Polar bears are key indicators of the effects of climate change on the arctic ecosystem, because their existence is directly related to the sea ice habitat, where they hunt. As the Arctic continues to warm, their habitat will be reduced further and local extinction is likely to occur, especially in southern populations.
Jospe, Alex C.; Peck, Bethany C.; and Sinnott, Emily, "Climate Change and its Effects on Polar Bears" (2006). Undergraduate Research Symposium (UGRS). Paper 23.