Polar Bear - Threats

The IUCN Polar Bear Specialist Group (PBSG) documents that, both historically and currently, the main threat to polar bears remains over-hunting, although much of the traditional harvesting in local communities is sustainable.

The area covered by arctic sea ice is melting at an unprecedented rate. Polar bears need sea ice to access their food, and to move from hunting grounds to their denning or summer resting areas. This loss of habitat is the greatest threat to polar bears in the near to longer term.

Toxic chemicals transported to the Arctic from the south have long-term effects on polar bear health and longevity while oil exploration in the Arctic affects polar bears by fragmenting and disturbing their habitat, and by introducing oil and other toxic substances to their environment.

Hunting
Today, legal hunting of polar bears by non-native sport hunters is only found in Canada. The community itself decides what proportion of the quota it has been issued will be used for outside sport hunters.

In the areas that lack proper monitoring, such as Russia and Greenland, little information is available on current hunting practices. Since it is not known whether killing polar bears is balanced against the sustainable yield of a known population size in such areas, there is reason for concern regarding the sustainability of these practices.

The international Agreement on the Conservation of Polar Bears allows for the taking of polar bears for use by local people using traditional methods and exercising traditional rights. Though much traditional hunting by local communities is sustainable, the IUCN Polar Bear Specialist Group (PBSG) documents that, both historically and currently, the main threat to polar bears remains over-hunting.

Six of the 20 polar bear populations have unknown status. Some of these, for example the Arctic Basin and Queen Elizabeth populations, are in areas with few or no humans and are not hunted. However, in other areas, such as East Greenland, hunting takes place but there are no quota systems in place.
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Climate change
The results of computer modeling of future climate vary in detail, but all show a clear trend towards an overall warming in the Arctic, and a resulting melting of the sea ice. The models suggest that by 2080, arctic sea ice will completely disappear during the summer months.

In the southern range of polar bears, for example the Hudson and James Bays of Canada, sea ice is now melting earlier in the spring and forming later in the autumn. The time bears have on the ice, storing up energy for the summer and autumn when there is little available food, is becoming shorter.

As the periods without food become longer, the overall body condition of these polar bears declines. This is particularly serious for bears that are pregnant or have cubs, and for the cubs themselves. In Hudson Bay, scientists have found the main cause of death for cubs to be either lack of food or lack of fat on nursing mothers.

For every week earlier the ice breaks up in Hudson Bay, bears come ashore roughly 10 kg (22 lbs) lighter and in poorer condition. Rising temperatures in the southern Arctic, therefore, mean less sea ice, leading to less healthy bears. Reduced body condition can lead to lower reproduction rates, which in the long run could lead to local extinction.

This situation is expected to extend to other parts of the Arctic given current climate change scenarios.
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Toxic pollution
As a top predator, polar bears are exposed to high levels of pollutants through their food. Persistent organic pollutants (POPs) include a wide range of poisonous substances such as heat resistant chemicals (e.g. PCBs), industrial by-products such as dioxins and furans; and pesticides like DDT, dieldrin and lindane. Long-range POPs currently represent the most serious pollution-related threat to polar bears.

In addition to staying in the environment for a long time, POPs are a special concern because, as one animal eats another, these poisons are concentrated in fat and stored in vital organs in the animal that has eaten poisoned prey.

Bears with high levels of some POPs have low levels of vitamin A, thyroid hormones, and some antibodies. These are important for a wide range of biological functions, such as growth, reproduction, and the ability to fight off diseases among other.

Newborn cubs are especially vulnerable to these pollutants, as some of them affect the learning abilities of young animals. In some areas, the mother's milk on which they are totally dependent contains particularly high concentrations of these chemicals. The milk can actually poison the cubs, leading to lower survival rates.

There are also reasons to worry about other pollutants, such as brominated flame-retardants, which are found in many household goods. A wide range of such new, man-made persistent substances are making their way to and are being concentrated in the Arctic. The effects of these, or of the "cocktails" of combined chemicals and breakdown products of these, are still unknown.
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Habitat degradation
Petroleum exploration, extraction, transport, and processing in the Arctic affects polar bears and their habitat in many ways. There are already large installations and operations in the Arctic and the oil and gas business is set to expand in the years ahead.

Onshore arctic oil installations are currently found in Russia, Canada, and Alaska. Oil and oil products potentially pose serious health risks to polar bears.

Contact with oil spills can reduce the insulating effect of the bears' fur. The direct effect is that the bear must use more energy to keep warm, and must compensate for this energy loss by increasing its caloric intake, which may be difficult. Given that polar bears have very limited access to food for long periods of time, such an increased demand for food may result in starvation.

Polar bears can also ingest oil, which is poisonous, through grooming and through scavenging and preying on contaminated seals, seabirds, and other prey.

In addition to the threat of oil itself, the extraction process can result in discharges of a number of toxic substances that may pose a threat to polar bears and their environment.

Offshore operations pose the greatest risk, since routine emissions, spills or leaks will be discharged directly into the sea or on the sea ice. A large-scale spill at or near the ice edge, either from a ship or installation, represents the most dangerous scenario for polar bears.

There is currently no evidence to date of population-level impacts on polar bears that can be attributed to oil development. This is likely because oil development so far has been relatively limited in key polar bear habitats, and that precautions have been taken where obvious conflicts were identified. However, polar bear populations are expected to come under increased pressure as oil developments in the Arctic go ahead according to industry plans.
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