Sea level along USA coastlines will rise about 25 to 30 cm on average above current levels over the next 30 years. Consequently, tide and storm surge heights will increase and reach further inland worsening coastal flooding pattern. The additional rise in sea level is determined by the current and future carbon emissions. The greater the emissions, the greater the global warming, and the greater the likelihood of higher sea levels.
The updated Technical Report on sea level rise scenarios for the United States published by National Oceanic and Atmospheric Administration (NOAA) estimates that the relative sea level along the U.S. coastline will rise on average by about a foot over the next 30 years which is almost equal to rise in level in the last 100 years.
The sea level rise will vary regionally along coasts. Rise in the next three decades is expected to be, on average: 10 – 14 inches (0.25 – 0.35 meters) for the East coast; 14 – 18 inches (0.35 – 0.45 meters) for the Gulf coast; 4 – 8 inches (0.1 – 0.2 meters) for the West coast; 8 – 10 inches (0.2 – 0.25 meters) for the Caribbean; 6 – 8 inches (0.15 – 0.2 meters) for the Hawaiian Islands; and 8 – 10 inches (0.2 – 0.25 meters) for northern Alaska.
Consequently, tide and storm surge heights will increase and reach further inland worsening coastal flooding pattern. It is estimated that “moderate” (typically damaging) flooding will occur more frequently in 2050 (4 events/year) than “minor” (mostly disruptive, nuisance, or high tide) flooding occurs today (3 events/year). “Major” (often destructive) flooding is expected to occur five times as often in 2050 (0.2 events/year) as it does today (0.04 events/year). Without additional risk reduction measures, U.S. coastal infrastructure, communities, and ecosystems will face increased impacts.
The additional rise in sea level is determined by the current and future carbon emissions. The greater the emissions, the greater the global warming, and the greater the likelihood of higher sea levels. About 2 feet (0.6 meters) of sea level rise along the U.S. coastline is likely between 2020 and 2100 because of emissions to date. Failing to curb future emissions could cause an additional 1.5 – 5 feet (0.5 – 1.5 meters) of rise for a total of 3.5 – 7 feet (1.1 – 2.1 meters) by the end of this century.
Above 3°C of global warming, much greater sea level rise becomes possible for the USA and globally because of the potential for rapid melting of ice sheets in Greenland and Antarctica.
Sweet, W.V., et al, 2022: Global and Regional Sea Level Rise Scenarios for the United States: Updated Mean Projections and Extreme Water Level Probabilities Along U.S. Coastlines. NOAA Technical Report NOS 01. National Oceanic and Atmospheric Administration, National Ocean Service, Silver Spring, MD, 111 pp. Published 15 February 2022. Available at https://oceanservice.noaa.gov/hazards/sealevelrise/noaa-nostechrpt01-global-regional-SLR-scenarios-US.pdf