Recent glacier advances in the Premier Range, British Columbia

Abstract

Aerial photography (1948–1985) and field investigations are used to reconstruct recent ice-front fluctuations for 27 glaciers (size range 0.63–17.9 km2) in the Premier Range, British Columbia. Rapid rates of frontal recession between ca. 1930 and the mid-fifties were followed by glacier readvance at many sites, culminating in the 1973–1976 period, when 90% of the monitored ice fronts were either advancing (68%) or stable. Maximum downvalley advance was about 0.5 km (median ~90 m), and 14 glaciers formed new terminal or lateral moraine ridges between 1970 and 1985. Nine of these postdate 1976; one is dated to the 1980–1981 winter using tree rings. The glacial advance is attributed to significant mass-balance changes inferred from periods of increased winter precipitation (ca. 1951–1976) and low summer temperatures (1954–1968) measured at Valemount. Warmer summers and reduced winter precipitation after 1976 account for the slight recession of ice fronts from maximum downvalley positions in the last few years.