The unfortunate truth seems to be that Arctic mammals such as polar bears, walrus and some seals are facing a grim future. These are ice-dependent animals, as they use the sea ice as a platform for hunting, traveling, breeding, and even as a place to den and raise their young. As the global climate changes, and temperatures begin to warm, sea ice has made a noticeable reduction in size, summer ice loss in the Arctic has been described as equaling “an area the size of Alaska, Texas, and the state of Washington combined” (www.polarbearsinternational.org/polar-bears/maps -and-trackers/sea-ice-loss). The implications of this ice loss are severe, and may lead to the extinction of multiple species.
What is the situation with sea ice?
“According to NASA-processed satellite microwave data… perennial ice used to cover 50-60 percent of the Arctic, but this winter it covered less than 30 percent. Perennial sea ice is the long-lived layer of ice that remains even when the surrounding short-lived seasonal sea ice melts to its minimum extent during the summer.” – Steve Cole (NASA Headquarters) & Stephanie Renfrow (National Snow and Ice Data Center)
What this means: sea ice is smaller than in recorded history, and continues to reduce in size. There are two conditions to consider about sea ice, the extent of the coverage and also the volume/depth. The National Snow and Ice Data Center (University of Colorado) examined monthly sea ice extent, and noted that July 2010 was the “…second lowest in the satellite record for the month. The linear rate of decline of July ice extent over the period 1979 to 2010 is now 6.4% per decade.” (http://nsidc.org/arcticseaicenews)
You may have heard skeptics say that sea ice is increasing, so how does this fit with the data that says it’s shrinking? Some statistics show that sea ice is increasing (July 2010 conditions were 100,000 square miles above average since July 2007 recordings), and there is a large cover of sea ice. However it is important to understand that this sea ice is yearly ice (not the deep multiyear ice), and does not contain the depth that it has had previously. It is thinner ice, and therefore melts very quickly. As temperatures increase, this yearly ice will melt—and because it is not refreezing to create the foundational multiyear
ice, the Arctic ecosystem is in jeopardy. Sea ice fluctuates with the seasons, increasing its coverage in the winter, and shrinking in the summer. This is a normal process, however the rate at which this ice is melting, and not being replenished is one of the large-scale signs of climate change. Scientists are predicting an ice free arctic within our lifetime.
Implications for Arctic mammals: Polar Bears, Seals and Walrus“The PBSG [Polar Bear Specialist Group] renewed the conclusion from previous meetings that the greatest challenge to conservation of polar bears is ecological change in the Arctic resulting from climatic warming.”(15th Meeting of PBSC in Denmark, 2009)
In May 2008, Polar Bears were listed as a threatened species in the Endangered Species Act. U.S. Geological Survey scientists believe that two thirds of the world’s polar bears (estimated between 20,000-25,000 individuals) could disappear by 2050 (www.nwf.org/Global-Warming/Effects-on-Wildlife-andHabitat/Polar-Bears.aspx).
Polar bears have attracted attention in the global community, as they are facing some very real, “right now” effects of global warming. These bears are iconic Arctic animals. They exist in one of our worlds harshest climates. Changes from global warming are drastically affecting Arctic regions, and as such the wildlife implications are equally as drastic. Changing sea ice and suffering Arctic mammal populations are something we can observe in our own lifetime; they are not obscure possibilities.
There are 19 different polar bear populations worldwide, existing in 5 different countries. Understanding the population trends is an important factor in understanding the effects climate change and decreasing sea ice has on these bears. Of the 19 groups, only 2 are considered to be thriving and increasing, 6 groups are stable (but not increasing), and 5 groups are steadily declining. There are 6 additional groups of bears, however their exceedingly remote locations make counting their numbers virtually impossible.
Distribution and Welfare of Polar Bears in Various Regions
Fish & Wildlife Service, Polar Bear FAQ The Alaska Fish & Wildlife Service estimates Alaskan polar bear populations to be around 3,500 individuals (1500 in the southern Beaufort Sea, and a declining 2000 bears in the Chukchi/Bering Sea). http://alaska.fws.gov/fisheries/mmm/polarbear/issues.htm
Polar bears are apex predators (at the top of the food chain) and live in a unique environment that is among the first to be drastically affected by a changing climate. Polar Bears currently live in Arctic habitats in Alaska, Canada, Greenland, Norway and Russia.
