Just read a letter that the climate scientist David Archer sent to Nature magazine. He co-wrote it with Gavin Schmidt, another climate scientist. In it he talks about CO2 stabilization targets. And he specifically refers to the definition of climate sensitivity, in that many climate scientists are using the "traditional" Charney sensitivity, which excludes slow feedbacks. Thing is that I wrote to Archer a few weeks ago to point out exactly that, and I think I referred to Gavin Schmidt's blog post on realclimate.org. Archer never replied to my email. Maybe he was thinking about it anyway - who knows.
I'm going to email my friend Eberhard in the Munich Re georisks department and explain the climate sensitivity issue. If you think that there is a good chance that climate sensitivity is a high number, then it is impossible to recommend a high CO2 target. I want the Munich Re GeoRisks department to understand the climate sensitivity issue and to decide how likely it is that slow feedbacks are important. If they think that they are important then I will suggest that any high CO2 stabilization target gives guaranteed disaster. Hence the target has to be low. And I want to suggest that Munich Re has more expertise in risk than any politician, economist or climate scientist, there is no-one in a better position to recommend a target than the Munich Re Geo risks department. Then I want the Geo Risks department to convince Munich Re management to pick a low CO2 target (350) and lobby for it. Then I want Munich Re to convince Swiss Re to go for the target. That's the first stage. Watch this space.