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Global Warming/Photo Gallery
Feeling the Heat
A warmer climate will affect all species, but here are some whose world could change dramatically.

 

Atlantic Salmon
As early as 1866 there was enough concern about the future of the Atlantic salmon that the first private salmon hatcheries were built in New England. Despite determined efforts since then, the species continues to decline. North America’s wild Atlantic salmon populations have plunged from 1.8 million in the mid-1970s to fewer than 650,000 today, according to the Atlantic Salmon Federation. If the overall trend is bad, the situation is particularly dire in the United States, where a combination of dam building, habitat destruction, and acidity in rivers has depleted salmon populations to the point that the U.S. Fish and Wildlife Service placed the Maine population on the endangered species list in 2000. Now climate change appears to be compounding the problem. Paul Santavy, a supervisory fish biologist at the Maine Fisheries Program Complex, is finding that hatchery salmon, which are living in water that’s almost too warm for them to survive, are taking cues from warmer oceans and returning to the Maine hatchery earlier in the year to spawn. If this same behavior is happening in wild populations, it could disrupt the fish’s entire reproduction and development. “The major issues are timing,” says Santavy. Earlier spawning results in earlier hatching periods at a time when food such as zooplankton and larval insects might be unavailable, Santavy explains. “It only really takes one part of the equation to get them out of whack with the rest of their environment.”—Michael Lowe

American Pika
Scurrying across talus slopes in North America’s western mountains, American pikas, eight-inch-long, rabbitlike mammals, forage for fireweed, thistles, and grasses, which they store for the long winter ahead. In their range’s southern extremes, they rarely live below 8,200 feet, often in “sky islands”—remote, highelevation habitats separated from other similar habitats by intervening warmer, lower ecosystems (see “Band of Brothers,” page 66). Biologists predict that heat will creep up mountainsides, eventually driving peakdwelling species into extinction. “They live at the tops of the mountains, so to get from one island—or one mountaintop—to another, they have to go down to very inhospitable valley bottoms,” says wildlife biologist Erik Beever. “Pikas are probably the first or second worst species able to do that.” Under favorable conditions, pikas thrive, but where it’s already warmer, biologists have seen fewer individuals and believe those populations are shrinking. The pikas’ thick coats make them extremely sensitive to heat, and it is hard for them to survive for even a few hours when the temperature tops 77 degrees and they can’t find refuge. NOAA and the U.N. Intergovernmental Panel on Climate Change estimate that western temperatures will rise 5.4 degrees by 2050, so pikas are clearly in trouble. Still, some federal biologists believe pikas will hang on by migrating to higher, cooler habitats and changing their behavior at hotter sites, and
earlier this year the U.S. Fish and Wildlife Service declined to list them under the Endangered Species Act.—Susan Cosier

Mosquito
In the mountainous region west of Fort Collins, Colorado, mosquitoes barely survive. That’s why it’s the ideal spot to study how rising temperatures may affect the insects, including those that transmit West Nile virus. The virus, first found in North America in 1999, has been detected in at least 326 bird species. Humans are susceptible, too, though mortality rates are low: Less than one percent of people who become infected will develop severe illness, the CDC reports. The agency says 64 mosquito species are known to carry the disease, including several from the Culex, Aedes, and Anopheles (above) genuses. In the northern Colorado Front Range, mosquito expert Lars Eisen is investigating the upper elevation limits for Culex West Nile vectors. His findings indicate future warming might cause the skeeters’ range to shift north, meaning the disease would likely move to higher altitudes, too. “Still, with any climate change, they’ll gain some ground but lose some ground,” says Eisen, who leads the Risk Assessment and Management Solutions for Arthropod-borne and Infectious Diseases program at Colorado State University. As the northern tip of a mosquito’s range warms, allowing it to move into previously uninhabitable areas, the southern limit might become too hot. And overall, climate likely won’t be the only, or even the primary, factor in where it lives, says Eisen. “We’ve been creating a lot of mosquito habitat over the last 20 years with development and irrigation. It’s not just the climate changing; we’re changing the landscape as well.”—Alisa Opar

