Melting Future: The Impact of Climate Change on Polar Bears

According to WWF, the polar bear is the world's largest bear and lives in extreme cold environments such as ice-covered water of the arctic. The life of a polar bear depends on the sea ice. The polar bear does not live in one place; they are in distributed form in different regions of the arctic. Polar bears do not occur in large numbers. In 2006 the total number of polar bears in the arctic was between 20,000 to 25,000. Males reach sexual maturity at eight to ten years old, while females do so at four to five. The female bears can have one to three cubs, but the infant mortality rate is high. The rate is high and can go above 70%. Just one-third of cubs live to the age of two. Consequently, there are extremely few individuals who can be replaced in the population, and the rate of population growth is incredibly low. 

A polar bear's lifespan of 20 to 30 years helps to make up for its low reproductive efficiency. Polar bears inhabit the nearshore annual sea ice over the continental shelf, where their primary prey, ringed seal and bearded seal, is abundant, even though they are scarce in the far north up to the North Pole. The sea ice serves as a platform for the bears' movement, mating, and hunting. Most polar bear populations' females give birth to their cubs in snow dens on land, although all polar bears are virtually entirely dependent on the environment but for their food they depend on marine ice. However, the polar bears' very habitat and with it their survival is under threat due to significant decreases in sea ice in the Arctic over the past few decades as a result of climate change.

In some regions, bears already experience lower nutrition and have worse physical health. This has an effect on their survival and cubbing. The IUCN Polar Bear Specialist Group (PBSG) identified climate change as the biggest threat to polar bear conservation in 2009. 19 bear populations are present. Eight populations were in decline, three populations were stable, one population was growing, and there was insufficient data on the remaining seven populations to assess their status.  

The World Conservation Union (the IUCN) also listed polar bears as "Threatened" in 2008. As a result of their extensive generation times and the present, the global warming gains a great momentum as the Arctic continues to warm, it appears unlikely that polar bears will be able to adapt. Within a century, most of the polar bears' range could be lost to extinction due to climate change (IUCN 2009). 

The Arctic sea ice has been significantly impacted by a change in temperature caused by changes in the climate in the 20th century. Normally, the area covered by sea ice fluctuates from 7 million square kilometers in September to around 14 million square kilometers in March. However, from 1979 to 2006, there was a 3.2% per decade decline in the annual sea ice area. These scientists predicted the number of bears that could starve to death as a result of additional climate change using data gathered from this region and mathematical models. In some areas, sea ice changes have  an impact on how female polar bears mate. Polar bears that are expecting give birth in the middle of the winter and raise their cubs in the den until early spring. Most bears build dens on land. It is evident from the explanation above that polar bears are already in trouble due to changes in sea ice brought on by climate change, and that their future is in danger. 

The sea ice serves as the polar bears' habitat. Using this information, a research team from the United States Geological Survey came to the 2007 conclusion that, if greenhouse gas emissions continue at their current rate, two thirds of the world's polar bear population might disappear by 2050.  However, if we are able to reduce greenhouse gas emissions, there is more hope for the polar bears. A paper released in 2010, it was demonstrated through the use of mathematical models that, if greenhouse gas emissions are reduced, a significant amount more Arctic sea ice would be retained, and polar bear populations could continue to increase throughout this century compared to what was predicted under the business as usual scenario.