Friday, November 29, 2013

Much uncertainty, but none of it good

Continued global warming after CO2 emissions stoppage : Nature Climate Change 

The depressing course of the recent meeting hoping to get some sort of international co-operation going on climate change seems to have led to less commentary on climate science blogs about the actual science.

This paper seems significant if you are looking on the long term scale, even if it is rather academic (in the sense that CO2 emissions are not going to stop any time soon):
 Recent studies have suggested that global mean surface temperature would remain approximately constant on multi-century timescales after CO2 emissions1, 2, 3, 4, 5, 6, 7, 8, 9 are stopped. Here we use Earth system model simulations of such a stoppage to demonstrate that in some models, surface temperature may actually increase on multi-century timescales after an initial century-long decrease. This occurs in spite of a decline in radiative forcing that exceeds the decline in ocean heat uptake—a circumstance that would otherwise be expected to lead to a decline in global temperature. The reason is that the warming effect of decreasing ocean heat uptake together with feedback effects arising in response to the geographic structure of ocean heat uptake10, 11, 12 overcompensates the cooling effect of decreasing atmospheric CO2 on multi-century timescales. Our study also reveals that equilibrium climate sensitivity estimates based on a widely used method of regressing the Earth’s energy imbalance against surface temperature change13, 14 are biased. Uncertainty in the magnitude of the feedback effects associated with the magnitude and geographic distribution of ocean heat uptake therefore contributes substantially to the uncertainty in allowable carbon emissions for a given multi-century warming target.

1 comment:

nottrampis said...

yeah more grist to the mill.

I have a few articles on this topic in my Around the traps one on the oceans is well worth a geek