This is an amicus brief from climate scientists to the Supreme Court. The scientists argue that the Environmental Protection Agency should be acting to prevent climate change. It contains a good summary of the science.
…scientific uncertainty is a double-edged sword: outcomes may turn out better than our current prediction, but it is just as possible that they will turn out worse (as in the case of stratospheric ozone depletion cited in point 8). Thus, it is a mistake to infer that because a prediction of an undesirable outcome is uncertain, that the risk posed by that undesirable outcome is low. The absence of absolute certainty in science does not by itself provide a rational reason for avoiding policy action on a scientifically identified public risk (like global climate change), any more than the absence of absolute certainty prevents decisions or actions in other areas such as health care, financial decisions, or national security. Similarly, low probability of a potentially large harm does not by itself rationally justify inaction any more than the low probability of devastating fire rationally justifies nonpurchase of home insurance policies.