Abstract

The Fifth National Climate Assessment is the US Government’s preeminent report on climate change impacts, risks, and responses. It is a congressionally mandated interagency effort that provides the scientific foundation to support informed decision-making across the United States.

The Global Change Research Act of 1990 mandates that the US Global Change Research Program (USGCRP) deliver a report to Congress and the President not less frequently than every four years that “integrates, evaluates, and interprets the findings of the Program and discusses the scientific uncertainties associated with such findings; analyzes the effects of global change on the natural environment, agriculture, energy production and use, land and water resources, transportation, human health and welfare, human social systems, and biological diversity; and analyzes current trends in global change, both human-induced and natural, and projects major trends for the subsequent 25 to 100 years.”

The Fifth National Climate Assessment (NCA5) fulfills that mandate by delivery of this Assessment and provides the scientific foundation to support informed decision-making across the United States. By design, much of the development of NCA5 built upon the approaches and processes used to create the Fourth National Climate Assessment (NCA4), with a goal of continuously advancing an inclusive, diverse, and sustained process for assessing and communicating scientific knowledge on the impacts risks, and vulnerabilities associated with a changing global climate.

The findings in this report are based on a comprehensive review and assessment of information sources determined to meet the standards and documentation required under the Information Quality Act and the Foundations for Evidence-Based Policymaking Act of 2018, including peer-reviewed literature, other literature, Indigenous Knowledge, other expert and local knowledge, and climate data processed and prepared for authors by NOAA’s Technical Support Unit.

NCA5 was thoroughly reviewed by Federal Government experts, external experts, and the public multiple times throughout the report development process. An expert external review was performed by an ad hoc committee of the National Academies of Sciences, Engineering, and Medicine. Additional information on the development of this Assessment can be found in Appendix: Assessment Development Process.

The Fifth National Climate Assessment (NCA5) Companion Podcast is a limited series intended to introduce the report, showcase the perspectives of NCA5 authors and staff, and demonstrate how the Assessment can help inform decisions. This limited series is available on all popular streaming platforms.

The full report is available for download in English and Spanish.

Affiliated Organizations

U.S. Global Change Research Program

The U.S. Global Change Research Program (USGCRP) coordinates and integrates federal research on changes in the global environment and their implications for society. The USGCRP began as a presidential initiative in 1989 and was mandated by Congress in the Global Change Research Act of 1990 (P.L.

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