Resources

Sea level along the U.S. coastline is expected to rise, on average, 10 - 12 inches 0.25 - 0.5 meters in the next 30 years, which will be as much as the rise measured over the last 100 years (1920 - 2020). Sea level rise will vary regionally along U.S. coasts because of changes in both land and ocean height.

On average, rise in the next three decades is anticipated to be:

• East Coast: 10-14 inches 0.25 - 0.35 meters
• West Coast: 4-8 inches 0.1 - 0.2 meters
• Gulf Coast: 14-18 inches 0.35 - 0.45 meters
• Carribean: 8-10 inches 0.2 - 0.25 meters
• Hawaiian Islands: 6-8 inches 0.15 - 0.2 meters
• Northern Alaska: 8-10 inches 0.2 - 0.25 meters

This report provides greater confidence in estimates of sea level rise out to 2050 than the previous 2017 report because of advances in sea level science, as captured in the Intergovernmental Panel on Climate Change’s Sixth Assessment Report, and the use of multiple lines of evidence: both the trends in the amount of relative sea level rise already observed and the models of future sea level rise closely match one another in the next 30 years.

Sea level rise will create a profound shift in coastal flooding over the next 30 years by causing tide and storm surge heights to increase and reach further inland.

With this shift, by 2050:

• Minor flooding is expected to occur, on average, more than 10 times as often as it does today, and can be intensified by local factors.
• Moderate flooding will occur more frequently than minor flooding does today.
• Major flooding is expected to occur five times as often as it does today.

Coastal flooding can be exacerbated by many factors that are not included in these estimates, such as rainfall, river discharge, wave impacts like coastal erosion, and existing infrastructure.

Without additional risk reduction measures, U.S. coastal infrastructure, communities, and ecosystems will face increased impacts.

Current and future emissions will determine the amount of additional rise in the future: the greater the emissions, the greater the warming, and the greater the likelihood of higher sea levels.

• Because of emissions to date, 2 feet 0.6 meters of sea level rise will likely occur along the U.S. coastline between 2020 and 2100. Failing to curb future emissions could cause an additional 1.5 to 5 feet 0.5 to 1.5 meters of rise, for a total of 3.5 to 7 feet 1.1 - 2.1 meters.
• Above 5.5°F 3°C of global warming, much greater sea level rise becomes possible for the U.S. and globally because of the potential for rapid melting of ice sheets in Greenland and Antarctica. The amount of additional warming required to trigger this is unknown because ice sheet instability is difficult to model and there is great variability in current modeling approaches.

This report provides greater confidence in estimates of sea level rise out to 2050 than the previous 2017 report because of advances in sea level science, as captured in the Intergovernmental Panel on Climate Change’s Sixth Assessment Report, and the use of multiple lines of evidence: both the trends in the amount of relative sea level rise already observed and the models of future sea level rise closely match one another in the next 30 years.

Continuously tracking how and why sea level is changing is an important part of informing plans for adaptation. Our ability to monitor and understand the individual factors that contribute to sea level rise allows us to track sea level changes in a way that has never before been possible.

U.S. federal agencies monitoring and assessing key sea level rise contributors can provide early indications of change in the trajectory of sea level rise— which can inform shifts in adaptation planning.