Defenders Magazine

Feeling the Heat

Rapid changes in our global climate are wreaking havoc on wildlife in some unexpected ways.

By Jad Davenport

© USFWS

Global warming should have been a boon for the 123,000-strong Porcupine caribou herd of northern Alaska and Canada’s Yukon. With the spring thaw arriving earlier and winter storms returning later, the tundra on their summer grazing grounds along the Beaufort Sea has grown richer and thicker. Milder winters have meant decreased snow cover. In the caloric budget of the barren ground caribou, this should have meant higher winter survival rates and more prolific summers.

Unfortunately for the caribou, and for many other large mammals of North America, the short-term benefits of global warming and climate change come with a heavy price. Ecosystems out of balance, increased opportunities for invasive species and changing habitat all have the potential to make the chaotic period of climate change a mammalian disaster, often in unexpected ways.

"The mosquitoes are doing great," says David Klein, professor emeritus at the Institute of Arctic Biology with the University of Alaska in Fairbanks. "Unfortunately, they have made life miserable for caribou. On warm, still days, the mosquitoes swarm all over them."

The caribou are so frantic trying to shake off the whining clouds of voracious insects, he says, they can’t graze effectively or put on sufficient winter stores of fat. "In winters following warm summers, we have found that body conditions of the caribou are deteriorating. They haven’t fed as well and have much less fat to help them get through the winter."

If mosquitoes aren’t bad enough, caribou also have to contend with another insect species that, again thanks to global warming, is extending its season. Bot flies are bumblebee-sized parasitic flies that squirt their microscopic eggs into the caribou’s nostrils. "The larvae make their way to the lungs where they incubate before migrating out to just below the skin," Klein explains. "During the short summers, the juvenile flies live off nutrients in the fat and punch holes through the caribou’s skin to breathe."

In the past, most caribou had a few bot fly larvae, and it wasn’t a big deal, says Klein. "But when you start to see individuals infested with hundreds, it becomes a serious issue. The larvae can choke off a caribou’s air passage and make breathing difficult, especially if they have to run to escape a predator. If a caribou has too many larvae eating holes in its skin, the resulting infections can draw on its winter fat reserves. This, in turn, can cause its hair to fall out, reducing winter insulation."

For now, the Porcupine herd finds refuge in drier, windier tundra along the coast. The grazing isn’t as good, but they are able to find some respite from the biting insects. If the climate change continues, says Klein, the caribou will run out of these safe havens. "They can’t move any farther north; they are already at the top of the continent. Where are they going to go?"

The science behind the caribou’s quandary tells an ominous story.

Through the millennia, sunlight has poured through our relatively thin atmosphere. Some of the sun’s heat is absorbed by the oceans and forests and tundra and deserts, and the remainder is reflected back into space. Before it escapes, however, a fraction is trapped by atmospheric gasses. The result is the greenhouse effect.

When it achieves its own equilibrium, there is nothing inherently bad about the greenhouse effect. Naturally occurring greenhouse gases such as water vapor, carbon dioxide and methane allow life to exist on Earth. Without their insulating blanket, the planet would be a frozen wasteland like Mars or a boiling cauldron like Venus.

And through the eons there have been long periods of warming and cooling across the globe. Greenhouse gases raised the Earth’s mean temperature by 10 degrees F at the end of the last ice age. Not long after dinosaurs went extinct, it went up by 25 degrees F. Fossil records of palm trees and crocodiles have been found on the same snowy shores where polar bear tracks meander today along the Hudson Bay.

The difference today is the speed and magnitude of change. Ancient species were able to adapt to the new conditions because the changes to their environments occurred at a glacial pace, over tens of thousands of years. Those that weren’t able to adapt migrated slowly toward more favorable climates as vegetation and prey species evolved.

The future for global warming refugees this time around is bleaker. Not only do species face a gauntlet of immovable human-constructed steel and asphalt on their way to keep up with changing climates, but the planet is entering a contemporary warming phase that the overwhelming majority of scientists say is being artificially enhanced and accelerated by humans. The Intergovernmental Panel on Climate Change, a UN-sponsored consortium of international scientists, recently announced that the Earth’s average surface temperature is up 1.1 degrees Farenheit over the last 100 years, a change of unprecedented speed. And the current level of carbon dioxide in the atmosphere has increased 31 percent since 1750, likely reaching the highest level in 20 million years.

It would be a mistake, however, to assume that the entire planet is simply warming. Although the average temperature is indeed rising, the result is more accurately described as global climate change — a chaotic interference in planetary weather systems that is causing longer droughts, bigger floods and storms that are both more frequent and more severe. These changes and their impacts can vary significantly at the regional level.

At the Institute of Arctic and Alpine Research, part of the University of Colorado’s Mountain Research Station west of Boulder, Colorado, climatologist Mark Losleben has just returned from checking several weather stations. Twelve thousand feet up on the divide, the stations are part of a network established by the National Science Foundation to study long-term ecology. Conventional science says areas at the highest elevations and latitudes will be impacted earliest and hardest by global climate change. These stations, in use for three decades, are de- signed to act as early warning systems.

