The Effects of Global Warming on Polar Bears - Research Paper Example

?Bingyan Hu ESRM 100 Rob Harrison 20 The Effects of Global Warming on Polar Bears Once abundant, bounding on the ice and swimming in the sea, the noble Polar Bear appears to be at a critical point in their fight for survival. With many possible issues facing the world population of Polar Bears, the IUCN Red List of Threatened Species categorized the polar bears as ‘vulnerable’ last 2010 (IUCN Red List 1). Primarily, citing a variety of reasons, the continuing concern is that the species of the world’s largest living carnivore continues to get fewer and fewer. Over the recent past, the population of polar bears has steadily declined. Despite ongoing activism this decrease in numbers still continues up to the present day. Indeed, it is a frightening possibility that soon, polar bears will be just parts of history and will become another name on the list of extinct animals. The decline in Polar Bear population is due to many harsh realities in today’s world. With not only traditional adversaries in the wild to contend with, the additional factors of climate and the encroachment of man begin to play a big factor in the Polar Bear saga. Chief among the causes of the polar bear’s steep mortality rate is hunting by humans (Schliebe et al. 34). Another cruel by-product of the influence of man is the exposure of the bears to Persistent Organic Pollutants (POP), highly toxic chemicals. The high levels of accumulation of POP compounds cause impacts to the polar bear’s nervous system, reproduction, and even their immunity (IUCN Red List 1). This man made problem has begun to substantially threaten the health and well-being of the animals. Taken together, these problems alone would be hard for any species to face. However, overshadowing other issues is the advancing argument that the biggest threat to the existence of polar bears is the phenomenon of global warming. The continuous and intensifying climate changes have already made impacts on the polar bears’ sea – ice habitat. With entire shelves falling prey to the cracking and once mighty ice floes reduced to a mere shade of their former selves the ability to deny that the polar caps are warming is nearly impossible to dispute. As a result, their ice covered habitat has been disrupted in a complete and fundamental manner. With even the very fabric of their existence shifting under their feet, their instincts hold little recourse. This deeply affects their access to prey and den areas. It is a very strong position to state that the effects of global warming are seen to be critical to the polar bear’s extinction (IUCN Red List 1). This research will explore the possible effects of global warming on polar bears. The issue is in need of special attention because the likelihood of polar bear’s extinction is a very important environmental concern. With the continuous climate changes, and the human population stuck in perpetual deadlock, affecting the habitat of polar bears, it is very likely that our environment will lose another biological component. This research paper will assess how the impacts of global warming are contributing to the likelihood of polar bear’s extinction. In order to gain a full understanding of the effects of global warming on polar bears, this paper will focus on three areas of literature. First, the study looks at the area that attempts to comprehend and illustrate that the polar bears are the bears of the sea. Second, the paper will examine the literature that discusses the effects of global warming on the earth in general. Third, the research will delve into the effects of global warming on polar bears specifically. By taking the time to examine all of these basic facets, the picture of the plight of the Polar Bear begins to come into focus. First, we start by learning about the polar bear. Long regarded as the largest terrestrial carnivore in the whole world (World Life Fund for Nature’s Status Report), the bear has few natural enemies. According to Norris et al, its scientific name is Ursus maritmus (8) was provided by Phipps in 1774. Long a natural wonder, generations of scientists have been recording the Polar Bear. Polar bears are characterized differently from the other existing species of bears by Phipps (Schliebe et al., 219). Meanwhile, Kurt’en has examined revealing fossil evidence in 1964. In his examination, he suggests that the polar bear has come from the period of glacial ice advances of the mid Pleistocene era. Kurt’en goes on to illustrate that the polar bears may have originated from the Siberian grizzly bears. There have been conflicting studies both supporting and debunking this theory, with one study agreeing and then another study according to Shields and Kocher in 1991, found that polar bears may have originated