Cite journal |last1=Wright |first1=Malcolm J. |last2=Teagle |first2=Damon A. H. |last3=Feetham |first3=Pamela M. |date=February 2014 |title=A quantitative evaluation of the public response to climate engineering |url=https://www.nature.com/articles/nclimate2087 |url-status=live |journal=Nature Climate Change |language=en |volume=4 |issue=2 |pages=106–110 |bibcode=2014NatCC...4..106W |doi=10.1038/nclimate2087 |issn=1758-6798 |archive-url=https://web.archive.org/web/20200728153000/https://www.nature.com/articles/nclimate2087 |archive-date=2020-07-28 |access-date=2020-05-22}}</ref>
Techniques that do not remove [[greenhouse gases]] from the [[atmosphere]] may control [[global warming]], but do not reduce other effects from these gases, such as [[ocean acidification]].<ref>[http://infohost.nmt.edu/~chem/wingenter/Wingenter_PeECE_III_GRL_2007.pdf ]{{dead link|date=September 2012}}</ref> While not an argument against geoengineering ''per se'', this is an argument against reliance on geoengineering to the exclusion of greenhouse gas reduction.


Some environmental organizations (such as [[Friends of the Earth]] and [[Greenpeace]]) have been reluctant to endorse or oppose solar radiation modification, but are often more supportive of nature-based carbon dioxide removal projects, such as [[afforestation]] and [[peatland restoration]].<ref name="Extreme action guardian2" /><ref name="Geoengineering no solution2">{{cite news |last=Parr |first=Doug |date=1 September 2008 |title=Geo-engineering is no solution to climate change |work=Guardian Newspaper |location=London |url=https://www.theguardian.com/environment/2008/sep/01/climatechange.scienceofclimatechange1 |url-status=live |access-date=2009-05-23 |archive-url=https://web.archive.org/web/20180820234933/https://www.theguardian.com/environment/2008/sep/01/climatechange.scienceofclimatechange1 |archive-date=2018-08-20}}</ref>
===Control and predictability problems===
[[Image:Coccolithophore bloom.jpg|thumb|250px|right|The picture from space of a large natural accumulations of phytoplankton in the [[Bering Sea]]]]
The full effects of various geoengineering schemes are not well understood.<ref name="mongabay2007"/> Matthews et al.<ref>{{cite doi|10.1088/1748-9326/4/4/045105}}</ref> compared geoengineering to a number of previous environmental interventions and concluded that "Given our current level of understanding of the climate system, it is likely that the result of at least some geoengineering efforts would follow previous ecological examples where increased human intervention has led to an overall increase in negative environmental consequences."


==Research and projects ==
Performance of the systems may become ineffective, unpredictable or unstable as a result of external events, such as [[volcanic eruptions]], [[phytoplankton]] blooms, [[El Niño]], [[solar flares]], etc., potentially leading to profound and unpredictable disruption to the climate system.
Several organizations have investigated climate engineering with a view to evaluating its potential, including the [[US Congress]],<ref name="Bullis2">{{cite web |last=Bullis |first=Kevin |title=U.S. Congress Considers Geoengineering |url=http://www.technologyreview.com/view/416187/us-congress-considers-geoengineering/ |url-status=live |archive-url=https://web.archive.org/web/20130126213315/http://www.technologyreview.com/view/416187/us-congress-considers-geoengineering/ |archive-date=26 January 2013 |access-date=26 December 2012 |work=MIT Technology Review}}</ref> the US National Academy of Sciences, Engineering, and Medicine,<ref>{{Cite web |title=Climate Intervention Reports » Climate Change at the National Academies of Sciences, Engineering, and Medicine |url=https://nas-sites.org/americasclimatechoices/other-reports-on-climate-change/2015-2/climate-intervention-reports/ |url-status=live |archive-url=https://web.archive.org/web/20160729015758/http://nas-sites.org/americasclimatechoices/other-reports-on-climate-change/2015-2/climate-intervention-reports/ |archive-date=2016-07-29 |access-date=2015-11-02 |website=nas-sites.org}}</ref> the [[Royal Society]],<ref>{{cite press release |title=Stop emitting CO2 or geoengineering could be our only hope |url=http://royalsociety.org/Stop-emitting-CO2-or-geoengineering-could-be-our-only-hope/ |date=28 August 2009 |publisher=The Royal Society |access-date=14 June 2011 |archive-date=24 June 2011 |archive-url=https://web.archive.org/web/20110624054716/http://royalsociety.org/Stop-emitting-CO2-or-geoengineering-could-be-our-only-hope/ |url-status=live}}</ref> the [[UK Parliament]],<ref>{{cite web |date=March 2009 |title=Geo-engineering research |url=https://researchbriefings.files.parliament.uk/documents/POST-PN-327/POST-PN-327.pdf |access-date=2022-09-11 |work=Postnote |publisher=Parliamentary Office of Science and Technology}}</ref> the [[Institution of Mechanical Engineers]],<ref name="imeche092">{{cite web |title=Geo-engineering{{Snd}} Giving us the time to act? |url=http://www.imeche.org/Libraries/Key_Themes/IMechEGeoengineeringReport.sflb.ashx |url-status=dead |archive-url=https://web.archive.org/web/20110722191723/http://www.imeche.org/Libraries/Key_Themes/IMechEGeoengineeringReport.sflb.ashx |archive-date=2011-07-22 |access-date=2011-03-12 |publisher=I Mech E}}</ref> and the [[Intergovernmental Panel on Climate Change]].


In 2009, the Royal Society in the UK reviewed a wide range of proposed climate engineering methods and evaluated them in terms of effectiveness, affordability, timeliness, and safety (assigning [[Qualitative data|qualitative]] estimates in each assessment). The key recommendations reports were that "Parties to the [[UNFCCC]] should make increased efforts towards mitigating and adapting to climate change, and in particular to agreeing to global emissions reductions", and that "[nothing] now known about geoengineering options gives any reason to diminish these efforts".<ref name="Royal Society Policy Document2">{{cite report |url=http://royalsociety.org/uploadedFiles/Royal_Society_Content/policy/publications/2009/8693.pdf |title=Geoengineering the Climate: Science, Governance and Uncertainty |author=Working group |date=2009 |publisher=The Royal Society |location=London |page=1 |isbn=978-0-85403-773-5 |id=RS1636 |access-date=2011-12-01 |archive-url=https://web.archive.org/web/20140312031514/http://royalsociety.org/uploadedfiles/royal_society_content/policy/publications/2009/8693.pdf |archive-date=2014-03-12 |url-status=live}}</ref> Nonetheless, the report also recommended that "research and development of climate engineering options should be undertaken to investigate whether low-risk methods can be made available if it becomes necessary to reduce the rate of warming this century".<ref name="Royal Society Policy Document2" />
It may be difficult to predict the effectiveness of projects,<ref>Keith Bower et al., 2006 Computational assessment of a proposed technique for global warming mitigation via albedo-enhancement of marine stratocumulus clouds. Atmos. Res., vol. 82, no. 1-2, 2006, pp. 328–336</ref> with models of techniques giving widely varying results.<ref>http://royalsociety.org/page.asp?tip=1&id=6232</ref> In the instances of systems which involve [[tipping point (climatology)|tipping point]]s, this may result in irreversible effects. [[Climate modelling]] is far from an exact science even when applied to comparatively well-understood natural climate systems, and it is made more complex by the need to understand novel and unnatural processes which by definition lack relevant observation data.<ref>{{cite news| url=http://news.bbc.co.uk/1/hi/sci/tech/4762720.stm | work=[[BBC]] News | title=Guns and sunshades to rescue climate | date=2006-03-02 | accessdate=2010-03-30 | first=Molly | last=Bentley}}</ref>


In 2009, a review examined the scientific plausibility of proposed methods rather than the practical considerations such as engineering feasibility or economic cost. The authors found that "[air] capture and storage shows the greatest potential, combined with [[afforestation]], reforestation and bio-char production", and noted that "other suggestions that have received considerable media attention, in particular, "ocean pipes" appear to be ineffective".<ref name="lenton092">{{cite journal |last=Lenton |first=T.M. |author2=Vaughan, N.E. |year=2009 |title=The radiative forcing potential of different climate geoengineering options |url=http://www.atmos-chem-phys.net/9/5539/2009/acp-9-5539-2009.html |url-status=live |journal=[[Atmospheric Chemistry and Physics]] |volume=9 |issue=15 |pages=5539–5561 |bibcode=2009ACP.....9.5539L |doi=10.5194/acp-9-5539-2009 |archive-url=https://web.archive.org/web/20191214043800/https://www.atmos-chem-phys.net/9/5539/2009/acp-9-5539-2009.html |archive-date=2019-12-14 |access-date=2009-09-04 |doi-access=free}}</ref> They concluded that "[climate] geoengineering is best considered as a potential complement to the mitigation of {{co2}} emissions, rather than as an alternative to it".<ref name="lenton092" />
===Side effects===
The techniques themselves may cause significant foreseen or unforeseen harm. For example, the use of reflective [[balloons]] may result in significant [[litter]],<ref>{{cite web|url=http://books.nap.edu/openbook.php?record_id=1605&page=824 |title=Policy Implications of Greenhouse Warming: Mitigation, Adaptation, and the Science Base |publisher=Books.nap.edu |date= |accessdate=2012-09-06}}</ref> which may be harmful to [[wildlife]].


The IMechE report examined a small subset of proposed methods (air capture, urban albedo and algal-based {{co2}} capture techniques), and its main conclusions in 2011 were that climate engineering should be researched and trialed at the small scale alongside a wider [[decarbonization]] of the economy.<ref name="imeche092" />
[[Ozone depletion]] is a risk of some geoengineering techniques, notably those involving [[sulfur]] delivery into the [[stratosphere]].<ref>The Sensitivity of Polar Ozone Depletion to Proposed Geoengineering
Schemes", Science, vol. 320, no. 5880, 30 May 2008, pp. 1201–1204, {{doi|10.1126/science.1153966}}</ref>