Losleben peels off wet wool socks and laughs when asked whether he has found evidence of global warming here. The temperature outside has dropped five degrees in 15 minutes and a curtain of snow shrouds the Indian Peaks. "The real issue is global climate change," he says. "In truth, some parts of the planet are heating up and others are cooling off, some places are getting wetter and some places are drying out."

One of the regions that seems to be getting wetter and cooler — at least temporarily — is the northern Rockies. Grizzly bears there are facing lean times.

The challenge for the bears isn’t directly coping with the climate. Grizzlies are extremely adaptive predators; they once ranged from the high deserts of Mexico through the rain forests of the Pacific Northwest and across the shortgrass prairies of Kansas. The trouble this time is an invasive species expanding its range in the turbulent wake of climate change.

In the autumn as they prepare for hibernation, grizzlies in the greater Yellowstone ecosystem spend almost all their foraging time raiding small middens of pinecones collected by squirrels. They are after the highly nutritious nuts of the white bark pine tree. According to U.S. Geological Survey biologists, a single bear will consume hundreds of thousands of these seeds a day as it layers on fat for impending hibernation.

Laurie Koteen was studying grizzlies in the Yellowstone ecosystem while a Master’s student at the Yale School of Forestry and Environmental Studies when she began noticing something strange several years ago. The bears were ranging farther and farther outside their existing territories in search of pinecone stashes. At about the same time, Koteen started seeing pines flagged with sickly red and yellow branches. Something was killing the pine trees, the squirrels weren’t able to cache away as many pinecones and the bears were losing out on a critical pre-hibernation food source.

The culprit, it turned out, was an alien fungus known as blister rust. Originally from Asia, it spread through Northern Europe and was introduced to North America in 1910, where white bark pines have no natural resistance. The fungus, which first kills the branches, then erupts in cankers on the trunks, grows best in wet weather, with ambient temperatures below 67 degrees Farenheit. Storm patterns and a subtle climate shift in the northern Rockies seem to be creating ideal conditions for the exotic fungus. In some areas of the Pacific Northwest, botanists say, the fungus has eliminated white bark pines entirely.

David Armstrong, a biogeographer with the University of Colorado at Boulder, says it is this domino effect paired with the remaining checkerboard of protected land that makes predicting the impact of global climate change on wide-ranging animals like grizzlies so tough.

"How are large animals going to respond to global change?" he asks. "We don’t know, and we can’t predict it right now. Conventional biology says it takes 100 pounds of shrubbery to make 10 pounds of bunnies to make one pound of coyotes," he says. This transfer of energy through the food chain — the energy pyramid — means that if you increase or decrease one level, you directly affect the species above and below.

"You can anticipate that the bigger animals will be hit hardest by climate change," he says. "If you’re at the top of the food chain, you are necessarily rarer than the organisms you feed on. The more pressure exerted on these smaller populations, the more danger there is to them."

The pressure exerted on the grizzly has as much to do with climate change as it does to do with a restricted range. Two centuries ago, biologists estimate more than 50,000 of these bears roamed the American West south of present-day Canada. Today, less than 2 percent of that number survive in five isolated habitats in Montana, Idaho, Wyoming and Washington. Nearly half of these live in the Yellowstone ecosystem. The bears impacted by blister rust, like the Porcupine caribou, have nowhere to go.

Another animal backed into a corner of its ancestral range and feeling the pressures of climate change is the endangered Florida panther. A mountain lion subspecies, the Florida panther once roamed throughout the southeastern United States from Tennessee to South Carolina and down through the Florida peninsula. Development spelled doom for the shy cats, and today only 100 exist in pockets of wilderness in southwestern Florida.

Climate change isn’t the most immediate threat to the panther, says Darrell Land, the biological administrator for Florida Fish and Wildlife Conservation Commission’s panther research team. But it could have a significant impact on the survival of this rare cat over the next century.

Climate change by itself, Land says, won’t wipe out the cats. "You’re talking about a species that has already successfully adapted to habitat from the southern tip of Patagonia, through the tropics of Central America and up into the forests of British Columbia." The danger, he says, is in how humans will react to environmental changes.

Take the shifting sea level. Oceanographers have documented a four- to eight-inch rise in ocean level over the last century as global warming thaws polar ice caps, and the change seems to be accelerating. NASA scientists say sea level is likely to rise 16 to 26 more inches by 2100, threatening coastal cities and wetlands with increased flooding, erosion and encroachment of salt water into streams and aquifers.

"At first it will be a war against shoreline erosion," Land says. "We’ll be building sea walls to keep back the waves. But I don’t think in the long run that will be successful. We’ll never be able to put enough refrigeration units on the polar ice caps to slow the melting."

