We live in a world in which the climate is changing. Changes in climate have occurred since the formation of the planet. But humans are now influencing Earth’s climate and causing it to change in unprecedented ways.

It is in this rapidly changing world that EPA is working to fulfill its mission to protect human health and the environment. Many of the outcomes EPA is working to attain (e.g., clean air, safe drinking water) are sensitive to changes in weather and climate. Until now, EPA has been able to assume that climate is relatively stable and future climate will mirror past climate. However, with climate changing more rapidly than society has experienced in the past, the past is no longer a good predictor of the future. Climate change is posing new challenges to EPA’s ability to fulfill its mission.