According to the US Geological Survey, Alaska Science Center, summer sea ice melting has reduced ice cover by over half a million square miles. Polar bears depend on this ice to hunt for food. These bears eat mostly seal, and need the ice to stalk their prey. Sea ice is the platform on which these bears live—they use it as a hunting ground to catch seals, to breed, and they travel great distances on the ice in order to reach optimal denning grounds (www.polarbearsinternational.org/polar-bears/climate-change). They spend so much of their lives on the ice, that they are considered to be marine mammals.
The lives of the bears are so dependent on the pack ice flows, that they must follow the ice in order to follow the food that it provides. As sea ice shrinks the edge of the ice moves progressively farther away from land. The faster the ice retreats each year, the greater the distance bears must swim to reach the ice edge. In 2008, an unprecedented nine bears were seen swimming in open water (http://www.sciencedaily.com/releases/2008/08/080825210415.htm). The National Wildlife Federation also explained that multiple bears have been found drowned in the ocean, unable to reach their destinations because of rough waters and increased traveling distances (http://www.nwf.org/Global-Warming/Effects-on-Wildlife-and-Habitat/Polar-Bears.aspx). If this sea ice moves too far away, some of the polar bears are also stranded on land. This is particularly perilous for the bear population, as they are faced with a winter season without enough food, and then as a result cannot breed successfully (http://wwf.panda.org/what_we_do/where_we_work/arctic/area/species/polarbear/habitat/). Polar bears only have one to two cubs at a time, and are slow to mature. This is not a species that can quickly recover from a “bad year.”
Here is a visual map, showing the close relationship between sea ice and polar bears. You can see that as the ice melts, the consequences are dire for this species.
The Bigger Picture
As apex predators, part of the reason for the drastic declining population is because of the many effects climate change is having on the rest of the food chain. Climate change affects an entire ecosystem, from the smallest organisms to the apex predators. Polar bears are perched on top of the food chain, but as the foundation of their environment suffers—they are the first to not survive.
Polar bears are not the only arctic mammal to be affected by a loss of sea ice, and in many instances it is the animals (lower on the food chain), that also affected will ultimately create even larger issues for the polar bears. Polar bears rely on seals as a major part of their diet, but these seals are also facing a troublesome future.
Ringed seals are a staple in the polar bears diet. These seals will be highly affected by a reduction in sea ice, because they rely on it for all phases of their life cycle. They use it as a platform to make dens, rest, give birth and nurse seal pups (Arctic Climate Impacts Assessment http://www.greenfacts.org/en/arctic-climate-change/l-3/5-arctic-animals.htm#1p4 ), it also provides them a quick escape route from predators (seals need the ice to rest, but can flee to the safety of the water, where their predators are less agile).
As temperatures rise, and the abundance of snow and ice diminishes, pups will be exposed to predators, risk being separated from their mothers prematurely, and will ultimately reduce the success of the ringed seal population. Canada’s Gulf of St. Lawrence experienced ice-free years in ’67, ’81, 2000-2002, during those periods almost no seal pups survived (World Wide Fund for Nature, http://wwf.panda.org ).
As seal populations diminish, polar bears will have to travel significant distances to find food, and without the ice to travel upon—this may not be possible. Scientists frequently try to count the number of bears currently in the wild. The amount of bears being reported has increased in recent years—this can easily be misinterpreted to say that there are more bears than previously. However, it is more accurate to say that as sea ice has diminished, these bears are being pushed farther inland in their search for food. (http://www.google.com/hostednews/afp/article/ALeqM5gXJ86K6Qax3FwdFy-PuXmbTPTeEA)
WalrusLike the polar bear, walrus are also a threatened arctic mammal. The Arctic Climate Impacts Assessment described issues the walrus are facing as a result of loss of ice (http://www.greenfacts.org/en/arctic-climate-change/l-3/5-arctic-animals.htm#1p4). They explained that as ice coverage reduces the edge of arctic ice moves further away from land (where the highest concentrations of reachable shellfish live).
