Remote sensing of recent glacier changes in the Canadian Arctic

The Canadian Arctic contains the largest area of land ice (~150,000 km2) on Earth outside the ice sheets of Greenland and Antarctica and is a potentially significant contributor to global sea level change. The current ice cover includes large ice caps that are remnants of the Wisconsinan Laurentide and Innuitian ice sheets, and many smaller ice caps and valley glaciers that formed during the late Holocene. Most of these ice masses have decreased in area over the past century as a result of climate warming in the first half of the 20th century and since the mid-1980s. In general, smaller ice masses have lost a higher proportion of their area, but the largest total area losses have come from the larger ice caps. Both iceberg calving and negative surface mass balances have contributed to this episode of glacier shrinkage. Long-term calving rates are not well known, however, and many tidewater glaciers exhibit velocity variability on a range of timescales that may affect calving rates. Floating ice shelves in northern Ellesmere Island have lost over 90 % of their area in the 20th century, with the most recent phase of disintegration occurring since 2000. Some fjords in the region are now ice free for the first time in over 3000 years. Regional rates of mass loss have accelerated strongly since 2005, and Canadian Arctic glaciers and ice caps have emerged as the most significant non–ice sheet contributor to the nonsteric component of global sea level rise.