When the World Wildlife Federation declared them “threatened” on May 15, 2008, polar bears became the first species ever to be declared threatened because of global warming. However, polar bear populations have grown since 1970, by way of laws banning polar bear hunting and abundant prey. Since 1970, world polar bear populations have increased from 8,000 to 25,000 (Ritter 2012). However, these population increases are quite misleading. In 1973, with the Multilateral Conservation of Polar Bears Agreement which limited polar bear hunting in Greenland, The United States, Russia, Canada, and Norway, polar bear populations started to increase because of a decline in hunting. However, the immediate effects of the prevention of hunting are starting to wear off and polar bear populations in the Northern ice caps are starting to plateau. Average temperatures in Russia, Canada, Alaska, and Greenland have increased since 1970 by an average of +0.18 °C (Global Warming Art 2002). With melting ice caps, polar bears now have to swim farther for prey, making it harder for polar bears to capture seals and other prey (National Wildlife Federation 2014).
Historically, since 1950, polar bears have been following a logistical growth curve, meaning that their population has been constantly rising for a long time, but is expected to soon reach carrying capacity and fall from there. Carrying capacity is the maximum population a species can maintain in a certain ecosystem. As seen in figure 1, polar bear populations have reached a maximum and are expected to fall. With the steady melting of ice caused by global warming in northern polar bear habitats, polar bear populations are set to decline; and in some cases, eventually reach zero (Polar Bears and Climate Change 2011). In figure two, we see that average northern arctic temperatures have reached an all time high, meaning that there is less and less ice every year for polar bears to live and hunt resting seals on. Instead of catching resting seals on ice, polar bears now must swim long distances into the ocean to catch seals, where they are often out swam by the seals (National Wildlife Federation 2014). Polar bear populations are also set to plummet because of an inability to have large numbers of cubs- an effect of melting ice caps and difficult hunting conditions. Although many adult polar bears have been able to survive since the 1980’s when polar bear hunting was first restricted, those adults are starting to die off without many offspring (National Wildlife Federation 2014a).
Graph from: Polar Bears and Climate Change 2011
Graph from: Ahlenius 2007
Historically, since 1950, polar bears have been following a logistical growth curve, meaning that their population has been constantly rising for a long time, but is expected to soon reach carrying capacity and fall from there. Carrying capacity is the maximum population a species can maintain in a certain ecosystem. As seen in figure 1, polar bear populations have reached a maximum and are expected to fall. With the steady melting of ice caused by global warming in northern polar bear habitats, polar bear populations are set to decline; and in some cases, eventually reach zero (Polar Bears and Climate Change 2011). In figure two, we see that average northern arctic temperatures have reached an all time high, meaning that there is less and less ice every year for polar bears to live and hunt resting seals on. Instead of catching resting seals on ice, polar bears now must swim long distances into the ocean to catch seals, where they are often out swam by the seals (National Wildlife Federation 2014). Polar bear populations are also set to plummet because of an inability to have large numbers of cubs- an effect of melting ice caps and difficult hunting conditions. Although many adult polar bears have been able to survive since the 1980’s when polar bear hunting was first restricted, those adults are starting to die off without many offspring (National Wildlife Federation 2014a).
Works Cited:
Global Warming Art. (2002) Climate Change in Antarctica. (Date Accessed: February 10, 2014.)
Ritter, J. (2012) True Lies in the Lighting World. Professional Lighting Design Convention Countdown Blog. (Date Accessed: February 11, 2014.)
National Wildlife Federation. (2014b) Global Warming and Polar Bears. (Date Accessed: February 17, 2014.)
Polar Bears and Climate Change. (2011) Climate Change and Polar Bears. (Date Accessed: February 13, 2014.)
Ahlenius, H. (2007) Trends in Arctic Temperature. GRID-Arendal. 1880-2006. (Date Accessed: February 13, 2014)
http://www.grida.no/graphicslib/detail/trends-in-arctic-temperature-1880-2006_14cf
National Wildlife Federation. (2014a) Polar Bear. (Date Accessed: February 25, 2014.)
http://www.nwf.org/wildlife/wildlife-library/mammals/polar-bear.aspx
National Wildlife Federation. (2014a) Polar Bear. (Date Accessed: February 25, 2014.)
http://www.nwf.org/wildlife/wildlife-library/mammals/polar-bear.aspx
This is one of the funnies articles I have ever read. The graph of historic and projected populations is hilarious and speaks for itself.
ReplyDelete