Polar bear's survival under the global warming

The polar bear, Ursus maritimus, or the sea bear, evolved about 200,000 years ago from brown bear ancestors. They are superbly adapted for survival in the Far North.

Photograph by Norbert Rosing

Polar bears range throughout the Arctic in areas where they huntseals at openings in sea ice called leads. Five nations have polar bear populations: the United States (Alaska), Canada, Russia, Denmark (Greenland), and Norway.

From Sierra Club

At the March 2009 range states meeting of the five polar bear nations, scientists agreed that climate change is the single biggest threat facing polar bears.

The Arctic is experiencing the warmest air temperatures in four centuries. The Arctic has experienced warm periods before, but the present, rapid shrinking of sea ice is unprecedented. Scientists predict a mostly ice-free Arctic summer by 2040 if present trends continue.

From Peas in a pod, Peapod's blog

Today's polar bears are facing rapid loss of the sea ice where they hunt, breed, and, in some cases, den. Changes in their distribution or numbers affect the entire arctic ecosystem.

Scientists believe that we still have time to save polar bears if we significantly reduce greenhouse emissions within the next few years. Yet it will take 30 to 40 years for changes reversing the warming trend to show.

Polar bears are finding too much open water. In 2004, four polar bears drowned off the coast of Alaska when trying to swim to the pack ice.

Nikita, Ovsyanikov. Polar Bears : Living with the White Bear / Nikita Ovsyanikov. Stillwater, Minn: Voyageur Press, 1996.

http://www.actionbioscience.org/environment/derocher.html
http://www.pitara.com/discover/earth/online.asp?story=140&page=2
http://e360.yale.edu/content/feature.msp?id=2161
http://www.seaworld.org/animal-info/info-books/polar-bear/habitat-&-distribution.htm

Global warming impacts Arctic

During the past several decades, the Arctic has warmed at an alarming rate, and it is projected to continue to warm by as much as 18 degrees Fahrenheit by 2100. This warming trend has had a devastating impact on Arctic ecosystems, including sea ice, permafrost, forests and tundra. Warming has contributed to increases in lake temperatures, permafrost thawing, increased stress on plant and animal populations and the melting of glaciers and sea ice. Research has revealed decreases in both sea ice extent and cover.

Photograph by James Balog

Meltwater has carved a canyon 150 feet deep.

Melting sea ice affects populations of marine mammals, caribou, polar bears and the subsistence livelihoods of people that depend on them. Because sea ice forms a natural breakwater against storm wave action, ice melting allows larger storm surges to develop and causes erosion, sedimentation, and coastal inundation.

Photograph by Rich Reid

Tundras are among Earth's coldest, harshest biomes. Tundra ecosystems are treeless regions found in the Arctic and on the tops of mountains, where the climate is cold and windy and rainfall is scant. Tundra lands are snow-covered for much of the year, until summer brings a burst of wildflowers.
Forest and tundra ecosystems are important features of the Arctic environment. In Alaska, substantial changes in patterns of forest disturbance, including insect outbreaks, blowdown, and fire, have been observed in both the boreal and southeast coastal forest. Rising temperatures have allowed spruce bark beetles to reproduce at twice their normal rate. A sustained outbreak of the beetles on the Kenai Peninsula has caused over 2.3 million acres of tree mortality, the largest loss from a single outbreak recorded in North America. Outbreaks of other defoliating insects in the boreal forest, such as spruce budworm, coneworm, and larch sawfly, also have increased sharply in the past decade.

Photograph by Joel Sartore

Tundra and Rivers

Photograph by Ira Block

Melting Ice

Porter, Stephen. Climate Change and Arctic Impacts. 15 Feb. 2005. . http://www.ciel.org/Climate/Climate_Arctic.html.

How to help polar bear

      

     As a creature that’s highly dependent on a single habitat, a polar bear’s whole life span is connected to the sea ice. Sirling said “Without sea ice to hunt seals, polar bears are in big trouble”. In the short term, it looks like a disaster, but in the long run, it is likely to put this already threatened species onto the brink of extinction. Scientists forecast that as time passes, the polar bear population will suffer a rapid decline, and as much as two thirds of current population could disappear by 2050 (Polar Bears). Extinction will be the result if there is no protection from now on, and the only way to stop the fast speed of global warming is that everyone making a change together. Everyone can do their part to cut down on these these terrible wastes and help save polar bears. Fortunately, there are more and more people joining the green recycling plan. If everyone does a little, then the whole world can curb a huge number of greenhouse gas emissions. Nobody want to see the polar bears go extinct in the next century, so allowing the polar bears a chance to live by cutting down on CO2 emissions is every one's responsibility

