Annual push moraines as climate proxy

Abstract

We reconstruct the terminus position of a mountain glacier in British Columbia, Canada from annual push moraines formed between 1959 and 2007. Our reconstruction represents the longest, annually‐resolved record of length change for a North American glacier. Comparison of annual recession with climate records indicates that glacier recession is controlled by air temperatures during the ablation season and accumulation season precipitation during the previous decade. Analysis among records of glacier frontal variation and mass balance in western North America similarly reveals an immediate terminus reaction to summer and net balance and a delayed reaction to winter and net balance. Other mountain ranges may contain long series of push moraines that could be exploited as climate proxies, and to improve understanding of glacier response to climate.

Nine decades of glacier change in the Canadian Rocky Mountains.

“…Area changes are correlated with temperature anomalies lagged one to ten years and precipitation anomalies lagged six years. These values are comparable to other studies that have shown terminus changes responding to temperatures lagged a few years and precipitation lagged five to ten years (Salinger et al, 1983;Sigurdsson et al, 2007;Beedle et al, 2009). However, the rates of area change do not correlate with temperature and precipitation anomalies lagged the same number of years as area change.…”

“…I correlated lagged temperature and precipitation anomalies with glacier changes in the Columbia Icefield and found that annual and accumulation season precipitation anomalies have higher and more significant correlations than temperature anomalies. The higher correlations occurred at lag times similar to those reported by Salinger et al (1983), Sigurdsson et al (2007), and Beedle et al (2009). They determined that terminus changes are correlated with temperatures lagged a few years and precipitation lagged five to ten years.…”

Glacier change and contribution to streamflow in the Canoe Basin, British Columbia, 1948-2005.

“…Terminus behavior at Illecilliwaet Glacier, in the Columbia Basin, was recorded since 1887 on a near-decadal basis, using photographs, field surveys and remotely sensed imagery (Champoux and Ommaney, 1986). Luckman et al (1987) Glacier was examined by dating annual push moraines (Beedle et al, 2009). …”

Modelling Dynamics of Valley Glaciers

“…Third, the dynamical response of glaciers leaves footprints of past climate in their moraines (e.g. Beedle et al, 2009); they have hence become proven indicators of climate change. More importantly, the ice flow in valley glaciers and icefields comprises a high degree of complexity, primarily due to the irregular valley geometry.…”