Dass mein Beitrag am Thema vorbei ist, leuchtet mir jetzt nicht so ganz ein. "Forscher entsetzt..." - das ist ja noch schärfer als "alarmiert..."
Zur Frage des wahrscheinlichen Temperaturanstiegs hat Stevens sich im Zeit-Interview auch konkret geäussert (englische Version, da Original hinter Bezahlschranke):
Stevens: If we continue as before, yes. In the last IPCC report , it was agreed that the global average temperature would then probably rise by 2.5 to 4.0 degrees Celsius. According to the simulations, the higher temperatures are mainly caused by a change in the clouds. We consider this effect to be overestimated today.
ZEIT: Were the models faulty?
Stevens: Yes. Too many children’s book clouds, not enough real clouds. In the world climate research program we have tackled the climate models. The models with the most extreme predictions have failed, and confidence in the less catastrophic values of climate sensitivity has increased . In my opinion, however, the contribution of the clouds is still overstated.
ZEIT: How great is it?
Stevens: Based on our latest measurements and advances in theory, I would say today: zero.
ZEIT: Zero?
Stevens: Right, at least that’s my working hypothesis. The climate sensitivity is then at the lower end of the IPCC estimate, around 2.8 degrees. We should keep looking, but so far there’s no evidence that clouds play a major role.
Er meint also mit der Studie gezeigt zu haben, dass man von den schlimmsten Prognosen doch wieder abrücken sollte.