Antarctica cooling controversy: Difference between revisions
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#REDIRECT [[Climate change in Antarctica#Temperature and weather changes]] {{R from merge}} {{R to section}} |
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{{short description|Part of the public debate in the global warming controversy}} |
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[[File:Antarctic surface trends.jpg|thumb|300px|right|Antarctic surface temperature trends.<ref name="SteigSchneider2009">{{cite journal| doi = 10.1038/nature07669| last1 = Steig | first1 = E. J.| last2 = Schneider | first2 = D. P.| last3 = Rutherford | first3 = S. D.| last4 = Mann | first4 = M. E.| last5 = Comiso | first5 = J. C.| last6 = Shindell | first6 = D. T.| date = 2009| title = Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year| journal = [[Nature (journal)|Nature]]| volume = 457| issue = 7228| pages = 459–462| pmid = 19158794|bibcode = 2009Natur.457..459S | s2cid = 4410477 | url = https://docs.rwu.edu/fcas_fp/313 }}</ref> Red represents areas where temperatures have increased the most during the last 50 years, particularly in West Antarctica. The temperature trends are given in °C/decade. Credit: [[Eric Steig]], University of Washington, with NASA/GSFC Scientific Visualization Studio.]] |
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The '''Antarctica cooling controversy''' was the result of an apparent contradiction in the observed cooling behavior of [[Antarctica]] between 1966 and 2000, which became part of the public debate in the [[global warming controversy]], particularly between advocacy groups of both sides in the public arena<ref name=Spotts2002>{{cite news|url=http://www.csmonitor.com/2002/0118/p02s01-usgn.html|title=Guess what? Antarctica's getting colder, not warmer|author=Peter N. Spotts |work=[[The Christian Science Monitor]]|date=2002-01-18|access-date=2013-04-13}}</ref> including politicians,<ref name=Senate2006>{{cite web|url=http://epw.senate.gov/speechitem.cfm?party=rep&id=264027|title=America Reacts To Speech Debunking Media Global Warming Alarmism|publisher=U.S. Senate Committee on Environment and Public Works|date=2006-09-28|access-date=2013-04-13|url-status=dead|archive-url=https://web.archive.org/web/20130305155142/http://epw.senate.gov/speechitem.cfm?party=rep&id=264027|archive-date=2013-03-05}}</ref> as well as the popular media.<ref>{{cite news |last=Davidson |first=Keay |date=4 February 2002 |title=Media goofed on Antarctic data / Global warming interpretation irks scientists |work=[[San Francisco Chronicle]] |url=http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2002/02/04/MN159039.DTL |access-date=13 April 2013}}</ref><ref>{{cite news |author=Bijal P. Trivedi |date=25 January 2002 |title=Antarctica Gives Mixed Signals on Warming |work=[[National Geographic (magazine)|National Geographic]] |url=http://news.nationalgeographic.com/news/2002/01/0125_020125_antarcticaclimate.html |access-date=13 April 2013}}</ref> In contrast to the popular press, there is no similar controversy within the scientific community,<ref name="keay2013">{{cite news |last=Davidson |first=Keay |date=2002-02-04 |title=Media goofed on Antarctic data / Global warming interpretation irks scientists |work=[[San Francisco Chronicle]] |url=http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2002/02/04/MN159039.DTL |access-date=2013-04-13}}</ref> as the small observed changes in Antarctica are consistent with the small changes predicted by climate models, and because the overall trend since comprehensive observations began is now known to be one of warming. Observations unambiguously show the [[Antarctic Peninsula]] to be warming. The trends elsewhere show both warming and cooling but are smaller and dependent on season and the timespan over which the trend is computed.<ref>{{cite journal |vauthors=Chapman WL, Walsh JE |year=2007 |title=A Synthesis of Antarctic Temperatures |journal=Journal of Climate |volume=20 |issue=16 |pages=4096–4117 |bibcode=2007JCli...20.4096C |doi=10.1175/JCLI4236.1 |doi-access=free}}</ref> |