In 2015, the US National Academy of Sciences, Engineering, and Medicine concluded a 21-month project to study the potential impacts, benefits, and costs of climate engineering. The differences between these two classes of climate engineering "led the committee to evaluate the two types of approaches separately in companion reports, a distinction it hopes carries over to future scientific and policy discussions."<ref name="www8.nationalacademies.org2">{{Cite press release |title=Climate Intervention Is Not a Replacement for Reducing Carbon Emissions; Proposed Intervention Techniques Not Ready for Wide-Scale Deployment |url=http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=02102015 |website=NEWS from the national academies |date=Feb 10, 2015 |access-date=2015-11-24 |archive-date=2015-11-17 |archive-url=https://web.archive.org/web/20151117032144/http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=02102015 |url-status=live}}</ref><ref name="Climate Intervention2">{{Cite book |author=National Research Council<!--|last2 = Impacts|first2 = Committee on Geoengineering Climate: Technical Evaluation Discussion of|last3 = Division On Earth And Life Studies|first3 = National Research Council (U.S.)|last4 = Ocean Studies Board|first4 = National Research Council (U.S.)|last5 = Climate|first5 = Board on Atmospheric Sciences--> |title=Climate Intervention: Reflecting Sunlight to Cool Earth |date=2017 |publisher=The National Academies Press |isbn=978-0-309-31482-4 |doi=10.17226/18988}} Ebook: {{ISBN|978-0-309-31485-5}}.</ref><ref>{{Cite book |author=National Research Council |url=https://www.nap.edu/catalog/18805/climate-intervention-carbon-dioxide-removal-and-reliable-sequestration |title=Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration |date=2015 |isbn=978-0-309-30529-7 |language=en |doi=10.17226/18805 |access-date=2018-08-20 |archive-url=https://web.archive.org/web/20180821031740/https://www.nap.edu/catalog/18805/climate-intervention-carbon-dioxide-removal-and-reliable-sequestration |archive-date=2018-08-21 |url-status=live}}</ref> The resulting study titled ''Climate Intervention'' was released in February 2015 and consists of two volumes: ''Reflecting Sunlight to Cool Earth''<ref name="Council2">{{Cite book |author=National Research Council |url=https://www.nap.edu/catalog/18988/climate-intervention-reflecting-sunlight-to-cool-earth |title=Climate Intervention: Reflecting Sunlight to Cool Earth |year=2015 |publisher=National Academies Press |isbn=978-0-309-31482-4 |language=en |access-date=2018-08-20 |archive-url=https://web.archive.org/web/20191214192318/http://www.nap.edu/catalog.php?record_id=18988 |archive-date=2019-12-14 |url-status=live}}</ref> and ''Carbon Dioxide Removal and Reliable Sequestration''.<ref>{{Cite book |author=National Research Council |url=https://www.nap.edu/catalog/18805/climate-intervention-carbon-dioxide-removal-and-reliable-sequestration |title=Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration |year=2015 |publisher=National Academies Press |isbn=978-0-309-30529-7 |language=en |access-date=2018-08-20 |archive-url=https://web.archive.org/web/20180821031740/https://www.nap.edu/catalog/18805/climate-intervention-carbon-dioxide-removal-and-reliable-sequestration |archive-date=2018-08-21 |url-status=live}}</ref>
The active nature of geoengineering may in some cases create a clear division between winners and losers. Most of the proposed interventions are regional, such as albedo modification in the [[Arctic]].<ref>{{cite web|url=http://www.newscientist.com/article/dn12397 |title='Sunshade' for global warming could cause drought - environment - 02 August 2007 |publisher=New Scientist |date=2007-08-02 |accessdate=2012-09-06}}</ref>


In June 2023 the US government released a report that recommended conducting research on stratospheric aerosol injection and marine cloud brightening.<ref>{{Cite web |last=Hanley |first=Steve |date=2023-07-03 |title=US & EU Quietly Begin To Discuss Geoengineering |url=https://cleantechnica.com/2023/07/03/us-eu-quietly-begin-to-discuss-geoengineering/ |access-date=2023-07-06 |website=CleanTechnica |language=en-US}}</ref>
There may be unintended climatic consequences, such as changes to the [[hydrological cycle]]<ref>{{cite web|url=http://www.sciencedaily.com/releases/2008/05/080527155519.htm |title=Geoengineering Could Slow Down Global Water Cycle |publisher=Sciencedaily.com |date=2008-05-28 |accessdate=2012-09-06}}</ref> including [[droughts]]<ref>I. M. Held et al., "Simulation of Sahel drought in the 20th and 21st centuries", Proceedings of the National Academy of Sciences, vol. 102, no. 50, pp. 17891–17896, {{doi|10.1073/pnas.0509057102}}. Available online at: http://climate.envsci.rutgers.edu/pdf/2008JD010050small.pdf</ref> or [[floods]], caused by the geoengineering techniques, but possibly not predicted by the [[climate modelling|models]] used to plan them.<ref>Keith Bower et al., 2006 Computational assessment of a proposed technique for global warming
mitigation via albedo-enhancement of marine stratocumulus clouds. Atmos. Res., vol. 82, no. 1-2, 2006, pp. 328–336</ref> Such effects may be cumulative or [[chaos theory|chaotic]] in nature, making prediction and control very difficult.<ref>{{cite web
| last = Robock
| first = Alan
| title = ''20 reasons why geoengineering may be a bad idea ''
| publisher = ''[http://www.thebulletin.org "Bulletin of the Atomic Scientists"]''
| date = May / June 2008
| url = http://thebulletin.metapress.com/content/r567g4063g1h562l/?p=a537203c8e7b4be3b0cd5cd51fa30b61&pi=5
| doi= 10.2968/064002006
| accessdate = 2009-08-04 }}</ref>


As of 2024 the Coastal Atmospheric Aerosol Research and Engagement (CAARE) project was launching [[sea salt]] into the marine sky in an effort to increase cloud "brightness" (reflective capacity). The sea salt is launched from the [[USS Hornet Sea, Air & Space Museum]] (based on the project's regulatory filings).<ref>{{Cite web |title=Marine Cloud Brightening Program studies clouds, aerosols and pathways to reduce climate risks |url=https://environment.uw.edu/news/2024/04/marine-cloud-brightening-program-studies-clouds-aerosols-and-pathways-to-reduce-climate-risks |access-date=2024-04-08 |website=College of the Environment |language=en-US}}</ref>
===Unreliable systems===
The performance of the interventions may be inconsistent due to mechanical failure, non-availability of consumables or funding problems.

The geoengineering techniques would, in many instances, be vulnerable to being switched off or deliberately destroyed. As examples, cloud making ships could be switched off or sunk and space mirrors could be tilted to make them useless. Anyone capable of exerting such power may seek to abuse it for commercial gain, military advantage or simple terrorism.

===Termination shock===
If [[solar radiation management]] were to abruptly stop, the climate would rapidly warm.<ref name="ReferenceB">{{cite doi|10.1088/1748-9326/4/4/045103}}</ref> This would cause a sudden rise in global temperatures towards levels which would have existed without the use of the geoengineering technique. The rapid rise in temperature may lead to more severe consequences than a gradual rise of the same magnitude.<ref name="ReferenceB"/>

===Weaponisation===
Geoengineering research began as a war tactic in the 1940s for the US and the [[Soviet Union]] during the [[Cold War]].<ref name = geoengineering_option/> During the Vietnam War, the US used geoengineering to flood certain areas. Then in 1976, 85 countries signed the U.N. Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques.<ref name = benefits_risks_costs/>

The [[Environmental Modification Convention]] generally prohibits weaponising geoengineering techniques. However, this does not eliminate the risk. Geoengineering techniques may serve as [[weapon of mass destruction|weapons of mass destruction]], creating droughts or famines designed to destroy or disable an enemy.<ref>{{cite web|url=http://www.foreignpolicy.com/story/cms.php?story_id=4146 |title=Battlefield Earth |publisher=Foreign Policy |date= |accessdate=2012-09-06}}</ref> They could also be used simply to make battlefield conditions more favourable to one side or the other in a war<ref>{{cite web|url=http://www.fas.org/spp/military/docops/usaf/2025/v3c15/v3c15-1.htm |title=AF2025 v3c15-1 &#124; Weather as a Force Multiplier: Owning... &#124; (Ch 1) |publisher=Fas.org |date= |accessdate=2012-09-06}}</ref> (such as in [[Operation Popeye]]). For example, [[laser-guided]] weapons are confounded by clouds, and thus switching off cloud machines would favour forces using such weapons, and switching them on would favour ground forces defending against them.<ref>{{cite web|url=http://www.fas.org/man/dod-101/sys/smart/lgb.htm |title=Laser Guided Bombs - Smart Weapons |publisher=Fas.org |date= |accessdate=2012-09-06}}</ref>

Whilst laws or treaties may prevent the manipulation of the climate as a weapon of war,<ref>http://www.state.gov/t/ac/trt/4783.htm</ref> it could be argued that geoengineering is itself a manipulation, and thus destroying or disabling the geoengineering structures is not prohibited. A new legal framework may be necessary in the event that large-scale geoengineering becomes established.{{Or|date=November 2010}}

[[Carnegie Institution for Science|Carnegie]]'s [[Ken Caldeira]] said, "It will make it harder to achieve broad consensus on developing and governing these technologies if there is suspicion that gaining military advantage is an underlying motivation for its development..."<ref>
{{cite web|url=http://groups.google.com/group/climateintervention/browse_thread/thread/60f448608e209134?pli=1|title=DARPA and Geoengineering|last=Caldiera|first=Ken|coauthors=Various|date=March 18, 2009|work=Climate Intervention [[Google Groups|Google group]]|accessdate=2009-03-21}}</ref>

===Effect on sunlight, sky and clouds===
Managing solar radiation using aerosols or cloud cover will change the ratio between direct and indirect solar radiation. This may affect plant life<ref>L. Gu et al., "Responses of Net Ecosystem Exchanges
of Carbon Dioxide to Changes in Cloudiness: Results from Two North American Deciduous Forests", Journal of Geophysical Research, vol. 104, no. 31, pp. 421–31, 434 (1999); L. Gu et al., "Advantages of Diffuse Radiation for Terrestrial Ecosystem Productivity", Journal of Geophysical Research, vol. 107, (2002); L. Gu et al., "Response of a Deciduous Forest to the Mount Pinatubo Eruption: Enhanced Photosynthesis", Science, vol. 299, pp. 2,035–38 (2003)</ref> and [[solar energy]].<ref>Balan Govindasamy and Ken Caldeira, "Geoengineering Earth's Radiation Balance to Mitigate CO2-Induced Climate Change", Geophysical Research Letters, vol. 27, pp. 2,141–44 (2000). For the response of solar power systems, see Michael C. MacCracken, "Geoengineering: Worthy of Cautious Evaluation?" Climatic Change, vol. 77, pp. 235–43 (2006)</ref> There will be a significant effect on the appearance of the [[sky]] from [[aerosol]] projects, notably a hazing of blue skies and a change in the appearance of [[sunset]]s.<ref>[http://www.nasa.gov/centers/langley/news/researchernews/rn_robockfeature.html NASA - Geoengineering: Why or Why Not?<!-- Bot generated title -->]</ref> Aerosols may affect the formation of clouds, especially [[cirrus cloud]]s.<ref>K. Sassen et al., ";The 5–6 December 1991 FIRE IFO II Jet Stream Cirrus Case Study: Possible Influences of Volcanic Aerosols", [[Journal of the Atmospheric Sciences]], vol. 52, pp. 97–123 (1993)</ref>

===Moral hazard===
The existence of such techniques may reduce the political and social impetus to reduce carbon emissions.<ref>David Adam, "Extreme and risky action the only way to tackle global warming, say scientists",
Guardian, 1 September 2008. Available online at: http://www.guardian.co.uk/environment/
2008/sep/01/climatechange.scienceofclimatechange2</ref> The problem of [[moral hazard]] in relation to geoengineering by academics, such as [[David Keith (scientist)|David W. Keith]]<ref>{{cite doi|10.1038/463426a}}</ref> and [[Martin Bunzl]].<ref>{{cite doi|10.1088/1748-9326/4/4/045104}}</ref> This issue has been researched in an in-depth study by [[Ipsos MORI]] for [[Natural Environment Research Council|NERC]]<ref>[[Ipsos MORI]] (for NERC) (2010) Experiment Earth? Report on a Public Dialogue on Geoengineering http://www.nerc.ac.uk/about/consult/geoengineering-dialogue-final-report.pdf</ref> The issue of moral hazard means that many environmental groups and campaigners are reluctant to advocate geoengineering for fear of reducing the imperative to cut [[greenhouse gas]] emissions.<ref name="Moral hazard">{{cite web|url=http://www.celsias.com/article/geo-engineering-a-moral-hazard/|title=Geo-Engineering – a Moral Hazard|date=14 November 2007|publisher=celsias.com|accessdate=9 September 2010}}</ref>

