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 the rampant burning of fossil fuels like carbon dioxide and methane in the atmosphere (see figure below). The atmosphere acts like a blanket. When we burn oil, coal, or natural gas for energy, we thicken the blanket that envelops our planet. This disrupts the balance of incoming and outgoing solar radiation, and creates an exponentially warming system that cannot naturally repair itself in the span of the coming centuries. 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 (1.4 degrees F), 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 at different rates and in different ways. As a large scale example, 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 and increasing wildlfire risk. Locally, the timing and amount of rainfall is changing, which is resulting in more frequent or heavier storms. This could lead to increased hillside erosion and flooding. In other words, the climate is becoming more extreme in response to global warming.