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A study released in 2009, combined historical weather station data with satellite measurements to deduce past temperatures over large regions of the continent, and these temperatures indicate an overall warming trend. One of the paper's authors stated, "We now see warming is taking place on all seven of the earth's continents in accord with what models predict as a response to greenhouse gases."<ref>{{Cite news |author=Kenneth Chang |date=21 January 2009 |title=Warming in Antarctica Looks Certain |newspaper=The New York Times |url=https://www.nytimes.com/2009/01/22/science/earth/22climate.html?ref=science |url-status=live |access-date=13 April 2013 |archive-url=https://web.archive.org/web/20141113191509/http://www.nytimes.com/2009/01/22/science/earth/22climate.html?ref=science |archive-date=13 November 2014}}</ref> According to 2011 paper by Ding, et al., "The Pacific sector of Antarctica, including both the Antarctic Peninsula and continental West Antarctica, has experienced substantial warming in the past 30 years."<ref>{{cite journal |last=Ding |first=Qinghua |author2=Eric J. Steig |author3=David S. Battisti |author4=Marcel Küttel |date=10 April 2011 |title=Winter warming in West Antarctica caused by central tropical Pacific warming |journal=Nature Geoscience |volume=4 |issue=6 |pages=398–403 |bibcode=2011NatGe...4..398D |citeseerx=10.1.1.459.8689 |doi=10.1038/ngeo1129}}</ref><ref>{{cite news |date=16 January 2002 |title=Antarctic cooling pushing life closer to the edge |work=[[USA Today]] |url=https://www.usatoday.com/news/science/cold-science/2002-01-13-antarctic-cooling.htm |access-date=13 April 2013}}</ref> |
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This controversy began with the misinterpretation of the results of a 2002 paper by Doran et al.,<ref name="Doran022">{{cite journal |author=Doran PT |author2=Priscu JC |author3=Lyons WB |last4=Walsh |first4=John E. |last5=Fountain |first5=Andrew G. |last6=McKnight |first6=Diane M. |last7=Moorhead |first7=Daryl L. |last8=Virginia |first8=Ross A. |last9=Wall |first9=Diana H. |last10=D. |first10=Gary |last11=H. |first11=Christian |display-authors=3 |date=January 2002 |title=Antarctic climate cooling and terrestrial ecosystem response |url=http://www.uic.edu/classes/geol/eaes102/Doran.pdf |journal=Nature |volume=415 |issue=6871 |pages=517–20 |doi=10.1038/nature710 |pmid=11793010 |s2cid=387284 |archive-url=https://web.archive.org/web/20041211081457/http://www.uic.edu/classes/geol/eaes102/Doran.pdf |archive-date=11 December 2004}}</ref><ref>{{cite journal |author=Doran |display-authors=etal |date=13 January 2002 |title=Antarctic climate cooling and terrestrial ecosystem response |url=http://www.montana.edu/lkbonney/DOCS/Publications/DoranEtAl2002ClimteCooling.pdf |url-status=dead |journal=Nature |publisher=[[University of Illinois at Chicago]] |volume=415 |issue=6871 |pages=517–20 |doi=10.1038/nature710 |pmid=11793010 |s2cid=387284 |archive-url=https://wayback.archive-it.org/all/20120712222502/http://www.montana.edu/lkbonney/DOCS/Publications/DoranEtAl2002ClimteCooling.pdf |archive-date=12 July 2012 |access-date=13 April 2013}} PDF version: advance online publication Letters to Science (archived original)</ref> which found "Although previous reports suggest slight recent continental warming, our spatial analysis of Antarctic meteorological data demonstrates a net cooling on the Antarctic continent between 1966 and 2000, particularly during summer and autumn."<ref name="Doran022" /> In his novel ''[[State of Fear]]'', [[Michael Crichton]] asserted that the Antarctic data contradicted global warming.<ref name="State_of_Fear" /> The few scientists who have commented on the supposed controversy state that there is no contradiction,<ref name="RealClim" /> while the author of the paper whose work inspired Crichton's remarks has said that Crichton misused his results.<ref name="DoranNYT">{{Cite news| url=https://www.nytimes.com/2006/07/27/opinion/27doran.html | author=Peter Doran |title=Cold, Hard Facts |newspaper=[[The New York Times]] | date=2006-07-27 | access-date=2008-08-14 | archive-url= https://web.archive.org/web/20090411124340/http://www.nytimes.com/2006/07/27/opinion/27doran.html| archive-date=April 11, 2009| url-status= live}}</ref> |
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==Background== |
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[[File:Antarctic_Temperature_Trend_1981-2007.jpg|thumb|Antarctic Skin (the roughly top millimeter of land, sea, snow, or ice) temperature trends between 1981 and 2007, based on thermal infrared observations made by a series of NOAA satellite sensors; note that they do not necessarily reflect air temperature trends.]] |