Other criticism comes from those who see geoengineering projects as reacting to the symptoms of global warming rather than addressing the [[Attribution of recent climate change|real causes of climate change]]. Because geoengineering is a form of controlling the risks associated with global warming, it leads to a [[moral hazard]] problem. The problem is that knowledge that geoengineering is possible could lead to climate impacts seeming less fearsome, which could in turn lead to an even weaker commitment to reducing greenhouse gas emissions.<ref>{{cite web|url=http://www.ted.com/index.php/talks/view/id/192|title=A surprising idea for solving climate change (lecture at TED conference)|author=David Keith|accessdate=2008-04-06}}</ref>

==Governance==
Geoengineering opens up various political and economic issues. [[David Keith (scientist)|David Keith]] argues that the cost of geoengineering the Earth is within the realm of small countries, large corporations, or even very wealthy individuals.<ref name=Keith2 /> Steve Rayner agrees that not all geoengineering possibilities are expensive, and that some, such as ocean iron fertilisation, are within the reach of very wealthy individuals, calling them a "Greenfinger" (after the fictional [[Auric Goldfinger|Goldfinger]]).<ref name="news.bbc.co.uk">{{cite news| url=http://news.bbc.co.uk/nol/shared/spl/hi/programmes/analysis/transcripts/31_07_08.txt | work=[[BBC News]] | accessdate=2010-03-30}}</ref><ref name=Randerson>{{cite news|url=http://www.guardian.co.uk/environment/2008/nov/18/climatechange-greentech|title=Geoengineering 'no substitute' for climate targets, UK minister warns|date=2008-11-18|work=[[The Guardian]] |author=James Randerson|publisher=Guardian News and Media Limited | location=London}}</ref> David Victor suggests that geoengineering is within the reach of any individual who has a small fraction of the bank account of [[Bill Gates]], who takes it upon him or her self to be the "self-appointed protector of the planet".<ref>{{cite journal|journal=[[Oxford Review of Economic Policy]]|year=2008|volume=24|issue=2|pages=322–336|doi=10.1093/oxrep/grn018|publisher=Oxford University Press|title=On the regulation of geoengineering|author=[[David G. Victor]]}}</ref>

This effectively eliminates any control over who gets to decide when to cool the Earth and how often this should be done.<ref name=Keith2>{{cite web|url=http://keith.seas.harvard.edu/papers/89.Keith.EngineeringThePlanet.e.pdf|format=PDF|title=Engineering the Planet|author=David Keith|accessdate=2008-04-08|pages="3–4,8"}}</ref> The resulting power would be enormous, and could not necessarily be readily controlled by legal, political or regulatory systems.<ref name="news.bbc.co.uk"/> These legal and regulatory systems may themselves be far less powerful than the geoengineers controlling the climate become.

It is quite feasible for [[carbon offsetting]] firms to set up unregulated, unsupervised and dangerous geoengineering projects. This may be done in order to sell [[carbon credits]] to individuals and firms.

Geoengineering schemes have the potential to cause significant [[environmental damage]], and may even end up releasing further [[greenhouse gases]] into the [[atmosphere]].<ref>[http://www.abc.net.au/science/articles/2007/11/09/2085584.htm Urea 'climate solution' may backfire › Analysis (ABC Science)<!-- Bot generated title -->]</ref> Opposition to some early schemes has been intense, with respected environmental groups campaigning against them.<ref>[http://www.worldwildlife.org/who/media/press/2007/WWFPresitem973.html News & Press | WWF<!-- Bot generated title -->]</ref>

There is presently a lack of a universally agreed framework for the regulation of either geoengineering activity or research. The [[London Dumping Convention]] addresses some aspects of the law in relation to [[List of proposed geoengineering schemes|biomass ocean storage]] and [[ocean fertilization]]. The [[Oxford Martin School]] at [[Oxford University]] has a programme to evaluate geoengineering [[governance]]. The 'Oxford Principles' have resulted from this work:
*Principle 1: Geoengineering to be regulated as a [[public good]].
*Principle 2: Public participation in geoengineering decision-making
*Principle 3: Disclosure of geoengineering research and [[open access publication|open publication]] of results
*Principle 4: Independent assessment of impacts
*Principle 5: Governance before deployment
These principles have been endorsed by the [[House of Commons of the United Kingdom]] Science and Technology [[Select Committee]] on “The Regulation of Geoengineering”,<ref>http://www.geoengineering.ox.ac.uk/oxford-principles/history/</ref> and have been referred to by authors discussing the issue of governance.<ref name="economist.com">http://www.economist.com/node/15814427</ref>

The [[Asilomar conference]] was replicated to deal with the issue of geoengineering governance,<ref name="economist.com"/> and covered in a [[TV documentary]], broadcast in Canada.

==Implementation issues==
There is no general consensus that geoengineering is safe, appropriate or effective, for the reasons listed above. Other [[environmentalists]] see calls for geoengineering as part of an explicit strategy to delay emissions reductions on the part of those with connections to [[coal]] and [[petroleum|oil]] industries.<ref>[http://www.worldchanging.com/archives//009753.html Worldchanging | Evaluation + Tools + Best Practices: Don't Wait for the Lifeboat: A Response to Geoengineering<!-- Bot generated title -->]</ref>{{Synthesis-inline|date=April 2011}}

All proposed geoengineering techniques require implementation on a relatively large scale, in order to make a significant difference to the Earth's climate. The least costly schemes are budgeted at a cost of millions,<ref>http://docs.google.com/gview?attid=0.1&thid=11e473ed2477ae05&a=v&pli=1</ref> with many more complex schemes such as [[space sunshade]] costing far more.

Many techniques, again such as space sunshade, require a complex technical development process before they are ready to be implemented. There is no clear institutional mechanism for handling this [[research and development]] process. As a result, many promising techniques do not have the engineering development or experimental evidence to determine their feasibility or efficacy at present.

Once a technique has been developed and tested, its implementation is still likely to be difficult. Climate change is by nature a global problem, and therefore no one institution, company or government is responsible for it. The substantial costs of most geoengineering techniques therefore cannot currently be apportioned. Roll-out of such technologies is therefore likely to be delayed until these issues can be resolved. A notable exception is the use of small [[albedo]] manipulation projects, known as ''cool roof'', in which the colour of roofing or paving surfaces can be manipulated to reflect solar radiation back into space. These can be, and are, implemented by individuals, companies and governments without controversy.<ref>[http://www.consumerenergycenter.org/coolroof/ Cool Roofs<!-- Bot generated title -->]</ref>

Due to the radical changes caused by geoengineering interventions, legal issues are also an impediment to implementation. The changes resulting from geoengineering necessarily benefit some people and disadvantage others. There may therefore be legal challenges to the implementation of geoengineering techniques by those adversely affected by them.<ref>[http://ieet.org/index.php/IEET/more/2094/ The Politics of Geoengineering<!-- Bot generated title -->]</ref>

==Evaluation of geoengineering==
Most of what is known about the suggested techniques is based on laboratory experiments, observations of natural phenomena and on [[computer modelling]] techniques. Some geoengineering schemes employ methods that have analogues in natural phenomena such as [[stratospheric sulfur aerosols]] and [[cloud condensation nuclei]]. As such, studies about the efficacy of these schemes can draw on information already available from other research, such as that following the 1991 [[volcanic eruption|eruption]] of [[Mount Pinatubo]]. However, comparative evaluation of the relative merits of each technology is complicated, especially given modelling uncertainties and the early stage of engineering development of many geoengineering schemes.<ref>http://www.imeche.org/media/Public+Affairs/geoenginq.htm</ref>

Reports into geoengineering have also been published in the [[United Kingdom]] by the [[Institution of Mechanical Engineers]]<ref name="imeche09"/> and the [[Royal Society]].<ref name="roysoc09"/> The IMechE report examined a small subset of proposed schemes (air capture, urban albedo and algal-based {{co2}} capture schemes), and its main conclusions were that geoengineering should be researched and trialled at the small scale alongside a wider [[decarbonisation]] of the economy.<ref name="imeche09"/>

The Royal Society review examined a wide range of geoengineering schemes and evaluated them in terms of effectiveness, affordability, timeliness and safety (assigning [[qualitative data|qualitative]] estimates in each assessment). Similarly to Lenton and Vaughan,<ref name="lenton09"/> the report divided schemes into "carbon dioxide removal" (CDR) and "solar radiation management" (SRM) approaches that respectively address longwave and shortwave radiation. The key recommendations of the report were that "Parties to the [[UNFCCC]] should make increased efforts towards mitigating and adapting to climate change, and in particular to agreeing to global emissions reductions", and that "[nothing] now known about geoengineering options gives any reason to diminish these efforts".<ref name="roysoc09"/> Nonetheless, the report also recommended that "research and development of geoengineering options should be undertaken to investigate whether low risk methods can be made available if it becomes necessary to reduce the rate of warming this century".<ref name="roysoc09"/>

In a 2009 review study, Lenton and Vaughan evaluated a range of geoengineering schemes from those that sequester {{co2}} from the atmosphere and decrease [[longwave radiation]] trapping, to those that decrease the Earth's receipt of [[shortwave radiation]].<ref name="lenton09"/> In order to permit a comparison of disparate techniques, they used a common evaluation for each scheme based on its effect on net radiative forcing. As such, the review examined the scientific plausibility of schemes rather than the practical considerations such as engineering feasibility or economic cost. Lenton and Vaughan found that "[air] capture and storage shows the greatest potential, combined with afforestation, reforestation and bio-char production", and noted that "other suggestions that have received considerable media attention, in particular "ocean pipes" appear to be ineffective".<ref name="lenton09"/> They concluded that "[climate] geoengineering is best considered as a potential complement to the mitigation of {{co2}} emissions, rather than as an alternative to it".<ref name="lenton09"/>


==See also==
==See also==
{{Portal|Environment|Sustainable development}}
{{Portal|Environment|Weather|Global warming}}
{{div col|colwidth=30em}}
{{Div col}}
* [[Arctic geoengineering]]
* [[Arctic geoengineering]]
* [[Carbon sink]]
* [[Climate justice]]
* [[Earth systems engineering and management]]
* [[Carbon negative fuel]]
* [[Carbon dioxide removal]]
* [[Land surface effects on climate]]
* [[Carbon sequestration]]
* [[Convention on Biological Diversity]]
* [[Five Ways to Save the World]]
* [[Haida Gwaii]]
* [[List of geoengineering topics]]
* [[List of geoengineering topics]]
* [[Macro-engineering]]
* [[Weather modification]]
{{Div col end}}
* [[Outline of geoengineering]]
{{Clear}}
* [[Solar radiation management]]
* [[Terraforming]]
* [[Virgin Earth Challenge]]
* [[Weather control]]
{{div col end}}