from grizzly bears (Schiebe et al. 218 – 221). According to Calvert and Stirling, what makes the polar bears distinct from the other bears is that they are carnivorous (352). They are regarded as the Arctic marine ecosystem’s upper level predator. Regarding seals as their main source of sustenance, Polar bears routinely target the ringed seals, followed by the bearded seals. Though in differing regions, polar bears eat the other species of seal. Polar Bears are also well known for killing and eating much bigger animals such as walruses, narwhal and belugas (Calvert and Stirling 351 – 356). During the non- availability of seals, for what every cause, eating something other than seals is vital to the survival of the bears. According to Stirling and Oritsland, it is very common for the Polar bears to substitute other prey species if seals are not present (2609). Very much able to obtain nutrition from many sources, a study conducted by Lunn and Stirling have found out that sometimes, polar bears have even eaten human garbage for food, though no increase in changes of survival or successful reproduction among polar bears is observed (2291 – 2297). Typically in terms of reproduction, polar bears have very low reproductive rate. In a study by Anglish and Lodge in 2004, the maximum increase rate per annum of polar bears is approximately 6% (220). This low rate of increase is explained by the following reasons: sexual maturity occurs at a late age; litter sizes are small; and parents of the polar cubs invest their time in raising the young (Anglish and Lodge 114 – 230). When foraging conditions are tough, it is possible for the polar bears to postpone their reproduction in preference of survival (Derocher et al. 1156). It only goes to show that this continuous deferral of production results in a decline in the numbers of polar bears that survive. (Derocher et al. 1156). With the very low reproductive rates among polar bears a high survival rate is needed in order to sustain their population levels. According to Derocher and Stirling, survival rates of polar bears have improved as they grow older (1249). However, as with every species, this means that the most vulnerable polar bears are the cubs and are noted for having the lowest survival rates among the life stages of polar bears (1249). Nonetheless, death at an early age is believed to be linked with starvation (1250). The species of Polar bears is a sea mammal. According to Amstrup, it is for this reason that the sea ice is the most important and primary habitat of polar bears (588). Since polar bears have evolved and developed to specifically utilize the ice-covered circumpolar Arctic. Primarily, the bears are spread throughout the sea ice of the Northern Hemisphere (Amstrup 589). Even though polar bears are not spread overly far, they are not equally dispersed all over the sea ice (Amstrup 589). Most of them are found in areas whose water is just shallow and whose flow as well as current cause them to improve their productivity (Amstrup 592). Generally, the majority of polar bears choose to be in ice water areas whose ice coverage does not solidify too much during winter season (Amstrup 592). It is also pivotal to the global warming argument that the polar bears rely greatly on the sea ice to search and prey on seals (Amstrup 592). Another crucial role of the ice-covered sea is the theatre to seek out and obtain a mate (Amstrup 592). Following the successful mating, the ice floes serve as a safe and secure haven and serve a vital function for long distance movements to the maternity denning areas in land or just for maternity denning (Amstrup 592 - 593). In a study entitled “Polar Bears and Seals in the Eastern Beaufort Sea and Amundsen Gulf: A Synthesis of Population Trends and Ecological Relationships over Three Decades” by Stirling in 2002, he stated that the annual changes of the sea ice due to the environmental factors have affected both the polar bears and their prey (59 – 76). The consequences made by these environmental changes are lowering the bear’s available food source. Their areas of traditional sustenance are no longer able to sustain them. Long a primary and favored food source, the ringed seals’ productivity has been lowered because of the heavy iced conditions in the southern Beaufort Sea during the mid–1970s and mid-1980s (Stirling 62). This effects the polar bears in terms of distribution, productivity, reproduction and survival (Stirling 74 – 75). The changes in the sea environment have resulted in the overall decline in the birthing of polar bears as well as the survival of the sub–adults (Stirling 74). Previously, after an earlier set of changes in the environment, the polar bears had managed to achieve very successful reproduction. These changes went on to be followed by an improvement in their