Read here. Prior to the most recent years of global cooling, the global warming hypotheses that climate models are assuming had already been 'falsified.' Unfortunately for the world's citizens, the UN-IPCC bureaucrats and political leaders attending the December Copenhagen meeting seem convinced the climate models are correct in their climate change conclusions. Climate change does exist but definitely not due to causes and in the manner that climate models assume:
"Studies such as the U.S. National Assessment and Chapters and the IPCC which use regional results from the multi-decadal climate models are constructed on models which have been falsified in their ability to accurately simulate even the linear trend of the tropical zonally averaged surface and tropospheric temperature trends over the last several decades. Since almost all impact studies require regional and smaller scale resolution, the current generation of multi-decadal global climate prediction models is inappropriate to use for impact prediction for the coming decades."