This publication provides supporting information for the 24 indicators that appear in EPA's report, Climate Change Indicators in the United States. For each indicator, this publication describes measurement and calculation methods, explains how the reader can obtain the underlying data, provides estimates of variability and uncertainty (if available), and points the reader to important references and sources of additional information. EPA prepared this technical documentation to ensure that each indicator is fully transparent, so readers can know where the data come from, how each indicator was calculated, and how accurately each indicator represents the intended environmental phenomenon.