Something has to give, Land says, and he’s pretty sure it won’t be people. "Right now between the state of Florida and the federal government, we have large chunks of panther territory protected, locked up. What is going to happen if folks start losing their sea-front properties? Will they pressure the government to open up these protected lands to rebuild the communities? What will take precedence in one hundred years: preserving the land we purchased and protected today, or relocating humans so people can have their golf-course beachfront communities?"

How much humans are willing to give up right now in exchange for slowing climate change is already being tested. On an international scale, more than 165 countries approved the Kyoto Protocol in December 1997. This agreement, sponsored by the United Nations, seeks to lower global greenhouse gas emissions from 1990 levels by an average of five percent by 2012.

Although President Clinton signed the Kyoto Protocol in 1997, President George W. Bush has backed away from the commitment, claiming it unfairly places the burden on industrial nations by setting no binding commitments for developing countries. The result, says the president, would hurt the national economy. President Bush also has reneged on his campaign pledge to lower carbon dioxide emissions in the United States and most recently called for years more study on climate change before he will consider taking steps to reduce emissions.

In fact, the United States is currently the single largest contributor of greenhouse gas emissions. With less than 5 percent of the world’s population, this country spits out 25 percent of the total pollutants entering the atmosphere. The bulk of these gases comes from burning fossil fuels in vehicles and power stations.

Changes are, however, being made across the nation, and grassroots efforts are taking hold. California and a handful of New England states have legislated tougher emission standards for new vehicles. According to a November report by the Pew Center on Global Climate Change, many states are implementing programs to reduce their greenhouse gas emissions including promotion of renewable energy and air pollution controls. However, Pew Center President Eileen Claussen cautions that a national policy addressing the issue would be more efficient. "These state initiatives are achieving real reductions and are opportunities for learning, but they should not be viewed as a substitute for a comprehensive national policy that includes mandatory measures," she said.

Along the windswept coast of the western shore of the Hudson Bay, the question of who owns the beachfront property is already being answered. And the winner isn’t wildlife.

The region’s polar bears spend the frozen winter months out on the ice, hunting the bearded and ringed seals that make up 90 percent of their diet. Every summer with the breakup of the sea ice, hundreds of polar bears come to shore to wait out the summer, living off fat reserves built up from the winter hunt. Unfortunately for the bears, global warming and shifting weather patterns are conspiring to put them on a collision course with the small community of Churchill, Manitoba.

Cam Elliott, regional wildlife manager for the government of Manitoba, Canada, explains that the bears’ traditional migration patterns have been disrupted. "If you look at the Hudson Bay as a system, the currents and therefore the ice move in a counterclockwise motion," he says. "Lately, the ice has been breaking up sooner in the north. We wind up with bears in the north who don’t want to be there, they want to be back down in the summer habitat they are familiar with, so they head south." Unfortunately, Elliott says, the town of Churchill sits squarely on this ice-highway off ramp. "The reverse is true in the fall because the ice forms more quickly up north. We have bears in the south who are anxious to get out on the ice so they can start hunting. They, of course, start walking north." In addition, the shorter hunting season for the bears has reduced their ability to build up sufficient fat reserves and has reduced cub survival rates. Hungry bears denied their natural food source and spending more time on land have become more likely to seek out sources of food closer to humans.

Conflict became inevitable. In 1983, after a local man was attacked and killed in town, the government established the Polar Bear Alert Program. This program establishes a four-mile bear-free zone around the town. Locals who spot bears tip off wildlife officers via a 24-hour hotline. The offending bears are then chased out of the area by patrollers armed with firecrackers and shotguns. Repeat offenders, bears that have become savvy enough to recognize and avoid the pickup trucks with rooflights, are tracked down, tranquilized and held in a polar bear "jail" out near the airport. There, they cool their heels until the sea ice forms and they can be released.

Standing outside his cabin on the outskirts of town in October, resident Kelly Turcotte muses over global warming and the fate of the bears. A thin 34-year-old with a Prussian mustache, Turcotte sympathizes with the carnivores. "It’s been a tough year for the bears," he says. "We’ve had 90 come wandering through town in July and August. I had three out here by my house. I had to fire my gun through my kitchen window to scare one of them off." Turcotte doesn’t know what the future holds for the polar bears of Churchill, and that worries him. "It’s only going to get worse," he says. "Each year the ice is melting earlier and earlier, and each year freeze-up happens later."

A few hours later a helicopter thumps past the huskies curled up on top of their dog houses, past the newly built duplexes still wrapped in Tyvek. Slung low beneath it in cargo nets, there are three shaggy white lumps. Manitoba officials are paroling several offenders to make more room at the polar bear jail.

These three bears, for the time being at least, are the lucky ones. They are escaping the pace of climate change. What worries biologists like Elliott, though, and Churchill locals like Turcotte, is that even if chartered helicopters are able to help the bears outfly global warming in the short term, somewhere down the line, unless climate change is slowed, there won’t be any place for them left to fly to.

Jad Davenport is a freelance writer living in Denver.