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Changes in the average temperature of the Antarctic continent have been the subject of various measurements. The trend differs at different locations on the continent.<ref name="keay2013" /> These trends have been labelled as "contradictory" in some accounts.<ref>{{cite news| url=http://www.cnn.com/2002/TECH/science/01/25/antarctica.hot.cold/index.html | publisher=[[CNN]] | title=Scientific winds blow hot and cold in Antarctica | date=2002-01-25 | access-date=2013-04-13}}</ref><ref>{{cite news| url=https://www.nytimes.com/2002/04/02/science/melting-freezing-antarctica-deciphering-contradictory-climate-patterns-largely.html?pagewanted=all&src=pm| work=[[The New York Times]] | title=The Melting (Freezing) of Antarctica; Deciphering Contradictory Climate Patterns Is Largely a Matter of Ice | first=Kenneth | last=Chang | date=2002-04-02 | access-date=2013-04-13}}</ref><ref>{{cite news|url=http://news.nationalgeographic.com/news/2002/01/0125_020125_antarcticaclimate.html|title=Antarctica Gives Mixed Signals on Warming|author=Bijal P. Trivedi|work=[[National Geographic (magazine)|National Geographic]]|date=2002-01-25|access-date=2013-04-13}}</ref> |
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Observations unambiguously show the [[Antarctic Peninsula]] to be warming. Some trends elsewhere on the [[Antarctica|continent]] have shown cooling,<ref>{{cite news| url=https://www.telegraph.co.uk/science/science-news/3289934/Antarctic-cools-in-warmer-world.html| archive-url=https://web.archive.org/web/20140602105210/http://www.telegraph.co.uk/science/science-news/3289934/Antarctic-cools-in-warmer-world.html| url-status=dead| archive-date=2014-06-02| work=[[The Daily Telegraph]] | location=London | title=Antarctic cools in warmer world | first=David | last=Derbyshire | date=2002-01-14 | access-date=2013-04-13}}</ref><ref>{{cite news| url=https://www.usatoday.com/news/science/cold-science/2002-01-13-antarctic-cooling.htm | work=[[USA Today]]| title=Antarctic cooling pushing life closer to the edge | date=2002-01-16 | access-date=2013-04-13}}</ref><ref>{{cite news| url=https://www.nytimes.com/2002/05/03/us/ozone-hole-is-now-seen-as-a-cause-for-antarctic-cooling.html| work=[[The New York Times]] | title=Ozone Hole Is Now Seen as a Cause for Antarctic Cooling | first=Kenneth | last=Chang | date=2002-05-03 | access-date=2013-04-13}}</ref> while others show warming over the entire continent,<ref name="ChapmanWalsh" /> but overall trends are smaller and dependent on season and the timespan over which the trend is computed. Climate models predict that temperature trends due to global warming will be much smaller in Antarctica than in the [[Arctic]],<ref>{{cite book |editor1-first=Houghton |editor1-last=John Theodore |chapter=Figure 9.8: Multi-model annual mean zonal temperature change (top), zonal mean temperature change range (middle) and the zonal mean change divided by the multi-model standard deviation of the mean change (bottom) for the CMIP2 simulations |chapter-url=http://www.grida.no/climate/ipcc_tar/wg1/fig9-8.htm |title=Climate change 2001: the scientific basis: contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change |publisher=Cambridge University Press |location=Cambridge, UK |year=2001 |isbn=978-0-521-80767-8 |url=https://archive.org/details/climatechange2000000unse |url-status=dead |url-access=registration |access-date=2019-12-18 |archive-url=https://web.archive.org/web/20160330214626/http://grida.no/publications/other/ipcc_tar/?src=%2Fclimate%2Fipcc_tar%2Fwg1%2Findex.htm |archive-date=2016-03-30 }}</ref> mainly because heat uptake by the [[Southern Ocean]] acts to moderate the radiative forcing by greenhouse gases. |
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In a study released in 2009, historical weather station data was combined with satellite measurements to deduce past temperatures over large regions of the continent, and these temperatures indicate an overall warming trend. One of the paper's authors, [[Eric Steig]] of the [[University of Washington]], stated "We now see warming is taking place on all seven of the earth’s continents in accord with what models predict as a response to greenhouse gases."<ref>{{Cite news| url=https://www.nytimes.com/2009/01/22/science/earth/22climate.html?ref=science | author=Kenneth Chang | title=Warming in Antarctica Looks Certain|newspaper=[[The New York Times]] | date=2009-01-21 | access-date=2009-01-21 | archive-url= https://web.archive.org/web/20141113191509/http://www.nytimes.com/2009/01/22/science/earth/22climate.html?ref=science| archive-date=November 13, 2014| url-status= live}}</ref> A follow-up study by O'Donnell and others that strongly criticized the Steig et al. work, finding significant warming in West Antarctica but general cooling over the bulk of the continent. O'Donnell et al. also confirmed that Antarctica overall has been warming since the 1950s, but disagreed with Steig et al. about the strength of that warming. Subsequent measurements of temperatures in a borehole at the center of the West Antarctic ice sheet, by Orsi and others,<ref name="Orsi2012">{{cite journal|title=Little Ice Age cold interval in West Antarctica: Evidence from borehole temperature at the West Antarctic Ice Sheet (WAIS) Divide |author1=A. Orsi |author2=Bruce D. Cornuelle |author3=J. Severinghaus |journal=[[Geophysical Research Letters]] |volume=39 |issue = 9|pages= L09710 |year=2012 |doi=10.1029/2012GL051260 |bibcode=2012GeoRL..39.9710O|doi-access=free }}</ref> found even larger positive trends than Steig et al. |