http://www.youtube.com/watch?v=aQwXvS1cT-Q&feature=player_embedded

Polar bears' populations are in decline

     Though there are still some skeptics insisting that polar bears won’t be endangered, but the fact is polar bears’ populations are going into decline . The World Wide Fund for Nature (WWF) issues warnings that the polar bears’ subpopulations are accelerating downwards, from one to five during 2001 to 2006, with only 19 polar bear subpopulations left in the world. What is more serious is in early July that eight of the Arctic’s 19 polar bear subpopulations are in decline (Struzik). The International Union for Conservation of Nature (IUCN) reports that in Western Hudson Bay, their populations have fallen from roughly 1200 to 900 in the past two decades (Derocher). Some skeptics state that “polar bear have survived periods of warming that occurred during the last interglacial period, about 120,000 years ago, and the maximum temperatures of the last interglacial were roughly 2 degrees F of warning than now” (Struzik). But Derocher says that 120,000 years ago, there was no oil and gas development, no contamination or pollution of the environment, and moreover, people weren’t pumping greenhouse gases into the atmosphere like today. Since the situation is changed, there is no use in compare today to the 120,000 years ago, and suggest that this species will do just fine (Struzik). The simulation result shows that if the sea ice is melting one month earlier in Hudson Bay, there will be 40% to 73% rate of pregnant female polar bear can not successful fertility; and the rate will be get high as 55% to100% if the sea ice is melting in two month’s time. At that time, not only will the Hudson Bay’s polar bear population decrease, but also the whole Arctic polar bears as well (“Global Warming and Polar Bears”).

http://www.youtube.com/watch?v=y7Oy-qSECmY&feature=player_embedded

http://www.polarbearsinternational.org/polar-bears/bear-essentials-polar-style/conservation/current-status

Polar bears resorted to cannibalism

    The global warming has already changed polar bear’s habits and behavior, sometimes to an extraordinary degree. There have been reports of famished polar bears resorting to cannibalism when they can find nothing else to subside on. Polar bears are accustomed to live and migrate on the pack of sea ice; after the Arctic ice becomes too thin to live and migrate; polar bear are forced to resort to the land for survival. But Dercher shows that “polar bear lose about a kilogram per day when they are stuck on land”. In January 2004, a male polar bear rushed into a mother polar bear’s den and surprise attacked the mother polar bear. This fierce male polar bear turned over the top of the den and bited her head and neck few times, then he drugged her dead body to the 75 meters far place, and began to eat her body. The den had collapsed upon the mother polar bear’s two cubs, and they were both choking to die (Stirling). Steven C. Amstrup, a polar bear scientist with the U.S. Geological Survey says that, despite the cannibalism was happened before, but such events like killed a female polar bear in postpartum were never recorded in the past in Arctic North (22-23). The other evidence shows polar bear is resorted to cannibalism as well. On December 8, a team of American scientists published a set of pictures which shows a adult polar bear is hunting a polar bear cub in Manitoba, Canada. There are already have seven cases which polar bear is going to hunt cubs which happened this year. The biologist Ian Stirling in Canada environment department indicates that this is the first time finding so many cannibalism among polar bear since he attended his science job (269). Scientists find that polar bear are going hungry for long period of time in summer, In addition, the sea ice is forming several weeks later than ever as well as getting thinner which causes polar bear hardships in their hunt.

Polar bears need sea ice to build their dens

     The breeding problem must also be taken into consideration. Since polar bears raise their cubs on Arctic ice, which is breaking up and melting at an alarming rate (“Polar Bears”), their reproduction rates are drastically reduced. Female polar bears usually give birth to two cubs at a time, with the cubs’ survival rate being only 50%. There are two main factors that affect polar bears’ breeding, the sufficient amount of fat to keep themselves warm and nurse cubs, and the thickness of the sea ice to build a den to raise the cubs when they are born (Stirling). With the melting sea ice, mother polar bears cannot store enough energy and nutrition for reproduction, since it has become more difficult to get food. Researchers revealed that from 1985 to 1994, 62% of female polar bears build their dens on the sea ice, but this number declined to only 37% between 1998 and 2004 (Struzik). The consolidated annual Arctic sea ice is going to disappear, so it becomes too unstable to contend with the polar bears’ needs to breed and feed cubs. More and more female polar bears are building their dens on land now, but without the sea ice to hunt prey, these undernourished females are having smaller litters, and giving birth to lighter cubs that do not survive well. Scientists have plenty of evidence to confirm that the polar bear’s fertility rate drops to an abysmal 15% due to the reasons above. They also hint that because the sea ice is decreasing far away from the shore, polar bears can be trapped in the sea one day, and be prevented from reaching their dens (Struzik).