==References==
==References==
{{Reflist|2}}
{{Reflist}}


{{Climate change}}
==Further reading==
{{Human impact on the environment}}
*[http://www.environmentmagazine.org/Archives/Back%20Issues/2012/September-October%202012/geoengineering_abstract.html ''Soft Geoengineering: A Gentler Approach to Addressing Climate Change''] September/October 2012 Environment magazine
{{Engineering fields}}
* {{cite journal
{{Population}}
| journal= [[Nature (journal)|Nature]]
{{Authority control}}
| volume= 479
| page= 293
| year=2011
| month=November
| doi=10.1038/479293a
| title=Environmental Science: Good Governance for Geoengineering
| author1=Macnaghten, Phil
|author2=Owen, Richard
| pmid=22094673
| issue=7373
|bibcode = 2011Natur.479..293M }} – Abstract only {{Subscription required}}
* {{cite report
|url=http://royalsociety.org/uploadedFiles/Royal_Society_Content/policy/publications/2009/8693.pdf
| author=[[Royal Society]]
| year=2009
|month=September
| title=Geoengineering the Climate: Science, Governance and Uncertainty
|city=London, England
|format=PDF
|ISBN=978-0-85403-773-5
|number=RS Policy document 10/09
|page=1
|accessdate=2011-12-01}}
* {{cite report
|url=http://psych.cf.ac.uk/understandingrisk/docs/spice.pdf
| author=GAO
| year=2011
|month=July
|title=Climate Engineering: Technical Status, Future Directions, and Potential Responses
|number=GAO-11-71
|publisher=Center for Science, Technology, and Engineering
|format=PDF
|page=
|accessdate=2011-12-01}}
* {{cite book|title=Geo-Engineering Climate Change: Environmental Necessity or Pandora's Box?|
editor1-first=Brian|editor1-last=Launder|editor1-link=Brian Launder|editor2-first=J. Michael T. |editor2-last=Thompson|publisher=[[Cambridge University Press]]|date=December 2009|isbn=978-0-521-19803-5}}
* {{cite book|author=[[Eli Kintisch]]|year=2010|title=Hack the Planet: Science's Best Hope, or Worst Nightmare, for Averting Climate Catastrophe|isbn=978-0-470-52426-8}}
* {{cite book|author=Jeff Goodell|authorlink=Jeff Goodell|year=2010|title=How to Cool the Planet: Geoengineering and the Audacious Quest to Fix Earth's Climate|isbn=978-0-618-99061-0}}
* {{cite journal| journal= [[Nature (journal)|Nature]]| volume= 447| pages= 132–136| date=May 10, 2007 | doi=10.1038/447132a| title=Climate change: Is this what it takes to save the world?| first=Oliver| last= Morton| pmid= 17495899| issue= 7141|bibcode = 2007Natur.447..132M }} – Abstract only {{Subscription required}}
* {{cite book|author=[[James Rodger Fleming]]|publisher=[[Columbia University Press]]|date=September 15, 2010|title=Fixing the Sky: The Checkered History of Weather and Climate Control|isbn=978-0-231-14412-4}}
* [http://www.irgc.org/-Granger-Morgan-.html Granger Morgan], Katharine Ricke (2010). ''An Opinion Piece for [http://www.irgc.org IRGC]. Cooling the Earth Through Solar Radiation Management: The need for research and an approach to its governance.'' ISBN 978-2-9700672-8-3
*[http://green.blogs.nytimes.com/2012/03/12/if-cutting-carbon-emissions-isnt-working-whats-next If Cutting Carbon Emissions Isn't Working, What's Next?] March 2012 "Suck It Up" book review


[[Category:Climate engineering| ]]
==External links==
[[Category:Climate change|Engineering]]

[[Category:Climate change policy|Engineering]]
===Studies===
[[Category:Emissions reduction]]
* [[Royal Society]] [http://royalsociety.org/uploadedFiles/Royal_Society_Content/policy/publications/2009/8693.pdf "Geoengineering the Climate: Science, Governance and Uncertainty."] Report. ISBN 978-0-85403-773-5. September, 2009
[[Category:Engineering disciplines]]
* [http://www.climate-engineering.eu/ Climate Engineering] [[Kiel Earth Institute]] and Marsilius Kolleg of [[Heidelberg University]], since Sept 2011
* [http://www.washingtonpost.com/wp-srv/nation/pdfs/Geongineeringreport.pdf Engineering the Climate : Research Needs and Strategies for International Coordination October 2010 report] from the [[U.S. House of Representatives]]
*[http://www.kurzweilai.net/blocking-the-sun-study-looks-at-costs-of-6-geoengineering-schemes?utm_source=KurzweilAI+Daily+Newsletter&utm_campaign=01ee9bd702-UA-946742-1&utm_medium=email Cost evaluation study of 6 geoengineering schemes]{{verify credibility|date=September 2012}}

===Articles (newspapers and magazines)===
*[http://www.scientificamerican.com/article.cfm?id=geoengineering-last-chance-save-sea-ice ''Geoengineering may be our best chance to save what sea ice is left''] by Peter Wadhams [[Scientific American]] December 15, 2012
*[http://www.huffingtonpost.co.uk/jon-taylor/geoengineering-climate-change_b_1873231.html ''Geo-engineering - A Tool in the Fight to Tackle Climate Change, or a Dangerous Distraction?''] by Jon Taylor, Climate Change Programme Manager at [[World Wide Fund for Nature|WWF-UK]], September 11, 2012 [[Huffington Post]]
*[http://www.sciencenews.org/view/generic/id/342377/title/Field_test_stashes_climate-warming_carbon_in_deep_ocean ''Field test stashes climate-warming carbon in deep ocean; Strategically dumping metal puts greenhouse gas away, possibly for good''] July 18, 2012 [[Science News]]
*[http://www.vagabondjourney.com/geoengineering-interim-strategy-curb-global-warming-john-latham/ Geoengineering: An Interim strategy to curb global warming?] - An interview with John Latham
* [http://www.newscientist.com/article/dn19660-what-the-un-ban-on-geoengineering-really-means.html What the UN ban on geoengineering really means] November 1, 2010 by [[Fred Pearce]] of [[New Scientist]]
* [http://www.washingtonpost.com/wp-dyn/content/article/2010/10/29/AR2010102906361.html Geoengineering sparks international ban, first-ever congressional report] Juliet Eilperin [[Washington Post]] October 30, 2010
* [http://www.washingtonpost.com/wp-dyn/content/article/2010/10/03/AR2010100303437.html Threat of global warming sparks U.S. interest in geoengineering] by Juliet Eilperin of the Washington Post October 3, 2010
* [http://www.guardian.co.uk/environment/2010/sep/13/geoengineering-coalition-world-climate The powerful coalition that wants to engineer the world's climate: Businessmen, scientists and right-wing thinktanks are joining forces to promote 'geo-engineering' ideas to cool the planet's climate] [[Clive Hamilton]] [[The Guardian]], September 13, 2010
* [http://www.guardian.co.uk/environment/2010/may/14/bill-gates-cloud-whitening-dangerous Bill Gates' cloud-whitening trials 'a dangerous experiment'], [[The Guardian]], May 14, 2010 regarding [[Bill Gates]]
* [http://www.guardian.co.uk/environment/2010/apr/06/geoengineering-carbon-emissions We need birth control, not geoengineering], [[The Guardian]], April 6, 2010
* [http://www.technologyreview.com/energy/24157/ "The Geoengineering Gambit"], [[Technology Review]], Jan. 2010
* [http://www.theatlantic.com/magazine/archive/2009/07/re-engineering-the-earth/7552/ Re-Engineering the Earth] July 2009 [[The Atlantic]]
* [http://orgprints.org/15528/01/15528.pdf Geo-engineering in the Southern Ocean], by John Paull, [[Australian National University]], 2009
* [http://www.time.com/time/specials/2007/article/0,28804,1720049_1720050_1721653,00.html 10 Ideas That Are Changing The World: 6.Geoengineering] [[Time (magazine)]], March 2008
* [http://www.worldchanging.com/archives/008364.html Geoengineering Retrospective] Overview of articles on geoengineering by Julia Levitt, [[Worldchanging]], August 2008
* [http://news.bbc.co.uk/2/hi/programmes/6354759.stm "Futuristic fleet of 'cloudseeders'"] John Latham [[BBC News]]. Feb. 15, 2007
* [http://geo-engineering.blogspot.com/ Geo-engineering website, describing current methods/proposals done to revert climate change by geo-engineering], by Sam Carana
* [http://www.wired.com/science/planetearth/news/2007/07/geoengineering Climate Engineering Is Doable, as Long as We Never Stop] [[Wired (magazine)]], July 2007
* [http://www.geocrisis.com/cpe_geoengineering_menu.htm Geoengineering links], [[GeoCrisis]] annotated list, 2006?
* [http://www.openthefuture.com/wcarchive/2005/08/terraforming_earth_iv_the_ques.html Terraforming Earth IV: The Question of Methane] August 11, 2005 [[Jamais Cascio]]
* [http://www.npr.org/templates/story/story.php?storyId=127245606 Geoengineering: 'A Bad Idea Whose Time Has Come'] discussion on [[NPR]]
* [http://www.metatronics.net/lit/geo2.html "Geoengineering: A Climate Change Manhattan Project"] by Jay Michaelson, Stanford Environmental Law Journal, 1998

===Videos (documentaries, interviews, video reports) ===
* [http://www.democracynow.org/2010/7/8/a_debate_on_geoengineering_vandana_shiva A Debate on Geoengineering: Vandana Shiva vs. Gwynne Dyer] – video report by ''[[Democracy Now!]]''
* [http://news.bbc.co.uk/1/hi/programmes/6298507.stm 5 ways to save the earth], BBC documentary about geo-engineering, 20 February 2007
* [http://fora.tv/2010/11/07/Wonderfest_2010_Dare_We_Try_to_Engineer_Earths_Climate Wonderfest 2010: Dare We Try to Engineer Earth's Climate?], Speakers: Julio Friedmann, Jane C.S. Long, Location: Stanley Hall, Berkeley (CA), 11 July 2010
* [[Project Earth (TV series)]] on geoengineering

[[Category:Global warming]]
[[Category:Planetary engineering]]
[[Category:Planetary engineering]]
[[Category:Emissions reduction]]
[[Category:Geoengineering| ]]

Latest revision as of 10:04, 10 December 2024

Climate engineering (or geoengineering, climate intervention[1]) is the intentional large-scale alteration of the planetary environment to counteract anthropogenic climate change.[2][3] The term has been used as an umbrella term for both carbon dioxide removal and solar radiation modification when applied at a planetary scale.[4]: 168  However, these two processes have very different characteristics, and are now often discussed separately.[4]: 168 [5] Carbon dioxide removal techniques remove carbon dioxide from the atmosphere, and are part of climate change mitigation. Solar radiation modification is the reflection of some sunlight (solar radiation) back to space to cool the earth.[6] Some publications include passive radiative cooling as a climate engineering technology. The media tends to also use climate engineering for other technologies such as glacier stabilization, ocean liming, and iron fertilization of oceans. The latter would modify carbon sequestration processes that take place in oceans.

