The Race Against Time: Threatened polar bear habitat under attack from climate change

Kasey Tenggren, Bachelor of Science in Earth Systems

Christopher O’Brien, Bachelor of Science in Turfgrass Science and Management

Katy Ziemlak, Bachelor of Science in Natural Resource Conservation


Imagine you live in a small neighborhood on an island that can only be accessed through one boat off the coast of the mainland. This boat operates on a normal schedule from September until early spring in April or May. You rely on these months and this boat’s schedule to get supplies you will need to survive on your island each year. From early spring until September the captain of this boat discontinues travel back and forth to the island each year to satisfy the persistence of their spouse. You see, the island transportation doesn’t pay well and their spouse wants them to get a better job during the summer months. For your whole time living on this island you learned how to adjust to the Captain’s schedule and make appropriate accommodations to gather the food, supplies, and other necessities you need to survive through those months. However, with further worsening of the economy the Captain’s spouse  requests they work their other job all the way into September this year. This means you and your family are on the island for an additional month with dwindling supplies. You’re forced to eat and use less in order to conserve what energy and supplies you have. At least it’s just this one year before you can adjust to the Captain’s change in schedule. Now imagine you can’t adjust because of the impromptu timing of the Captain’s cancellation. Imagine every year you get to the end of the summer, the end of August, and you find your supplies thinning, your energy withering, and your body getting weaker. This is how polar bears have lived for the past several years. Unlike you and your family, polar bears are incapable of evolving to fit their environment so quickly. Your accessibility to the boat is representative of polar bear’s accessibility to the vital sea-ice they rely on.

In the winter months, polar bears rely on sea-ice and the prey that are unique to that area to provide energy and food source. This will maintain their physique through the remainder of the year (Stirling & Derocher, 1993, p. 241). They rely on the refreezing of sea-ice in autumn months, typically September, in order to return for the winter. Arctic sea-ice has repetitive earlier breakup in the summer and delayed seasonal freezing in the winter due to warming climate (Stirling & Parkinson, 2006, p.262). This forces the polar bears to spend more time on land than usual, and like you and your family stuck on your island for an additional month, this has drastic effects on their ability to access important food sources (Stirling, Lunn, & Iacozza, 1999, p.294). The United States Geological Survey predicts that by 2050 two-thirds of the Earth’s polar bears will be gone (Amstrup et. al, 2010, p. 955). They developed this data to correlate with the trends of increasing human-caused greenhouse gas (GHG) concentrations in the atmosphere. These are responsible for the change in when the seasonal melting and freezing of the Arctic sea-ice occurs.

It’s clear that the large amounts of GHG dumpage into the atmosphere, specifically from humans, is greatly responsible for the increasing global temperatures and the recent climate change. National Aeronautics Space Administration states that about 97% of scientists agree that recent climate change is due to an increase in GHG concentrations in the atmosphere because of human-caused emissions (Shaftel, 2016). The concentrations are largely responsible for weakening fragile habitats including sea-ice. It is believed by multiple experts that “the twenty-first century will likely bring a summer when the Arctic Ocean is virtually free of ice” (Henson, 2014, p. 97). If this were to happen, it would be the first time in perhaps 100,000 years. This will have dangerous repercussions for the Arctic environments and ecosystems that rely on this sea-ice haven (Henson, 2014, p. 97 ).

The Arctic itself is particularly vulnerable to climate change, and its impacts on this area could be more detrimental than any other place on Earth. The problem isn’t just that the human-caused GHGs are raising global temperatures to an extent where sea-ice coverage is lessening in autumn months. It also includes the fact that warmer atmospheric temperatures create a warmer ocean (Henson, 2014, p. 100). This means that not only is ice coverage being shortened on a horizontal scale as it spreads across the ocean, but the ice is also melting vertically and thus eliminating the multiple layers that are responsible for its thickness. In the past, sea-ice thickness has been greatly contributed to the layers of ice that have accumulated over multiple years. These thick layers of sea-ice are now being replaced by thinner, more recently accumulated layers that tend to melt faster and more easily. Henson (2014) comments on the thinning of the ice as he writes, “data on ice thickness collected by U.S. nuclear submarines from the late 1950s to 2000 show that sea ice thinned by up to 40%” (p. 100). Easier melting circumstances of Arctic sea-ice will provide less of this environment to the species that heavily rely on it.

Polar bears are the top predator of the Arctic and one of the species that rely on the unique sea-ice habitat. They are at the top of the food chain and what they eat, or don’t eat, can have effects on the rest of the ecosystem (Stirling & Derocher, 1993, p. 244). With sea ice melting earlier than usual, polar bears are forced to move to land sooner which gives them less time to eat seals, their main source of food (Stirling & Derocher, 1993, p. 241). This can increase the seal population. An increase in this prey can set up a chain reaction throughout the Arctic food web. This causes polar bears to find other sources of food on land. Being on land longer can lead to an increase of human and polar bear interactions due to the polar bears’ needs to search for new food sources (Stirling et al., 1999, p. 341). Consequently these could become negative interactions between the two species. Polar bears may endanger humans, but humans may also threaten the polar bear populations (Stirling & Parkinson, 2006, p. 266). Due to increased numbers of sightings by the indigenous people, such as the Inuits, populations of polar bears were mistaken to have been increasing in size. In result these native people hunted more polar bears, and that proved to be detrimental to polar bear population. (Stirling & Parkinson, 2006, p. 271). It’s important to understand the repercussions of declining sea-ice availability on the lifestyles of polar bears. Such consequences will ultimately affect human populations as well as the organisms that are a part of the same Arctic food web.

