The U.S. Environmental Protection Agency says:
The Earth’s climate is changing. Temperatures are rising, snow and rainfall patterns are shifting, and more extreme climate events—like heavy rainstorms and record high temperatures—are already affecting society and ecosystems. Scientists are confident that many of the observed changes in the climate can be linked to the increase in greenhouse gases in the atmosphere, caused largely by people burning fossil fuels to generate electricity, heat and cool buildings, and power vehicles.
EPA is working with many other organizations to better understand the causes and effects of climate change. With help from these partners, EPA has compiled a set of 26 indicators tracking signs of climate change. Most of these indicators focus on the United States, but some include global trends to provide context or a basis for comparison. These indicators represent a selected set of key climate change measurements, and are not an exhaustive group of all climate change indicators. EPA’s indicators are based on peer-reviewed data from various government agencies, academic institutions, and other organizations. EPA selected these indicators based on the quality of the data and other criteria.
EPA published these indicators in a comprehensive report in December 2012. Indicators will be updated periodically on the Web as newer data become available.
Use this site to learn more about EPA’s indicators related to greenhouse gases, weather and climate, oceans, snow and ice, and society and ecosystems.