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[[Microwave Sounding Unit temperature measurements |UAH satellite data of temperatures]] of the lower troposphere since 1979 shows a slight warming over the Antarctic continent (0.4 degrees C, 1979 to 2021), and a very slight cooling over the Southern ocean to the 60th latitude. The region covered for Antarctic land and ocean combined (60S to 85S) shows a very slight warming. RSS satellite data for lower tropospheric temperatures only covers 60S to 70S for Antarctica, and shows a very slight warming (0.24 degrees C, 1979 to 2021) for this smaller region. |
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Over a longer time period, work by Stenni ''et al''. (2017) used isotope records from ice cores to compute a cooling trend in all major regions of the continent over the past 2000 years.<ref>Stenni, B., Curran, M. A., Abram, N. J., Orsi, A., Goursaud, S., Masson-Delmotte, V., ... & Frezzotti, M. (2017). "Antarctic climate variability on regional and continental scales over the last 2000 years," ''Climate of the Past, 13''(11), pp. 1609-1634; https://doi.org/10.5194/cp-13-1609-2017 . Retrieved 23 May 2021.</ref> This long term trend, however, is as expected from [[Milankovitch cycles]] and has no particular relevance to anthropogenic global warming. For example, Jones ''et al''. used high-resolution measurements from the West Antarctic Ice Sheet Divide ice core to show that Milankovitch forcing, with the additional of minor changes in elevation, explain the observed variations through the [[Holocene]] period.<ref>Jones, T.R., et al. Seasonal temperatures in West Antarctica during the Holocene. Nature 613, 292–297 (2023). https://doi.org/10.1038/s41586-022-05411-8. Retrieved 02 September 2023.</ref> |
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== Origin of the controversy == |
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[[Michael Crichton]], in his 2004 novel ''State of Fear'', asserted that cooling observed in the interior of [[Antarctica]] shows the lack of reliability of the models used for global warming predictions, and thus of climate theory in general. This novel has a [[docudrama]] plot based upon the idea that there is a deliberately alarmist conspiracy behind [[global warming]] activism. As presented in page 193 of the novel: "The data show that one relatively small area called the Antarctic Peninsula is melting and [[Ice calving|calving]] huge icebergs. That's what gets reported year after year. But the continent as a whole is getting colder, and the ice is getting thicker."<ref name= "State_of_Fear">{{Cite book| last = Crichton| first = Michael| year = 2004| title = State of Fear| publisher = [[HarperCollins]], New York| isbn = 978-0-06-621413-9| pages = [https://archive.org/details/stateoffearnove000cric/page/109 109]| url-access = registration| url = https://archive.org/details/stateoffearnove000cric/page/109}} First Edition</ref> Other sources then picked up the argument,<ref name=Spotts2002/><ref name=Senate2006 /><ref name="DoranNYT" /> labeling it the "Antarctic Cooling Controversy", despite the fact that the small and variable observed trends are broadly consistent with the small magnitude of model-predicted temperature trends for Antarctica. |
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Crichton footnoted his assertion of Antarctic cooling as originating from the paper Doran ''et al.'', 2002,<ref name="Doran02"/> although the paper referenced did not directly state that their measurements was evidence against global warming. The work stated:<ref name="Doran02">{{cite journal |title=Antarctic climate cooling and terrestrial ecosystem response |author=Doran |journal=[[Nature (journal)|Nature]] |volume=415 |issue=6871 |pages=517–520|year=2002 |doi=10.1038/nature710 |pmid=11793010 |last2=Priscu |first2=J. C. |last3=Lyons |first3=W. B. |last4=Walsh |first4=J. E. |last5=Fountain |first5=A. G. |last6=McKnight |first6=D. M. |last7=Moorhead |first7=D. L. |last8=Virginia |first8=R.A. |last9=Wall |first9=D. H. |s2cid=387284 | display-authors=8}} in Letters to Nature 2002-01-13</ref><ref>{{Cite journal|author=Doran|display-authors=etal|date=2002-01-13|title=Antarctic climate cooling and