Global Change Research and the Report on our Environment and Ecosystem

The U.S. Global Change Research Program (USGCRP) is pleased to announce the release of Volume II of the Fourth National Climate Assessment (NCA4) and the 2nd State of the Carbon Cycle Report (SOCCR2).
NCA4 Vol II, Impacts, Risks, and Adaptation in the United States, assesses a range of potential climate change-related impacts, with an aim to helping decision makers better identify risks that could be avoided or reduced. The assessment follows Vol I, the Climate Science Special Report (CSSR), which was released in November 2017. Together, these reports meet the requirements of the Global Change Research Act, which mandates a quadrennial assessment of our understanding of global change and its impacts on the United States.
NCA4 Vol II draws on the expertise of more than 300 authors from federal, state, and local governments, industry, academia, tribal organizations, and non-government organizations. Its findings are the result of an assessment of over 6,000 unique references, including the CSSR, which provides the climate science foundation for this volume.
The assessment places a strong emphasis on regional information, addressing the impacts of climate change on 10 regions of the United States. It also evaluates the risks from climate change across 15 national-level topics, often using case studies to provide additional context and showcase community success stories. The report concludes with two response chapters discussing how climate-related risks could be reduced or avoided through adaptation action or emissions mitigation.
SOCCR2 represents an important technical contribution to USGCRP’s sustained assessment process. The report provides an overview of how human and natural processes are affecting the global and North American carbon cycle, emphasizing advances in the understanding of carbon cycle science and associated human dimensions.
In addition to its focus on the carbon cycle across the United States, Mexico, and Canada, SOCCR2 assesses major elements of the global carbon cycle and key interactions with climate forcing and feedback components from a global perspective; carbon stocks and fluxes; carbon in managed and unmanaged systems; interactions and disturbance impacts to the carbon cycle; and management practices, tools, and needs at various scales.
On behalf of USGCRP and the Subcommittee on Global Change Research, we thank the hundreds of authors and review editors who volunteered their time and expertise to these efforts, the Technical Support Unit at NOAA’s National Center for Environmental Information, the team at Oak Ridge National Laboratory, the staff who worked so hard to make these reports a reality, and the many people across the country who informed and reviewed these authoritative scientific assessments.
Virginia Burkett
​Acting Chair, Subcommittee on Global Change Research
Michael Kuperberg
​Executive Director, U.S. Global Change Research Program