Fossils Show Chesapeake Bay Is Warmer

BALTIMORE —  Fossils found in Chesapeake Bay sediment samples indicate the bay has been getting warmer over the centuries. according to researchers.

The preliminary findings are part of a three-year study by the U.S. Geological Survey.

USGS researchers took samples of the sediment on the bay bottom near the Patuxent and Potomac rivers. The sediment cores range from 10 to 40 feet long. Geologists estimate they cover the last 1,000 to 9,000 years.

“Anything you can imagine that lived in the bay is preserved in those sediments,” said USGS researcher Thomas Cronin. “We’ve got a history book, and we’re using different tools to read the history.”

There’s no easy way to measure water temperatures from past eras and no way to pin a number on the degree of warming that might have taken place.

But USGS geologist Stacey Verardo estimated the changes by counting and dating fossils left behind by warm-water-loving, single-celled aquatic organisms called dinoflagellates. Over the last 1,000 years, the tiny creature’s numbers in bay sediments have nearly doubled, Verardo said.