A classic report, full of conservative information created by committee. Not that the IPCC does not represent the best science that we have. It’s just that these guys do things by enormous committees and compromise is the standard operating procedure when creating policy, or anything really, by committee.
So what does this report mean? Honestly, my focus is on impacts happening now. I did read the Summary for Policy Makers though. One statement stood out, relative to impacts happening now; “For the high emissions scenario, it is likely that the frequency of hot days will increase by a factor of 10 in most regions of the world.” Conservative? Yes.
The USGS tells us that 100 degree days will increase ten-fold across almost the entire country by the decade beginning 2080. (See entry for November 21, 2009.) This finding would support the SREX, except that it is based on one of the middle of the road scenarios, not a higher emission scenario. A higher emissions scenario means higher temperatures.
Diffenbaugh and Ashfaq tell us that some parts of the North American southwest will see the hottest season of the last 60 years repeated ten times during the decade of the 2030s — as in, every year of the 2030s will be as hot as the hottest season of the last 60 years. See entry for July 8, 2010: Time frames are everything. Except when the science tells us that things will be ten times worse than they are now based on a middle of the road climate scenario, like Diffenbaugh and Ashfaq have done.
April 7, 2011; a paper in Climate Change, a Wiley Interdisciplinary Review, tells us that by 2035 (the decade 2021 to 2030), Dust Bowl conditions will dominate a majority of the United States. In other words, Dust Bowl conditions will be the typical condition: the average, the normal condition, in just 24 years. Some years will be cooler, but just as many will be more extreme. This is another instance of extraordinary climate change happening far ahead of the conservative assessment process suggestion. This one too is based on the middle of the road scenario, not the worse-case scenario. I can not emphasize enough that our emissions are following the worst-case scenario, not one of the middle of the road scenarios.
And this year in Austin, and all across Texas (see entry for October 1, 2011) we experienced our first summer that was ten times more extreme than average. This year we had 90 days of 100 degree heat. Normally, we average 11 days of 100 degrees or above. Technically of course, 90 days of 100 degree heat is only 8.2 times more than our average of 11 days of 100 degree heat, but if you suffered through it like we all did in Central Texas, it was every bit as extreme as ten times more extreme than normal.
SREX Report: http://ipcc-wg2.gov/SREX/
Global Climate Change Impacts in the United States, A State of Knowledge Report from the U.S. Global Change Research Program, 2009, page 90.
Diffenbaugh and Ashfaq, Intensification of hot extremes in the United States, Geophysical Research Letters, July 2010
Dai, Drought under global warming – a review, Wiley Interdisciplinary Reviews – Climate Change, p 45-65, January-February 2011