The findings in this report are based on an assessment of the peer-reviewed scientific literature, complemented by other sources (such as gray literature) where appropriate. 3 Additional information on the development of this assessment can be found in Appendix 1: Report Development Process. An expert external peer review of the whole report was performed by an ad hoc committee of the National Academies of Sciences, Engineering, and Medicine (NASEM). NCA4 Volume II was thoroughly reviewed by external experts and the general public, as well as the Federal Government (that is, the NCA4 Federal Steering Committee and several rounds of technical and policy review by the 13 federal agencies of the USGCRP). Participants included decision-makers from the public and private sectors, resource and environmental managers, scientists, educators, representatives from businesses and nongovernmental organizations, and the interested public.
A series of regional engagement workshops reached more than 1,000 individuals in over 40 cities, while listening sessions, webinars, and public comment periods provided valuable input to the authors. A Federal Steering Committee, composed of representatives from USGCRP agencies, oversaw the report’s development.Ī team of more than 300 federal and non-federal experts-including individuals from federal, state, and local governments, tribes and Indigenous communities, national laboratories, universities, and the private sector-volunteered their time to produce the assessment, with input from external stakeholders at each stage of the process. The National Oceanic and Atmospheric Administration (NOAA) served as the administrative lead agency for the preparation of this report. Report Development, Review, and Approval Process
A summary of the CSSR is provided in Chapter 2 (Our Changing Climate) of this report the full report can be accessed at. As an assessment and analysis of the physical science, the CSSR provides important input to the development of other parts of NCA4 and their primary focus on the human welfare, societal, economic, and environmental elements of climate change. Projected changes in temperature, precipitation patterns, sea level rise, and other climate outcomes are based on a range of scenarios widely used in the climate research community, referred to as Representative Concentration Pathways (RCPs). It analyzes trends in climate change, both human-induced and natural, and projects major trends to the end of this century. The CSSR integrates and evaluates current findings on climate science and discusses the uncertainties associated with these findings.
It provides a detailed analysis of how climate change is affecting the physical earth system across the United States and provides the foundational physical science upon which much of the assessment of impacts in this report is based. The Climate Science Special Report (CSSR), published in 2017, serves as the first volume of NCA4. Climate Science Special Report: NCA4 Volume I
This assessment was written to help inform decision-makers, utility and natural resource managers, public health officials, emergency planners, and other stakeholders by providing a thorough examination of the effects of climate change on the United States. Where possible, NCA4 Volume II provides examples of actions underway in communities across the United States to reduce the risks associated with climate change, increase resilience, and improve livelihoods. 2 Volume II focuses on the human welfare, societal, and environmental elements of climate change and variability for 10 regions and 18 national topics, with particular attention paid to observed and projected risks, impacts, consideration of risk reduction, and implications under different mitigation pathways. This report, Volume II, draws on the foundational science described in Volume I, the Climate Science Special Report (CSSR). The Fourth National Climate Assessment (NCA4) fulfills that mandate in two volumes. Global Change Research Program (USGCRP) deliver a report to Congress and the President no less than every four years that “1) integrates, evaluates, and interprets the findings of the Program… 2) 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 3) analyzes current trends in global change, both human-induced and natural, and projects major trends for the subsequent 25 to 100 years.” 1 The Global Change Research Act of 1990 mandates that the U.S.