The Arctic is changing. As temperatures slowly rise and the ice recedes, the shore is getting further away. Food sources that the polar bear have come to rely on are becoming less plentiful. In this changing climate, the polar bear is already showing signs of distress.

While polar bears struggle, opportunistic grizzlies fare well, as they benefit from the melting Arctic’s effects on its ecosystem. While the grizzly moves into newly opened territories, the polar bear can only wait for the freezing of its one-time kingdom. If the changing world proclaims the grizzly the new king of the Arctic, what will become of the polar bear?

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Online content for Arctic Bears was originally posted February 2008.

There’s no doubt the Arctic is warming. In fact, this extreme region has warmed faster than any other on earth, with the Arctic temperature increasing three to five times faster than the Earth as a whole over the past 100 years. Climate models predict that the Arctic will become an additional 7 to 12 degrees Fahrenheit warmer during the next century.

Experts predict these rising temperatures are likely to cause the melting of at least half the Arctic sea ice by the end of the century. Melting ice is expected to lead to even higher Arctic temperatures as bright white ice plays a significant role in reflecting the sun’s radiation. As ice melts, more of the dark ocean and land are exposed to absorb the radiation, thus further warming the climate. Research has found that over a major portion of the ice-covered Arctic Ocean, sea ice is 40 percent thinner than it used to be. And some climate models predict that by 2070, there may be no summer ice cover in the Arctic at all.

The disappearance of sea ice is a particularly dire threat to the polar bear, a super specialist in the Arctic environment. Polar bears rely on the ice to hunt seals, their main food source, and also to rest between hunts out on the ice. Trapped, drowning and starving bears have become such a concern that in September 2007, the U.S. Geological Survey (USGS) released a series of studies that led its scientists to conclude that “future reduction of sea ice in the Arctic could result in a loss of two-thirds of the world’s polar bear population within 50 years.” As sad as such a fate for this majestic creature would be, the consequences would extend far beyond the bear. A polar bear decline could trigger what biologists call a “trophic cascade,” or a complete uncoupling of the Arctic food chain.

As much attention as the effects of melting sea ice on polar bears has drawn of late, it is important to understand that the thaw will have immediate effects on everything in the marine food chain, from benthic invertebrates to marine mammals. What will be the fate of the ringed seal, bearded seal, bowhead, beluga, and walrus — all creatures that depend on the ice for habitat or food?

Warming not only affects sea ice, it alters the Arctic’s terrestrial landscape. Melted permafrost means a proliferation of low-lying shrubs. These northern-spreading shrubs establish a new order of plant life, shading out low-growing lichens and plants like ground willow and cotton grass, all favorite foraging items for grazers like caribou. Without their main summer and winter foods, caribou are vulnerable to starvation.

Another species affected by changing Arctic vegetation is the lemming. Drastic changes in its food supply of sedges and mosses, along with a lack of snow tunnels to burrow in, will challenge the survival of these rodents and may cause their populations to crash beyond repair. When lemming numbers drop, so do the numbers of predators like snowy owls and Arctic foxes. Researchers have already observed warning signs in the Arctic fox population in the form of an invasion of red foxes into the traditional range of Arctic foxes.

With a warming Arctic comes an earlier spring and a proliferation of parasitic insects such as flies and mosquitoes. For Arctic dwellers as disparate as caribou and guillemots, a population explosion of insects is at best a nuisance, and at worst, life-threatening. Grazers spend less feeding time and more energy just trying to escape these pests. Arctic-nesting Brunnich’s guillemots in Canada have been such victims of relentless mosquito attack, they have been observed abandoning their nests.

A changed season for insects also has a different effect on some other species of birds, which time their migrations to coincide with insect swells. Northern Alaska dunlins, for example, migrate from Asia and lay their eggs to take advantage of peak insect populations in order to feed their young. Warmer temperatures may cause the insects to hatch earlier, throwing off the carefully timed breeding and nesting season of the dunlins.

With the Arctic experiencing the most rapid and severe climate change on Earth, the plants and animals that have evolved to survive in this extreme habitat come increasingly under threat. Like the canary in the coal mine, the Arctic can serve as our early warning sign of impending climate change. Observing the tumultuous change its inhabitants are experiencing can be a lesson to us about the changes in store for the rest of the world.

For the layperson, trying to understand the essence of climate change research can be exasperating — particularly when it comes to the potential impact of global warming on the Antarctic. On the one hand it is reported that the Antarctic Peninsula, which extends north toward Chile, is warming; that a massive ice shelf the size of Delaware broke off from the Larsen B peninsula in 2002, a collapse that scientists say was of a scale unprecedented in the last 12,000 years; and that significant Antarctic ice melting could result in a perhaps disastrous rise in sea levels. On the other hand research indicates that, over the last thirty-five years, the Antarctic as a whole has cooled, and that the levels of sea ice are actually increasing.

Such ostensible contradictions have been used to suggest that global warming is, in fact, not happening. Yet part of the confusion is due to the lack of a broader context that can only come from more research. According to the results of a 2004 study by NASA’s Goddard Institute of Space and Studies (GISS), the recent cooling trend is an effect of the depletion in the ozone layer over Antarctica. “In the coming decades, ozone levels are expected to recover due to international treaties that banned ozone-depleting chemicals,” states a NASA press release. Once it does, Antarctica’s cooling trend is likely to rapidly reverse. The increase in sea ice levels, meanwhile, is also the result of global warming. A 2005 satellite study funded by NASA suggests that warming of the climate has led to an increase in precipitation rates and deeper snow in the Southern Ocean, which becomes so heavy that it pushes Antarctic ice below sea level, resulting in more and thicker ice.

There is still a lot of uncertainty about what could happen to Antarctica, and this sense of doubt — about the climate in general — has been used by politicians on both the left and the right to bolster their respective positions. President George W. Bush, for instance, has declined to cut carbon dioxide emissions from power plants, “given the incomplete state of scientific knowledge of the causes of, and solutions to, global climate change.” And in 2006, former Vice President Al Gore returned to the public eye when An Inconvenient Truth, a successful documentary film based on Gore’s lecture series about climate change, raised concerns that an immediate response to global warming was required to prevent catastrophe.

Perhaps the best a concerned nature-lover can do is turn to an outside body. According to a 2001 report by the Intergovernmental Panel on Climate Change (IPCC), an assessment panel established by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), a few things, at least, seem clear:

• The Earth’s climate system has demonstrably changed on both global and regional scales since the pre-industrial era, with some of these changes attributable to human activities.
• Emissions of greenhouse gases and aerosols due to human activities continue to alter the atmosphere in ways that are expected to affect the climate.
• More hot days and heat waves and fewer cold and frost days are very likely over nearly all land areas.
• The projected rate and magnitude of warming and sea-level rise can be lessened by reducing greenhouse gas emissions.