Sea level rise is the gradual addition of water to oceans worldwide, caused by melting glaciers and ice sheets, thermal expansion, tectonic plate movement, land sinking, and human activities like fossil fuel extraction and groundwater pumping. It is a global phenomenon, with many coastal areas already experiencing increased flooding, higher storm surges and other impacts from climate change, and it is expected to worsen in the years ahead.
Scientists track the pace of sea level rise through a variety of methods, from direct measurements of glacier melt to tiny shifts in gravity observed by satellite. They are able to separate the natural variations in the oceans and tides from the human-caused increase, so they can focus on long-term trends.
During Earth’s history, sea levels have risen and fallen dramatically, with periods of no ice on the poles and times when oceans were hundreds of feet higher than they are now. Scientists know that current sea level rise is mostly due to global warming, with melting of the Greenland and Antarctic ice sheets contributing about half of the total.
The question of how fast seas will rise is a vital one for coastal communities and infrastructure. In some places, 6 inches of sea level rise could mean high-tide floods more often, while in others it might lead to constant flooding with saltwater contaminating freshwater aquifers that sustain agriculture and towns. The rate of sea level rise is also important to understand, as it helps determine when adaptation strategies might be needed and how quickly impacts might worsen.
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