Polar bears rely greatly on their environment to maintain their health, and this sea-ice habitat is fragile because of its dependency on climate and temperatures. With recent warming due to the constant release of human-caused GHG emissions into the atmosphere, this sea-ice habitat is greatly threatened. Just since the year of 2013, Arctic sea-ice has reached only about 65% of the area it has been known to cover in September, as compared to values from the 1970s. That’s 35% of sea-ice coverage that no longer exists in only about 30-40 years (Henson, 2014, p. 98). Imagine what could happen if humans keep dumping such large, careless amounts of GHGs into the atmosphere. There could potentially be future summer months where there is no sea-ice whatsoever if humans keep continuing their output of carbon and GHGs without conscious alterations in their behavior (Henson, 2014, p. 100). Although it may be easy to point fingers and blame other people and nations, the fact  is that every person is responsible for increasing carbon concentrations in the atmosphere. This trend has had significant increase since data started being collected in the 1950s and is responsible for atmospheric warming. To put it into perspective, an average person puts 10,700lbs of carbon dioxide into the atmosphere a year; “in other words, someone who weighs 68kg (150lbs) puts the equivalent of her weight in carbon dioxide into the atmosphere in less than a week” (Henson, 2014, p. 43). This does depend somewhat on where people live and perhaps on their income, but ultimately this is the average for those who have the privileges of using fossil fuels for their everyday technologies. Such people include citizens of the United States. Every bit of carbon and other GHG that is emitted into the atmosphere increases the global concentrations. With this increase in concentrations comes an increase in temperature and a decrease in the beloved polar bear’s habitat of sea-ice. A declining habitat can have serious effects on the well-being of polar bears and their ability to proceed as a species.

Declination in sea-ice threatens polar bears’ ability to obtain needed energy from food that they need to store in their bodies. This is mostly due to the reduced availability of polar bears’ main prey, seals, that reside in the Arctic (Derocher, Lunn, & Stirling, 2004, p. 168). Researched polar bear populations in the Hudson Bay area of Canada exemplifies the polar bears’ inability to hunt substantial prey. Stirling and Parkinson (2006) comment on how sea-ice affects polar bears and their accessibility to prey stating that “these populations must spend several months on shore surviving on their stored fat reserves and whatever limited and unpredictable food sources they might find on land” (p .271). The later freezing and earlier melting of the sea-ice shortens the polar bears feeding period dramatically. As a result polar bears increase their range of hunting in search for substinance since “such changes require bears to travel longer distances in search of seals, and to diversify their diet when possible, expending more energy and depleting adipose stores” (Prowse, Furgal, Wrona & Reist, 2009, p.285). This means that because polar bears hunt over broader areas, they use up more energy to find food then they get from those prey. This causes a weakening in their health and physique, which affects the mortality of polar bears (Stirling & Derocher, 1993, p. 241).

Along with the decline in the ability for polar bears to store energy, polar bear reproduction rates are also at risk. The polar bears embark on a fasting period when they move on land to rest and prepare for the birth of their young. This period is determined by spring ice break-up which signals the bears to go to land. With earlier break-up in the ice comes a longer fasting period, and the polar bears won’t have enough time out at sea to eat a sufficient amount of food for needed energy storage. This can lead to starvation of polar bears and malnutrition in young (Molnar, Derocher, Thiemann, & Lewis, 2010, p. 1613).

Female mating success rates are also slowing due to a loss of sea ice. Female polar bears gain weight until they are about 15 years old, but a decline in the amount of weight they have been able to gain demonstrates a slowing growth rate. If the growth rate slows even more due to the sea ice loss and reduced time able to eat seals, the female polar bears will have a later reproduction rate (Derocher et al., 2004, p. 170). Later reproduction rates could negatively affect the likelihood of survival for young polar bears and thus affecting their whole species.

In order to combat the environmental effects climate change has on polar bear health and reproduction, the world needs to unite to fight climbing temperatures. From the end of November into December of 2015 there was a conference held in Paris, France. This conference was held by the United Nations Framework Convention on Climate Change (UNFCCC) and is referred to as the twenty-first Conference of Parties (COP21). At COP21 there were representatives from 195 countries in attendance. This resulted in a “historic agreement to combat climate change and to accelerate and intensify the actions and investments needed for a sustainable low carbon future” (United Nations Framework Convention on Climate Change, 2014). At this historic meeting there arose a goal to hold the global average temperature change to under 2℃ from pre-industrial times. To go even further, the 195 nations agreed cap the global temperature increase to one and a half degrees Celsius above pre-industrial temperatures, and to recognize “that this would significantly reduce the risks and impacts of climate change” (United Nations Framework Convention on Climate Change, 2015). Although this is an encouraging sign of understanding and moving forward to a fossil fuel-free future, this means that people of these nations need to hold their leaders accountable to stick to this agreement.

