Originally posted on Climate Audit:
There has been considerable recent discussion of the fact that observations have been running cooler than models – see, for example, Lucia’s discussion of IPCC AR5 SOD Figure 9.8 (see here). However, Michael Mann at AGU took an entirely different line. Mann asserted that observations were running as hot or hotter than models. Mann’s assertion was taken even further by Naomi Oreskes, who asserted that climate models were under-estimating relative to observations. Oreskes squarely placed the blame for the supposed underestimates on climate skeptics.
In today’s post, I’ll look closely at the illustration in Mann’s AGU presentation, an illustration that gave an entirely different impression than the figure in the IPCC draft report. The reason for the difference can be traced to what I’ve termed here as “Mike’s AGU Trick”.
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