24 September 2010

IPCC on Extreme Events: Getting Better but Still Not Great

Yesterday, Michael Oppenheimer from Princeton University and coordinating lead author of the IPCC special report titled Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation, provided a briefing to the Select Committee on Energy Independence and Global Warming of the US House of Representatives (here in PDF).  Oppenheimer's testimony was far more in line with the state of the science on this subject than have been recent IPCC reports and press releases, but remains slanted and focused on advocating action on emissions.

Oppenheimer states:
So-called “joint attribution” the assignment of cause for the damaging outcomes of such extremes, such as wildfires or human mortality occurring during hot and dry spells, is a relatively new field, and it remains difficult to associate recent increases in most such impacts directly with greenhouse gas emissions, but indirect evidence is strongly suggestive of such a link in many cases.
This is a convoluted way of simply saying that the present state of the science does not support claims of attribution.  In suggesting that this is a "new" field he notably avoids discussing a large body of literature such as on tropical cyclones (in the US, Australia, China, India, Latin America, etc.), floods, European storms, Australian bushfires, etc. where peer reviewed work has explained damage trends solely in terms of increasing societal vulnerability.  Why is it so hard for IPCC authors to acknowledge any of this literature?  But, even so, I give Opeenheimer some credit for moving in the right direction.

Oppenheimer's conclusion acknowledges the importance of societal factors in driving disasters, but then completely ignores adaptation (which he does mention elsewhere in the presentation), which indicates to me that the desire to advocate among IPCC leaders will be a habit hard to control:
Finally, while extreme events are generally a physical phenomenon, circumstances where such events translate into disasters, like Hurricane Katrina or the great European heat wave of 2003, depend in large measure on individual and societal anticipation, planning, and response capacity and implementation. In other words, disaster is partly a social phenomenon. In both of these episodes, the toll was much higher than was imagined possible before the events. Unfortunately, if history is a guide, such situations may become ever more common. Even as we learn to cope better with certain extreme events, the climate may change faster than we learn about it, and faster than our ability to implement what we have learned. The only remedy for such a situation is to act to slow the climate change by slowing greenhouse gas emissions.
Oppenheimer's statement is a move in the right direction, but it is highly selective, slanted and gives some misleading policy advice.  The reality is that actions today to reduce emissions will not have an discernible effects for many decades.  By not mentioning the time scale of the effects of mitigation and the relative role of mitigation and adaptation for addressing future losses (another literature not mentioned), Oppenheimer is arguably misleading.

If I had to give a grade to the presentation -- if the IPCC 2007 was an "F," then Oppenheimer gets a "C-."  The IPCC leadership still has a ways to go on the issue of extreme events.  Its extremes report is not due out for another year (remarkably), so they have lots of time to up their game.