Posts Tagged ‘ipcc ar5’

Guest post from Andrew Cooper, AKA ‘Scute’. It’s a bit hard to tell if the baseline for temperature on video version from the IPCC press conference runs from 1861 or 1851, so we’ll let the talkshop readership decide. They certainly did switch the cumulative emissions baseline. It all makes a difference to presentational impact, especially the misleading slope  in temperature from 2000-2010.


graph from page 36 of the Summary for Policy Makers (SPM) with the version shown at the IPCC press conference below :

The graph includes an unabashed cherry-picking of temperature data points (2000, low and 2010, high) so as to fit the linear relationship the IPCC are promulgating between total accumulated CO2 and temperature since the late 19th century. It is true they can say they were just plotting in tens of years, to show a long term trend from 1860 but the current 15-year standstill is now turned into a soaring rise. They, of course, know this is a complete misrepresentation of the truth but are hiding behind the fig leaf argument that the decimal system dictates that you choose years with a ’0′ on the end.


My thanks to Roger Andrews for this succinct examination of the model-data comparisons from the leaked draft of IPCC AR5. He is absolutely right to draw attention to how poorly the models do in terms of tracking changes in sea surface temperature (SST). This metric is indicative of ocean heat content (OHC), which is the more important indicator of global change (though poorly understood and measured), because the ocean is the climate object with nearly all the heat capacity.

Roger Andrews – 1-2-2013

In each of its Assessment Reports the IPCC presents a global model-versus-observations comparison to show how good its climate models are. Its latest offering, reproduced below, appears in Figure TS-7(a) of the AR5 Draft. The Figure compares four “global mean temperature” series (HadCRUT4, GISS, NCDC and Japan Meteorological Agency) against the CMIP3 and CMIP5 climate models. At a glance, which is about all the IPCC’s average Policymaker will give it, the fit looks pretty good.


But when we dig deeper – and we don’t have to dig very far – we find that the fit is actually pretty bad.