terrestrial ecosystem response|url=http://www.uic.edu/classes/geol/eaes102/Doran.pdf|url-status=dead|journal=Letters to Nature|volume=415|issue=6871|pages=517–520|publisher=[[University of Illinois at Chicago]]|doi=10.1038/nature710|pmid=11793010|s2cid=387284|archive-url=https://web.archive.org/web/20071128074622/http://www.uic.edu/classes/geol/eaes102/Doran.pdf|archive-date=28 November 2007|access-date=2008-08-14}} PDF version: advance online publication Letters to Science</ref> "Although previous reports suggest slight recent continental warming our spatial analysis of Antarctic meteorological data demonstrates a net cooling on the Antarctic continent between 1966 and 2000, particularly during summer and autumn. The [[McMurdo Dry Valleys]] have cooled by 0.7 °C per decade between 1986 and 2000, with similar pronounced seasonal trends.... Continental Antarctic cooling, especially the seasonality of cooling, poses challenges to models of climate and ecosystem change." |
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In response to Crichton, the lead author of the research paper, [[Peter Doran]], published a statement in ''[[The New York Times]]''<ref name="DoranNYT"/> stating, "... our results have been misused as 'evidence' against global warming by Michael Crichton in his novel ''State of Fear''.... Our study did find that 58 percent of Antarctica cooled from 1966 to 2000. But during that period, the rest of the continent was warming. And climate models created since our paper was published have suggested a link between the lack of significant warming in Antarctica and the [[ozone hole]] over that continent. These models, conspicuously missing from the [[climate change denial]] literature, suggest that as the ozone hole heals — thanks to worldwide bans on ozone-destroying chemicals — all of Antarctica is likely to warm with the rest of the planet. An inconvenient truth?" He also emphasized the need for more stations in the Antarctic continent in order to obtain more robust results. |
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A rebuttal to Crichton's claims was presented by the group [[Real Climate]]:<ref name="RealClim">{{Cite web| url=http://www.realclimate.org/index.php?p=18 |author1=Eric Steig |author2=Gavin Schmidt |title=Antarctic cooling, global warming? |publisher=[[Real Climate]] | date=2004-12-03 | access-date=2008-08-14 }}</ref> |
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:Long term temperature data from the Southern Hemisphere are hard to find, and by the time you get to the Antarctic continent, the data are extremely sparse. Nonetheless, some patterns do emerge from the limited data available. The Antarctic Peninsula, site of the now-defunct Larsen-B ice shelf, has warmed substantially. On the other hand, the few stations on the continent and in the interior appear to have cooled slightly (Doran et al., 2002; GISTEMP). |
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:At first glance this seems to contradict the idea of "global" warming, but one needs to be careful before jumping to this conclusion. A rise in the global mean temperature does not imply universal warming. Dynamical effects (changes in the winds and ocean circulation) can have just as large an impact, locally as the radiative forcing from greenhouse gases. The temperature change in any particular region will in fact be a combination of radiation-related changes (through greenhouse gases, aerosols, ozone and the like) and dynamical effects. Since the winds tend to only move heat from one place to another, their impact will tend to cancel out in the global mean.<ref name="RealClim"/> |
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It is common to find statements that "climate models generally predict amplified warming in polar regions" (''e.g.'', Doran ''et al''.<ref name="Doran02"/>), a phenomenon called [[polar amplification]]. In fact, however, Arctic and Antarctic climates are out of phase with each other (the "[[polar see-saw]]" effect), and climate models predict amplified warming primarily for the Arctic and not for Antarctica.<ref name="RealClim"/> |
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==Observations of trends== |
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{{main article|Climate change in Antarctica}} |
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There are few long term weather observations for Antarctica. There are less than twenty permanent stations in all and only two in the interior. More recently [[Automatic weather station|AWS]]s supplement this, but their records are relatively brief. Hence calculation of a trend for the entire continent is difficult. [[Satellite temperature measurements|Satellite observations]] only exist since 1981 and provide surface temperature measurements only in cloud-free conditions. |
