One need only to look at a comparison of summer Arctic ice extent from 1979 to 2007 to understand something significant is happening. In the span of a generation, the millennia-old Arctic has shrunk by roughly two-thirds and could easily be ice free in the summer within a decade. Or if that is not enough, consider that in the winter of 2008, a massive chunk of ice broke off from the Antarctic Peninsula, and another ice sheet the size of Northern Ireland (or Connecticut, if you prefer) hangs on by a thread. Over the past fifty years, the Arctic and Antarctic have warmed by around 3 degrees Celsius, roughly double the rest of the world. The goal, simply put, is to prevent this harbinger.
Snape, William, "Radical Environmental Change in the Polar Regions" (2008). Articles in Law Reviews & Other Academic Journals. 1784.