Narwhal
Mariners who journeyed to the Arctic brought back curious souvenirs: spiral, javelinlike tusks that inspired fantasies of the mythical unicorn. In truth, they came from the narwhal (its tusk is a roughly seven-foot tooth that grows from the upper left jaw of males and is used for sexual displays). The world’s 80,000 or so narwhals are found primarily between west Greenland and the Canadian high Arctic and, to a lesser extent, off eastern Greenland. After summering in shallow, ice-free waters around northwest Greenland, Baffin Island, and Canada’s Arctic archipelago, they embark on a two-month migration to their wintering grounds, mainly in Baffin Bay and Davis Straight. For half the year and amid extremely dense sea ice—no cetacean occupies such packed ice offshore for such a long time—they search for their primary prey, Greenland halibut. Narwhals make nearly two dozen 30-minute dives daily, to depths of up to 4,500 feet, among the deepest of all whales. Their habitual nature, small numbers, and limited range and diet make them extremely sensitive to climate change, says a study in Ecological Applications. Global warming is already affecting the sea ice narwhals are adapted to, and will likely increase their exposure to such events as ice entrapments—phenomena caused by sudden weatherchanges that quickly seal cracks in dense ice, which can suffocate cetaceans. A warming ocean could have an even bigger impact on narwhals by disrupting their finely tuned ecosystems and, thus, their food source.—Julie Leibach

Canada Lynx
The Canada lynx doesn’t ask for much—just boreal forests that stay snow-covered from December through March and offer plenty of its favorite meal: snowshoe hares. But fulfilling these needs isn’t getting any easier. Projections from the Intergovernmental Panel on Climate Change suggest that by 2100, boreal forests could decline by almost a fifth across the continental United States and Canada. Records from NOAA show that the 20 hottest years on record happened in the past three decades, and that globally, we’re seeing a steady drop in annual snow cover. This spells bad news for the lynx and the hare, both of which thrive in deep, fluffy snow. The lynx, which weighs in at between 20 and 44 pounds, has large, specially adapted feet that, like snowshoes, prevent sinking and give it an edge over competing predators, such as coyotes and bobcats, says Tamara Smith, a biologist for the U.S. Fish and Wildlife Service. “There’s not much overlap in their core ranges because of their different physiology and the way their feet are structured,” she explains. “But if the snow’s not quite as deep, other animals that would compete for the snowshoe hare would have more of an advantage.” For their part, hares, which turn white during winter, are more exposed if there’s not enough snow to blend in with. And fewer snowshoe hares equals less food for the lynx. Scientists have already determined that substandard sustenance decreases the size of the lynx’s litter, and a species that doesn’t repopulate doesn’t survive.—Michele Wilson

Vampire Bat
They say never to invite a vampire over your threshold, but warmer temperatures may usher some bloodsucking creatures across our southern border, invitation or no. The common vampire bat currently dwells in southern Mexico and up the country’s coastlines. Studies suggest you won’t find this bat anywhere the thermostat dips below 50 degrees Fahrenheit. As North America warms, the bat’s range is expected to increase by at least a third, pushing north into parts of Texas and possibly other southern states, including Arizona and Louisiana. “Vampire bats are a very opportunistic species,” says biologist Shahroukh Mistry. “It wouldn’t take much if the temperature limitation was removed.” Still, the shift would likely take place over decades, and other factors, like disease, might inhibit expansion. Government agencies and biologists are interested in tracking vampire bats partly because they transmit rabies. Using their razor-sharp incisors to puncture the skin, a bat can lap up more than half its body weight in blood in a half hour. Vampire bats prefer livestock but have been known to dine on other mammals, even humans. (People may benefit from the bat’s bite: Desmoteplase, an anticoagulating drug made from its saliva, is in clinical trials for stroke treatment.) While the risk of rabies—which the bats can get, too—is a serious concern, Mistry points out that livestock can be vaccinated. Noting indiscriminate killings in Mexico, he says, “The worst thing that could happen is a knee-jerk reaction that harms vampire bats when they move into a new area.”—Alisa Opar

 

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