Warming Imperils Md. Species
Scientists Fear Loss Of Baltimore Oriole, Native Brook Trout

By David A. Fahrenthold
Washington Post Staff Writer
Monday, March 19, 2007

The Baltimore oriole is the state bird of Maryland. The brown pelican is the state bird of Louisiana. But now, as climate change seems to be leaving its first footprints here, local scientists worry that the Washington area may be slowly trading one for the other.

About 1,000 brown pelican chicks hatched in Maryland last year. That was about 1,000 more of the birds, ungainly fish-eaters comfortable in the steamy Southeast, than there were in the state in 1985.

The oriole, by contrast, might be gone from here in a century. Researchers say that as Maryland's climate warms, the bird could shift its territory to the north, becoming, perhaps, the Philadelphia oriole.

As the global scientific community has settled on a consensus that the world is warming, local researchers have begun trying to understand the impact here. Already they've found enough to create serious concerns for the future -- about shifting bird migrations, increased "dead zones" in the Chesapeake Bay and bringing some beloved species to the edge of their tolerance for heat. Brook trout, the area's only native trout, could be disappearing from its last refuges in the woods of Frederick County, for instance.

This issue will take center stage in Washington tomorrow with a rally at the U.S. Capitol calling for reductions in greenhouse gases. Organizers, from the Episcopal Church to the National Wildlife Federation to the U.S. Public Interest Research Group, say Climate Crisis Action Day will be the largest rally about climate change ever in the capital.

It will be a political sign of what scientists already know: Washington is being changed by warming temperatures.

"We certainly know that we've been experiencing climate change impacts," said Bill Dennison, a vice president at the University of Maryland Center for Environmental Science. He added that even a seemingly slight warming trend can be significant in the interdependent world of nature.

"What's a degree? Well, think about if you ran a couple degrees' temperature," Dennison said. "We're already a couple degrees elevated. That's affecting our health."

The public's interest has been stoked recently by the Oscar-winning documentary "An Inconvenient Truth" and a U.N. report that says the temperature increase is "very likely" man-made, at least in part.

The causes of the warming, authorities believe, are the so-called greenhouse gases, which include emissions from cars and power plants burning fossil fuels. The gases accumulate in the atmosphere, creating a layer of insulation that holds in more heat.

Certainly, Washington has not missed out on the heat. Climate data show that the average annual temperature in the District has climbed about two degrees since the early 1960s. Weather data going back to the 1870s show that five of the 10 warmest years on record in the District have come since 1989.

Researchers have begun trying to learn how that trend is changing the surrounding ecosystems, from the wooded ridge of Catoctin Mountain to the weedy bottom of the bay. So far, the evidence is spotty, anecdotal and often inconclusive -- but it can still be arresting, when it shows eons-old processes threatened by change.

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."