Between 1901 and 2010, global sea levels rose an average of 0.19 meters, or roughly seven inches. Over the next century, they’ll continue to rise—but at this point, that’s one of the few things scientists know for certain. Less understood is how fast they’ll rise, or where in the world these changes will be the most pronounced—information that will be crucial in helping coastal communities adapt to climate change.
“This is the burning question,” said Andrea Dutton, an assistant professor of geology at University of Florida. “How quickly will the sea levels rise, and by how much?”
To figure it out, Dutton and other scientists across the United States are studying sea-level changes dating back 125,000 to 400,000 years ago, when global mean temperatures were 1.5 or two degrees Celsius higher than they are today. In some cases, the global mean sea levels during these eras peaked at 20-30 feet above present rates.
According to the Intergovernmental Panel on Climate Change (IPCC), the planet is likely to reach those temperatures again by 2100—which means understanding the past millennia could help researchers determine how best to protect vulnerable areas from the rising tides.
The IPCC estimates a maximum 2.69-foot increase over the next hundred years or so, though other estimates are as high as three or four feet. In the meantime, some places have already begun to feel the impact. In southeast Florida, for example, four counties—including Miami Dade and Palm Beach—have formed a coalition called the Southeast Florida Regional Compact to develop strategies for problems like nuisance flooding, land subsidence, and saltwater intrusion into fresh water sources. Similar local efforts are taking place in the communities surrounding the Chesapeake Bay, and in other flooding hotspots around the country.