Polar bears swim huge distances to find food

   Now, polar bears are facing a more serious test; with the melting of the sea ice, polar bears are forced to swim longer distances, which can jeopardize their lives and cubs’ health (“Polar Biology”). Expert testimony shows that “Remaining ice is farther from shore, making polar bear less accessible. The larger gap of open water between the ice and land also contributes to rougher wave conditions, making the bears’ swim from shore to sea ice more hazardous” (qtd. in “Global warming and polar bears”). There already have been several reports indicating that polar bears have drowned and died due to the long distance swim. In 2004, biologists found 4 drowned polar bears in the Beaufort Sea. They spend too much energy swimming in order to find floating sea ice to take a rest. Even though polar bears are quite good at swimming, the longer distances tax them too heavily, and they become too exhausted, famished, and weak to face the rougher waves (“Global Warming and Polar Bears”). More evidence found in the Beaufort Sea shows that polar bears are finding it hard to find food on the ice caps as well. In August 2008, researchers tracked a polar bear’s hunting activities for two months. One of the researchers, George, says that the bear made a continous swim of total 687 kilometers over 9 days in the cold water, and intermittently swam and walked on the sea ice surface an additional 1,800 km. Researchers indicate that this polar bear paid the extraordinary high cost for this epic journey. Dorena, another researcher, says that in these two months, the bear’s body fat was reduced by 22%, and tragically lost her one years old cub as well (16-17). In these twenty years, as the arctic ice broke up constantly, the polar bears that died through drowning and starvation have significantly increased. If the arctic ice further melts in the future, then polar bears deaths will increase as well.

Sea ice affects food source of polar bears

   

       Prior to the melting of the ice caps, polar bears hunted seals by the sea ice. Seals are the polar bears’ primary food supply, and are rather plentiful in the Arctic. They provide sufficient calories for a polar bear to consume, which in turn keeps the bears warm in cold climates. Though polar bears are great swimmers, they lack the ability to dive underwater, which is why they cannot hunt seals and other animals under the sea. Polar bear always use two ways to catch seals, one being patiently waiting near a seal’s breathing hole on the ice cap, and the other being directly submerging under the floating sea ice, then attacking resting seals until they are very near the shore (“Polar Bears”). As a result, ice caps are very important for polar bears to maintain their predatory lifestyles. Polar bears are always following the movements of the ice pack, and they can be found sometimes clustering together in a place where there is a lot of sea ice.   

The global warming affects polar bear's habitat

   

   



















 The most serious factor altering polar bears’ habitat is the melting of the sea ice. Polar bears need the sea ice as a platform for hunting their prey, as well as a place to breed. Sea ice is considered as the premier place for polar bears to mate, travel, and migrate (Derocher). Polar bears depend on the sea ice platforms for survival, but with the mounting temperatures produced by global warming, the sea ice now melts earlier in the summer and freezes later in the winter. Scientists are shocked by the rate of sea ice melting in the Arctic Ocean, and they are finding more and more open waters where sea ice originally was. Dates provided by satellite passive microwave sensors have shown that from 1979 to 2006, the annual sea ice area has decreased every month of a year. The most serious sea ice reduction occured in every September, about 9% per decade, which caused the Arctic Ocean to lose about one hundred thousand square kilometers of sea ice (Vongraven, Peacock 15). Furthermore, Derocher indicates that polar ice caps are shrinking steadily which causes more difficulty in getting to and hunting prey (“Polar”). These records prove polar bears’ ability to survive is being obviously threatened.

The Introduction of the polar bear's living status under the global warming

    When one thinks of the frozen ice-lands of the north, the image of the polar bear is one of the first that floats into the mind. These majestic animals are the top predators in their local environment, and are a symbol of the Arctic North. However, with global warming continuing to melt the glacial ice caps, the habitats of these animals are being reduced at a rate that could see the species extinct by the next century. Though there are still some skeptics insisting that polar bears won’t be endangered, the truth of the matter is that global warming is already affecting polar bears in many aspects, including their feeding, breeding, behavior, and population.   

http://www.youtube.com/watch?v=1i8soGsPpcA&feature=player_embedded