What is Climate Change?

The terms global warming and climate change are often used interchangeably, but the two phenomena are different.

Global warming is the rise in global mean temperature due to an increase of heat-trapping greenhouse gases such as carbon dioxide and methane in the atmosphere (see figure below). Based on surface and atmospheric temperatures from thousands of locations, and from satellites worldwide, scientists have determined that the global mean temperature has risen 0.8 degrees C, since 1880.

Climate change is a more general term that refers to changes in many climatic factors (such as temperature and precipitation) from the global to the local scale. These changes are happening in response to global warming and other factors at different rates and in different ways. For example on a large scale, the United States has become wetter over the 20th century, while the Sahel region of central Africa has become drier. In California, global warming and associated climate change is decreasing the Sierra snow pack and melting it sooner, causing water shortages across the state. Locally, the timing and amount of rainfall may change, potentially resulting in more frequent or heavier storms. This could lead to increased hillside erosion and flooding.