The current disequilibrium of North Cascade glaciers

Abstract

Abstract:Three lines of evidence indicate that North Cascade (Washington, USA) glaciers are currently in a state of disequilibrium. First, annual balance measured on nine glaciers yields a mean cumulative balance for the 1984-2004 period of 8Ð58 m water equivalent (w.e.), a net loss of ice thickness exceeding 9Ð5 m. This is a significant loss for glaciers that average 30-50 m in thickness, representing 18-32% of their entire volume.Second, longitudinal profiles completed in 1984 and 2002 on 12 North Cascade glaciers confirm this volume change indicating a loss of 5Ð7 to 6Ð3 m in thickness (5Ð0-5Ð6 m w.e.) between 1984 and 2002, agreeing well with the measured cumulative balance of 5Ð52 m w.e. for the same period. The change in thickness on several glaciers has been equally substantial in the accumulation zone and the ablation zone, indicating that there is no point to which the glacier can retreat to achieve equilibrium. Substantial thinning along the entire length of a glacier is the key indicator that a glacier is in disequilibrium.Third, North Cascade glacier retreat is rapid and ubiquitous. All 47 glaciers monitored are currently undergoing significant retreat or, in the case of four, have disappeared. Two of the glaciers where mass balance observations were begun, Spider Glacier and Lewis Glacier, have disappeared. The retreat since 1984 of eight Mount Baker glaciers that were all advancing in 1975 has averaged 297 m. These observations indicate broad regional continuity in glacial response to climate.

Quantifying changes and trends in glacier area and volume in the Austrian Ötztal Alps (1969-1997-2006)

“…Such a behaviour is also supported by other studies (e.g. Paul and Haeberli, 2008;Pelto, 2006). One possible reason could be that the positive precipitation anomalies of the early 2000s (Fig.…”

Glacier annual balance measurement, forecasting and climate correlations, North Cascades, Washington 1984–2006

“…There are no distinct regional variations within the range. The glaciers are in disequilibrium with the present climate as indicated by the mean annual balance loss of −0.54 m/a, a cumulative loss of −12.38 m, 20-40% of their entire volume and increasing negative balances despite retreat (Pelto, 2006) The combined mean annual balance of the ten glaciers can be reliably calculated using ablation season temperatures from Diablo Dam and 1 April SWE from SNOTEL stations. If the annual balance is calculated for individual glaciers the error increases appreciably.…”

“…During the 1984During the -2006 period all 47 observed glaciers have been retreating (Pelto, 2006). The importance of monitoring glacier mass balance was recognized during the International Geophysical Year in 1957.…”

Glacier volume response time and its links to climate and topography based on a conceptual model of glacier hypsometry

“…This is a reasonable approximation for valley and mountain glaciers whose tops are constrained by hard rock topography. If the ELA rises above the top of the glacier the glacier will simply disappear before it reaches a new equilibrium (Pelto, 2006). From Fig.…”