The Maryland Center for Environmental Science has found that the surface water temperature of the Chesapeake Bay is warming more rapidly than the surrounding air, which could complicate state and county Bay restoration efforts. The study identified urbanization and use of Bay waters to cool power plants as key causes of the increased warming. From the Center’s web page on the project:

The study, completed by Haiyong Ding and Andrew Elmore of the University of Maryland Center for Environmental Science’s Appalachian Laboratory, was published in the October issue of Remote Sensing of Environment.

“I was surprised that the pattern of increasing water temperature was so clear,” said study co-author Andrew Elmore. “If you take any group of five years, they are generally warmer than the previous five years. A consistent warming trend happening over a really large portion of the Bay.”

Trends of increasing water temperature were found for more than 92% of the Chesapeake Bay. Water temperature has been increasing more rapidly than air temperature in some areas, particularly in the main stem of the Bay and in the Potomac estuary. The Patapsco River in Baltimore showed the fastest warming of any area of the Bay, implicating urbanization of the watershed and use of the Bay’s waters to cool power plants along its shore.

An October 14, 2015, Baltimore Sun article analyzed the challenge the warming trend presented to Bay restoration efforts:

If unchecked, scientists say, the [warming] trend could complicate costly, long-running efforts to restore the ailing estuary, worsen fish-suffocating dead zones and alter the food web on which the bay’s fish and crabs depend. …

The increase averaged nearly 1.2 degrees Fahrenheit per decade, according to Andrew J. Elmore, co-author of the study and a geologist at the center’s Appalachian laboratory in Frostburg. …

“Many of the changes we see in the bay are tied in with these changes in temperature,” said Elmore. “What are we restoring the bay to?” …

Rising water temperatures could make it harder to shrink [the Bay’s oxygen] dead zone, or keep it from coming back, said Lora Harris, an ecologist with the University of Maryland’s Chesapeake Biological Laboratory in Solomons. …

[Harris] suggested that the most useful aspect of the new study is the focus it has put on land-based sources of warmer water, reinforcing the need to curb stormwater runoff and power plant discharges.

“Now we have a much clearer picture of what’s happening where,” Harris said. “That does give us the ability to think about how to optimize investments in restoration.”