Some types of climate engineering are highly controversial due to the large uncertainties around effectiveness, side effects and unforeseen consequences.[7] Interventions at large scale run a greater risk of unintended disruptions of natural systems, resulting in a dilemma that such disruptions might be more damaging than the climate damage that they offset.[8] However, the risks of such interventions must be seen in the context of the trajectory of climate change without them.[9][8][10]

The Union of Concerned Scientists warns that solar radiation modification could become an excuse to slow reductions in fossil fuel emissions and stall progress toward a low-carbon economy, as the technology does not address these root causes of climate change.[11]

Terminology

[edit]

Climate engineering (or geoengineering) has been used as an umbrella term for both carbon dioxide removal and solar radiation management, when applied at a planetary scale.[4]: 168  However, these two methods have very different geophysical characteristics, which is why the Intergovernmental Panel on Climate Change no longer uses this term.[4]: 168 [5] This decision was communicated in around 2018, see for example the Special Report on Global Warming of 1.5 °C.[12]: 550 

According to climate economist Gernot Wagner the term geoengineering is "largely an artefact and a result of the term's frequent use in popular discourse" and "so vague and all-encompassing as to have lost much meaning".[7]: 14 

Specific technologies that fall into the climate engineering umbrella term include:[13]: 30 

The following methods are not termed climate engineering in the latest IPCC assessment report in 2022[4]: 6–11  but are included under this umbrella term by other publications on this topic:[25][7]

Technologies

[edit]

Carbon dioxide removal

[edit]
Planting trees is a nature-based way to remove carbon dioxide from the atmosphere, however the effect may only be temporary in some cases.[35][36]

Carbon dioxide removal (CDR) is a process in which carbon dioxide (CO2) is removed from the atmosphere by deliberate human activities and durably stored in geological, terrestrial, or ocean reservoirs, or in products.[37]: 2221  This process is also known as carbon removal, greenhouse gas removal or negative emissions. CDR is more and more often integrated into climate policy, as an element of climate change mitigation strategies.[38][39] Achieving net zero emissions will require first and foremost deep and sustained cuts in emissions, and then—in addition—the use of CDR ("CDR is what puts the net into net zero emissions"[40]). In the future, CDR may be able to counterbalance emissions that are technically difficult to eliminate, such as some agricultural and industrial emissions.[41]: 114 

CDR includes methods that are implemented on land or in aquatic systems. Land-based methods include afforestation, reforestation, agricultural practices that sequester carbon in soils (carbon farming), bioenergy with carbon capture and storage (BECCS), and direct air capture combined with storage.[41][42] There are also CDR methods that use oceans and other water bodies. Those are called ocean fertilization, ocean alkalinity enhancement,[43] wetland restoration and blue carbon approaches.[41] A detailed analysis needs to be performed to assess how much negative emissions a particular process achieves. This analysis includes life cycle analysis and "monitoring, reporting, and verification" (MRV) of the entire process.[44] Carbon capture and storage (CCS) are not regarded as CDR because CCS does not reduce the amount of Carbon dioxide in Earth's atmosphere|carbon dioxide already in the atmosphere]].

Solar radiation modification

[edit]
refer to caption and image description
Proposed solar radiation modification using a tethered balloon to inject sulfate aerosols into the stratosphere

Solar radiation modification or solar radiation management (SRM), also known as solar geoengineering, are planetary-scale approaches to limit global warming by reducing the greenhouse effect, the atmospheric trapping of outgoing thermal radiation that would leave Earth to outer space. SRM includes mainly methods of increasing the reflection of incoming sunlight (solar radiation) by the atmosphere back to space. Among the multiple potential approaches, stratospheric aerosol injection (SAI) is the most-studied,[45]: 350  followed by marine cloud brightening (MCB). SRM also includes ground-based albedo modification (GBAM).[45]: 348  Space-based concepts, such as space sunshades and space mirrors, are not currently included in the IPCC Sixth Assessment Report as a relevant option.[46] SRM is a form of climate engineering. It could be a supplement but would not be a substitute to the main climate change mitigation measures,[46] reducing greenhouse gas emissions and removing greenhouse gases from the atmosphere.

Scientific studies, based on evidence from climate models, have generally shown that some forms of SRM could in theory reduce global warming and therefore many effects of climate change.[47][48][49] However, because warming from greenhouse gases and cooling from SRM would operate differently across latitudes and seasons, a world where global warming would be offset by SRM would have a different climate from one where this warming did not occur in the first place. Furthermore, confidence in the current projections of how SRM would affect regional climate and ecosystems is low.[46] SRM would therefore pose environmental risks.

Passive daytime radiative cooling

[edit]

Enhancing the solar reflectance and thermal emissivity of Earth in the atmospheric window through passive daytime radiative cooling has been proposed as an alternative or "third approach" to climate engineering[26][50] that is "less intrusive" and more predictable or reversible than stratospheric aerosol injection.[51]

PDRC can lower temperatures with zero energy consumption or pollution by radiating heat into outer space. Widespread application has been proposed as a solution to global warming.[52]
Passive daytime radiative cooling (PDRC) (also passive radiative cooling, daytime passive radiative cooling, radiative sky cooling, photonic radiative cooling, and terrestrial radiative cooling[53][54][55][56]) is the use of unpowered, reflective/thermally-emissive surfaces to lower the temperature of a building or other object.[57] It has been proposed as a method of reducing temperature increases caused by greenhouse gases by reducing the energy needed for air conditioning, [58][59] lowering the urban heat island effect,[60][61] and lowering human body temperatures.[62][52][63][64][58]
Video to explain some of the marine geoengineering approaches with a focus on their risks, negative impacts and potential side-effects, as well as on the question of governance of these technologies.

Ocean geoengineering

[edit]

Ocean geoengineering involves modifying the ocean to reduce the impacts of rising temperature. One approach is to add material such as lime or iron to the ocean to increase its ability to support marine life and/or sequester CO
2
. In 2021 the US National Academies of Sciences, Engineering, and Medicine (NASEM) requested $2.5 billion funds for research in the following decade, specifically including field tests.[34]

Another idea is to reduce sea level rise by installing underwater "curtains" to protect Antarctic glaciers from warming waters, or by drilling holes in ice to pump out water and heat.[65]

Ocean liming

[edit]

Enriching seawater with calcium hydroxide (lime) has been reported to lower ocean acidity, which reduces pressure on marine life such as oysters and absorbs CO
2
. The added lime raised the water's pH, capturing CO
2
in the form of calcium bicarbonate or as carbonate deposited in mollusk shells. Lime is produced in volume for the cement industry.[34] This was assessed in 2022 in an experiment in Apalachicola, Florida in an attempt to halt declining oyster populations. pH levels increased modestly, as CO
2
was reduced by 70 ppm.[34]

A 2014 experiment added sodium hydroxide (lye) to part of Australia's Great Barrier Reef. It raised pH levels to nearly preindustrial levels.[34]

However, producing alkaline materials typically releases large amounts of CO
2
, partially offsetting the sequestration. Alkaline additives become diluted and dispersed in one month, without durable effects, such that if necessary, the program could be ended without leaving long-term effects.[34]

Ocean sulfur cycle enhancement

[edit]

Enhancing the natural marine sulfur cycle by fertilizing a small portion with iron—typically considered to be a greenhouse gas remediation method—may also increase the reflection of sunlight.[66][67] Such fertilization, especially in the Southern Ocean, would enhance dimethyl sulfide production and consequently cloud reflectivity. This could potentially be used as regional SRM, to slow Antarctic ice from melting.[citation needed] Such techniques also tend to sequester carbon, but the enhancement of cloud albedo also appears to be a likely effect.

Iron fertilization

[edit]
Iron fertilization is the intentional introduction of iron-containing compounds (like iron sulfate) to iron-poor areas of the ocean surface to stimulate phytoplankton production. This is intended to enhance biological productivity and/or accelerate carbon dioxide (CO2) sequestration from the atmosphere. Iron is a trace element necessary for photosynthesis in plants. It is highly insoluble in sea water and in a variety of locations is the limiting nutrient for phytoplankton growth. Large algal blooms can be created by supplying iron to iron-deficient ocean waters. These blooms can nourish other organisms.

Submarine forest

[edit]

Another 2022 experiment attempted to sequester carbon using giant kelp planted off the Namibian coast.[34] Whilst this approach has been called ocean geoengineering by the researchers it is just another form of carbon dioxide removal via sequestration. Another term that is used to describe this process is blue carbon management and also marine geoengineering.

Glacier stabilization

[edit]
A proposed "underwater sill" blocking 50% of warm water flows heading for the glacier could have the potential to delay its collapse and the resultant sea level rise by many centuries.[30]

Some engineering interventions have been proposed for Thwaites Glacier and the nearby Pine Island Glacier to physically stabilize its ice or to preserve it. These interventions would block the flow of warm ocean water, which currently renders the collapse of these two glaciers practically inevitable even without further warming.[68][69] A proposal from 2018 included building sills at the Thwaites' grounding line to either physically reinforce it, or to block some fraction of warm water flow. The former would be the simplest intervention, yet equivalent to "the largest civil engineering projects that humanity has ever attempted". It is also only 30% likely to work. Constructions blocking even 50% of the warm water flow are expected to be far more effective, yet far more difficult as well.[70] Some researchers argued that this proposal could be ineffective, or even accelerate sea level rise.[71] The authors of the original proposal suggested attempting this intervention on smaller sites, like the Jakobshavn Glacier in Greenland, as a test.[70][69] They also acknowledged that this intervention cannot prevent sea level rise from the increased ocean heat content, and would be ineffective in the long run without greenhouse gas emission reductions.[70]

In 2023, it was proposed that an installation of underwater curtains, made of a flexible material and anchored to the Amundsen Sea floor would be able to interrupt warm water flow. This approach would reduce costs and increase the longevity of the material (conservatively estimated at 25 years for curtain elements and up to 100 years for the foundations) relative to more rigid structures. With them in place, Thwaites Ice Shelf and Pine Island Ice Shelf would presumably regrow to a state they last had a century ago, thus stabilizing these glaciers.[72][73][69] To achieve this, the curtains would have to be placed at a depth of around 600 metres (0.37 miles) (to avoid damage from icebergs which would be regularly drifting above) and be 80 km (50 mi) long. The authors acknowledged that while work on this scale would be unprecedented and face many challenges in the Antarctic (including polar night and the currently insufficient numbers of specialized polar ships and underwater vessels), it would also not require any new technology and there is already experience of laying down pipelines at such depths.[72][73]

Problems

[edit]

Interventions at large scale run a greater risk of unintended disruptions of natural systems, resulting in a dilemma that such disruptions might be more damaging than the climate damage that they offset.[8]

Ethical aspects

[edit]

Climate engineering may reduce the urgency of reducing carbon emissions, a form of moral hazard.[74] Also, most efforts have only temporary effects, which implies rapid rebound if they are not sustained.[75] The Union of Concerned Scientists points to the danger that the use of climate engineering technology will become an excuse not to address the root causes of climate change, slow our emissions reductions and start moving toward a low-carbon economy.[11] However, several public opinion surveys and focus groups reported either a desire to increase emission cuts in the presence of climate engineering, or no effect.[76][77][78] Other modelling work suggests that the prospect of climate engineering may in fact increase the likelihood of emissions reduction.[79][80][81][82]

If climate engineering can alter the climate, then this raises questions whether humans have the right to deliberately change the climate, and under what conditions. For example, using climate engineering to stabilize temperatures is not the same as doing so to optimize the climate for some other purpose. Some religious traditions express views on the relationship between humans and their surroundings that encourage (to conduct responsible stewardship) or discourage (to avoid hubris) explicit actions to affect climate.[83]

Society and culture

[edit]

Public perception

[edit]

A large 2018 study used an online survey to investigate public perceptions of six climate engineering methods in the United States, United Kingdom, Australia, and New Zealand.[13] Public awareness of climate engineering was low; less than a fifth of respondents reported prior knowledge. Perceptions of the six climate engineering methods proposed (three from the carbon dioxide removal group and three from the solar radiation modification group) were largely negative and frequently associated with attributes like 'risky', 'artificial' and 'unknown effects'. Carbon dioxide removal methods were preferred over solar radiation modification. Public perceptions were remarkably stable with only minor differences between the different countries in the surveys.[13][84]

Some environmental organizations (such as Friends of the Earth and Greenpeace) have been reluctant to endorse or oppose solar radiation modification, but are often more supportive of nature-based carbon dioxide removal projects, such as afforestation and peatland restoration.[74][85]

Research and projects

[edit]

Several organizations have investigated climate engineering with a view to evaluating its potential, including the US Congress,[86] the US National Academy of Sciences, Engineering, and Medicine,[87] the Royal Society,[88] the UK Parliament,[89] the Institution of Mechanical Engineers,[90] and the Intergovernmental Panel on Climate Change.