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The 2007 IPCC [[AR4|Fourth Assessment Report]] states, "Observational studies have presented evidence of pronounced warming over the Antarctic Peninsula, but little change over the rest of the continent during the last half of the 20th century."<ref>{{cite report|url=http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter11.pdf|title=Regional Climate Projections (In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change)|author1=J. H. Christensen|author2=B. Hewitson|author3=A. Busuioc|author4=A. Chen|author5=X. Gao|author6=I. Held|author7=R. Jones|author8=R.K. Kolli|author9=W.-T. Kwon|access-date=2007-11-05|archive-url=https://web.archive.org/web/20071215200933/http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter11.pdf|archive-date=15 December 2007|url-status=dead|year=2007|author15=A. Rinke|author17=P. Whetton|author16=A. Sarr|author14=J. Räisänen|author13=C. G. Menéndez|author11=V. Magaña Rueda|author10=R. Laprise|author12=L. Mearns}}</ref> Chapman and Walsh<ref name="ChapmanWalsh">{{cite journal|title=A Synthesis of Antarctic Temperatures|author1=William L. Chapman |author2=John E. Walsh |journal=[[Journal of Climate]]|volume=20|issue=16|pages=4096–4117|year=2007|doi=10.1175/JCLI4236.1|bibcode = 2007JCli...20.4096C |doi-access=free}}</ref><ref>{{cite journal|title=A synthesis of Antarctic temperatures |author1=William L. Chapman |author2=John E. Walsh |journal=Journal of Climate |publisher=Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign |year=2005 |volume=20 |issue=16 |pages=4096 |doi=10.1175/JCLI4236.1 |bibcode=2007JCli...20.4096C |doi-access=free }}</ref> note that "Trends calculated for the 1958–2002 period suggest modest warming over much of the 60°–90°S domain. All seasons show warming, with winter trends being the largest at +0.172 °C per decade while summer warming rates are only +0.045 °C per decade. The 45-year temperature trend for the annual means is +0.082 °C per decade corresponding to a +0.371 °C temperature change over the 1958–2002 period of record. Trends computed using these analyses show considerable sensitivity to start and end dates, with trends calculated using start dates prior to 1965 showing overall warming, while those using start dates from 1966 to 1982 show net cooling over the region." |
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Several scientific sources<ref name="Comiso2000">{{cite journal|author=Josefino C. Comiso|year=2000|title=Variability and Trends in Antarctic Surface Temperatures from In Situ and Satellite Infrared Measurements|journal=[[Journal of Climate]]|volume=13|issue=10|pages=1674–1696|bibcode=2000JCli...13.1674C|doi=10.1175/1520-0442(2000)013<1674:vatias>2.0.co;2|doi-access=free}} PDF available at AMS Online</ref><ref name="ThompsonSolomon">{{cite journal|url=http://ao.atmos.colostate.edu/other_papers/ThompsonSolomon_Science2002.pdf |title=Interpretation of Recent Southern Hemisphere Climate Change |author1=David W. J. Thompson |author2=Susan Solomon |journal=[[Science (journal)|Science]] |volume=296 |issue=5569 |pages=895–899 |year=2002 |doi=10.1126/science.1069270 |access-date=2008-08-14 |pmid=11988571 |bibcode=2002Sci...296..895T |s2cid=7732719 |url-status=dead |archive-url=https://web.archive.org/web/20110811141844/http://ao.atmos.colostate.edu/other_papers/ThompsonSolomon_Science2002.pdf |archive-date=2011-08-11 }} PDF available at Annular Modes Website</ref> have reported that there is a cooling trend observed in the interior of the continent for the last two decades of the 20th century, while the Antarctic Peninsula shows a warming trend. |
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In early 2013, David Bromwich, a professor of polar meteorology at Ohio State University, and a team including Antarctic weather station experts from the University of Wisconsin, published a paper in ''Nature Geoscience'' showing that the warming in central West Antarctica was unambiguous—and likely about twice the magnitude estimated by Steig et al. The key to Bromwich et al.'s work was the correction for errors in the temperature sensors used in various incarnations of the [[Byrd Station]] record (the only long record in this part of Antarctica); miscalibration had previously caused the magnitude of the 1990s warmth to be underestimated, and the magnitude of the 2000s to be overestimated. The revised Byrd Station record is in very good agreement with the borehole temperature data from nearby WAIS Divide.