NCA4 U.S. Caribbean Regional Chapter

The National Climate Assessment is a federal, Congressionally-mandated report that presents the historical, present, and projected effects and impacts of climate change on natural and human systems in the United States. The U.S. Caribbean chapter is a new addition to the 4^th National Climate Assessment and presents an analysis for Puerto Rico and the U.S. Virgin Islands.

Historically, the U.S. Caribbean has experienced relatively stable seasonal rainfall patterns, moderate annual temperature fluctuations, and regularly occurring extreme weather events, such as tropical cyclones, hurricanes, heat episodes, and drought. However, the Caribbean climate is changing and is projected to be increasingly variable as greenhouse gases increase.

The U.S. Caribbean shares climate-related challenges with U.S. continental areas. There are also unique vulnerabilities and risks, as well as unique opportunities. The high percentage of coastal area relative to land area means that a large proportion of the region's people, infrastructure, and economic activity are vulnerable to sea level rise, coastal flooding, and saltwater intrusion. High levels of exposure and sensitivity to risk are compounded by a low level of adaptive capacity, due in part to the high costs of mitigation and adaptation measures relative to the region's gross domestic product. Disruptions from extreme climate-related events, such as the recent droughts of 2014-2016 and Hurricanes Irma and Maria during 2017, can devastate local economies, affect health care systems, and cause widespread damage to crops, water supplies, complex infrastructure, and other critical resources and services.

The U.S. Caribbean chapter elaborates on the risks faced in the region by focusing on freshwater resources, marine resources, coastal systems, rising temperatures, and extreme weather events. The chapter reviews the potential for adaptation and resilience through regional collaboration.