Science: Most dire global warming forecasts unlikely

Most dire global warming forecasts unlikely, study finds - Capital Weather Gang - The Washington Post

New research takes some of the most dire global warming projections off the table. A study published last week in the journal Science concludes that the more extreme climate change scenarios, which involve temperature increases of up to 10°F are implausible. Instead, the study finds, we are likely in the midst of a more manageable, albeit still potentially dangerous, shift in the planet’s climate.

This could be good, although not great, news, since even if the worst-case scenarios were to be ruled out, we’d still be looking at a planet that is warmer than it has been for all of human history. According to the study, if atmospheric concentrations of carbon dioxide (CO2), the most important global warming gas, were to double, the global average surface temperature would increase by between 3 to 4.7°F, with a median value of 4.1°F (or 1.7 to 2.6°C, with a median value of 2.3°C). This is a narrower range, with a lower upper estimate, than other studies have concluded.

...A useful way to think about CO2 and other greenhouse gases comes from climate scientist Richard Alley of Penn State University, who is one of the foremost experts in paleoclimatology. He refers to carbon dioxide as the “biggest control knob” of the earth’s climate...Texas A&M University climate scientist Andrew Dessler says he views the new study as largely consistent with previous climate sensitivity estimates.