Monday, March 23, 2009

Chart of the Day

Lucia at The Blackboard compares the IPCC's warming prediction with measured temperatures:

source: The Blackboard based on Christopher Monckton

Lucia explains:
I’ve superimposed my best understanding of "The IPCC’s currently-predicted" best estimate of warming using a dark blue line. I interpret this to be multi-model mean over trend obtained by averaging over 22 models that form the basis of the IPCC projections in the AR4." This gives 0.21 C/decade for the specific period between Jan. 1980 and Dec. 2008. The alternative choice for the IPCC’s best estiamte is is "about 0.2 C/decade" based on the text or various other trends on can obtain from tables. (They are all around 0.21 C/decade).

My lighter, grey-blue lines show the trends associated with ±1 standard error in the mean trend as determined using the method described by Santer et al 2008. (That is: I correct assuming all residuals from linear are AR(1) noise; also, this is not the standard deviation for all trends. )

Based on additional analysis applying the method Santer applied to test the multi-model mean trend in tropospheric temperature against observations, I find that the IPCC projected trend for this period would be rejected if we use 90% confidence levels. The trend would fail to reject at 95% confidence.
(via Watts Up With That?)

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