Climate Change Brings Risk of More Extinctions

In 2004, University of Tennessee professor Lee W. Cooper was off the north Alaskan coast when he saw about a dozen calves swimming toward his boat. His theory: The calves, alone and desperate without ice nearby, thought the boat might be a large iceberg.

There was nothing the scientists could do to help, Cooper said. "I think they were doomed."

Other changes have been less deadly, but they show centuries-old patterns shifting. Scientists have noticed changes in the timing of seasonal migrations, presumably caused by the earlier onset of warm weather.

In some cases, migrating animals suddenly find themselves out of rhythm, missing the weather conditions or the food they need. In parts of the Rocky Mountains, American robins arrive two weeks earlier than they used to -- and often discover the ground snow-covered and little food to be found.

In other cases, an animal's entire territory that shifts, as old habitats become too warm. In many cases, this means a move north. In others, it means a move up.

The American pika, a small rodent that lives on the slopes of mountains in the western United States, can overheat when temperatures hit 80 degrees. Over the past century, these creatures have kept climbing, reaching new ranges that can be 1,300 feet up the slope.

In some cases, there is no escape. In Costa Rica's Monteverde Cloud Forest, a famous region that is kept damp by fog and mist, climate change has brought more variable weather and less of the clouds that some animals need.

Two amphibian species -- the golden toad and the Monteverde harlequin frog -- have not been seen since the late 1980s. These may be some of the first extinctions linked to climate change, said cloud forest researcher Alan Pounds. "It's been an interesting puzzle to work on," Pounds said. "But, at the same time, very alarming and frightening."

At the Blackwater refuge, it is rising waters, not rising temperatures, that are eliminating habitat. A quirk of geology means that water rises especially fast here: Paradoxically, the land in this area is sinking as North America slowly unbends from the weight of glaciers during the last ice age.

Add that to the effect of melting polar ice, and scientists expect that most of the marsh will become open water by 2030. When it goes, there could be a shortage of habitat for the Eastern Shore's marsh animals and migratory birds, said Stone, the refuge biologist.

"Birds will return for spring migration, and they'll be looking for territory, and there just won't be enough territory to go around," he said.

So what happens then?

"They'll . . ." he paused, looking for the right word, ". . . die. They'll disappear."

Not all animals, of course, will suffer. There are examples of creatures that are thriving in a warmer world. Fish such as pollock and pink salmon have begun moving into now-warmer Arctic waters. In the northern woods of North America, some tick species are making it through the winter in record numbers.

Livestock herds might increase in a warmer world, an analysis by the Agriculture Department found. That's because food crops such as corn and rice could become harder to grow if the fields dry out, leaving more land for grazing. Researchers say that, even if all greenhouse-gas emissions were shut off today, the gases already in the atmosphere will cause Earth to warm for years to come. But, many say, it's still imperative to reduce these emissions to head off even more warming.

"Unfortunately, it takes a generation or two to turn this supertanker around," said Stephen Schneider, a professor at Stanford University, talking about the climate change already in progress. But still, he said, it is important to start trying. "What we're looking at is a planetary environmental train wreck if we don't start some compromising here."

Already, some are trying to make it easier for wild animals to adjust. In Australia, conservationists are trying to set aside a north-south cordon of open land so animals can move if they need to. In the western United States and Canada, environmentalists are trying to create a similar corridor between Yellowstone National Park and the Yukon Territory.

Overall, scientists say, the news of climate change will not be bad for all animals. But, they say, that's cold comfort for the rest -- and for humans, as well, if it means that we watch some of the planet's most beloved species decline or disappear.

"Yeah, the earth will recover," said Scott Wing, who studies the biology of previous eras at the Smithsonian Institution. But, he said, "would you have wanted to be one of the dinosaurs when the asteroid hit? No."