Walrus are not particularly excellent swimmers. Pacific walrus typically only dive to depths of less than 100 meters, however drifting sea ice has moved over to deeper waters, with depths of up to 3,000 meters (http://news.mongabay.com/2006/0413-walrus.html). These bottom-feeders are being separated from the shallow waters they rely on, and also struggle to find adequate amounts of ice to rest upon, because of their heavy weight, adult walrus need an ice thickness of 60+cm, (http://alaska.fws.gov/fisheries/mmm/walrus/nhistory.htm). As adequate ice moves away from shallow areas the walrus will have a harder search for food. Unable to find the necessary amount of food, they will have reduced fat reserves, which will limit their survival in the harsh winter climates, in addition to putting stress on the population, reducing their success in breeding after the winter season.
Lessening ice also means that more walrus are pushed into a smaller space. Many walrus are gathering together on unusually small pieces of ice, and when frightened they all rush to the water. Recently, many young walrus were killed during a stampede because of overcrowding, as there is not enough space for all of the walrus to exist on the increasingly smaller pieces of ice http://www.huffingtonpost.com/2009/10/01/131-walruses-trampled-to_n_306663.html.
Walrus dive to the bottom of the oceans, stirring up all kinds of sediments and organism in their search for food. This process, bioturbation, is vital to maintaining the health and distribution of nutrients among these shallow waters. University of Virginia scientists described the process as “should sea ice continue to move northward as a result of climate change, the walrus’ ecological role could be diminished or lost, the benthic ecosystem could be fundamentally altered” (Ray, Pacific Walrus, Benthic Bioturbator of Beringia). Climate change presents a complicated series of issues that are deeply intertwined. Melting ice, polar bears, seals and walrus are each parts of a changing marine environment.
Implications for Indigenous Peoples
Indigenous people rely on traditional practices to maintain their cultural and historic identity. For these native groups, the arctic is a resource unlike any other, and they have survived by using its many unique attributes. As climate change affects the sea ice, and the animals, it also affects the people who rely on these resources.
Polar bears have long been considered an icon of the North. And it should be no surprise, that they are cherished by the indigenous peoples who call these extreme climates, home. Hunting of polar bears has been a traditional and cultural practice for native Alaskans for centuries.
In 1973 all 5 nations—the “States of the Arctic Region”—signed an “International Agreement on Conservation of Polar Bears”. In an attempt to preserve this species from possible extinction, it protects the bears from being hunted, captured or killed. Indigenous people, such as native Alaskans are exempt from this agreement, so long as they continue to use traditional methods of subsistence hunting, and it is a continuation of their cultural practices.
Polar bears are a resource used by traditional cultures. All parts of the bear (with the exception of the liver, which is highly toxic) are used by the community, as a source of food, medicine, crafts and clothing.
Just how important are these resources?
“The ringed seal is the single most important food source to the Inuit, representing the majority of the food supply in all seasons. No other species is present on the land or in the waters of Nunavut in the quantities needed to sustain the dietary requirements of the Inuit. In recent decades, local people have observed that ringed seal pup production has suffered as increased temperatures have led to a reduction and destabilization of the sea ice…To hunt, catch, and share these foods is the essence of Inuit culture.” - Arctic Climate Impact Assessment, Key Finding #8
Ringed seals, polar bears and walrus all play vital roles in the health, culture and tradition of indigenous arctic people. These species are part of the complex web that ties our world together. Losing any one of these animals will have detrimental effects on the arctic ecosystem, and its people.
Ask the visitor if they can think of other animals that will be affected by a loss of sea ice, have them draw a food chain, what similarities do we have to polar bears in our own ecosystem (top of the food chain etc.)? What do they think will happen to the arctic if we lose foundational species, like plankton?
Ask your visitor what they think about it being illegal to hunt polar bear? What about it being legal for subsistence hunting?
What would life be like, without these creatures around? Ask your visitor how these animals appear in their daily lives (Yes, even for those of us who don’t live in the Arctic, these animals are around us!)
We are surrounded by information about these creatures. They are in our childhood bedtime stories, our songs, poems and artwork—especially for those people living in northern climates. At the rate these species are dwindling, it is possible that they will not exist for us to tell future generations about. Coca-Cola’s famous advertising uses a polar bear; Alice in Wonderland has a great scene about a Walrus, even the Beatles reference walrus in their songs.
National Geographic Video - “State of Polar Bears”