<ref>{{Cite journal | last1 = Bromwich | first1 = D. H. | last2 = Nicolas | first2 = J. P. | last3 = Monaghan | first3 = A. J. | last4 = Lazzara | first4 = M. A. | last5 = Keller | first5 = L. M. | last6 = Weidner | first6 = G. A. | last7 = Wilson | first7 = A. B. | doi = 10.1038/ngeo1671 | title = Central West Antarctica among the most rapidly warming regions on Earth | journal = [[Nature Geoscience]] | volume = 6 | issue = 2 | pages = 139 | year = 2012 |bibcode = 2013NatGe...6..139B | citeseerx = 10.1.1.394.1974 }}<br>{{Cite web | last = Steig | first = Eric | title = The heat is on in West Antarctica | url = http://www.realclimate.org/index.php/archives/2012/12/the-heat-is-on-in-west-antarctica/ | publisher = RealClimate | date = 23 December 2012 | access-date = 20 January 2013 }}</ref> A new statistical reconstruction<ref name="NicholasBromwich2013">{{cite journal|title=New reconstruction of Antarctic near-surface temperatures: Multidecadal trends and reliability of global reanalyses |author1=J P. Nicolas |author2=J. P. |author3=D. H. Bromwich |journal=[[Journal of Climate]] |volume=27 |issue = 21|pages= 8070–8093 |year=2014 |doi=10.1175/JCLI-D-13-00733.1 |bibcode=2014JCli...27.8070N |citeseerx=10.1.1.668.6627 |s2cid=21537289 }}</ref> shows significant warming over all of West Antarctic in the annual mean, driven by significant warming over most of the region in winter and spring. Summer and fall trends, are insignificant except over the Antarctic Peninsula where they are widespread only in fall. These finding are in good agreement with the 2009 study in Nature, though in general the new results show greater warming in West Antarctica and less warming over East Antarctica as a whole. Nicholas and Bromwich<ref name="NicholasBromwich2013"/> argue that while the warming in East Antarctica is not statistically significant, it would be greater in magnitude if not for the ozone hole. There is no evidence that any significant region of Antarctic has been cooling over the long term, except in fall. In a 2016 paper, Turner and others<ref>{{Cite journal | doi=10.1038/nature18645| pmid=27443743| title=Absence of 21st century warming on Antarctic Peninsula consistent with natural variability| journal=Nature| volume=535| issue=7612| pages=411–415| year=2016| last1=Turner| first1=John| last2=Lu| first2=Hua| last3=White| first3=Ian| last4=King| first4=John C.| last5=Phillips| first5=Tony| last6=Hosking| first6=J. Scott| last7=Bracegirdle| first7=Thomas J.| last8=Marshall| first8=Gareth J.| last9=Mulvaney| first9=Robert| last10=Deb| first10=Pranab| bibcode=2016Natur.535..411T| s2cid=205249862| url=http://nora.nerc.ac.uk/id/eprint/514089/1/Turner%20Nature%20with%20figures.pdf}}</ref> point out that if one considers just the last ~18 years, the trend on the Antarctic Peninsula has been cooling. This is likely connected with tropical variability,<ref>{{Cite journal |doi = 10.1038/535358a|pmid = 27443735|title = Cooling in the Antarctic|journal = Nature|volume = 535|issue = 7612|pages = 358–359|year = 2016|last1 = Steig|first1 = Eric J.|doi-access = free}}</ref> perhaps associated with the phase of the Interdecadal Pacific Oscillation.<ref>{{Cite journal |doi = 10.1038/NCLIMATE2341|title = Seasonal aspects of the recent pause in surface warming|journal = Nature Climate Change|volume = 4|issue = 10|pages = 911–916|year = 2014|last1 = Trenberth|first1 = Kevin E.|last2 = Fasullo|first2 = John T.|last3 = Branstator|first3 = Grant|last4 = Phillips|first4 = Adam S.|bibcode = 2014NatCC...4..911T|url = https://zenodo.org/record/1233365}}</ref> |
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==Scientific sources and interpretations == |
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According to a NASA press release:<ref>{{Cite web|url=http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17257 |author=NASA |title=Antarctic Temperature Trend 1982–2004 |publisher=Earth Observatory Newsroom |year=2004 |access-date=2008-08-14 |archive-url=https://web.archive.org/web/20080924163242/http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17257 |archive-date=24 September 2008 |url-status=dead |author-link=NASA }} NASA image based on data provided by Josefino Comiso, NASA-GSFC</ref> |
