I've updated Nic Lewis's graph of his new climate sensitivity estimates by adding the IPCC's likely range of 1.5°C–4.5°C as a grey box. Something of a contrast here I would say.
;)
The situation for TCR is only marginally better.
;)
I've updated Nic Lewis's graph of his new climate sensitivity estimates by adding the IPCC's likely range of 1.5°C–4.5°C as a grey box. Something of a contrast here I would say.
The situation for TCR is only marginally better.
Bishop Hill
In the comments at CA, Shub and Nic Lewis point to another important implication of the Stevens paper:
SHUB: Do low estimates for aerosol cooling imply the 1940-1978 drop in global temperatures were not due to coal plant emissions from post-war industrialization?
LEWIS: Yes, they strongly suggest that the main reason for global temperature going down rather than up from 1940 to the mid-1970s despite quite strong greenhouse gas forcing (+0.7 W/m2 for long-lived GHG, +0.85 W/m2 including ozone) lay elsewhere. Internal variability (here the AMO) seems the obvious cause. On Steven’s best estimates, aerosol forcing became a bit under -0.3 W/m2 more negative during this period. Sulphate emissions from coal plants etc. grew rapidly and reached their peak level in the mid/late 1970s.