14 November 2011

Leaked Text of IPCC Extremes Report

Has the Intergovernmental Panel on Climate Change finally gotten the issue of extreme events right?  Maybe so. At the BBC Richard Black says that he has a copy of the forthcoming IPCC extremes report and shares some of what it says prior to being considered by governments this week:
For almost a week, government delegates will pore over the summary of the IPCC's latest report on extreme weather, with the lead scientific authors there as well. They're scheduled to emerge on Friday with an agreed document.

The draft, which has found its way into my possession, contains a lot more unknowns than knowns.
He  describes a report that is much more consistent with the scientific literature than past reports (emphasis added):
When you get down to specifics, the academic consensus is far less certain.
There is "low confidence" that tropical cyclones have become more frequent, "limited-to-medium evidence available" to assess whether climatic factors have changed the frequency of floods, and "low confidence" on a global scale even on whether the frequency has risen or fallen.

In terms of attribution of trends to rising greenhouse gas concentrations, the uncertainties continue.

While it is "likely" that anthropogenic influences are behind the changes in cold days and warm days, there is only "medium confidence" that they are behind changes in extreme rainfall events, and "low confidence" in attributing any changes in tropical cyclone activity to greenhouse gas emissions or anything else humanity has done.

(These terms have specific meanings in IPCC-speak, with "very likely" meaning 90-100% and "likely" 66-100%, for example.)

And for the future, the draft gives even less succour to those seeking here a new mandate for urgent action on greenhouse gas emissions, declaring: "Uncertainty in the sign of projected changes in climate extremes over the coming two to three decades is relatively large because climate change signals are expected to be relatively small compared to natural climate variability".

It's also explicit in laying out that the rise in impacts we've seen from extreme weather events cannot be laid at the door of greenhouse gas emissions: "Increasing exposure of people and economic assets is the major cause of the long-term changes in economic disaster losses (high confidence).

"Long-term trends in normalized economic disaster losses cannot be reliably attributed to natural or anthropogenic climate change."
None of this is a surprise to me, and it won't be to regular readers of this blog. After working for more than a decade on this issue with many colleagues around the world, it is indeed satisfying to see the climate science community on the brink of finally get this topic right, after botching it at almost every previous opportunity.

But before declaring victory, it is worth noting Black's expectation that governments will be pressing for different conclusions because money is at stake:
Developing countries like the fact that under the UN climate process, the rich are committed to funding adaptation for the poor.

Yet as the brief prepared for the Dhaka meeting by the humanitarian charity Dara shows, it isn't happening anywhere near as fast as it ought to be.

Only 8% of the "fast-start finance" pledged in Copenhagen, it says, has actually found its way to recipients.

It's possible - no, it's "very likely" - that the IPCC draft will be amended as the week progresses, and presumably the governments represented at the Climate Vulnerable Forum will be asking their delegates to inject a greater sense of urgency.
The good news about the leaked document is that efforts to alter the text will be noticed. Based on Black's report, it seems that the IPCC has at long last done the right thing on extreme events and climate change.  It will be most interesting to see the reactions.