Sea levels are soaring.
In fact, ocean surfaces are rising faster than they ever have in 2,800 years, scientists reported Monday. Humans are largely responsible for the acceleration, they said, due to global warming likely caused by fossil fuel emissions and greenhouse gases.
Get Data Sheet, Fortune’s technology newsletter.
"The 20th century rise was extremely likely faster than during any of the 27 previous centuries," said the authors of a study published in the scientific journal Proceedings of the National Academy of Sciences. The teams models could not reliably project further into the past, the Washington Post reports.
The researchers estimated, using tidal data and reconstructive techniques, that in the absence of global warming, 20th century sea levels likely would have either receded three centimeters or climbed seven centimeters. That would have been consistent with sea level averages that have held for millennia, tending not to fluctuate more than 7.6 centimeters in either direction per century, as the Guardian notes.
Instead, sea levels appear to have risen by 14 centimeters, or about 5.5 inches, in the past century. About half of observed sea level gains between 1900 and 2000 are likely due to human activity and industrialization, the scientists determined.
For more on climate change, watch:
The paper's ten university-affiliated co-authors, led by Robert Kopp, a climate scientist at Rutgers University, said that oceans could rise three or four feet by 2100 if present-day emission rates are left unchecked. In a lower emissions future, as promoted at the the recent climate talks in Paris, sea levels could rise one to two feet.
“Physics tells us that sea-level change and temperature change should go hand-in-hand,” Dr. Kopp told the New York Times. “This new geological record confirms it.”