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.
Date Range: 1880 - 2018
Rate of global sea level rise is increasing
Global sea level has risen by about 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.
About Sea Level RiseRising 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 Louisiana, for example, local sea level is rising about 4 inches per decade because the land is sinking and sea level is rising.
Global average sea level has risen by about 8 inches (about 21 cm) since 1900, with about 3 of those inches (about 7.5 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 the 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 5- to 10-fold since the 1960s in several U.S. coastal cities (very high confidence). Rates of increase are accelerating in over 25 Atlantic and Gulf Coast cities (very high confidence).
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.