In 2009, the Royal Society in the UK reviewed a wide range of proposed climate engineering methods and evaluated them in terms of effectiveness, affordability, timeliness, and safety (assigning qualitative estimates in each assessment). The key recommendations reports were that "Parties to the UNFCCC should make increased efforts towards mitigating and adapting to climate change, and in particular to agreeing to global emissions reductions", and that "[nothing] now known about geoengineering options gives any reason to diminish these efforts".[91] Nonetheless, the report also recommended that "research and development of climate engineering options should be undertaken to investigate whether low-risk methods can be made available if it becomes necessary to reduce the rate of warming this century".[91]

In 2009, a review examined the scientific plausibility of proposed methods rather than the practical considerations such as engineering feasibility or economic cost. The authors found that "[air] capture and storage shows the greatest potential, combined with afforestation, reforestation and bio-char production", and noted that "other suggestions that have received considerable media attention, in particular, "ocean pipes" appear to be ineffective".[92] They concluded that "[climate] geoengineering is best considered as a potential complement to the mitigation of CO2 emissions, rather than as an alternative to it".[92]

The IMechE report examined a small subset of proposed methods (air capture, urban albedo and algal-based CO2 capture techniques), and its main conclusions in 2011 were that climate engineering should be researched and trialed at the small scale alongside a wider decarbonization of the economy.[90]

In 2015, the US National Academy of Sciences, Engineering, and Medicine concluded a 21-month project to study the potential impacts, benefits, and costs of climate engineering. The differences between these two classes of climate engineering "led the committee to evaluate the two types of approaches separately in companion reports, a distinction it hopes carries over to future scientific and policy discussions."[93][94][95] The resulting study titled Climate Intervention was released in February 2015 and consists of two volumes: Reflecting Sunlight to Cool Earth[96] and Carbon Dioxide Removal and Reliable Sequestration.[97]

In June 2023 the US government released a report that recommended conducting research on stratospheric aerosol injection and marine cloud brightening.[98]

As of 2024 the Coastal Atmospheric Aerosol Research and Engagement (CAARE) project was launching sea salt into the marine sky in an effort to increase cloud "brightness" (reflective capacity). The sea salt is launched from the USS Hornet Sea, Air & Space Museum (based on the project's regulatory filings).[99]

See also

[edit]

