Effectsof climatic change on polar bears
TheArctic experiences the fastest increase in temperatures compared toany other region in the world. Within the circumpolar Arctic, theBarents Sea and Svalbard Archipelago experience the highest rise intemperatures and sea ice loss. These climatic changes greatly affectthe organisms that inhabit the region as well as the organisms thatlive there seasonally. One of the most affected organisms is thepolar bear (Mosley S., 2013). Polar bears are mostly affected by theloss of the sea ice since they spend most of their time at sea thanthey do on land. Herein, evidence of the effects of climatic changeon marine and terrestrial organisms is reviewed with a focus on polarbears.
Oneof the greatest threats to biological diversity is the loss ofhabitat. According to the 2006 Norwegian Red List, about 85% ofspecies are threatened by habitat changes and highly-specializedspecies are the most vulnerable. The polar bear is one of the mostaffected species since the sustainability and extent of sea ice arevital for its survival. Polar bears rely on sea ice for food (RodeV. etal.,2014), as a breeding habitat for maternity denning (Laidre L. etal.,2015) among other things. A reduction in sea ice, especially duringthe summer season, makes the ocean areas very unproductive. As aresult, polar bears are forced to move to the mainland areas or someof the less productive areas in the Arctic. When this happens, theindividual survival rate of polar bears is affected, and the speciestend to suffer in the long run.
Effectson primary prey species
Theother way that climatic change affects species is by affecting theirprimary prey. Polar bears primarily prey on seals. Ripple J. etal., (2015)asserts that climatic warming causes increased precipitation thatmight have substantial effects on seals. He explains thatprecipitation in the form of snow during the winter might greatlyimprove the survival rate of seals pups. However, if theprecipitation is in the form of rain, the pups’ survival rate islower. This is because the birth lairs become more exposed not onlyto polar bears but also to foxes and other predators. The competitionfor food among predators greatly reduces their population. As aresult, the polar bear population is affected because there is lessfood which affects the survival of the species.
Climaticchanges also affect seals’ reproductive rates. When the iceplatform is affected, the number of fish that seals rely on for theirsurvival reduces (National Wildlife Federation). As a result, thenutritional status of seals is affected. This has a negative impacton their reproductive rate which leads to a decreased number of sealbirths. Consequently, the polar bear population also suffers due to alack of food. Polar bears might turn to cannibalism where they eattheir young to survive.
Apartfrom the loss of habitat, the retreating of ice also causes increaseddrowning among polar bears. When the ice retreats, there is a largerspace between land and the remaining ice which causes increased roughwaves (National Wildlife Federation) that make it difficult for thepolar bears to swim to safety. Therefore, the environment not onlybecomes less productive but also very dangerous, especially for theyoung polar bears. In 2008, a survey in Northern Hampshire areacovered by sea reported that 4 of 10 polar bears in open waterdrowned(MosleyS., 2013).
Polarbears are forced to live on land during the summer season because thesea ice is absent during this season. Sometimes they move tounproductive areas of the Arctic region as they wait for the water tofreeze (National Wildlife Federation). In these areas, there islittle and sometimes no food and the polar bears, therefore, go fordays without eating anything. Consequently, this leads to a reductionin body weight and lower reproductive rate which in turn cause adecrease in polar bear population. According to the polar bearspecialist group of IUCN, 3 of 18 of the world’s polar bearpopulation are stable, 8 are declining ,only 1 is increasing andthere is no information on the status of 7 (Wiig et al. 2016). Thisclearly shows the significant impact that climate change has on polarbears.
TheEndangered Species Act listed polar bears as one of the threatenedspecies due to their declining primary habitat (Abate, 2015). Oneresearch study predicts that the decline in sea ice might result intwo-thirds polar bear extinction by the middle of the 21stcentury. However, since the number of prey and sea conditions variesfrom one region of the Arctic to another, there is a possibility thatnot all polar bears will respond in this manner. Scientists,therefore, advice researchers to be careful not to make predictionsbased on just a single population. In order to keep the polar bearnumbers within a healthy range, experts suggest that globaltemperatures be maintained at 1.25 degrees Celsius and not abovethis. These predictions emphasize the need for everyone to makeefforts to reduce global warming. Since global warming is mainly aresult of human activities, it is suggested that if a change is to beseen, human beings must take an active role by making changes totheir daily lives that are in line with bettering the environment.This will benefit not only the polar bears but also other organismsaffected by global warming including the future generations.
Inan effort to find food during periods where there is limited sea ice,polar bears sometimes move into human settlements. They scavenge ongarbage and whatever they can find. This results in conflict betweenhumans and polar bears. A good example is when polar bears enteredthe town of Churchill in Western Hudson Bay. Bears relied on garbagefor their survival. Their survival created a lot of unrest among thehumans as they did not feel safe with the polar bears in theirenvirons. In 2011, they started shooting down the polar bears as away of defending themselves. There is also a possibility that polarbears might also prey on humans if the open water period extendsbeyond the expected period (Intergovernmental Panel on Climate Change2014). When this happens, the first regions to be affected will bearound the Southern limit of the area the polar bears are residingbut might increase further to the northern region depending on howlong the open water period lasts.
Effectson long distance movements
Long-termclimatic changes eventually lead to seasonal movements and migrationsof polar bears as they are normally attracted to areas where theleads form in the sea ice (National Wildlife Federation). However, ithas been suggested that the rough waves and currents that form whenthe open water area increases might affect long distance movement ofpolar bears. This is mainly because polar bears are unable to swimfor long distances in the open water due to the rough waves.Researchers have tried to study the effects that the change inphenomena has on the migration of polar bears. They have discoveredan increased rate of drowning among polar bears during increased openwater periods. The findings are, however, inconclusive and there isno significant evidence to explain whether or not these phenomenahave a significant impact on the migration of polar bears.
Effectson maternity denning
Researchhas shown that polar bears in most areas prefer spending their timeon the sea ice. During fall, the open water that is between the polarpark and the coast freezes and multi-year pack ice tends to movetowards the South. This makes it very easy for the pregnant polarbears to reach the land for denning. If freeze up is delayed and theextent of polar park is reduced, this might prevent the pregnantbears from getting to the coastal region. In such situations, themothers choose to den in the multilayer ice region. Some choose toget to shore at break-up and go into fasting until they go intomaternity denning(Mulvaney,2011). In very warm winters, the mothers are at a great disadvantage.This is because the high temperatures lead to collapsing of thematernity dens before the mothers and the cubs have a chance todepart. As a result, the bears might end up being crushed to death.
Declinein body size
Theskull and body length of polar bears was reported to have decreasedsignificantly between the year 1982 and 2006 in the Southern BeaufortSea and the effects were attributed to nutritional stress (NationalWildlife Federation).If the climatic conditions keep changing and getting worse, it ispossible that the body size of polar bears in most regions of theArctic will reduce significantly. This is something that might affectthe overall well-being of the species, and it might be a contributingfactor to their extinction. For this reason, experts are at worktrying to determine ways in which global warming can be controlled inorder to protect species from extinction.
Polarbears are an example of highly specialized species that survivemainly by preying on seals. At the same time, polar bears can bequite opportunistic when it comes to looking for food. They have theability to move from one area to another in search for food whenseals are not readily available. The decrease in the extent of seaice during summer seasons greatly affects polar bear survival.Two-thirds of the number of polar bears will be no more by the year2050. The situation might be even worse if the sea continuesexperiencing the same speed of retreat that it has experienced in thelast few years.
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