Scott Armstrong and Kesten Green were asked by Senator Inhofe for an analysis of the U.S. Environmental Protection Agency's proposed policies for greenhouse gases. They concluded that long-term forecasts of climate do not provide a sound basis for policy changes.
Scientific understanding about the Earth's climate is tentative at best. As a result of uncertainties over what causes climate to change and how and when, there are rival theories and arguments among scientists about how to interpret the evidence.
Rather than join these arguments, we have examined the processes that have been used to analyze the available data in order to derive forecasts of climate over the 21st Century. We have concluded that the forecasting process reported on by the Intergovernmental Panel on Climate Change (IPCC) lacks a scientific basis.