impact of global warming on polar bears

The Polar bear also known as the ‘Sea Bear’ is believed by scientists to have evolved from the brown bear some two hundred thousand years ago.  Ursus Maritimus, as the polar bear is known scientifically, is very well adapted to extremely cold weather having made the Arctic it’s natural habitat.  The polar bear can be found in five nations namely, Norway, Russia, Canada, Denmark (Greenland) and the United States of America (Alaska) (“About Polar Bears”).  They are the kings of the arctic, being at the top of their food chain and primarily feeding on Seals.  They are known to be opportunistic hunters and will feast on the carcass of a washed up whale any day. They are also known to eat narwhals, bowhead whales, walruses and when nothing else is available, eggs, fish, sea birds, rodents, vegetation, human garbage and berries (“Polar Bears”).

Polar Bears can weigh up to 1500 pounds for males and 550 pounds for females.  They are accustomed and adapted to the extremely cold weather, having a layer of fat that can be as much as four and a half inches thick under their skin.  Polar bears have been known to consume up to one hundred pounds of fat at one go in a bid to increase their own stores of blubber. Additionally, they have very thick fur that aids in keeping their body temperature at 98.6 degrees Fahrenheit like any other mammal (“About Polar Bears”).

The impact of global warming is being felt strongly in the North Pole.  Global warming is caused by greenhouse gases that include methane, carbon dioxide, tropospheric ozone, CFCs and nitrous oxide.  These gases do not block shortwave radiation created by the sun from passing through the atmosphere.  This causes the earth’s surface to heat up and create longwave radiation.  However, they do not allow the longwave radiation to get out of the atmosphere.  It is then trapped causing oceans, air and land to heat up (Santana).  As a direct result of this, ice in the North Pole is melting, directly affecting the natural habitat of the Polar Bear.  So badly have they been affected that Ursus Maritimus have been placed in the list of endangered animals on our planet.  Being naturally adapted for extreme winter weather, the Polar Bears are struggling to cope with the rising temperatures.  The changes are happening so fast that it may be difficult for the bears to adapt themselves backwards in order to save their lives (Harden).

Currently the number of Polar Bears in the Arctic is said to be between twenty and twenty five thousand.  However, a 30% decline is expected in their population in the next thirty five to fifty years.  The main cause of this is their shrinking environment due to the effects of global warming on their icy habitat.  This negatively affects their ability to reproduce, find food, and survive.  With ice melting approximately 3 weeks earlier than it use to before, the bears are apparently losing 3 weeks of prime time feasting.  This is because at this time, seal pups can be found in plenty which means that the bears can eat and store up the blubber needed for the 4 months they will be onshore (Harden).  This in turn leads to significant weight loss of about 15% of their body mass.  According to scientists who have been studying polar bears in Manitoba, Canada on Hudson Bay, there has been a 17% drop in the population of polar bears in the last ten years from 1200 to less than 1000 bears.  All this is believed to be a direct result of the effects of global warming (Harden).  With their habitat being destroyed, the polar bears are forced to find food onshore.  This leads them to interact with humans further endangering their lives as some have been shot in the process of finding food to eat (Harden).

The ringed seal, which is the main diet of the polar bear, will make a liar for itself in the snow in which to bear its young.  Much of the time, polar bears will find these liars and eat the pups.  Without enough snow, the seals will suffer a decline in the number of seals produced.  This will then affect the bear’s consumption of food.  Additionally, it is of note that the bear also creates a cave for itself in the snow during the hibernation season when it bears its young.  It is feared that the absence of adequate snow will interfere with this process leading to fewer polar bear births.  When the ice breaks too fast and the seals go into open waters, the lack of food will lead to the mother bear not packing enough fat.  She is therefore unable to produce enough milk for her cubs which could lead to their death (Morrison).  It takes 2.5 years to wean the majority of polar bear cubs.  Even then, less than half the cubs born make it to maturity, with the main reason being that they lacked food.  Indeed cubs that are of a lighter body weight have a much lower chance of survival (Morrison).  This being the case, it is imperative that something is done about the threat of global warming if the Polar Bear is to escape extinction.

Should the current trend continue unchecked, extinction of this great species will be the result.  In the event that this should happen, the food chain will be completely skewed leading to the unchecked flourishing of one species over another.  The polar bears feast on large numbers of seals every year.  This ensures that the seal population is kept in check.  If the bears are no longer there to ensure this, then the seals will undoubtedly increase at an alarming rate.  This will lead to a major decrease of saffron cod, squid, arctic cod, amphipods and sculpins, which make up the seal’s diet (“Ringed Seals”).

It is critical that something is done about the current decline of the Polar bears natural habitat.  Putting the polar bear on the list of endangered species is just a start.  Greenhouse emissions must be curbed by each country to ensure that global warming is combated at every level.  However, saving the Polar Bear will take more than just that.  It will also include ensuring that other non-climatic stressors are also reduced.  This include limiting the development of oil and gas mining in their habitat as the bears rely heavily on some of those places for denning and hunting (“Polar Bears and Global Warming”).  Only when all measures are taken can the world hope to keep this great species alive.

Works Cited

“About the Polar Bear.”  Polar Bears International.  Accessed 13 Mar. 2009. http://www.polarbearsinternational.org/bear-facts/about-the-polar-bear/

Harden, Blaine. “Experts Predict Polar Bear Decline: Global Warming Is Melting Their Ice Pack Habitat.” Washington Post 7 Jul. 2005, pg A03. Accessed 13 Mar. 2009. http://www.washingtonpost.com/wp-dyn/content/article/2005/07/06/AR2005070601899.html

Morrison, Jim. “The Incredible Shrinking Polar Bears.” National Wildlife Federation.  Accessed 13 Mar. 2009. http://www.nwf.org/nationalwildlife/article.cfm?issueID=66&articleId=880

“Polar Bears and Global Warming.” National Wildlife Federation.  Accessed 13 Mar. 2009. http://www.nwf.org/polarbearsandglobalwarming/

“Polar Bears: Diet & Eating Habits.”  Sea World. Accessed 13 Mar. 2009. http://www.seaworld.org/animal-info/info-books/polar-bear/diet.htm

“Ringed Seals” Alaska Fisheries Science Center. 2009. Accessed 13 Mar. 2009. http://www.afsc.noaa.gov/nmml/education/pinnipeds/ringed.php

Santana, Francisa.  “Global Warming: What, How, Why?” Center for Biological Diversity. Accessed 13 Mar. 2009. http://www.biologicaldiversity.org/programs/climate_law_institute/global_warming_what_how_why/index.html


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