Global Warming is Happening Now
Scientists are no longer telling us what will happen, they are telling us what is happening.
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Arctic fox : The polar bear sits at the pinnacle of the Arctic ecosystem. Temperature shifts and melting ice have a ripple effect throughout the Arctic circle. If the polar bear vanishes, the entire ecosystem will be impacted. |
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Changes in habitat will inevitably affect distribution and abundance of associated wildlife populations. For example, mosses and lichens are particularly vulnerable to warming which, because they form the basis of important food chains (providing, for example, primary winter food sources for reindeer/caribou), will have significant repercussions throughout the ecosystem. Caribou (the North American form of the species Rangifer tarandus) and reindeer (Eurasian form of the same species) will be affected not only by declines in some of their food sources, but also by increased difficulty in reaching some of those food sources as a result of climatic changes. For example, numbers of Peary caribou on Canada's arctic islands plummeted from 26,000 in 1961 to 1,000 by 1997, apparently largely as a result of autumn rains icing the winter food supply and crusting the snow cover, limiting access to forage.
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Mild weather and wet snow prompt the collapse of under-snow spaces that provide burrows for lemmings and voles, affecting population cycles of those species and leading to declines in their populations, with impacts on their predators, such as snowy owls, skuas, weasels, and ermine.
Changes in the thickness and extent of sea ice are likely to affect the species which live on sea ice habitat, and indeed there is evidence that such impacts are already occurring. For example, a 1999 study showed that polar bears in Hudson Bay suffered 15% declines in average weight and the number of cubs born between 1981 and 1998. These changes are likely correlated to late sea-ice formation in fall and early break-up in spring, which leads to a longer winter fasting period for females, for whom healthy fat reserves are essential to survival and reproductive success.
According to the Arctic Climate Impact Assessment, a study conducted on behalf of the Arctic Council, polar bears "are unlikely to survive as a species if there is an almost complete loss of summer sea-ice cover, which is projected to occur before the end of this century by some climate models."
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