survival. This goes to show how the fluctuations in the sea ice environment directly affect the Polar Bear. In short, the simplicity of the arctic marine ecosystems, as well its species of different sorts, is all delicately affected by every transformation of the ice – covered sea environment (Stirling 59 – 76). Before the effects of Global warming were thought of, the population of polar bears already had already been in a steady decline. There were many more causes than the environment for their gradual slide. These include human–caused factors like harvesting, subsistence hunting, or just by accidentally killing a polar bear due to defense of life or property (Schliebe et al. 34 – 35) alongside the cumulative effects of global warming (Hansen 173 – 190). The full effect of the human influence on the population of Polar Bears is still not known for certainty. It is of alarming concern how the complexity of effects brought by the fluctuations of environment has caused the death of polar bears. The total count of polar bears has gone down to a rough estimate of about 20,000 to 25,000 in the entire world (Schliebe et al. 34 – 35). Given this substantial and continued decline in the population of the polar bear, the species has been categorized as ‘vulnerable’ on the IUCN Red List of Threatened Species last 2010. This categorization marks an uptick in the overall level of anxiety facing the survival of the species. Over the past decades, it has been observed that the sea–ice region in the Arctic has a deep–seated seasonal cycle. Aside from the seasonal fluctuations, there is also a decadal as well as inter–decadal change in the ice–covered area. This is because of the transformations in the patterns of atmospheric pressures together with its winds. The decadal and inter – decadal fluctuations in the sea ice are also brought by the continental discharge as well as the Atlantic and the Pacific’s inflow. All of these factors merge together to determine the amount of snow and ice that will accumulate. The records of satellite data suggest that the approximated rates of decrease of ice water covered regions in the late summer are the following: a -6.5% per decade from 1978 to 2001, followed by a -7.3% per decade over 2002, and a 7.8% per decade through 2004. This lowering of sea ice has even gotten worse than it has ever been before. Between 2002 and 2005, the negative trend has accelerated to a -8.5% per decade. Likewise, the thinning of the Artic sea ice is also observed. From 32% in the 1960s to 1990s, it has gone down to a thinning of about 2.5 to 3.75 % per decade. These factors all continue to slide downward, contributing to a rapidly shrinking Polar Bear habitat. The duration of the melt period is regarded as a very significant cause affecting the thickness of the sea-ice cover. With the continuous increase in the temperature of the earth, accumulated body of observations has directed to an earlier start of melting as well as the extending the melt season. Thus, this means a decrease in the total ice cover. All of these factors directly affect the Polar Bears eating and mating habits. The less sea ice available for the bear, the less food and shelter there is. With this scenario, it is noted that an extended melt period is an indication of shorter growth for the ice season. Thus, the sea ice cover is less extended and less in thickness. This trend continues to develop and impact regional hunting and mating patterns. Standing alongside the discussed changes in the living environment of the Polar Bear are a lot more other observed changes in the Arctic. Changes such as the decrease of the snow–cover extent, shrinking of glaciers, thawing of permafrost due to increase of temperature which is accompanied by warming, increase of river discharge, breaking up early and freezing up later of rivers and lakes, rise of sea – level and increase of precipitation, serve to stifle the Polar bear even further. These observations theorize that these conditions are projected to worsen with the persistent warming of the Earths surface. The Arctic serves as a global warning system of the largest sort. The impacts of global warming in the Arctic are much more intensified than any place else on Earth. The effects of climate change in the Polar Regions are recorded to be the most tremendous and fastest developing. These arctic evolutions result in huge modifications on all aspects of the Earth. If these changes continue, there are projections that the sea– ice will be totally wiped out in the not too distant future. If this is the case, lots of animals relying on the sea–ice for survival, like the polar bears, will certainly suffer and perhaps become extinct (Schliebe et al. 64 – 71). With the recorded effects of environmental changes in the Arctic region, sea–ice dependent creatures including the polar bears are greatly put at risk. Since polar bears are a kind of bear that has relied with great totality upon the sea–ice water habitat in the Arctic in order to survive, the huge effects of the global change in their habitat completely cause adverse impacts to any increase in polar bear movements or travel. These factors also hamper the distribution changes of polar bears as well as their access to their most favorite ringed seal prey, to their access and seasonal migration between the sea – ice and the land denning areas, to their open water swimming, to their reproduction as well as their resting. Indeed, it has already been argued how the global warming largely affects the Arctic. Given that with the continuous rise of temperature means a continuous decrease of the width of the multi–sea ice, and thus an intensified rate of movement of the ice flow, bears of this sort must increase their travel and do bigger movements in their search for prey and denning areas (Derocher et al. 163 - 176). With the increased rates and extent of ice movement, polar bears have to walk against the ice movement. This is for them to sustain their habitats instead of searching for a fixed location. In this case, polar bears have used more of their energy to sustain their location near their selected habitats. Such situations when the ice has moved in a more rapid movement or even has become more disintegrated cause the polar bears to use more energy to uphold their contact with the ice. The increase of spent energy drastically lowers the bears chances of survival. It is also the case that the reduction of the habitat patch sizes can also lessen the food sources. As the availability of food is put in decline, the Polar Bears big movements and need for travel in the sea ice is no longer sustained by the energy. As a result of this, the polar cubs which are dependent on their parents for survival, also suffer the consequential impacts of climate change. Another possible scenario, pointing to the plight of the polar bear, is observed in some areas as an impact of global warming. The rise of sea–ice movement and the rise of areas of unconsolidated ice have caused the polar bears lose contact with the ice. As a result of this the polar bears to drift down to the water. The said impacts are undeniably contributors to the decline of population of polar bears (Derocher et al. 163 - 176). In the evaluations of Stirling and Parkinson concerning the ice conditions as well as the distributions of polar bears in the Eastern Canada, they have determined that the sea ice is at a progressive breaking up point. In their analysis on population size as well as the conditions of polar bears, they have observed that the total number of polar bears are already in decline and will probably continue to decline. This is for the reason that most of them are nutritionally stressed at high levels (Stirling and Parkinson 271 – 272) In terms of their access to their preferred denning areas, many polar bears usually and repetitively come back to a particular denning area on land. To achieve a successful bearing, polar bears must achieve their preferred land denning area in which the ice must float just nearby or must freeze beforehand the fall. This is for pregnant female bears to go to their chosen areas and dig a den in the late October or November. However, as global warming has progressed, the effects on the sea ice advance has decreased.. In fact, the bigger variation on the distance is already taking place between the denning areas and the ices. This still worsens the situation, making it far more difficult for the pregnant polar bears to reach their preferred denning locations (Derocher et al. 163 - 176). The thinning of the sea ice and the probable rise of ice floes drift rates also affect the denning areas. Slightly more than half of the dens are found drifting some several hundred kilometers away from the north of the coast. It is also the case that the increased sea ice drifting with maternity dens result to a longer distance travel. This means that female polar bears have used more energy in order to go back to their normal habitat range with small cubs. Thus, it only shows that possibilities of reduced survival of cubs (Derocher et al. 163 - 176). In the arctic every ounce of energy is necessary for the Polar Bear to survive the harsh, unforgiving climate. Meanwhile, the changes in the Arctic affect the prey of the polar bears as well. The decrease of sea–ice would cause an effect to the distribution, abundance, and accessibility of ringed seals among polar bears. There has been a sharp decrease in the ability of the Polar Bear to successfully hung the ringed seal. As a result of this, the bears body conditions are affected. Some female polar bears are not able to produce an offspring