Climate Science Special Report

Fourth National Climate Assessment (NCA4), Volume I  >>

This report is an authoritative assessment of the science of climate change, with a focus on the United States. It represents the first of two volumes of the Fourth National Climate Assessment, mandated by the Global Change Research Act of 1990.

Fourth National Climate Change Assessment Volume II: Impacts, Risks, and Adaptation in the United States  >>

The National Climate Assessment (NCA) assesses the science of climate change and variability and its impacts across the United States, now and throughout this century.