2 C
There has been a lot of back and forth about what happens when global temperature rises. Much of the confusion is that global responses tend to average out extremes, but there are two useful diagrams which date back to 2007 on Rabett Run. The first is from the AR4 (remember the 2C number is from pre-industrial, the diagram below is from a 1980-1999 baseline)
and the second from the Stern Report
Both of these were from six years ago or a bit more. Comparisons with what has happened since offer a great opportunity for discussion. It is open season on comparisons with what certain others said would happen
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7 comments:
2C seems consistent.
Why is there so much made up speculative stuff at the bottom?
Eunice
Anderson & Bows (2011)
Dear Rabbett,
We would have you know that two degree's C is the new one degree's C
http://www.pnas.org/content/106/11/4133.full
Yours sincerely,
Tom Thumb and Hunca Munca
Something strange about those images. IE and Firefox on Windows display them; Chrome does not.
-Browsing Mouse
AFAEK they are straight vanilla jpg but on flikr
http://www.pnas.org/content/106/11/4133.full
That one's good. It actually does use the word 'benefit' although it's only to say, "benefits aren't going to be as much or as enduring as we thought.
John Schellnhuber, who states he was involved, as a coordinating lead author for the IPCC Third Assessment report, when "we came up with" the first "burning embers" diagram Sterns data comes from, addressed the "4 Degrees and Beyond" conference held 28 September 2009 in Oxford, UK. His talk was entitled "Terra quasi-incognita: beyond the 2 degrees C line". Audio here. Slides here. The video seems to be unavailable now. Conference presentation downloads page is here.
Schellnhuber showed the "Updated Reasons for Concern" data, i.e. the revised "burning embers" chart published by Smith et.al. 2009 PNAS, cited by commenter(s) "Tom Thumb and Hunca Munca", as his slide 4.
Schellnhuber commented that 2 degrees was never regarded as "safe".
"Its a compromise", he said.
"Of course we will lose all the coral reefs if we go up to 2 degrees, or most of them, but who needs coral reefs anyway.... But we will at least save the Greenland ice sheet, blah blah blah [sic], and so in the end this is a good political compromise".
He then commented on Smith et.al.: "But if you look at the recent work which was published in PNAS... then all the red color is coming down in all the columns. That is quite a dramatic finding. And ten thousands of studies have gone into that. This is the stark evidence that 2 degrees is NOT certainly a very good line, but we are talking at this conference of going even beyond that".
He said there was a 25% chance even if civilization managed to limit warming to 2 degrees C, that the planetary system would become unstable in ways civilization would regret profoundly. He said no one would tolerate a nuclear reactor in their neighbourhood that engineers certified had a 25% chance of melting down and destroying the neighbourhood.
"But its only about the planet we are talking about", he commented.
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