This assessment strengthens and expands our understanding of climate-related health impacts by providing a more definitive description of climate-related health burdens in the United States. It builds on the 2014 National Climate Assessment and reviews and synthesizes key contributions to the published literature. Acknowledging the rising demand for data that can be used to characterize how climate change affects health, this report assesses recent analyses that quantify observed and projected health impacts. Each chapter characterizes the strength of the scientific evidence for a given climatehealth exposure pathway or link in the causal chain between a climate change impact and its associated health outcome. This assessments findings represent an improvement in scientific confidence in the link between climate change and a broad range of threats to public health, while recognizing and identifying emerging issues. These considerations provide the context for understanding Americans changing health risks and allow us to identify, project, and respond to future climate change health threats. The overall findings underscore the significance of the growing risk climate change poses to human health in the United States.