Climate Change may refer to a change in average weather conditions, or in the time variation of weather around longer-term average conditions.

Climate Change is caused by factors such as biotic processes, variations in solar radiation received by Earth, plate tectonics, and volcanic eruptions.

Certain Human activities have been identified as primary causes of ongoing Climate Change.

Science has made enormous inroads in understanding Climate Change and its causes, and is beginning to help develop a strong understanding of current and potential impacts that will affect people today and in coming decades.

This understanding is crucial because it allows decision makers to place Climate Change in the context of other large challenges facing the nation and the World.

There are still some uncertainties, and there always will be in understanding a complex system like Earth’s climate.

Nevertheless, there is a strong, credible body of evidence, based on multiple lines of research, documenting that climate is changing and that these changes are in large part caused by Human activities.

While much remains to be learned, the core phenomenon, scientific questions, and hypotheses have been examined thoroughly and have stood firm in the face of serious scientific debate and careful evaluation of alternative explanations.