Which is a bit of a mouthful, so they call it SREX. In the traditional and slightly unlovely IPCC way, you can read the SPM now but will have to wait awhile for the report. But it provides enough for me to mount my hobby horses, so giddy-up!
The first point is that extremes are useless for detecting or attributing climate change: if you want to know if the globe is warming, you should look at the global temperature series. Attempting to say “floods in Pakistan – global warming must be real” is silly (depending on what you mean by “real”. I mean, “is actually happening”. If you mean “will have actual noticeable effects on you in real life more interesting and alarming than just a gradual rise in average temperature” then you might just justify the “real”, but its a confusing use of the word. And of course, floods in Pakistan don’t have any effect on me. Or you). Extreme events don’t have stable statistics, because they are extreme, so concluding anything from them is much harder than concluding things from averages. So they start with
There is evidence from observations gathered since 1950 of change in some extremes. Confidence in observed changes in extremes depends on the quality and quantity of data and the availability of studies analyzing these data, which vary across regions and for different extremes. Assigning “low confidence” in observed changes of a specific extreme on regional or global scales neither implies nor excludes the possibility of changes in this extreme.
which is really only preparing you for the lack of excitement later on:
It is very likely that there has been an overall decrease in the number of cold days and nights, and an overall increase in the number of warm days and nights, on the global scale… there is medium confidence that the length or number of warm spells, or heat waves, has increased… There have been statistically significant trends in the number of heavy precipitation events in some regions. It is likely that more of these regions have experienced increases than decreases, although there are strong regional and subregional variations in these trends.
So far so dull: it has got warmer. We knew that anyway. Then they go on to wind up the cyclone-trend folks:
There is low confidence in any observed long-term (i.e., 40 years or more) increases in tropical cyclone activity (i.e., intensity, frequency, duration), after accounting for past changes in observing capabilities. It is likely that there has been a poleward shift in the main Northern and Southern Hemisphere extra-tropical storm tracks. There is low confidence in observed trends in small spatial-scale phenomena such as tornadoes and hail because of data inhomogeneities and inadequacies in monitoring systems
but don’t forget their original point that low confidence doesn’t exclude an effect. And then:
Increasing exposure of people and economic assets has been the major cause of the longterm increases in economic losses from weather- and climate-related disasters (high confidence). Long-term trends in economic disaster losses adjusted for wealth and population increases have not been attributed to climate change, but a role for climate change has not been excluded (medium evidence, high agreement)
Attribution:
There is evidence that some extremes have changed as a result of anthropogenic influences… It is likely that anthropogenic influences have led to warming of extreme daily minimum and maximum temperatures on the global scale. There is medium confidence that anthropogenic influences have contributed to intensification of extreme precipitation on the global scale… The uncertainties in the historical tropical cyclone records, the incomplete understanding of the physical mechanisms linking tropical cyclone metrics to climate change, and the degree of tropical cyclone variability provide only low confidence for the attribution of any detectable changes in tropical cyclone activity to anthropogenic influences.
Yup, that’s right: its got warmer, as wedunnit. We knew that already. But the cyclones are too wobbly to say much about them. And dealing with it? Deep insights such as
Developed countries are often better equipped financially and institutionally to adopt explicit measures to effectively respond and adapt to projected changes in exposure, vulnerability, and climate extremes than developing countries
So all in all, nothing exciting or surprising. RP Jr is happy with it, no surprise, and Romm is well pissed off, ditto. As usual, Pielke wipes the floor with Romm. Revkin appears to be sane but dull.
I seem to have forgotten what my second point was. Never mind. I didn’t quite get to the end of the SPM. Hopefully that isn’t too obvious.
Refs
* Nurture – boring
* RC is mostly interested in the cyclones
* JF has the right idea
wmconnolley: scienceblogs.com/stoat archive 