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:"Across most of the continent and the surrounding Southern Ocean, temperatures climbed... The temperature increases were greater and more widespread in West Antarctica than in East Antarctica, where some areas showed little change or even a cooling trend. This variability in temperature patterns across Antarctica complicates the work of scientists who are trying to understand the relative influence of natural cycles and human-caused climate change in Antarctica."<ref name="NASA07">{{Cite web| url=http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17838 | author=NASA |title=Two Decades of Temperature Change in Antarctica |publisher=Earth Observatory Newsroom | year= 2007| access-date=2008-08-14 | archive-url= https://web.archive.org/web/20080920041805/http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17838| archive-date= 20 September 2008 | url-status= dead| author-link=NASA }} NASA image by Robert Simmon, based on data from Joey Comiso, GSFC.</ref> |
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As a complement to NASA's findings, the [[British Antarctic Survey]], which has undertaken the majority of Britain's scientific research in the area, has the following positions:<ref>{{cite web|title=Climate Change—Our Research |publisher=British Antarctic Survey |url=http://www.antarctica.ac.uk/Key_Topics/Climate_Change/Climate_Change_Position.html |url-status=dead |archive-url=https://web.archive.org/web/20060207221259/http://www.antarctica.ac.uk/Key_Topics/Climate_Change/Climate_Change_Position.html |archive-date=2006-02-07 }}</ref> |
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* Ice makes polar climate sensitive by introducing a strong [[positive feedback]] loop. |
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* Melting of continental Antarctic ice could contribute to global [[sea level rise]]. |
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* [[Climate model]]s predict more snowfall than ice melting during the next 50 years, but models are not good enough for them to be confident about the prediction. |
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* Antarctica seems to be both warming around the edges and cooling at the center at the same time. |
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* Sea ice extent surrounding Antarctica has trended higher since satellite measurements began in 1979. |
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* The central and southern parts of the west coast of the Antarctic Peninsula have warmed by nearly 3 °C. The cause is not known. |
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Research by Thompson and Solomon (2002)<ref name="ThompsonSolomon"/> and by Shindell and Schmidt (2004)<ref>{{cite journal|last1=Shindell |first1=Drew T. |last2=Schmidt |first2=Gavin A. |title=Southern Hemisphere climate response to ozone changes and greenhouse gas increases |journal=Geophys. Res. Lett. |volume=31 |issue=18 |pages=L18209 |year=2004 |doi=10.1029/2004GL020724 |bibcode=2004GeoRL..3118209S |doi-access=free }}</ref> provide explanations for the observed cooling trend during the 1970s through 2000. An updated paper by Thompson et al. (2012)<ref name="Thompson2012">{{cite journal|last1=Thompson|first1=David W. J.|last2=Solomon|first2=Susan|last3=Kushner|first3=Paul J.|last4=England|first4=Matthew H.|last5=Grise|first5=Kevin M.|last6=Karoly|first6=David J.|date=23 October 2011|title=Signatures of the Antarctic ozone hole in Southern Hemisphere surface climate change|journal=[[Nature Geoscience]]|volume=4|issue=11|pages=741–749|bibcode=2011NatGe...4..741T|doi=10.1038/ngeo1296|s2cid=40243634}}</ref> emphasized that this explanation only applies to austral summer; during the fall, winter and spring seasons, the mean trend is warming, and this is believed to be largely due to changes in atmospheric circulation related to warming trends in the tropical Pacific region.<ref name = "Ding2011">{{cite journal|url=http://www.nature.com/ngeo/journal/v4/n6/full/ngeo1129.html |title= Winter warming in West Antarctica caused by central tropical Pacific warming |author1=Ding Q. |author2=E. J. Steig |author3=D.S. Battisti |author4=M. Kuettel. |journal=[[Nature Geoscience]] |volume=4 |pages=398–403|year=2011 |doi= 10.1038/ngeo1296 |access-date=2012-08-08 |issue=6|bibcode = 2011NatGe...4..741T }}</ref> |
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==See also== |
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*[[Climate of Antarctica]] |
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==References== |
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{{Reflist|30em}}{{Michael Crichton}} |
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[[Category:Environment of Antarctica]] |
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[[Category:Climate change controversies]] |
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[[Category:Climate change denial]] |
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[[Category:Climate of Antarctica]] |
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