Many people argue that climate change is an issue that cannot be capped at a certain level of temperature rise, and thus don’t believe it is possible to save polar bears and other threatened species. Because of this belief, many might not think it is not worth worrying about their emission input into the atmosphere. However, Matthews and Weaver (2010) argue that actively conducting ways to reduce emissions in the future can lead to successful restrictions to  global temperature rise “to a level that will prevent dangerous impacts on both human and environmental systems” (p.143). If the effects of these emissions are affecting species such as the polar bear, it would be worthwhile to attempt to reduce our carbon footprint. In doing so we could protect the fragile arctic ecosystem as a whole, and inadvertently protect the interests of humans around the world.

Arctic sea-ice habitat that polar bears rely on to survive is at a significant risk due to the human-caused climate changes discussed at COP21, and carbon taxes by nations’ governments need to be implemented in order to reduce GHG emissions into the atmosphere. Carbon taxes act as an emissions-trading system that put a price on the use of fossil fuels (Oreskes, 2015, p. 76). This means that people will be taxed on their over-usage and dumpage of carbon into the atmosphere. Doing this may make it possible to protect the Arctic and other environments that are particularly at risk due to increasing global temperatures. Naomi Oreskes (2015), an affiliated professor of Earth and planetary sciences at Harvard University,  confirms this as she writes that, “a hefty price on carbon, coupled with major investment in technology, can definitely limit climate change” (p. 78). Strong encouragement and investment in cleaner, non-fossil fuel energy sources will slow down and combat human-caused climate change through the reduction of carbon in the atmosphere. Money can then be put towards technologies in cleaner energy, including solar and wind energy, that need more funding and investment in order to completely replace fossil fuels (Oreskes, 2015, p. 78). This will in turn help save species, such as polar bears, that have no significant control over the changing climate or GHG concentrations in the atmosphere.

Since the U.S. was in attendance at COP21, it’s especially important for this country to step up. Unlike some other nations, the U.S. has the freedom of speech and the freedom of its citizens to elect officials. It’s important to elect those who will carry out the duties of keeping global temperature rise below 2℃. Citizens can do their individual part in the U.S. by voting for such people to represent us as a nation. Another action that will be beneficial in combatting climate change and capping the temperature rise to 2℃ would be implementing a carbon tax that would limit the amount of carbon people can put into the atmosphere on a daily basis. This goes back to electing government officials that will carry out such a task. Millions and millions of people are wasteful with technologies that rely heavily on fossil fuels. In the U.S., that’s most of everyone’s main way of getting electricity. If there’s a tax on how much carbon one can emit into the atmosphere in a given week, consumers would put pressure on companies providing electricity to use cleaner energy instead of fossil fuels. This would create a desire and focus to find the best way to get energy as readily available in a much cleaner way. Oreskes (2015) puts it into perspective as she writes “we are dumping carbon into the atmosphere without paying for that privilege” (p.77). Oreskes (2015) mentions that completing these acts and overusing this privilege causes a failure in the economy. She states that, “a price on carbon emissions that reflects the toll they take would correct that failure” (Oreskes, 2015, p. 77). This means more long-term sea-ice in the Arctic. This means better health for the Arctic’s apex predator, the polar bear, meaning more balance in the fragile Arctic ecosystem that coastal people and other Arctic species rely heavily on (Henson, 2014, p. 108).

If we as humans create a plan to mitigate the expulsion of GHGs, the effects of global warming can be slowed down. It is possible to do this if people of the world, and especially countries like the U.S., take action to limit their carbon footprint. This can be done through the encouragement to abide to the COP21 agreements, and by the election of government officials who will implement and create policies that coincide with the global temperature cap of 2℃. Policies such as carbon taxes will be especially rewarding in combatting climate change in nations such as the U.S. These types of nations dump an overwhelming amount of GHG emission concentrations into the atmosphere. Reducing the amount of carbon that nations input into the atmosphere can help hold global temperature rise to 2℃ and thus limit the dangers temperature rise can have on specific environments. This decrease in global temperature will be in the polar bears’ favor by providing more time for polar bears to adapt to their ever changing sea-ice habitat. This may be the difference between a future with or without an effective and complete Arctic ecosystem. There is no doubt that the modern polar bear has been proven to be a product of evolution, adapting to survive sub-freezing ice age temperatures and warmer interglacial periods over the span of thousands of years as Henson (2014) writes that, “recent studies indicate that polar bears as a species have some 600,000 years behind them” (p. 106). It is known that polar bears are capable of surviving temperature increase, but never before have they experienced such rapid warming (Henson, 2014, p.107). By slowing climatic temperature rise, polar bears can be given a fighting chance to adapt to survive in a habitat with limited sea-ice.



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