Warming Imperils Md. Species

Using an electrofishing backpack, John Mullican, left, and Mark Toms of Maryland's Natural Resources Department monitor brook trout in Little Fishing Creek. (Photos By Katherine Frey -- The Washington Post)

The work has taken them to such places as Little Fishing Creek, a glass-clear stream running through woods north of Frederick City. Brook trout, which once lived all over the Washington area, remain there. They were decimated by urban pollution, and officials fear that climate change will finish them off.

"All it takes is a couple of degrees to lose those fish," said Don Cosden, a state fisheries official.

The local trout prefer water colder than 68 degrees, he said. Already, streams such as this one can get that hot on summer days. State officials estimate that the fish might be gone from central Maryland in less than a century -- although they would probably survive in the cooler western mountains and in states farther north.

"This habitat is right on the edge of their ability to survive," Cosden said. "If you throw climate change in on top of that . . . then you hit a tolerance level that can take out a whole population."

Other studies of local plants and animals have found ways in which warming already seems to be re-tuning the rhythms of nature.

One of the first appeared in 2000, when Smithsonian scientists found that plant species, including Washington's famous cherry blossoms, were flowering days earlier than they had in 1970. One theory was that the plants were being tricked by weather that said spring, even if the calendar did not.

People who watch birds -- for fun or for a living -- have noted other changes that seem linked to warmer weather. This winter in Maryland, the Chesapeake Bay's flotilla of migratory ducks was smaller than usual, with thousands fewer canvasbacks, scaups and mergansers. Researchers' theory: The Great Lakes, where ducks often stop before venturing to the Washington region, didn't freeze in January, so the ducks saw no reason to head south.

In the Chesapeake, the most dramatic sign of warm weather's impact came in summer 2005. A long hot spell killed 95 percent of the bay's eelgrass, a crucial plant species that shelters baby blue crabs from predators.

"There was this really hot bath water sitting on top of eelgrass," which exceeded its temperature limit of 82 to 86 degrees, said Bob Orth, a professor at the Virginia Institute of Marine Sciences. "They go into heatstroke, and they just die."

Bay scientists said temperatures began climbing again in the summer. Luckily, they said, the remnants of Hurricane Ernesto cooled the water before the eelgrass was decimated again.

"We dodged a bullet, but the bullets are flying faster and faster," said Dennison, of the University of Maryland.

Armed with studies such as these, scientists have begun trying to forecast the future. One answer seems fairly certain: more heat. A recent U.N. panel on climate change predicted that global temperatures could rise about 0.7 degrees, on average, by 2027.

There are actually some benefits that added warmth brings. It might mean, for instance, that fewer blue crabs will freeze to death in their winter burrows. Larry Simns, president of the Maryland Watermen's Association, said his group has seen no reason for alarm so far.

"We think it's a natural cycle, and we're used to living in natural cycles," Simns said. "We'll deal with it."

But many local experts are more concerned.

Hot weather could supercharge the algae blooms that create low-oxygen dead zones in the Chesapeake. It could aggravate a disease that's killing off the bay oyster. It could cause sea levels to rise and swamp key wildlife habitats on islands and marshes. And it could make Maryland too hot for its remaining orioles.

The problem: It's difficult to foresee how small changes will ripple through nature's complex systems of predators and prey, flowers and pollinators.

"We know it will be different," said Jay Gulledge, staff scientist at the Pew Center on Global Climate Change. "Not knowing exactly what that means makes it more difficult to manage."