THE GLOBAL WARMING
the effects of global warming
AS CLIMATE CHANGE AFFECTS POLAR BEARS
The subpopulation of Hudson Bay has declined by 22%.
The most notable impacts of climate change on polar bears were observed in western Hudson Bay, where declines in body condition, reproduction and survival have resulted in a 22% reduction in the size of subpopulation between 1987 and 2004.
The early melting of sea ice in Hudson Bay is the major force behind this decline in population size, but also the continued unsustainable harvesting of seals has aggravated the situation.
The early melting of sea ice has two consequences for polar bears: Shorten feeding period during the period when newly weaned seal pups are available, and lengthen the period that must pass fasting bears.
Polar bears must travel longer distances today.
The warming climate is altering sea ice conditions and affecting polar bears in other ways. In many areas, the polar ice changes with the wind currents and water and polar bears often walk against the flow of ice in order to keep in touch with their preferred habitats.
Using more energy for locomotion means that less power will be available for growth and reproduction.
Some examples of the expected effects of the changes in sea ice are:
• Increased energy costs movement;
• Alteration of territory size and configuration;
• Altering the boundaries of subpopulations;
• Reduced access to areas of burrows;
• Increased periods without access to prey;
• Alteration of prey species;
• Increased amount of time spent swimming, which can resfriar puppies and reduce their survival.
Some bears drowned, others resorted to cannibalism.
Polar bears have been found drowned off the coast of Alaska that have been perishing due to the rapid shrinkage of sea ice to the north: The largest expanse of open water and greater distances between land and ice make it more difficult for bears find shelter.
In the same area, have been cases of bears killing polar bears and other situations of cannibalism, which may be related to reduced availability of prey.
Changing sea ice conditions are affecting the ability of the bears to hunt their prey
Some areas may be abandoned completely dens.
Recently, a new study in Alaska found that polar bear dens on pack ice has decreased by 62% between 1985 and 1994 to 37% between 1998 and 2004. As the ice continues to change, it is expected that more areas are abandoned burrows.
If we continue like this, what will happen to polar bears in the future?
Can polar bears adapt to life on land?
Can polar bears adapt to life on land without the presence of sea ice? Polar bears often reach sizes of more than 300 kg in females and 500 kg in males. In contrast, brown bears living in the Arctic, practically next door to polar bears rarely exceed 200 kg, reflecting the scarce food resources that provide terrestrial environments at high latitudes.
Expected changes in polar bears with respect to climate warming include:
• Reduced access to prey species;
• Reduction in body condition;
• Lower survival of cubs;
• Low reproductive rate;
• Increased intraspecific aggression;
• Increased cannibalism;
• Low adult survival;
• altered turnover rates;
• Changes in the areas of burrows;
• Changes in the boundaries of the populations;
• Increased interactions with humans;
• Changes in the composition of the dams;
• Reduction in population size.
Unlike other species, polar bears are not going to respond well to a change in its distribution further north, because the polar area is deep, cold and very low productivity. The loss of highly productive coastal habitats will be a serious loss. However, the sea ice is more than a platform. It is the habitat of polar bears and the many species that depend on them. From phytoplankton to fish, sea ice is an integral part of the Arctic marine ecosystem.