Polar Bears Face Challenges From Toxins And Climate Change
Many of us are familiar with the plight of polar bears: these charismatic species have been profiled in films like An Inconvenient Truth and the Planet Earth series, and most of us have seen images of them, malnourished and beset by melting ice. While these images have raised awareness, it’s important to stay informed of the issues polar bears face that are ongoing. This article reviews the latest research findings from about 300 publications concerning the amount of pollution in the arctic and its effects on polar bears in the Arctic region.
Scientists now consider the second biggest threat to polar bears (after melting sea ice) to be exposure to toxic substances in their environment. Polar bears are one of the Arctic species most at risk from chemicals because they are at the top of the food chain, and pollution bioaccumulates: in addition to the pollution they absorb ambiently, bigger animals eat smaller animals, and absorb the pollution from their bodies. They hunt primarily ringed and bearded seals. But, with less ice, polar bears have started to feed on land-based animals like sea birds, geese, and reindeer, as well as eating animals’ eggs, and whale carcasses they find. Chemical levels in whales can be especially high, possibly because they migrate near pollution sources.
What are the compounds of concern? Polychlorinated biphenyls (also known as PCBs), pesticides, flame retardants, and mercury. These compounds travel north to the Arctic from industrial and agricultural facilities, moving via air and ocean currents and river flows.
A number of these toxins are covered by the Stockholm Convention on Persistent Organic Pollutants. The Convention is a global treaty that limits or outlaws substances to safeguard environmental health. These organic chemicals can stay in the bodies of wildlife for long periods of time. More than 90% of the mercury found in Arctic marine animals is likely from human dumping regulated by the Minamata Convention on Mercury. East Greenland polar bears appear to have the highest mercury levels.
According to the review, polar bears’ endocrine and immune systems appear to be most affected by these chemicals that persist in their bodies. Field and in vitro studies show that toxic compounds change polar bears’ thyroid hormone levels and lipid metabolism. Research also has shown that brain function is affected by pollution.
Decades ago, the biggest threat to polar bears was hunting. In reaction, The International Agreement on the Conservation of Polar Bears was signed in 1973 by Canada, Denmark (Greenland), Norway, the Soviet Union (Russian Federation), and the United States. In 2019, the estimated global polar bear population stands at about 26,000 individuals, with two-thirds living in Canada. Arctic nations have created the Circumpolar Action Plan: Conservation Strategy for the Polar Bear to study new challenges. The Plan lists a range of current major threats: melting sea ice, pollution, diseases, drilling for energy, shipping, and tourism. In fact, the IUCN Red List of Threatened Species has labeled the polar bear “vulnerable” since 1982, meaning that they have a higher risk of extinction in the wild. Absorbing pollution at the level that they do could have serious negative implications for this vulnerable population.
The authors suggest that future research look at the links between climate change and pollution risks to polar bears. Melting Arctic ice will probably affect transportation, food, emissions, and polar bear mobility. These all could increase polar bears’ exposure to toxins. Research also should investigate new pollution sources and chemicals in the Arctic. Advocates can use this information to help in their work for Arctic species’ and habitat, and to continue to keep the plight of polar bears (and other Arctic species) in the public consciousness.