Saturday, December 10, 2011

Main points

1. Melting of polar ice caps.

With global warming continuing to melt the glacial ice caps, polar bears are losing pieces of their habitat everyday.

2. Ice caps are the traditional hunting grounds for polar bears.

Polar bears live only in the arctic and depend on the sea ice for survival. They need the sea ice to hunt, breed, mate and travel. So sea ice is fundamental to their survival for they cannot live without it.

3. Polar bears travel huge distances to find food which jeopardizes their lives and the lives of their cubs.

Through my research, I found that the dramatic decrease in the area and thickness of the Arctic sea ice due to rising temperatures has been especially hard on polar bears.

In 2004, biologists found 4 drowned polar bears in the Beaufort Sea. These master swimmers drowned because the huge distances between ice floes taxed them too heavily.

Over these twenty years, as the arctic ice broke up constantly, the number of polar bears that died through drowning and starvation is significantly on the rise.
4.Most importantly, female polar bears use the ice caps as dens to raise their cubs. But now, some den areas are abandoned completely.

There is also the breeding problem which must be taken into consideration. Prior to the melting of the ice caps, polar bears build dens and raise cubs all on the Arctic ice.

More and more female polar bears are leaving the sea ice to den on land, even in the winter.

5. The sea ice breaks up earlier in spring and frezzes later in winter which causes polar bears are going hungry for longer periods of time and resulting in cannibalistic behavior.

As more polar bears are forced to resort to the land for survival, more and more cases of cannibalism within the species is being reported.

6. The U.S Geological Survey predicts within next 50 years, 2/3 of the polar bears will disappear.

As a creature that’s highly dependent on a single habitat, a polar bear’s whole life span is connected to the sea ice.

Tuesday, November 29, 2011

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
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.

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

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

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. .

Monday, November 28, 2011

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

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”).

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).