During the last ice age thousands of years ago, the weight of glaciers pushed down land in what is now the northern U.S. When those glaciers receded, that northern land began to rise, and land here started sinking, as if Virginia were on the end of a see-saw after the other rider got off.
Throughout most of the 20th century, the sea level in southeastern Virginia rose about twelve-hundredths of an inch a year -- or 12 inches per century.
But over the past two decades or so, the rate appears to have doubled in places. About half of that increase seems to be due to the sinking of land, and half to global warming, said Carl Hershner, a professor at the Virginia Institute of Marine Science.
"And the forecast -- this is the scary part -- is for that acceleration to rise," Hershner said.
Scientists say the future increases will be caused almost entirely by climate change. "We will still be sinking," Hershner said, "but that will be a smaller and smaller fraction of the change we experience."