A Shrinking world: polar bears struggle with climate change
Climate change is a problem that affects every living thing on earth. Climate change has always been a natural occurrence in the history of the earth for an extreme examples the several ice ages that the planet has gone through, the climate change that is an issue is the accelerated climate change that is due to the increased emissions of green house gases into the atmosphere, these green house gases are largely due to human activity either via direct methods such as exhaust fumes from combustion engines or through sources such as increased methane production from cows due to mass cow farming and mega farms. Climate change is changing the face of our planet, by increasing the average global temperature it is causing sea ice to melt, the polar ice is shrinking each year, and this in turn affects all of the oceans by changing average salinities and possibly interrupting natural occurrences such as the Gulf Stream. This change is causing the destruction of many creatures’ habitats and is affecting many species. Some organisms will be affected more severely than others and some organisms will feel the effects sooner than others.
One species that is being affected by climate change in a massive way already is Ursus maritimus or more commonly known as polar bears. Polar bears are the world’s largest species of bear. Male polar bears also known as boars can weigh between 350-700kg, female bears also
called sows typically are half this size. They are found on the ice of the Arctic Circle and adjacent landmasses, they have been sighted in the northern parts of Canada and even the northern islands of Scotland. Due to their habitat being so formidable it is sparkly populated by humans meaning polar bears haven’t lost much of their natural range to human settlements, they instead have lost it to climate change due to its effect of melting sea ice and causing the all year arctic ice to recede more and more each year (has receded by 14% since 1978).
The effects of climate change
As the sea ice recedes so does the availability of the polar bears main food sources such as ringed and bearded seals, there for they may be forced to switch to other prey such as harbour seals. They may also be forced to eat more of the intestines and internal organs of the seals rather than the calorie rich skin and blubber if the bear is an adult and the protein rich red meat if its cub, this will mean higher levels of exposure to pathogens that polar bears will not have come in contact with. The lack of food sources may also venture closer to human settlements looking for food and this may cause conflict and the possible demonization of polar bears by the locals and possible active culling. The diminished food source may also cause more conflict between bears over the remaining food supplies as well as might lead to cannibalism especially of young cubs by even their mothers.
The incredibly cold climate of the arctic has historically limited the diversity of infectious agents and pathogens, due to this polar bears are highly immunologically naive. This is a problem because as the temperature in the arctic rises new pathogens that polar bears would never encountered before, these pathogens could be carried
via biotic vectors such as in the bodies of the prey of polar bears or old carcases if they resort to scavenging, pathogens can also be transferred via abiotic factors such as the ballast waters of large ships are by people on expeditions especially if their capture release expeditions as they will be coming into contact with the bears. This could also cause problems as new born cubs won’t have strong enough immune systems to deal with any pathogens and whereas most mammals will get the antibody’s through breast milk from the mother the mothers immunes system won’t be able to produce the antibodies fast enough as it wouldn’t have experienced these new diseases yet.
The receding ice can In addition to creating nutritional stress, a warming climate is expected to affect various other aspects of polar bear life: Changes in sea ice affect the ability of pregnant females to build suitable maternity dens. As the distance increases between the pack ice and the coast, females must swim longer distances to reach favoured denning areas on land. Thawing of permafrost would affect the bears who traditionally den underground, and warm winters could result in den roofs collapsing or having reduced insulative value. For the polar bears that currently den on multi-year ice, increased ice mobility may result in longer distances for mothers and young cubs to walk when they return to seal-hunting areas in the spring.
The future and controversies
There is much controversy behind the protection of this species. Polar bears are one of the figure head species behind the movement to cut down our impact on the planets climate. There have been countless warnings about the future of the species due to climate change they are listed as vulnerable by the IUCN, these reports contrast with the fact that the world wide estimated population for polar bears has been increasing for the last 50 years and is
relatively stable at this point in time. Their current numbers are estimated to be at around 20,000-25,000 at this time compared to the estimated 5,000-10,000 in the early 1970’s. There are several reasons behind these numbers, first the early numbers were estimated using stories told by explorers and hunters rather than being based on scientific study, second is that control of harvest laws were introduced to control the number of polar bears being hunted, allowing this once overhunted species to recover.