© Daniel J. Cox/NaturalExposures.com
Polar bears depend on a cold Arctic for their survival. Sea ice, frozen tundra, and deep snow are instrumental to their existence.
Polar bears live in four different Arctic regions dispersed among Canada, the United States, Russia, Norway, and Greenland.
The eco-regions are categorized as...
This occurs at the southern extreme of the polar bear's range, where the sea ice melts completely each summer and the bears must wait for freeze-up in the fall until they can hunt again.
Sea ice forms along the shore but then retreats. As the sea ice retreats farther from shore in a warming Arctic, polar bears are faced with a choice of coming ashore—and fasting until the ice returns in the fall—or swimming long, exhausting distances to reach the remaining pack ice. Because ice far from shore lies over less productive waters, it doesn't offer ample hunting opportunities.
Sea ice formed locally and transported from other parts of the Arctic collects along the shores of these habitats, providing polar bears with access to seals over productive waters. Scientists predict that, without action to reduce climate change, ice in these areas will disappear within 75 years.
Islands in the Canadian High Arctic and Greenland are far enough north that sea ice remains along the coast even in summer. These areas, along with other High Arctic Islands, are likely to provide a final refuge for polar bears and their ice seal prey. But they too are ultimately threatened unless we take action.
One of the most important aspects of sea ice for polar bears is feeding. Ice seals provide the fat-rich diet polar bears have evolved to exploit—a diet critical for survival in the cold Arctic.
In fall, seals create and maintain breathing holes in the ice using the sharp claws on their fore flippers. They keep the breathing holes open all winter long and surface every five to fifteen minutes for air.
As polar bears like Anuri walk across the ice, they use their heightened senses to locate a seal’s breathing hole.
Patience is essential to the polar bears' skill. At times, they'll wait for hours or days before they make a confident attack. Using speed, claws, and teeth, they catch the seal and feed on the fat-rich prey.
Polar bears' lives are a cycle of feasting and fasting. When hunting is good
and a polar bear is in optimal physical condition, the bear eats only what it needs—often focusing on just the fat.
For a polar bear, this is sustainable nutrition.
With changing temperature patterns and increased human activity in the Arctic, the ecosystem is vulnerable. Changes at the top of the food chain reflect even more significant changes to the animals and organisms that support them. It is possible, if not likely, that we will see entire ecosystems change fundamentally.
Increased greenhouse gas emissions warm the earth by layering the ozone with pollution. This heat increases the rate of melting sea ice, destroying polar bears’ natural habitat and the ecosystem they rely on.
Sea ice extent observations (1970 to 2007) and forecast (2030 to 2100) are reproduced here using data from the National Oceanic and Atmospheric Administration Geophysics Fluid Dynamics Laboratory (NOAA GFDL) model. Yearly extent represents an average sea-ice concentration of approximately 80%.
Climate change, and the melting sea ice associated with it, invites complex threats to the Arctic ecosystem—not just limited access to food for polar bears, but increased human activity in the North, industrialization of the habitat, increased exposure to pollution, and new diseases.
Despite year-to-year variation, satellite data shows that the September sea-ice extent has declined more than 13% per decade since the satellite record began in 1979.
Forces bears to swim long distances to find food for themselves and their offspring.
Reduces access to food, which is less plentiful as sea ice disappears.
Decreases body condition, due to expending significant energy reserves on swimming.
Decreases cub survival rates because of the cubs' increased chances of drowning.
Melting sea ice invites more human activity—without any consideration for the natural ecosystem and the challenges facing its inhabitants.
With less sea ice, there's more opportunity for commercial and industrial exploration in the Arctic, adding the risk of serious environmental threats to the area.
More shipping routes means increased oil and natural gas transportation and exploration. Scientists are concerned there is no emergency response infrastructure in the event of an oil spill on the ice, or in ice-mixed waters. Increased oil exploration and development also adds to the likelihood of seismic disturbances, potentially interfering with prey distribution. The production of Arctic fossil fuels also has the added irony of “fueling” the very warming trend that is causing the loss of sea-ice habitat.
Mining activity disturbs habitats along sea ice by adjusting the environment to service infrastructure, ports, and warehousing. This is especially dangerous during the denning season for polar bears.
Increased human activity can lead to a surge of human-to-polar-bear conflicts. Polar bears are naturally curious animals drawn to unusual sights and smells. They check out campsites, cabins, and tourists. Without careful management and education, these encounters could end tragically—for polar bears and people.
At first glance, the polar bear’s natural environment seems white and pristine—far removed from the pollution of major cities and industrial areas.
But in reality, polar bears can carry surprisingly high loads of toxic chemicals.
Wind and ocean currents transport pollutants to parts of the Arctic, where they're concentrated as they make their way up the food chain. Polar bears like Anuri and her cubs absorb these higher levels when they eat seals, their main food source.
Toxicity changes their hormonal systems, including hormones essential to growth, reproduction, and metabolism.
It suppresses their immune system.
At high levels, it can even affect polar bears' nervous systems and potentially their cognitive function.