Air temperatures in the Baltimore region rose between 2 and 3 degrees in the last century, according to the Chesapeake Bay Program’s annual Bay Barometer report, which measured climate change in the watershed for the first time.

The annual Bay Barometer report tracks the goals for the Chesapeake Bay Watershed Agreement, signed in 2014 by former Gov. Martin O’Malley and the leaders of other watershed states.

This year’s 2017-2018 report, released last week, found “encouraging signs of resilience” and noted positive trends for the bay’s underwater grasses, fish passage, protected lands and water quality standards.

The report included three climate change indicators for the first time — air temperature change, stream temperature change and sea level rise. Experts said last week that as the program works to restore the bay, it needs to take into account a changing climate, which can impact habitat and species.

Peter Tango, the Chesapeake Bay monitoring coordinator with the U.S. Geological Survey, said there are climate impacts from the headwaters to the lower bay.

For example, he said, rising water temperatures affect fish like the brook trout, which live in the upper reaches of the watershed and need cold, clean water. Submerged aquatic plants can be stressed by extreme temperatures.

Adding climate change to the annual report will help officials and researchers understand how those stress points relate to the recovery of the bay, Tango said.

Bill Dennison of the University of Maryland Center for Environmental Science said understanding those effects on a regional scale is also important.

“It’s not equal,” he said.

Some areas are experiencing more effects, some less, he said, and officials need to know what is happening where to more precisely target restoration. The barometer report looked at rising temperatures in 33 NOAA-defined climate divisions.

“In general, the climate signal means we have to work harder to achieve our goals,” Dennison said.

This year’s barometer shows that between 1901 and 2017, average air temperature changed between 2 and 3 degrees in the Baltimore region.

The increase was less in other parts of the Chesapeake Bay watershed, but overall 32 of 33 areas experienced significant long-term air temperature increases, according to the report.

As air temperatures increase, rivers and streams will absorb more heat, the report said. Between 1901 and 2014, 27 of 72 stream sites in the watershed showed increased water temperatures. Of those, the average increase was 2.1 degrees. The report states that the largest water temperature increases were in the southern part of the watershed.

The report also highlights a fact well-known in Annapolis — the sea level is rising. According to the report, between 1960 and 2017 the sea level in Annapolis increased 8.01 inches.

“Chesapeake Bay Program partners are embracing science, pollution prevention and community resilience as the climate impacts of warmer, wetter and wilder weather intensify,” Maryland Department of Environment Secretary Ben Grumbles said in a statement. “It’s more important than ever to measure our progress and treasure our assets, with steady stewardship and innovation.”

Rachel Felver, a spokeswoman for the Chesapeake Bay Program, said this year’s report overall is a cautionary success story. Between 2015 and 2017, 42 percent of the bay and its tributaries met water quality standards. Still, areas remained that need improvement — the report also found that in 2016, 83 percent of waterways were impaired by toxic contaminants.

rpacella@capgaznews.com