Global mean sea level rise scenarios provide an overall estimate of how sea level could change in the future. However, local effects can produce sea level changes that are substantially different than the global average. To capture those effects, sea level projections were produced for a 1-degree grid (approximately 69 mi. by 55 mi. at 38° north latitude) covering the coastlines of the U.S. mainland, Alaska, Hawaii, the Caribbean, and the Pacific island territories as well as the precise location of tide gauges along these coastlines. Adjustments to sea level projections included 1) shifts in oceanographic factors such as circulation patterns, 2) changes in the Earth’s gravitational field and rotation, and flexure of the crust and upper mantle, due to melting of land-based ice, 3) vertical land movement (subsidence or uplift) due to glacial isostatic adjustment (ongoing changes in elevation due to the retreat of ice sheets at the end of the last Ice Age), sediment compaction, groundwater and fossil fuel withdrawals and other non-climatic factors.

Changes to sea level are quantified on a decadal basis from 2000 to 2150. Decadal projections allow the information to more easily be incorporated into decision making, while projections extending into the 22^nd century highlight the continuous nature of sea-level rise.

The probability of exceeding a given sea-level-rise scenario is based on future greenhouse-gas emissions. The range of probabilities for the selected sea-level rise scenario is provided in the Summary Statistics table for each scenario to account for a variety of potential future emissions pathways.

Updated science indicates physically plausible global mean sea-level-rise scenarios of up to 2.0 m (6.56 ft) by 2100. The 2017 report which precedes the most current 2022 edition included an Extreme (2.5-m, 8.9 ft) scenario which was meant to capture this low-probability, high-impact possibility, but updates to this information indicate that this scenario is so unlikely that it would be misleading to continue to include. For this reason, the 2.0 m scenario is considered to be the most extreme-but-still-possible scenario, and the highest impact that this may have on certain U.S. locales is around 3m (9.8ft).