Fourth National Climate Assessment

The Fourth National Climate Assessment (NCA4), completed in November 2018, is a comprehensive and authoritative report on climate change and its impacts in the United States.

NCA4 Vol II: Impacts, Risks, and Adaptation in the United States

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Download the report and related materials

View or request a free copy of the Overview

View or request a free copy of the Report-in-Brief

Ver o solicitar una copia impresa gratuita del Informe Resumido

NCA4 Vol I: Climate Science Special Report

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Download the report and related materials

View or request a free copy of the Executive Summary

About NCA4

Below you will find information related to Volumes I and II of NCA4, including background information and frequently asked questions about the report development process.

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GCRA Mandate

Learn more about USGCRP and the National Climate Assessment, mandated by the Global Change Research Act (GCRA) of 1990.

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About NCA4 Vol. I (CSSR)

Learn about the Climate Science Special Report (CSSR), a component of the mandated quadrennial National Climate Assessment. CSSR was released in November 2017.

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About NCA4 Vol. II

Learn about the Fourth National Climate Assessment, Volume II: Impacts, Risks, and Adaptation in the United States.

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NCA4 Vol. II Engagement

Stakeholder engagement was vital to the NCA4 Vol. II development process. Learn about assessment-related Regional Engagement Workshops and national chapter engagement activities here.

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How to Contribute

Public engagement is critical to the entire NCA process. Learn more about how the public contributed the development of NCA4.

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NCA4 Vol. I and II: FAQs

Have questions about the NCA4 process? Want to better understand the difference between Volume I and Volume II? Check out our FAQs.

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Fourth National Climate Assessment