Mapping extent changes of the Barnes Ice Cap since the Little Ice Age

Abstract:

Over the past decade glaciers and ice caps of the Canadian Arctic Archipelago have experienced large mass losses and contributed significantly to sea level rise. The Barnes Ice Cap, a remnant of Laurentide Ice Sheet, is of particular importance as it has been found to be highly sensitive to changes in summer temperature. Here we determine changes in the extent of the Barnes Ice Cap to understand its evolution from the Little Ice Age to present. Trimlines of the Barnes Ice Cap are extracted from ASTER imagery providing a maximal extent of the ice cap during the Little Ice Age. Extent changes over the past half-century are mapped and quantified with the aid of Landsat imagery and a digitized map sheet derived from 1961 photogrammetry. From these data we identify an accelerating rate of recession, with higher rates of retreat on the western side of the ice cap. Since observations began in the early 1950s there has been little change annual precipitation amounts but a warming trend in summer air temperatures. The observed accelerating rate of retreat is therefore attributed to regional changes in summer temperature.