Computer climate models fall short

BBC : Precise prediction of catastrophic climate events remains impossible for even the best computer models, according to Paul Valdes of Bristol University in the UK. Models have not been able to “predict” at least four major transformations in the past: the rapidly rising temperatures of the Paleocene–Eocene Thermal Maximum, the drying trend over North Africa, the serial weakening or shutting down of the Gulf Stream, and the sharp warmings recorded in Greenland ice cores. “State-of-the-art climate models are largely untested against actual occurrences of abrupt change,” writes Valdes in a commentary published in Nature Geoscience. “It is a huge leap of faith to assume that simulations of the coming century with these models will provide reliable warning of sudden, catastrophic events.” Valdes believes that Earth’s climate is sensitive to small changes and suspects computer models are underestimating climate change.