References

[edit]
  1. ^ "Research to Inform Decisions about Climate Intervention". www.wcrp-climate.org. Retrieved 2024-12-10.
  2. ^ Shepherd, John (2009). Geoengineering the climate: science, governance and uncertainty. Royal Society of London. p. 1. ISBN 978-0-85403-773-5. Retrieved 2024-10-28. {{cite book}}: |website= ignored (help)
  3. ^ Union of Concerned Scientists (6 November 2017). "What is Climate Engineering?". www.ucsusa.org. Retrieved 2024-10-28.{{cite web}}: CS1 maint: date and year (link)
  4. ^ a b c d e IPCC (2022) Chapter 1: Introduction and Framing in Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA
  5. ^ a b IPCC, 2021: Annex VII: Glossary [Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. Masson-Delmotte, C.  Méndez, S. Semenov, A. Reisinger (eds.)]. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 2215–2256, doi:10.1017/9781009157896.022.
  6. ^ National Academies of Sciences, Engineering (2021-03-25). Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. doi:10.17226/25762. ISBN 978-0-309-67605-2. S2CID 234327299. Archived from the original on 2021-04-17. Retrieved 2021-04-17.
  7. ^ a b c Gernot Wagner (2021). Geoengineering: the Gamble.
  8. ^ a b c Matthias Honegger; Axel Michaelowa; Sonja Butzengeiger-Geyer (2012). Climate Engineering – Avoiding Pandora's Box through Research and Governance (PDF). FNI Climate Policy Perspectives. Fridtjof Nansen Institute (FNI), Perspectives. Archived from the original (PDF) on 2015-09-06. Retrieved 2018-10-09.
  9. ^ Trakimavicius, Lukas. "Playing God with climate: the EU's geoengineering conundrum". EUISS.
  10. ^ Zahra Hirji (October 6, 2016). "Removing CO2 From the Air Only Hope for Fixing Climate Change, New Study Says; Without 'negative emissions' to help return atmospheric CO2 to 350 ppm, future generations could face costs that 'may become too heavy to bear,' paper says". insideclimatenews.org. InsideClimate News. Archived from the original on November 17, 2019. Retrieved October 7, 2016.
  11. ^ a b "What Is Solar Geoengineering?". The Union of Concerned Scientists. Dec 4, 2020.
  12. ^ Global Warming of 1.5°C: IPCC Special Report on impacts of global warming of 1.5°C above pre-industrial levels in context of strengthening response to climate change, sustainable development, and efforts to eradicate poverty (1 ed.). Cambridge University Press. 2022. doi:10.1017/9781009157940.008. ISBN 978-1-009-15794-0.
  13. ^ a b c Carlisle, Daniel P.; Feetham, Pamela M.; Wright, Malcolm J.; Teagle, Damon A. H. (2020-04-12). "The public remain uninformed and wary of climate engineering" (PDF). Climatic Change. 160 (2): 303–322. Bibcode:2020ClCh..160..303C. doi:10.1007/s10584-020-02706-5. ISSN 1573-1480. S2CID 215731777. Archived (PDF) from the original on 2021-06-14. Retrieved 2021-05-18.
  14. ^ Dominic Woolf; James E. Amonette; F. Alayne Street-Perrott; Johannes Lehmann; Stephen Joseph (August 2010). "Sustainable biochar to mitigate global climate change". Nature Communications. 1 (5): 56. Bibcode:2010NatCo...1...56W. doi:10.1038/ncomms1053. ISSN 2041-1723. PMC 2964457. PMID 20975722.
  15. ^ Obersteiner, M. (2001). "Managing Climate Risk". Science. 294 (5543): 786–7. doi:10.1126/science.294.5543.786b. PMID 11681318. S2CID 34722068.
  16. ^ "Guest post: How 'enhanced weathering' could slow climate change and boost crop yields". Carbon Brief. 2018-02-19. Archived from the original on 2021-09-08. Retrieved 2021-11-03.
  17. ^ Committee on Geoengineering Climate: Technical Evaluation and Discussion of Impacts; Board on Atmospheric Sciences and Climate; Ocean Studies Board; Division on Earth and Life Studies; National Research Council (2015). Climate Intervention: Reflecting Sunlight to Cool Earth. National Academies Press. ISBN 978-0-309-31482-4. Archived from the original on 2019-12-14. Retrieved 2016-10-21.
  18. ^ Oberth, Hermann (1984) [1923]. Die Rakete zu den Planetenräumen (in German). Michaels-Verlag Germany. pp. 87–88.
  19. ^ Oberth, Hermann (1970) [1929]. ways to spaceflight. NASA. pp. 177–506. Retrieved 21 December 2017 – via archiv.org.
  20. ^ Oberth, Hermann (1957). Menschen im Weltraum (in German). Econ Duesseldorf Germany. pp. 125–182.
  21. ^ Oberth, Hermann (1978). Der Weltraumspiegel (in German). Kriterion Bucharest.
  22. ^ Kaufman, Rachel (August 8, 2012). "Could Space Mirrors Stop Global Warming?". Live Science. Retrieved 2019-11-08.
  23. ^ Sánchez, Joan-Pau; McInnes, Colin R. (2015-08-26). "Optimal Sunshade Configurations for Space-Based Geoengineering near the Sun-Earth L1 Point". PLOS ONE. 10 (8): e0136648. Bibcode:2015PLoSO..1036648S. doi:10.1371/journal.pone.0136648. ISSN 1932-6203. PMC 4550401. PMID 26309047.
  24. ^ Crutzen, P. J. (2006). "Albedo Enhancement by Stratospheric Sulfur Injections: A Contribution to Resolve a Policy Dilemma?". Climatic Change. 77 (3–4): 211–220. Bibcode:2006ClCh...77..211C. doi:10.1007/s10584-006-9101-y.
  25. ^ "Chapter 2 : Land–Climate interactions: Special Report on Climate Change and Land". Retrieved 2023-10-20.
  26. ^ a b Zevenhovena, Ron; Fält, Martin (June 2018). "Radiative cooling through the atmospheric window: A third, less intrusive geoengineering approach". Energy. 152: 27. Bibcode:2018Ene...152...27Z. doi:10.1016/j.energy.2018.03.084 – via Elsevier Science Direct. An alternative, third geoengineering approach would be enhanced cooling by thermal radiation from the Earth's surface into space.
  27. ^ Wang, Tong; Wu, Yi; Shi, Lan; Hu, Xinhua; Chen, Min; Wu, Limin (2021). "A structural polymer for highly efficient all-day passive radiative cooling". Nature Communications. 12 (365): 365. doi:10.1038/s41467-020-20646-7. PMC 7809060. PMID 33446648. One possibly alternative approach is passive radiative cooling—a sky-facing surface on the Earth spontaneously cools by radiating heat to the ultracold outer space through the atmosphere's longwave infrared (LWIR) transparency window (λ ~ 8–13 μm).
  28. ^ Chen, Meijie; Pang, Dan; Chen, Xingyu; Yan, Hongjie; Yang, Yuan (2022). "Passive daytime radiative cooling: Fundamentals, material designs, and applications". EcoMat. 4. doi:10.1002/eom2.12153. S2CID 240331557. Passive daytime radiative cooling dissipates terrestrial heat to the extremely cold outer space without using any energy input or producing pollution. It has the potential to simultaneously alleviate the two major problems of energy crisis and global warming.
  29. ^ Wang, Zhuosen; Schaaf, Crystal B.; Sun, Qingsong; Kim, JiHyun; Erb, Angela M.; Gao, Feng; Román, Miguel O.; Yang, Yun; Petroy, Shelley; Taylor, Jeffrey R.; Masek, Jeffrey G.; Morisette, Jeffrey T.; Zhang, Xiaoyang; Papuga, Shirley A. (2017-07-01). "Monitoring land surface albedo and vegetation dynamics using high spatial and temporal resolution synthetic time series from Landsat and the MODIS BRDF/NBAR/albedo product". International Journal of Applied Earth Observation and Geoinformation. 59: 104–117. Bibcode:2017IJAEO..59..104W. doi:10.1016/j.jag.2017.03.008. ISSN 1569-8432. PMC 7641169. PMID 33154713.
  30. ^ a b Wolovick, Michael J.; Moore, John C. (20 September 2018). "Stopping the flood: could we use targeted geoengineering to mitigate sea level rise?". The Cryosphere. 12 (9): 2955–2967. Bibcode:2018TCry...12.2955W. doi:10.5194/tc-12-2955-2018.
  31. ^ Wolovick, Michael; Moore, John; Keefer, Bowie (27 March 2023). "Feasibility of ice sheet conservation using seabed anchored curtains". PNAS Nexus. 2 (3): pgad053. doi:10.1093/pnasnexus/pgad053. PMC 10062297. PMID 37007716.
  32. ^ Wolovick, Michael; Moore, John; Keefer, Bowie (27 March 2023). "The potential for stabilizing Amundsen Sea glaciers via underwater curtains". PNAS Nexus. 2 (4): pgad103. doi:10.1093/pnasnexus/pgad103. PMC 10118300. PMID 37091546.
  33. ^ "The radical intervention that might save the "doomsday" glacier". MIT Technology Review. Retrieved 2022-01-14.
  34. ^ a b c d e f g Voosen, Paul (16 December 2022). "Ocean geoengineering scheme aces its first field test". www.science.org. Retrieved 2022-12-19.
  35. ^ Buis, Alan (November 7, 2019). "Examining the Viability of Planting Trees to Help Mitigate Climate Change". Climate Change: Vital Signs of the Planet. Retrieved 2023-04-13.
  36. ^ Marshall, Michael (26 May 2020). "Planting trees doesn't always help with climate change". BBC. Retrieved 2023-04-13.
  37. ^ IPCC, 2021: "Annex VII: Glossary". Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. Masson-Delmotte, C. Méndez, S. Semenov, A. Reisinger (eds.). In "Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change". Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 2215–2256, doi:10.1017/9781009157896.022
  38. ^ Schenuit, Felix; Colvin, Rebecca; Fridahl, Mathias; McMullin, Barry; Reisinger, Andy; Sanchez, Daniel L.; Smith, Stephen M.; Torvanger, Asbjørn; Wreford, Anita; Geden, Oliver (2021-03-04). "Carbon Dioxide Removal Policy in the Making: Assessing Developments in 9 OECD Cases". Frontiers in Climate. 3: 638805. doi:10.3389/fclim.2021.638805. hdl:1885/270309. ISSN 2624-9553.
  39. ^ Geden, Oliver (May 2016). "An actionable climate target". Nature Geoscience. 9 (5): 340–342. Bibcode:2016NatGe...9..340G. doi:10.1038/ngeo2699. ISSN 1752-0908. Archived from the original on May 25, 2021. Retrieved March 7, 2021.
  40. ^ Ho, David T. (2023-04-04). "Carbon dioxide removal is not a current climate solution — we need to change the narrative". Nature. 616 (7955): 9. Bibcode:2023Natur.616....9H. doi:10.1038/d41586-023-00953-x. ISSN 0028-0836. PMID 37016122. S2CID 257915220.
  41. ^ a b c M. Pathak, R. Slade, P.R. Shukla, J. Skea, R. Pichs-Madruga, D. Ürge-Vorsatz,2022: Technical Summary. In: Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [P.R. Shukla, J. Skea, R. Slade, A. Al Khourdajie, R. van Diemen, D. McCollum, M. Pathak, S. Some, P. Vyas, R. Fradera, M. Belkacemi, A. Hasija, G. Lisboa, S. Luz, J. Malley, (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA. doi: 10.1017/9781009157926.002.
  42. ^ Rackley, Steve; Andrews, Graham; Clery, Diarmaid; De Richter, Renaud; Dowson, George; Knops, Pol; Li, We; Mccord, Stephen; Ming, Tingzhen; Sewel, Adrienne; Styring, Peter; Tyka, Michael (2023). Negative Emissions Technologies for Climate Change Mitigation. Elsevier. ISBN 978-0-12-819663-2.
  43. ^ Lebling, Katie; Northrop, Eliza; McCormick, Colin; Bridgwater, Liz (November 15, 2022), "Toward Responsible and Informed Ocean-Based Carbon Dioxide Removal: Research and Governance Priorities" (PDF), World Resources Institute: 11, doi:10.46830/wrirpt.21.00090, S2CID 253561039
  44. ^ Schenuit, Felix; Gidden, Matthew J.; Boettcher, Miranda; Brutschin, Elina; Fyson, Claire; Gasser, Thomas; Geden, Oliver; Lamb, William F.; Mace, M. J.; Minx, Jan; Riahi, Keywan (2023-10-03). "Secure robust carbon dioxide removal policy through credible certification". Communications Earth & Environment. 4 (1): 349. Bibcode:2023ComEE...4..349S. doi:10.1038/s43247-023-01014-x. ISSN 2662-4435.
  45. ^ a b de Coninck, H., A. Revi, M. Babiker, P. Bertoldi, M. Buckeridge, A. Cartwright, W. Dong, J. Ford, S. Fuss, J.-C. Hourcade, D. Ley, R. Mechler, P. Newman, A. Revokatova, S. Schultz, L. Steg, and T. Sugiyama, 2018: Strengthening and Implementing the Global Response. In: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [MassonDelmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. In Press. Pg. 348.
  46. ^ a b c Trisos, Christopher H.; Geden, Oliver; Seneviratne, Sonia I.; Sugiyama, Masahiro; van Aalst, Maarten; Bala, Govindasamy; Mach, Katharine J.; Ginzburg, Veronika; de Coninck, Heleen; Patt, Anthony. "Cross-Working Group Box SRM: Solar Radiation Modification" (PDF). Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press. pp. 221–222. doi:10.1017/9781009325844.004. In Climate Change 2022: Impacts, Adaptation and Vulnerability [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke,V. Möller, A. Okem, B. Rama (eds.)].
  47. ^ Intergovernmental Panel on Climate Change (IPCC) (2023-07-06). Climate Change 2021 – The Physical Science Basis: Working Group I Contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (1 ed.). Cambridge University Press. doi:10.1017/9781009157896.006. ISBN 978-1-009-15789-6.
  48. ^ UNEP (2023). "One Atmosphere: An Independent Expert Review on Solar Radiation Modification Research and Deployment". UNEP - UN Environment Programme. Retrieved 2024-03-09.
  49. ^ World Meteorological Organization (WMO) (2022). Scientific Assessment of Ozone Depletion: 2022. Geneva: WMO. ISBN 978-9914-733-99-0.
  50. ^ Wang, Tong; Wu, Yi; Shi, Lan; Hu, Xinhua; Chen, Min; Wu, Limin (2021). "A structural polymer for highly efficient all-day passive radiative cooling". Nature Communications. 12 (365): 365. doi:10.1038/s41467-020-20646-7. PMC 7809060. PMID 33446648. One possibly alternative approach is passive radiative cooling—a sky-facing surface on the Earth spontaneously cools by radiating heat to the ultracold outer space through the atmosphere's longwave infrared (LWIR) transparency window (λ ~ 8–13 μm).
  51. ^ Munday, Jeremy (2019). "Tackling Climate Change through Radiative Cooling". Joule. 3 (9): 2057–2060. Bibcode:2019Joule...3.2057M. doi:10.1016/j.joule.2019.07.010. S2CID 201590290. A reduction in solar absorption is usually proposed through the injection of reflective aerosols into the atmosphere; however, serious concerns have been raised regarding side effects of these forms of geoengineering and our ability to undo any of the climatic changes we create.
