Fifth National Climate Assessment (NCA5) Chapter 4 – Water

The National Climate Assessment (NCA) is a congressionally mandated quadrennial report prepared and submitted by the US Global Change Research Program. The fifth iteration of this report (NCA5), published in November 2023, provides the scientific foundation to support informed decision-making across the United States.

WWA’s Liz Payton is the lead author of the water chapter. She built and led a team of 11 experts from across the country who work in academia, local utilities, state and federal agencies, and private consulting. They brought expertise in hydrology, climate science, groundwater, drought, extreme precipitation and flooding, Tribal water topics, water quality, snow, and water resources tools and data. The chapter analyzes current climate trends and projects future trends based on a comprehensive review and assessment of peer-reviewed literature and climate and infrastructure data. 

The water chapter findings can be summarized as follows:  Climate change will continue to cause profound changes in the water cycle, increasing the risk of flooding, drought, and degraded water supplies for both people and ecosystems. These impacts will disproportionately affect frontline communities. While data and tools for water resources planning are improving, water infrastructure standards and management policies have been slow to meet the new challenges.

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