Global warming has been proven to have adverse effects on different ecosystems, and species of both flora and fauna. Amongst the latter, polar bears are the most affected (Molnár et al., 2010; Derocher et al., 2004; Rode et al., 2010). For instance, according to Cherry et al. (2013), global warming, as manifested in the melting of ice in the Arctic, has led to a significant loss of the species’ habitat. This has far reaching consequences since polar bears are principally marine mammals, and thus spend most of their life at sea than on land. Polar bears have been found to spend part of their life on land hunting for berries. Their interaction with human species has further decreased their population. For instance, people hunt and kill them for sport. Therefore, with increased climate change-induced melting of ice, the polar bears might be forced to spend more time on land. Their presence on land might result in increased sports hunting, leading to their extinction. Moreover, the fact that these mammals cannot mate on land implies that the time spent on land negatively affects their ability to grow their population. This, as a result, might lead to their extinction. Against this backdrop, this essay is aimed at describing how global warming has affected polar bears, and why their imminent extinction is a concern.
An important consequence of the melting of ice as a result of climate change is the loss of food for polar bears. This is because the seals are polar bears’ primary prey. These are best hunted while on sea ice. Melting of the ice, therefore, implies that polar bears are unable to hunt seals for their survival. As a consequence, they are highly likely to starve. Likewise, unlike other marine mammals which hunt for their food on a daily basis, polar bears depend on food reserves in their bodies for survival (Sims et al., 2004). For instance, during winter, polar bears hunt and excessively feed on seals. This is aimed at helping them to gain sufficient weight that helps them to survive through the autumn to summer. In these seasons, the population of seals is low. Therefore, melting of ice implies that the polar bears are unable to get enough food, and to gain sufficient weight. This threatens their survival before the subsequent next winter. Similarly, melting of ice implies that the bears have to spend their fat reserves traveling for long distances in search of food. This process leaves them with either little or no fat reserves to take them through the summer.
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The reproductive life of polar bears is dependent on their success at hunting seals (Molnár et al., 2010). Thus, long periods of unsuccessful hunts gradually reduce the reproductive chances of these mammals. For instance, the size and weight of the female bears determine their readiness for mating (Molnár et al., 2010; Rode et al., 2010). In this regard, zoologists have established that most bears mate towards the end of winter. This is because, at this point, they have accumulated enough fat reserves to survive for an extended period without much feeding. As a result, female bears weigh more in winter than they do in summer. In this regard, a female bear that has not gained sufficient weight is less likely to give birth. This is because it cannot sufficiently sustain gestation to successful delivery. Moreover, in case a female bear conceives when it does not have sufficient fat reserves, its mammary glands fail to produce enough milk to feed the cubs. This results in the death of cubs at a very early age. In some cases, such female bears might die immediately after delivery. Alternatively, the female bear may abandon the cubs to fend for themselves, and thereby drastically reducing their chances of surviving to maturity (Singh et al., 2011; Derocher et al., 2004). Hence, the melting of ice due to global warming is detrimental to the population of polar bears and is bound to reduce the numbers further.
Melting of ice destroys not only the habitats of mature polar bears but also threatens the survival of their cubs. Stempniewicz (2006) cites that in the year 2004, American biologists discovered several bear cubs drowned in the Beaufort Sea. They subsequently concluded that the actual number of drowned cubs could have been significantly greater. This argument was based on the fact that predators might have eaten some. The initial cause of drowning was considered to be the rough sea conditions. However, subsequent studies established that the cubs drowned as a result of the combined effect of retreating ice and more turbulent sea (Stempniewicz, 2006). Cubs take a significant amount of time before they can master swimming in deep sea waters. As a result, they spend their early days in the shallow waters. However, the melting of ice combined by its retreating into the sea rapidly increases the amount of sea water. This leads drowning of the cubs. Recently, an increase in the sea water volume has killed many cubs before they learn how to swim.
In light of the above facts, why should human beings be concerned about the possible extinction of polar bears? Polar bears are known to be an umbrella species (Smetacek & Nicol, 2005; Derocher et al., 2004). This means the conservation and protection of the polar bear's habitat results in the indirect protection and conservation of other species within the ecosystem (Stirlin et al., 2009). Polar bears are connected to various marine and terrestrial species through the food web (Smetacek & Nicol, 2005). For instance, the Arctic Fox, which cannot directly hunt the seals, depends on the polar bears for food. The Arctic Fox feeds on leftover seal carcasses after the polar bears have eaten to their fill. Likewise, given the fact that seals feed on fish, lack of a predator might lead to an imbalance in the ecosystem. This is in the form of an increase in the seal's population and a subsequent decrease in fish population. Hence, polar bears maintain the fish population by preying on the seals. Their presence at sea, therefore, sustains an ecological balance. Thus, human beings should not let polar bears become extinct because this would alter the ecological balance.
Smetacek & Nicol (2005) emphasize that polar bears ought to be conserved for the sake of biodiversity. Biodiversity refers to the presence of different species within an ecosystem. The concept of biodiversity recognizes that each and every living organism has its unique role in the ecosystem, and this cannot be substituted. Therefore, besides their roles in the food web, polar bears have other inherent functions in the ecosystem. Since such roles can neither be substituted nor replaced, extinction of polar bears is bound to leave a gap in the ecosystem. Other species will feel the effects of this within the same and different ecosystems. Hence, human beings should ensure that polar bears are conserved for the sake of the broader ecological balance of different ecosystems.
Global warming, as well as the resultant climate change, are human-caused problems. Their solutions, subsequently, lie with human beings. It is, therefore, the responsibility of humankind to embrace environmental protection through reduced greenhouse gas (GHG) emission so as to avert global warming. The accumulation of carbon in the atmosphere has been cited as the primary source of destruction of the ozone layer which renders the earth unprotected from the sun’s radiation. As a result, the first step towards environmental protection lies in the ability to reduce the rate of carbon emission. In conclusion, a significant reduction in GHG emissions can successfully protect polar bears, and subsequently, give them a chance to survive. This is important given their vital role in fostering a balance in the ecological systems.
References
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