  52. ^ a b Chen, Meijie; Pang, Dan; Chen, Xingyu; Yan, Hongjie; Yang, Yuan (2022). "Passive daytime radiative cooling: Fundamentals, material designs, and applications". EcoMat. 4. doi:10.1002/eom2.12153. S2CID 240331557. Passive daytime radiative cooling (PDRC) dissipates terrestrial heat to the extremely cold outer space without using any energy input or producing pollution. It has the potential to simultaneously alleviate the two major problems of energy crisis and global warming.
  53. ^ Wang, Tong; Wu, Yi; Shi, Lan; Hu, Xinhua; Chen, Min; Wu, Limin (2021). "A structural polymer for highly efficient all-day passive radiative cooling". Nature Communications. 12 (365): 365. doi:10.1038/s41467-020-20646-7. PMC 7809060. PMID 33446648. Accordingly, designing and fabricating efficient PDRC with sufficiently high solar reflectance (𝜌¯solar) (λ ~ 0.3–2.5 μm) to minimize solar heat gain and simultaneously strong LWIR thermal emittance (ε¯LWIR) to maximize radiative heat loss is highly desirable. When the incoming radiative heat from the Sun is balanced by the outgoing radiative heat emission, the temperature of the Earth can reach its steady state.
  54. ^ Zevenhovena, Ron; Fält, Martin (June 2018). "Radiative cooling through the atmospheric window: A third, less intrusive geoengineering approach". Energy. 152: 27. Bibcode:2018Ene...152...27Z. doi:10.1016/j.energy.2018.03.084. S2CID 116318678 – via Elsevier Science Direct. An alternative, third geoengineering approach would be enhanced cooling by thermal radiation from the Earth's surface into space." [...] "With 100 W m2 as a demonstrated passive cooling effect, a surface coverage of 0.3% would then be needed, or 1% of Earth's land mass surface. If half of it would be installed in urban, built areas which cover roughly 3% of the Earth's land mass, a 17% coverage would be needed there, with the remainder being installed in rural areas.
  55. ^ Heo, Se-Yeon; Ju Lee, Gil; Song, Young Min (June 2022). "Heat-shedding with photonic structures: radiative cooling and its potential". Journal of Materials Chemistry C. 10 (27): 9915–9937. doi:10.1039/D2TC00318J. S2CID 249695930 – via Royal Society of Chemistry.
  56. ^ Aili, Ablimit; Yin, Xiaobo; Yang, Ronggui (October 2021). "Global Radiative Sky Cooling Potential Adjusted for Population Density and Cooling Demand". Atmosphere. 12 (11): 1379. Bibcode:2021Atmos..12.1379A. doi:10.3390/atmos12111379.
  57. ^ Chen, Jianheng; Lu, Lin; Gong, Quan (June 2021). "A new study on passive radiative sky cooling resource maps of China". Energy Conversion and Management. 237: 114132. Bibcode:2021ECM...23714132C. doi:10.1016/j.enconman.2021.114132. S2CID 234839652 – via Elsevier Science Direct. Passive radiative cooling utilizes atmospheric transparency window (8–13 μm) to discharge heat into outer space and inhibits solar absorption.
  58. ^ a b Bijarniya, Jay Prakash; Sarkar, Jahar; Maiti, Pralay (November 2020). "Review on passive daytime radiative cooling: Fundamentals, recent researches, challenges and opportunities". Renewable and Sustainable Energy Reviews. 133: 110263. Bibcode:2020RSERv.13310263B. doi:10.1016/j.rser.2020.110263. S2CID 224874019 – via Elsevier Science Direct.
  59. ^ Benmoussa, Youssef; Ezziani, Maria; Djire, All-Fousseni; Amine, Zaynab; Khaldoun, Asmae; Limami, Houssame (September 2022). "Simulation of an energy-efficient cool roof with cellulose-based daytime radiative cooling material". Materials Today: Proceedings. 72: 3632–3637. doi:10.1016/j.matpr.2022.08.411. S2CID 252136357 – via Elsevier Science Direct.
  60. ^ Khan, Ansar; Carlosena, Laura; Feng, Jie; Khorat, Samiran; Khatun, Rupali; Doan, Quang-Van; Santamouris, Mattheos (January 2022). "Optically Modulated Passive Broadband Daytime Radiative Cooling Materials Can Cool Cities in Summer and Heat Cities in Winter". Sustainability. 14 (3): 1110. Bibcode:2022Sust...14.1110K. doi:10.3390/su14031110. hdl:2454/46738.
  61. ^ Anand, Jyothis; Sailor, David J.; Baniassadi, Amir (February 2021). "The relative role of solar reflectance and thermal emittance for passive daytime radiative cooling technologies applied to rooftops". Sustainable Cities and Society. 65: 102612. Bibcode:2021SusCS..6502612A. doi:10.1016/j.scs.2020.102612. S2CID 229476136 – via Elsevier Science Direct.
  62. ^ Liang, Jun; Wu, Jiawei; Guo, Jun; Li, Huagen; Zhou, Xianjun; Liang, Sheng; Qiu, Cheng-Wei; Tao, Guangming (September 2022). "Radiative cooling for passive thermal management towards sustainable carbon neutrality". National Science Review. 10 (1): nwac208. doi:10.1093/nsr/nwac208. PMC 9843130. PMID 36684522.
  63. ^ Munday, Jeremy (2019). "Tackling Climate Change through Radiative Cooling". Joule. 3 (9): 2057–2060. Bibcode:2019Joule...3.2057M. doi:10.1016/j.joule.2019.07.010. S2CID 201590290. By covering the Earth with a small fraction of thermally emitting materials, the heat flow away from the Earth can be increased, and the net radiative flux can be reduced to zero (or even made negative), thus stabilizing (or cooling) the Earth.
  64. ^ Yin, Xiaobo; Yang, Ronggui; Tan, Gang; Fan, Shanhui (November 2020). "Terrestrial radiative cooling: Using the cold universe as a renewable and sustainable energy source". Science. 370 (6518): 786–791. Bibcode:2020Sci...370..786Y. doi:10.1126/science.abb0971. PMID 33184205. S2CID 226308213. ...terrestrial radiative cooling has emerged as a promising solution for mitigating urban heat islands and for potentially fighting against global warming if it can be implemented at a large scale.
  65. ^ Richter, Hannah (12 July 2024). "To avoid sea level rise, some researchers want to build barriers around the world's most vulnerable glaciers". Science magazine.
  66. ^ Wingenter, Oliver W.; Haase, Karl B.; Strutton, Peter; Friederich, Gernot; Meinardi, Simone; Blake, Donald R.; Rowland, F. Sherwood (8 June 2004). "Changing concentrations of CO, CH4, C5H8, CH3Br, CH3I, and dimethyl sulfide during the Southern Ocean Iron Enrichment Experiments". Proceedings of the National Academy of Sciences of the United States of America. 101 (23): 8537–8541. Bibcode:2004PNAS..101.8537W. doi:10.1073/pnas.0402744101. ISSN 0027-8424. PMC 423229. PMID 15173582.
  67. ^ Wingenter, Oliver W.; Elliot, Scott M.; Blake, Donald R. (November 2007). "New Directions: Enhancing the natural sulfur cycle to slow global warming". Atmospheric Environment. 41 (34): 7373–5. Bibcode:2007AtmEn..41.7373W. doi:10.1016/j.atmosenv.2007.07.021. S2CID 43279436. Archived from the original on 13 August 2020. Retrieved 18 September 2020.
  68. ^ Joughin, I. (16 May 2014). "Marine Ice Sheet Collapse Potentially Under Way for the Thwaites Glacier Basin, West Antarctica". Science. 344 (6185): 735–738. Bibcode:2014Sci...344..735J. doi:10.1126/science.1249055. PMID 24821948. S2CID 206554077.
  69. ^ a b c Temple, James (14 January 2022). "The radical intervention that might save the "doomsday" glacier". MIT Technology Review. Retrieved 19 July 2023.
  70. ^ a b c Wolovick, Michael J.; Moore, John C. (20 September 2018). "Stopping the flood: could we use targeted geoengineering to mitigate sea level rise?". The Cryosphere. 12 (9): 2955–2967. Bibcode:2018TCry...12.2955W. doi:10.5194/tc-12-2955-2018. S2CID 52969664.
  71. ^ Moon, Twila A. (25 April 2018). "Geoengineering might speed glacier melt". Nature. 556 (7702): 436. Bibcode:2018Natur.556R.436M. doi:10.1038/d41586-018-04897-5. PMID 29695853.
  72. ^ a b Wolovick, Michael; Moore, John; Keefer, Bowie (27 March 2023). "Feasibility of ice sheet conservation using seabed anchored curtains". PNAS Nexus. 2 (3): pgad053. doi:10.1093/pnasnexus/pgad053. PMC 10062297. PMID 37007716.
  73. ^ a b Wolovick, Michael; Moore, John; Keefer, Bowie (27 March 2023). "The potential for stabilizing Amundsen Sea glaciers via underwater curtains". PNAS Nexus. 2 (4): pgad103. doi:10.1093/pnasnexus/pgad103. PMC 10118300. PMID 37091546.
  74. ^ a b Adam, David (1 September 2008). "Extreme and risky action the only way to tackle global warming, say scientists". The Guardian. Archived from the original on 2019-08-06. Retrieved 2009-05-23.
  75. ^ "Geoengineering". International Risk Governance Council. 2009. Archived from the original on 2009-12-03. Retrieved 2009-10-07.
  76. ^ Kahan, Dan M.; Jenkins-Smith, Hank; Tarantola, Tor; Silva, Carol L.; Braman, Donald (2015-03-01). "Geoengineering and Climate Change Polarization Testing a Two-Channel Model of Science Communication". The Annals of the American Academy of Political and Social Science. 658 (1): 192–222. doi:10.1177/0002716214559002. ISSN 0002-7162. S2CID 149147565.
  77. ^ Wibeck, Victoria; Hansson, Anders; Anshelm, Jonas (2015-05-01). "Questioning the technological fix to climate change – Lay sense-making of geoengineering in Sweden". Energy Research & Social Science. 7: 23–30. Bibcode:2015ERSS....7...23W. doi:10.1016/j.erss.2015.03.001.
  78. ^ Merk, Christine; Pönitzsch, Gert; Kniebes, Carola; Rehdanz, Katrin; Schmidt, Ulrich (2015-02-10). "Exploring public perceptions of stratospheric sulfate injection". Climatic Change. 130 (2): 299–312. Bibcode:2015ClCh..130..299M. doi:10.1007/s10584-014-1317-7. ISSN 0165-0009. S2CID 154196324.
  79. ^ Reynolds, Jesse (2015-08-01). "A critical examination of the climate engineering moral hazard and risk compensation concern". The Anthropocene Review. 2 (2): 174–191. Bibcode:2015AntRv...2..174R. doi:10.1177/2053019614554304. ISSN 2053-0196. S2CID 59407485.
  80. ^ Morrow, David R. (2014-12-28). "Ethical aspects of the mitigation obstruction argument against climate engineering research". Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 372 (2031): 20140062. Bibcode:2014RSPTA.37240062M. doi:10.1098/rsta.2014.0062. ISSN 1364-503X. PMID 25404676.
  81. ^ Urpelainen, Johannes (2012-02-10). "Geoengineering and global warming: a strategic perspective". International Environmental Agreements: Politics, Law and Economics. 12 (4): 375–389. Bibcode:2012IEAPL..12..375U. doi:10.1007/s10784-012-9167-0. ISSN 1567-9764. S2CID 154422202.
  82. ^ Moreno-Cruz, Juan B. (2015-08-01). "Mitigation and the geoengineering threat". Resource and Energy Economics. 41: 248–263. Bibcode:2015REEco..41..248M. doi:10.1016/j.reseneeco.2015.06.001. hdl:1853/44254.
  83. ^ Clingerman, F.; O'Brien, K. (2014). "Playing God: why religion belongs in the climate engineering debate". Bulletin of the Atomic Scientists. 70 (3): 27–37. Bibcode:2014BuAtS..70c..27C. doi:10.1177/0096340214531181. S2CID 143742343.
  84. ^ Wright, Malcolm J.; Teagle, Damon A. H.; Feetham, Pamela M. (February 2014). "A quantitative evaluation of the public response to climate engineering". Nature Climate Change. 4 (2): 106–110. Bibcode:2014NatCC...4..106W. doi:10.1038/nclimate2087. ISSN 1758-6798. Archived from the original on 2020-07-28. Retrieved 2020-05-22.
  85. ^ Parr, Doug (1 September 2008). "Geo-engineering is no solution to climate change". Guardian Newspaper. London. Archived from the original on 2018-08-20. Retrieved 2009-05-23.
  86. ^ Bullis, Kevin. "U.S. Congress Considers Geoengineering". MIT Technology Review. Archived from the original on 26 January 2013. Retrieved 26 December 2012.
  87. ^ "Climate Intervention Reports » Climate Change at the National Academies of Sciences, Engineering, and Medicine". nas-sites.org. Archived from the original on 2016-07-29. Retrieved 2015-11-02.
  88. ^ "Stop emitting CO2 or geoengineering could be our only hope" (Press release). The Royal Society. 28 August 2009. Archived from the original on 24 June 2011. Retrieved 14 June 2011.
  89. ^ "Geo-engineering research" (PDF). Postnote. Parliamentary Office of Science and Technology. March 2009. Retrieved 2022-09-11.
  90. ^ a b "Geo-engineering – Giving us the time to act?". I Mech E. Archived from the original on 2011-07-22. Retrieved 2011-03-12.
  91. ^ a b Working group (2009). Geoengineering the Climate: Science, Governance and Uncertainty (PDF) (Report). London: The Royal Society. p. 1. ISBN 978-0-85403-773-5. RS1636. Archived (PDF) from the original on 2014-03-12. Retrieved 2011-12-01.
  92. ^ a b Lenton, T.M.; Vaughan, N.E. (2009). "The radiative forcing potential of different climate geoengineering options". Atmospheric Chemistry and Physics. 9 (15): 5539–5561. Bibcode:2009ACP.....9.5539L. doi:10.5194/acp-9-5539-2009. Archived from the original on 2019-12-14. Retrieved 2009-09-04.
  93. ^ "Climate Intervention Is Not a Replacement for Reducing Carbon Emissions; Proposed Intervention Techniques Not Ready for Wide-Scale Deployment". NEWS from the national academies (Press release). Feb 10, 2015. Archived from the original on 2015-11-17. Retrieved 2015-11-24.
  94. ^ National Research Council (2017). Climate Intervention: Reflecting Sunlight to Cool Earth. The National Academies Press. doi:10.17226/18988. ISBN 978-0-309-31482-4. Ebook: ISBN 978-0-309-31485-5.
  95. ^ National Research Council (2015). Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration. doi:10.17226/18805. ISBN 978-0-309-30529-7. Archived from the original on 2018-08-21. Retrieved 2018-08-20.
  96. ^ National Research Council (2015). Climate Intervention: Reflecting Sunlight to Cool Earth. National Academies Press. ISBN 978-0-309-31482-4. Archived from the original on 2019-12-14. Retrieved 2018-08-20.
  97. ^ National Research Council (2015). Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration. National Academies Press. ISBN 978-0-309-30529-7. Archived from the original on 2018-08-21. Retrieved 2018-08-20.
  98. ^ Hanley, Steve (2023-07-03). "US & EU Quietly Begin To Discuss Geoengineering". CleanTechnica. Retrieved 2023-07-06.
  99. ^ "Marine Cloud Brightening Program studies clouds, aerosols and pathways to reduce climate risks". College of the Environment. Retrieved 2024-04-08.