Don't blame the sulphates
Oct 15, 2015
Bishop Hill in Climate: Models

A new paper in Climate Dynamics examines the hypothesis that the indirect effects of aerosols (aka pollution) has been behind the hiatus/pause/thing-with-no-name/non-existent-thing that has, or has not, been affecting the global temperature average for the best part of two decades.

Andrew Gettelmann and colleagues focus on sulfate aerosols and plug revised forcing figures into climate models to see if this can bridge the gap to the temperature records. Unfortunately the answer seems to be a pretty firm "no".


Sulfate aerosol emissions increase globally from 2000 to 2005, and then decrease slightly to 2010. Thus the change in anthropogenic sulfate induced net global radiative forcing is small over the period. Sulfate ACI might be a contributor to the spatial patterns of recent temperature forcing, but not to the global mean ‘hiatus’ itself.


Of course there is always the possibility - or likelihood - that the models just can't simulate the cloud-aerosol interactions properly. Nevertheless, if they do then another explanation for the pause has been ticked off and the mystery deepens.

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