Area change of glaciers in the Canadian Rocky Mountains, 1919 to 2006

Glaciers in the Canadian Rocky Mountains con- stitute an important freshwater resource. To enhance our understanding of the influence climate and local topogra- phy have on glacier area, large numbers of glaciers of dif- ferent sizes and attributes need to be monitored over pe- riods of many decades. We used Interprovincial Boundary Commission Survey (IBCS) maps of the Alberta-British Columbia (BC) border (1903-1924), BC Terrain Resource Information Management (TRIM) data (1982-1987), and Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) imagery (2000-2002 and 2006) to doc- ument planimetric changes in glacier cover in the central and southern Canadian Rocky Mountains between 1919 and 2006. Over this period, glacier cover in the study area de- creased by 590± 70 km 2 (40± 5 %), 17 of 523 glaciers disappeared and 124 glaciers fragmented into multiple ice masses. Glaciers smaller than 1.0 km 2 experienced the great- est relative area loss (64 ± 8 %), and relative area loss is more variable with small glaciers, suggesting that the local topographic setting controls the response of these glaciers to climate change. Small glaciers with low slopes, low mean/median elevations, south to west aspects, and high in- solation experienced the largest reduction in area. Similar rates of area change characterize the periods 1919-1985 and 1985-2001; 6.3± 0.6 km 2 yr 1 ( 0.4± 0.1 % yr 1 ) and 5.0± 0.5 km 2 yr 1 ( 0.5± 0.1 % yr 1 ), respectively. The