IPCC (2001) graph illustrating how a shift and/or widening of a probability distribution of temperatures affects the probability of extremes. (Via RealClimate)
The full 592-page (!) IPCC extreme weather report is out. Like most Intergovernmental Panel on Climate Change reports it has some value for people who don’t follow the science closely, which is to say the overwhelming majority of the media and policymakers.
Of course, the TV media ignored the summary report in November, so we will have to see if they pay any attention to this one now that the United States has just been through the most extreme winter heat wave in our recorded history.
But as Kevin Trenberth, one of the world’s leading experts on the link between climate change and extreme weather, put it to me in an email:
I have seen the chapter on the physical climate and I found it quite disappointing…. I don’t think it adds to AR4 [IPCC Fourth Assessment] much.
I agree with Trenberth that if, for instance, you want a more up to date and straightforward discussion of the impact of climate change on precipitation, you should just read his 2011 paper, “Changes in precipitation with climate change” (online here).
Indeed, the actual scientific literature from 2011 is generally more useful than this report — see “NOAA Study Finds Human-Caused Climate Change Already a Major Factor in More Frequent Mediterranean Droughts” and Hansen et al: “Extreme Heat Waves … in Texas and Oklahoma in 2011 and Moscow in 2010 Were ‘Caused’ by Global Warming.”
It is, as I wrote when the summary came out in November, the report is “Another Blown Chance to Explain the Catastrophes Coming If We Keep Doing Nothing.” I also wrote that the summary has a good chart that hints at dust-bowlification, but is mostly silent on warming’s gravest threat to humanity.
The full report has more on drought, but fails to clearly describe what the literature now suggests is coming if we stay anywhere near our current emissions path. In 2010, the National Center for Atmospheric Research did a far more valuable literature review and analysis of what we face, which makes clear we risk multiple, devastating global droughts even on moderate emissions path.
In the case of extreme weather, my guess is that decades from now, people will look back on the staggering growth in off-the-charts “outlandish” extreme events in the past few years and conclude that a regime change had occurred in the climate. That change is probably a combination of the sharp loss in summer/fall Arctic sea ice and the sharp increase in ocean heat content.
We’re only in the past year or so seen analyses that demonstrate the human fingerprint in these uber-extreme events, including the studies above and these two:
- Nature Climate Change: Strong Evidence Manmade ‘Unprecedented Heat And Rainfall Extremes Are Here … Causing Intense Human Suffering’
- Study Finds 80% Chance Russia’s 2010 July Heat Record Would Not Have Occurred Without Climate Warming
So rather than citing this timely, but already out-of-date IPCC report, let me just repost below an excellent new piece from RealClimate by the authors of those two studies, who have been doing some of the best recent work in this area.