Climate Change Indicators in the United States

Michael Kolian*, Jason Samenow, Kevin Rosseel and Jim Titus
USEPA, OAR/OAP/Climate Change Division
1200 Pennsylvania Avenue NW, Mail Code: 6207J
Washington, DC 20460

Collecting and interpreting environmental indicators play a critical role in our understanding of climate change and its causes. An indicator represents the state of certain environmental conditions over a given area and a specified period of time. Examples of climate-related indicators include surface temperature, precipitation, sea level, and greenhouse gas concentrations in the atmosphere. They can be either directly measured or derived from underlying measurement data and then related to climate variables. Although some indicators may show that fundamental environmental changes are now occurring likely as a result of climate change, others are not as clear. In addition, indicators may represent changes in complex large-scale ecological processes which occur over several decades to centuries.

Understanding the causes and effects of climate change require consideration of a broad suite of conditions than climate variables alone. Approaches for identifying relevant climate indicators including basic criteria and discussion of how various agencies can cooperatively contribute to providing useful indicators shall be presented.

Context is provided by EPA's recently released Climate Change Indicators in the United States report which presents a set of 24 key climate indicators to better understand and communicate climate change. The report describes how the indicator relates to the causes and effects of climate change, how the indicator was developed, data sources, and factors associated with uncertainty or „indicator limitations?. The report focuses primarily on the United States, but in some cases trends are representative of global changes to provide appropriate context or a basis for comparison. EPA uses these indicators to:

EPA will be continuing to develop a national capacity related to climate indicators by expanding existing ones and adding others where gaps currently exist (e.g., hydrologic processes, forest resources, air quality) in the future. In addition, EPA will continue to engage multiple stakeholders in the project to provide credibility, avoid duplicative efforts, and diversify input. This is an important opportunity for long-term monitoring and research programs to contribute policy-relevant information and demonstrate the environmental effects of climate change on ecosystems and society.

*Corresponding Author: Phone: 202-343-9261, E-mail: