Generally, the global warming refers to an average increase in the Earth’s temperature, which in turn causes changes in climate. Some scientists like to mention the global warming as green house effect. “Global warming has reached a level such that we can ascribe with a high degree of confidence a relationship between the green house effect and the observed warming” (Paterson, 1996, p. 330).
On of the major causes of global warming is the global climate that is changing because of the build-up in the atmosphere of carbon dioxide (CO2), methane, nitrous oxide (N20), and the CFC (powerful green house gases as well as destroyers of stratospheric ozone). (O’Carrol, 2002) Another reason of the global warming is green house effect. About 30 gases produced by human activity have been identified as contributing to the green house effect.
Emission of Co2 and other harmful gases from the man made factories and industries affects the ozone layer of the earth and contribute to the global warming. However, the problem of global warming imposes even greater challenges on the populations of some species. Analyses of the extent of species loss from global warming are sparse, and so far quantification in the corresponding economic valuation remains nonexistent. Yet some argue that overall biosphere viability depends on biodiversity because of lessened ability to respond to shock with a narrower biological range.
In any case, many species are already endangered or threatened in the United States (including the polar bears, bald eagle, the grizzly bear, the Florida panther, the whooping crane, and numerous other fauna and flora; Council on Environmental Quality 1991, 138). Polar bears inhabiting southern areas of the Arctic Circle are stranded each summer as the melting of ice packs starts. Moreover, being separated from their principal prey of ringed seals, the bears endure a summer-long last until the ice returns in November.
According to explanations given by Arctic ecosystems expert Derocher, “The climate predictions coming out are showing massive changes in sea-ice distribution…You don’t have to be a polar scientist to see that if you take away all the sea ice you don’t have polar bears anymore” (Cristol, 2003, p. 6). Indeed, over the last 35 years, Arctic ice has thinned from an average of 3. 1 meters to 1. 8 meters (Cristol). As a consequence of the climatic shifts, polar bears are eating less, thus building up less fat reserves and have fewer chances to survive during hard seasons.
Moreover, it diminished cubs’ birth rate as well as their survival rate because they do not have enough fat too. Polar bears are systematically hunted by a few men every year, on hunts lasting a day or two and conducted in the area of the Elsie Islands (75 km northeast of the village). Bear hunting is a high-prestige and competitive activity; on hearing that one hunter plans to go out, other men may make separate plans to hunt on the same day. Polar bears are relatively rare, and locating one is an unpredictable business -a matter of “being lucky enough to be in the right place at the right time” according to one informant.
Nevertheless, some men find the monetary rewards (from sale of the pelt) or enhanced prestige sufficient to justify the high search costs. Overall, few bears (ca. 5/year) are taken by Inujjuamiut, and some of these are opportunistically encountered in the course of other types of hunting. Although a true bear, and thus taxonomically a terrestrial species, the polar bear (nanuq) is behaviorally and ecologically a marine mammal most of the time. These long, slender bears spend the major part of the year in the water or on the sea ice.
Adult males reach a length of 2-3 m and 420-500 kg in weight (Banfield, 1974, p. 311). The species has a circumpolar distribution, occurring in all arctic seas and along associated coastlines. It is found as far south as James Bay at the southern end of Hudson Bay, but it is more common along the western coast and northern end of Hudson Bay than in the study area (Banfield 1974, 313). The favored habitat is pack ice, with solidly frozen areas and open seas being avoided when possible.
Polar bears are generally solitary animals, but cubs will stay with their mother for about one and a half years. Bears breed in April or May, and gestation lasts about 8 months. In areas such as Hudson Bay where sea ice melts in the summer, the bears come ashore to forage, while in the High Arctic they may remain on the ice year-round (Stirling and McEwan, 1995, p. 1021). In the late fall, females excavate hibernation dens on hillsides or on the sea ice itself. Cubs are born in the dens in midwinter; litter size is 1-4, with a mean of 2 (Banfield, 1974, p. 311).
Like other bears, polar bears are omnivorous if the occasion demands it, but this species is heavily carnivorous and its preferred prey is the ringed seal (Stirling and McEwan, 1995). Great tales are told by Inuit and white explorers alike of skillful hunting by nanuq, involving stalking, breathing-hole hunting, and even the use of ice projectiles to catch the seals. Bearded seals, walrus, fish, carrion, waterfowl, and even eggs and marine invertebrates will be taken if ringed seals are scarce. When foraging on land, lemmings, berries, and even grasses are consumed.
Although polar bears may occasionally fall prey to an orca or a bull walrus, their major predator is man. The abundance and growth rate of polar bears on the east coast of Hudson Bay are poorly understood (Smith, 1975, p. 180), but informants claim that in the study area at least bears are more numerous now than two or three decades ago. Since the animals favor offshore island groups that used to be settled by Inuit camps but are now rarely visited (Ottowa, Kidney, and Elsie Islands), there may be good reason for such an increase in the area.
Present hunting pressure is light and sporadic. A significant rise in Siberian temperatures during the late twentieth century has been provoked by “a speeding up of atmospheric circulation in the Northern Hemisphere [which] results in more warm air being transported deep into the region” (Burroughs, 1999, p. 70). Tundra and taiga (high-latitude forests in Asia) have been moving northward during the late twentieth century, as satellite surveys indicate that the amount of photosynthesis between 45 and 70 degrees north latitude has increased. This trend is linked by William J.
Burroughs to a “rise in spring temperatures, which lengthened the growing season at high altitudes” (Burroughs, 1999, p. 74). In this context, Burroughs raises one of many perplexing questions regarding how the Earth manages carbon: The possible increase in the growth of the taiga touches on another interesting aspect of the current global warming, which relates to our limited knowledge…. Measurements in the early 1990s suggested that the amount of carbon dioxide being absorbed at high altitudes was much greater than previously estimated….
This“Great Northern Sink” has been the subject of a great deal of speculation among scientists. (Burroughs, 1999, p. 74–75) This point of view is not universally accepted among scientists. Witness a nearly opposite assertion by tundra researcher George W. Kling, an associate professor of biology of the University of Michigan, who said, “Our latest data show that the Arctic is no longer a strong [net] sink [absorber of] carbon. In some years, the tundra is adding as much or more carbon to the atmosphere than it removes” (Kling et al. , 2002). The thinning of ice in the Arctic affects life all along the food chain.
When the ice breaks up earlier than usual, polar bears have less time to build fat reserves, and must rely on these reduced reserves for a longer period of time before ice forms again in the fall. Calculations indicate that a mean air temperature increase of one degree C. could advance the date of ice breakup nearly a week in western Hudson Bay (Mathews-Amos and Berntson, 1999). Hunger among adult bears will be reflected in their offspring, who will be born smaller and more prone to die at an early age. In the Bering Sea and in Hudson Bay, evidence of stress in polar bear populations is mounting as sea ice retreats (Stirling and McEvan1995).
Some native people in the Arctic have reported difficulty in hunting marine mammals such as walrus in recent years as sea ice has diminished. Canadian Wildlife Service scientists reported during December 1998 that polar bears around Hudson Bay are 90 to 220 pounds lighter than 30 years ago, apparently because earlier ice melting has given them less time to feed on seal pups. When sea ice fails to reach a particular area, the entire ecological cycle is disrupted. When the ice melts, the polar bears can no longer use it to hunt for ring seals, many of which also have died, having had no ice on which to haul out.
Johnson continues his description of the cycle of life that is being broken by retreating ice: If the polar bears and seals disappear, and if there is no place for the walrus to rest, to give birth and to nurse their pups, and if fisheries change as currents shift because of the redistribution of heat, then Native populations that subsist and maintain their cultures, at least in part, on the polar bear, the seal, the fish, and the walrus, are going to find their way of life in grave danger (Johnson 1999, p. 1). Pungowiyi sees evidence of a warmer climate in the daily life of her village: Our community has seen real dramatic effects as a result of the warming that is occurring in the Arctic Ocean and the arctic environment. In the springtime we are seeing the ice disappearing faster, which reduces our hunting time for walrus, seals, and whales. The ice freezes later. Ice is a supporter of life. It brings the sea animals from the north into our area and in the fall it also becomes an extension of our land.
When it freezes along the shore, we go out on the ice to fish, to hunt marine mammals, and to travel. Ice is a very important element in our lives…. When it starts disintegrating and disappearing faster, it affects our lives dramatically (Moreno, 1999, p. 43). The offshore ice-based ecosystem is sustained by upwelling nutrients which feed the plankton, shrimp, and other small organisms which feed the fish, which feed the seals, which feed the bears. The Native people of the area also occupy a position in this cycle of life.
When the ice is not present, the entire cycle collapses. [T]he ice melts earlier, in the springtime, in March, when the seals are having their pups, and [as] the ice breaks up, their pups will not be fully weaned so a lot of them will starve and will not be fully developed. Twenty years from now, we’ll see a reduction in animals because that generation of pups [did] not reproduce. We’ll see a major reduction in seals that we depend upon. So our future generations will feel a major impact as a result of what’s happening today.
It will be felt in 20 years. (Moreno, 1999, p. 43) Pungowiyi continued, “[A]s Native peoples, we are the ones that live the closest to the land, to Mother Earth. We live with it, we experience it, with our hearts and souls, and we depend upon it. When this Earth starts to be destroyed, we feel it. We have to do something before it is too late. We can’t wait until the economic community of the world is destroyed and we finally come to our senses” (Moreno, 1999, p. 44–45).
A large number of polar bears have been foraging on land in recent years, a probable result of the retreat of Arctic Ocean near-shore ice. In studies in Canada and Europe, the bears are shown to suffer from nutrition and denning problems when the ice withdraws from shore until very late in the fall. Changes to birds and bears are just a part of the effects from the 14 percent reduction in permanent Arctic sea ice since 1970. The trend is that the Arctic Ocean could become icepack-free during the summer by 2100 (Motavalli, 2004).
According to Cristol, some scientists have even predicted the Arctic Ocean could be entirely ice-free already by 2050 (Cristol, 2003, p. 7). If these global warming forecasts are correct, they may be a harbinger of what is to come throughout the circumpolar region as the Earth’s climate continues to heat up. Long-term temperature increases will mean a diminished ice pack that, in turn, will affect the survival of ringed seals, polar bears, and other northern species in unknown ways. As always, that future depends on actions taken in the present.