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Fifth National Climate Assessment - Read the Report

Sea Level Rise

Sea level rise is primarily driven by two factors related to climate change. The first factor is “thermal expansion” – as ocean temperatures rise, the water expands. The second factor is melting of land ice (ice sheets and glaciers), which adds water to the world’s oceans.

The indicator shows the change in global average sea level since 1880, in inches.

The indicator shows the change in global average sea level since 1880, in inches. The blue line shows sea level as measured by tide gauges (1880-2013); the surrounding light blue-shaded area shows upper and lower 95% confidence intervals; the orange line shows sea level as measured by satellites for comparison (1993-2021). The lines become steeper in more recent decades, indicating an increased rate of change.

Date Range: 1880 - 2021

Rate of Global Sea Level Rise Is Increasing

Global average sea level has risen by more than 8 inches since scientific record keeping began in 1880. The rate of global sea level rise has increased in recent decades. The current rate is a little more than an inch per decade.

Why It's Important

  • Sea level rise and climate change-related threats like high tide and storm-surge flooding affects social, economic, and ecological systems along the U.S. coasts.

  • Sea level rise affects local infrastructure and economies in U.S. coastal communities as more areas are affected by tidal flooding and the effects of increasing storm surge during extreme weather events.

About Sea Level Rise

Rising global sea level is a critical consequence of climate change. As ocean waters warm, they expand. Also, as air temperatures warm, water from melting ice sheets, polar ice caps, and glaciers enters into our ocean basins.

Sea level rise is not uniform across the globe. Coastal communities are affected by their local sea level rise, which reflects global sea level rise, changes in local land elevation, tides and winds. In Grand Isle, Louisiana, for example, local sea level is rising about 3.5 inches per decade because the land is sinking and sea level is rising (NOAA 2022).

This indicator shows that global average sea level has risen by more than 8 inches (20 cm) since 1880, with about 2.5 of those inches (6 cm) occurring since 1993. Human-caused climate change has made a substantial contribution to sea level rise since 1900, contributing to a rate of rise greater than during any preceding century in at least 2,800 years. In addition to the global average sea level rise, local sea level rise – sometimes called “relative sea level rise” – happens at different rates in different places. Local sea level rise is affected by global sea level rise, but also by local land motions, and the effects of tides, currents, and winds. Many places along the United States coast have seen their local sea levels rise faster than the average global rate. As sea levels have risen, the number of tidal floods each year that cause minor impacts, often called “nuisance floods,” have increased in several U.S. coastal cities. Rates of increase are accelerating in over 80% of East and Gulf Coast tide gauge locations (Sweet et al. 2021).