New Data on Climate Change in the United States

post office building under water after midwest floods of 1993Upon a mandate by the Global Change Research Act of 1990, the U.S. Global Change Research Program (USGCRP) released the Fourth National Climate Assessment (NCA4). In its second volume, the report utilizes the scientific methodology presented in Volume I, the Climate Science Special Report (CSSR), 2017. Volume II expands on the foundational science of climate change by focusing on the human and societal welfare vis-à-vis the environmental elements. In addition, the report addresses “observed and projected risks, impacts, consideration of risk reduction, and implications under different mitigation pathways.”

The primary objective of this volume is to provide various stakeholders, including decision- and policy-makers, utility managers, as well as public health and emergency management officials with the utmost relevant and timely information on the effects of climate change in the United States. Significantly, the report emphasizes that “the evidence of human-caused climate change is overwhelming and continues to strengthen, that the impacts of climate change are intensifying across the country, and that climate-related threats to Americans’ physical, social, and economic well-being are rising.” 

In addition to chapters on topics of regional and national interest, the report contains twelve Summary Findings that highlight the synthesis of the data and list the Key Messages, including the following:

  • Climate change creates new risks and exacerbates existing vulnerabilities in communities and presents additional challenges to human health and safety, quality of life, and the rate of economic growth;
  • Climate change causes growing losses to American infrastructure and property and impedes the rate of economic growth over this century while affecting the natural, built, and social systems; and
  • Communities, governments, and businesses must take action to lower greenhouse gas emissions and implement adaptation strategies in order to reduce climate change risks and costs.

While the authors do not provide policy recommendations, the report includes a section on economic estimates, as well as risk framing, confidence, and likelihood of disastrous consequences when dealing with climate change uncertainties. In particular, the highlighted risks will disproportionately affect those that are “already vulnerable, including low-income communities, some communities of color, children, and the elderly.”

A copy of the Report-in-Brief can be found here.

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