As noted on the NIPCC website this week, a peer-reviewed paper published in Geophysical Research Letters concludes that climate models "lack -- or incorrectly parameterize -- fundamental processes by which surface temperatures respond to radiative forcings." In other words, climate computer models used by the IPCC are fundamentally incorrect on predictions of global warming due to greenhouse gas concentrations ["radiative forcings"].
"To distinguish between simultaneous natural and anthropogenic impacts on surface temperature, regionally as well as globally," authors Lean and Rind performed "a robust multivariate analysis using the best available estimates of each together with the observed surface temperature record from 1889 to 2006."
Lean and Rind report that "contrary to recent assessments based on theoretical models (IPCC, 2007) the anthropogenic warming estimated directly from the historical observations is more pronounced between 45°S and 50°N than at higher latitudes," which finding, in their words, "is the approximate inverse of the model-simulated anthropogenic plus natural temperature trends ... which have minimum values in the tropics and increase steadily from 30 to 70°N." Furthermore, as they continue, "the empirically-derived zonal mean anthropogenic changes have approximate hemispheric symmetry whereas the mid-to-high latitude modeled changes are larger in the Northern hemisphere."
Because of what their analysis revealed, the two researchers concluded that "climate models may therefore lack -- or incorrectly parameterize -- fundamental processes by which surface temperatures respond to radiative forcings."
Lean, J.L. and Rind, D.H, 2008. How natural and anthropogenic influences alter global and regional surface temperatures: 1889 to 2006. Geophysical Research Letters 35: 10.1029/2008GL034864.