Sea level rise is one of the most visible effects of climate change. It can be seen in tide gauge data, satellite laser altimeter measurements and on land with coastal erosion. The global average sea level (GMSL) has been rising faster than ever before, and the speed-up is likely due to the increasing ocean heat content from human emissions of greenhouse gases.
The ocean absorbs about 90 percent of the excess heat from global warming and, as it warms, expands. That is pushing the Greenland and Antarctic ice sheets to melt, adding water to the oceans. The oceans also lose liquid water from aquifers, lakes and rivers as they shrink or drain, and from people depleting groundwater.
This “one-two punch” of rising seas is pushing nuisance floods farther inland. And in the long run, it’s expected to drive coastal erosion and make islands disappear. It’s a frightening prospect, especially for Pacific island nations like Tuvalu and Kiribati, which could be flooded with as much as 3 feet of water by 2100 if current trends continue.
Of course, the Earth is not flat like a bathtub and there are regional differences in how much sea levels rise. That’s why scientists who study sea level changes-using local data such as tide stations and satellite laser altimeters, and global data such as from ocean observatories and climate model projections-trial to account for all of these complexities so that they can hone in on long-term trends.
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