because of the lower weight levels than the required to reproduce, (Derocher et al. 165). In the past it was the case that the mortality of polar bears is was most likely to occur during winter, for the reason that the complicated effects of climate change affect their access to prey. Their energy is mostly expended during winter when their fat reserves are low. The pregnant female polar bears are in dens on the winter season and are not feeding but consumed their stored fats (Derocher et al. 176). This shows how absolutely vital and precious every bit of sustenance and life giving food is needed. Conclusion Within the pages of this paper only a few of the possible impacts of global warming on polar bears are presented. With the given information on the species of polar bear as well as global warming and its effects still in its infancy, indeed, one thing is made clear. It is the case that the continuous warming of the temperature of the Earth, will absolutely negatively affect the polar bears. With the cumulative effects of climate change, it is very likely that our descendants will only know of the polar bears as be parts of the environmental history. In summary, the polar bear’s habitat, the sea ice–covered region located in the Arctic is found to be extremely vulnerable to global warming. The same sea–ice extent has been decreasing over the years. The width of the ice is also reduced, as well as the sea – ice platforms themselves being broken up. All the while, the ice floes are at a greater drift rate. All these changes in the Arctic are directly related to the continuous rise of temperature of Earth. As a result, species such as the Polar Bear are dying because of their reduced access to prey, their decrease in stored energy due to unavailability of foods, their long travel to the dens and back to their home range, to the floating dens, to their unsuccessful reproduction, to the difficulty of reaching the ice platform when drifted down to the water and many other earlier mentioned factors. Thus, without drastic and radical change that halts the continuous effects of the climate change, in the near future, the Arctic as we now know it could very well vanish never to be seen again by human eyes. Works Cited Amstrup, S.C.. “Polar Bear (Ursus maritimus).” in Feldhamer, B.C. Thompson, and J.A. Chapman, eds. Wild Mammals of North America- Biology, Management, and Conservation. John Hopkins University Press. 2003. 587-610. Print. Amstrup, S.C., Durner, G.M., Stirling, I., Lunn, N.J., and Messier, F. “Movements and Distribution of Polar Bears in the Beaufort Sea.” Canadian Journal of Zoology 78 (2000): 948–66. Print. Angliss, R.P. and K.L. Lodge. Alaska Marine Mammal Stock Assessments, 2003. United States Department of Commerce, NOAA Technical Memorandum NMFSAFSC- 144. 230. Web. Calvert, W. and Stirling, I. “Interactions between Polar Bears and Over-Wintering Walruses in the Central Canadian High Arctic.” International Conference on Bear Research and Management 8 (1990):351–56. Print. Derocher, A.E. and I. Stirling. “The Population Dynamics of Polar Bears in Western Hudson Bay.” in McCullough, D.R. and R. H. Barrett, eds. Wildlife 2001: Populations. London, UK : Elsevier Applied Science,1992. 1150 - 1159. Print. Derocher, A.E., N.J. Lunn, and I. Stirling. “Polar Bears in a Warming Climate.” Integrative and Comparative Biology 44 (2004):163-176. Print. Hansen, J. Climate Change: Understanding Global Warming. In R.t Lanza, One world: the health & survival of the human species in the 21st century, pp. 173–190. 2000 . Mexico: Health Press. Print. IUCN Red List. Species of the Day: Polar Bears. IUCN Red List, 2010. Web. 22 January 2012 Lunn, N.J. and I. Stirling. “The Significance of Supplemental Food to Polar Bears during the Ice-Free Period of Hudson Bay.” Canadian Journal of Zoology 63 (1985):2291– 97. Print. Norris, S., Rosentrater, L. & Eid, P.M. Polar Bears at Risk: A WWF Status Report. Switzerland: World Wide Fund for Nature. May 2002. Web. Schliebe, S., Evans, T., Johnson, K., Roy, M., Miller, S., Hamilton, C., Meehan, R., and Jahrsdoerfer, S. Range – Wide Study Review of Polar Bear (Ursus maritimus). Achorage, Alaska: U.S. Fish and Wildlife Service. December 2006. Web. Shields, G.F. and Kocher, T.D. “Phylogenetic Relationships of North American Ursids Based on Analysis of Mitochondrial DNA.” Evolution 45 (1991): 218– 221. Print. Stirling, I. and C. L. Parkinson. “Possible Effects of Climate Warming on Selected Populations of Polar Bears (Ursus maritimus) in the Canadian Arctic.” Arctic 99.3 (2006): 261-275. Print. Stirling, I. and Oritsland, N.A. “Relationships between Estimates of Ringed Seal (Phoca hispida) and Polar Bear (Ursus maritimus) Populations in the Canadian Arctic.” Canadian Journal of Fisheries and Aquatic Sciences 52 (1995):2594–2612. Print. Read More