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Isaac Held's Blog

17. Structure of low frequency internal variability in models


From DelSole et al, 2011 (pdf).  The component of sea surface temperature variability that maximizes its integral time scale, obtained from the combination of 14 control runs of CMIP3 climate models.

This is a continuation of the previous post in which I analyze the sources of my confidence that the warming trend of the past half-century is dominated by external forcing.

Taking a long control integration of CM2.1, a GCM that I have talked about here before, I’ve used the last 2,000 years from the simulation described by Wittenberg, 2009, and located the period with the largest positive 50-year trend in global mean surface air temperature.  The picture below is of the trend at each point, the global average of which is 0.41C.  The average over the Northern Hemisphere only is about twice as large.

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