Glacier change in the Cariboo Mountains, British Columbia, Canada (1952-2005)

We applied photogrammetric methods with aerial photography from 11 different years between 1946 and 2005 to assess changes in area and volume of 33 glaciers in the Cariboo Mountains of British Columbia for the latter half of the 20th century. These are used to identify changes in extent and elevation primarily for the periods 1952-1985, 1985-2005, and 1952-2005. All glaciers receded during the period 1952-2005; area retreat averaged -0.19 +/- 0.05% a(-1). From 1952 to 1985, nine glaciers advanced; following 1985, retreat rates accelerated to -0.41 +/- 0.12% a(-1). Thinning rates of a subset of seven glaciers likewise accelerated, from -0.14 +/- 0.04mw.e. a 1 1952-1985) to -0.50 +/- 0.07mw.e. a(-1) for the period 1985-2005. Temperatures increased from the earlier to the latter period for the ablation (+ 0.38 degrees C) and accumulation (+ 0.87 degrees C) seasons, and average precipitation decreased, particularly in the accumulation season (-32 mm, -3.2 %). Our comparison of surface area change with glacier morphometry corroborates previous studies that show primary relations between extent change and surface area. We also find that the strength and sign of these relations varied for different epochs. Our results also indicate that the 1985 glacier extent for the study area reported previously by other studies may be slightly overestimated due to errant mapping of late-lying snow cover.