Talk:Planetary boundaries

Plot differences

WRONG Plot of the planetary boundaries I recently added that plot of the boundaries. It differs from the one in the Nature paper though. I mean content-wise. There aren't even the same number of boundaries broken in the two plots. As I used the data from the table in the very same paper, this is confusing to me. I didn't read the whole thing though so maybe someone can help me out here and explain to me, how the discrepancy came about. I want the data to be accurate. --Mudd1 (talk) 12:04, 11 March 2012 (UTC)

I think we presume their data is accurate (who are we to contradict those eminent scientists? :-), and what you want is for the chart to accurately reflect the data (right?). So are you saying the original image doesn't reflect the data? Errors do happen, so the first thing to do is check for an erratum in a subsequent issue. I don't know how Nature handles these, but if you can get to the on-line version it probably incorporates any corrections. And you should read the whole article, just in case there is some explanation. Also check for any "supporting on-line material" that wasn't included in the article itself. And see if the Stockholm Resilience Centre has any similar images. ~ J. Johnson (JJ) (talk) 19:10, 11 March 2012 (UTC)

Nah, I had a closer look at the data and I partially got where I was being stupid: take ozone depletion for example – the measure given in the table is not actually depletion but ozone concentration. This means that more is better and the scale gets inverted. However, it's not that easy to fix as I don't know what scale to use instead. Especially the origin used is unclear. [1] corresponds to Figure 6 in their paper but I can't find any detailed description of the individual scales used. I'm going to try and contact the authors. Until then, I'll take down the figure as it's plain wrong. --Mudd1 (talk) 12:56, 19 April 2012 (UTC)

Thank you very much Mudd for the work you are doing on this alternate graphic. It is difficult to come up with a really satisfactory way of doing this. The original diagram by Johan Rockström et al. introduces a distortion by using a circle segment to represent the control variable for each boundary. This means that as the control value for a boundary increases, the graphic displays an area increasing as the square, which visually overrepresents higher control values.

By contrast, you are displaying the area with a triangle whose base is on the surface of the earth. If, like Rockström, you ignore the curvature of the earth, and use straight lines for each segment of the earth's surface, then the area by which the control variable is exceeded (or not) varies in a linear way with the variable, rather than as a square. This is an improvement over the Rockström representation. However, in other ways your representation is not as simple and intuitive as the Rockström approach. Still, I think it is a useful alternative way of representing the boundaries, and you should stick with your approach. I also like the way you have added the curvature of the earth so you can overlay an image of the earth at the center of your diagram. This introduces small distortions in the way the area represents changes in the control variable, but is justified by the visual aesthetics.

I don't see the problem you have with the ozone level, though it's true you got it the wrong way round. The control value 276 has reached 97.5% of the allowable value 283. The apex of your triangle for ozone should lie inside the earths surface at 97.5% of it's radius, rather than outside as you have drawn it. You say you are worried about the origin for the Dobson units used as a measure of ozone. I don't see a problem. It is roughly a linear measure of the amount of ozone on the atmosphere, and it's inverse is roughly linear over short distances. Even if there was issue with the origin, it wouldn't matter much given the small distance of the ozone value from the critical boundary value.

Generally this approach to graphically representing boundaries seems useful to me. You can refine it piece by piece over time. I think you should offset (rotate 22.5°) the red segment lines so they properly form the base of each triangle (or, better, you could remove them altogether). You are also drawing lines directly from one boundary to the next when you should be bringing them back to the base corner of each triangle. For example, the line you have drawn from climate change to acidification should be in two segments, returning to the surface of the earth halfway in between. You could play around with tinting to indicate safe and unsafe areas. It seems okay to me to include only those boundaries that have been quantified (though that should be mentioned in the caption). --Epipelagic (talk) 17:32, 19 April 2012 (UTC)

Thank you for your inspirations, Epipelagic. So you suggest replacing all values $x$ by ${\frac {1}{x}}$ that have no natural point of origin and whose unsafe range would otherwise be beyond $1$ when normalized. I'd have preferred to learn how they did it in the original figure but since Rockström did not reply to my email I guess we have to find a way to make do and this suggestion seems reasonable to me. I'll update my diagram when I find the time and upload it. I'll also see which other suggestions of yours are reasonably easy to implement.

I'm not sure about segmenting the triangles though. They would have to go back to the center of the earth, not to the surface as the base of the triangles is in fact a line through the origin parallel to the tangent, not the tangent itself. For the same reason, the unit circle is the circumscribed circle of the red octagon. I agree that this is confusing though, especially since the earth is mimicking an in-circle. --Mudd1 (talk) 16:07, 9 May 2012 (UTC)

Finally I took the time to make those changes to the image. I fixed the axes and obviously introduced some color. I'm not 100% sure this is a good thing but since it's an SVG, it's easily changed by anybody who doesn't like it. I also made the Earth larger so that it's now the circumscribed circle of the octagon. I did not rotate the octagon however. The red octagon is how the plot would look like if all eight values were exactly at their respective boundary. I also didn't implement any kind of returning to the origin or boundary or whatever of the spikes since we didn't finish discussing that. Thanks again for your input Epipelagic and maybe you can improve on the graphic if you have some more good ideas. --Mudd1 (talk) 10:03, 22 June 2012 (UTC)

There's a typo in the graphic. It should be Ocean acidification, not Ocean adidification — Preceding unsigned comment added by 188.195.152.41 (talk) 10:02, 7 March 2015 (UTC)

Improvements needed to the part on biogeochemical boundaries

I think the part on nitrogen needs to be improved (e.g. made more focussed) and the part on phosphorus could be expanded. Or perhaps it is sufficient to refer across to the article on peak phosphorus which I have done now.

I think the part on nitrogen fails to make it clear what the limit is regarding nitrogen, given that it is available in abundance - only takes energy to turn it into fertiliser for example. EvM-Susana (talk) 11:20, 18 February 2015 (UTC)

Make it clearer of you think that is needed, but try and avoid straying into original research by referencing your changes with sources that are focused on nitrogen as a planetary boundary. --Epipelagic (talk) 16:45, 18 February 2015 (UTC)

I have unfortunately not enough knowledge on nitrogen as a planetary boundary - didn't even know it was considered a planetary boundary before reading this article. I just think it (this section) is not well written, not really focused but talks more about the nitrogen cycle in general. I know a bit more about phosphorus which to me is more clear cut (hence the link to the article on peak phosphorus). Hoping that someone else out there could do some editing work in the nitrogen section... Sorry, can't be of more help for now. EvM-Susana (talk) 21:01, 18 February 2015 (UTC)

Atmospheric CO2 level needs updating

The atmospheric carbon dioxide concentration is currently at 401 and not 387 as the table listing the boundaries shows. It needs to be updated. Metanish (talk) 19:03, 17 August 2015 (UTC)

Thanks. I've updated it. SmartSE (talk) 21:12, 17 August 2015 (UTC)

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Article could be improved

The article overall is too wordy, it could be possibly tweaked with more inline references, and trimming down. prokaryotes (talk) 18:48, 1 November 2017 (UTC)