Published March 11, 2008 02:09PM
Earlier this year, conservation biologists from the U.K.’s Leeds University led a global survey to determine how climate change will affect wildlife population ranges. Their troubling findings? An average of 15 to 35 percent of animals in a given region face local extinction–they’ll shift ranges to more favorable conditions or simply not survive–by the end of this century. Here’s the projected fallout in North America.
American goldfinch
Depending on CO2 emissions, populations of these lovely yellow-and-black birds will drop significantly or disappear entirely from 33 states by 2100.
Bull trout
Typically found in alpine creeks and glacier-fed streams, this fish’s habitat is so isolated it won’t be able to shift ranges without being actively transplanted. It may be gone from the Lower 48 by the end of this century.
Warbler
Many warblers will shift their summer breeding ranges north, out of states like Maryland and Georgia. Of the 35 species that breed in the U.S., seven (like the black-throated blue warbler, below) have already moved an average 65 miles north in 24 years.
Sonoran pronghorn
This endangered, desert-dwelling antelope is now isolated in a region that includes Mexico, Southern California, and western Arizona. Already small in stature and numbers (the population has shrunk 80 percent since 2000), it’ll go under by 2050 from thermal stress, lack of food, and water shortages.
Cutthroat trout
Warming streams will send the cutthroat to cooler northern waters as it potentially leaves Utah and the mountains of Nevada. The Natural Resources Defense Council says that 10 percent of U.S. trout habitat will be gone by 2030.
Moose
More than 4,000 moose roamed northern Minnesota in 1985; today there are fewer than 400. “Warmer summers make moose more vulnerable to parasites brought in by a booming deer population,” says Doug Inkley of the National Wildlife Federation. “This causes chronic malnutrition and lower birth rates.”
Desert bighorn sheep
A temperature rise of about 1.8°F from 1901 to 1987, coupled with a 20 percent decrease in average precipitation in southeast California, has led to a 37 percent reduction in bighorn populations. The National Wildlife Federation claims bighorns will disappear from the region if there’s a 3.6°F temperature rise and a 12 percent decrease in precipitation over the next 60 years, which is expected if current energy-consumption trends continue.
Edith’s checkerspot
Butterflies are highly climate-sensitive, and few more so than this species, found in the West from Mexico to Canada. Lepidopterist Camille Parmesan discovered that its population extinction was four times greater at the southern end of its range and two times greater at elevations below 8,000 feet, for reasons directly related to rising temperatures. Expect this species to keep moving north.
Conditions in America’s mountains will push these animals into extinction–or Canada.
What’s killing pikas in the Rocky Mountains? It’s the heat. Scientists predict that these adorable “rock rabbits” will die off within the next few decades as rising temperatures overwhelm their ability to adapt or migrate. In general, alpine animals are faring poorly in a warming world, mainly due to their elevated, isolated habitats. Species that depend on fir forests, frigid winters, and heavy snowpack are hitting a topographical wall that blocks their attempts to escape the heat. As a result, scientists expect climate change to spawn a new wave of endangered and locally extinct plants and animals, starting with the species described below.
American pika
The high-pitched chirp of this tiny mammal could soon fade to silence within alpine zones in the Rockies and Sierra. Intolerant of heat and dependent on talus slopes for food and protection, the pika is running out of high-elevation terrain to escape rising temperatures. As a result, it could be one of global warming’s first documented extinctions. In the last 40 years, nearly a third of the pika population in the Great Basin (the drainage between the Rockies and Sierra) has vanished. Donald Grayson, a University of Washington evolutionary ecologist who authored another key study, describes this animal’s future as “markedly insecure.”
Wolverine
This tenacious scavenger, known to challenge a grizzly bear over a carcass, has staved off two centuries of persistent trapping and habitat destruction. But the effects of global warming might finally chase it out of its northern Rockies sanctuary. Slow to reproduce and requiring an enormous range, wolverines depend on deep snowpack for both shelter (a den for giving birth in early spring) and food (animals killed by cold and avalanches). But its preferred habitat will shrink as winters get milder and snowline rises; climate models predict a snowline increase of 150 feet per decade, which will force the wolverine steadily northward.
Marmot
According to a long-term study at the Rocky Mountain Biological Laboratory, the internal clock of the yellow-bellied marmot is wildly askew. The animal is coming out of hibernation 38 days earlier in the spring than its forebears did 23 years ago, and the study’s author, biologist David Inouye, blames climate change. The consequences of this premature wakeup? The marmot awakens to more snow cover (22 inches deeper on average), and the lack of food can force it back to bed. When it rises the second time, it burns muscle instead of fat to jump-start its metabolism–which makes it vulnerable to starvation and predation.
Bicknell’s thrush
Every spring, this sparrow-sized brown songbird migrates from the Caribbean to the northern Appalachians, where the entire population breeds in conifer forests above 4,000 feet. Notoriously shy and picky, the Bicknell’s thrush nests almost exclusively in balsam firs. As global warming threatens its tree of choice, this rare bird has become of the most range-restricted breeding species in eastern North America. A 2002 study predicted that a temperature increase of 1.5 to 6.3°F by 2100 could thin balsam trees in New England by 96 percent as advancing hardwoods such as beeches and yellow birches crowd them out.