Modelling historical and recent mass loss of McCall Glacier, Alaska, USA

C Delcourt,F Pattyn,M Nolan

doi:10.5194/tc-2-23-2008

C Delcourt, F Pattyn + Show 1 more

Open Access

https://doi.org/10.5194/tc-2-23-2008

Copy DOI

Abstract

Abstract. Volume loss of valley glaciers is now considered to be a significant contribution to sea level rise. Understanding and identifying the processes involved in accelerated mass loss are necessary to determine their impact on the global system. Here we present results from a series of model experiments with a higher-order thermomechanically coupled flowline model (Pattyn, 2002). Boundary conditions to the model are parameterizations of surface mass balance, geothermal heating, observed surface and 10 m ice depth temperatures. The time-dependent experiments aim at simulating the glacier retreat from its LIA expansion to present according to different scenarios and model parameters. Model output was validated against measurements of ice velocity, ice surface elevation and terminus position at different stages. Results demonstrate that a key factor in determining the glacier retreat history is the importance of internal accumulation (>50%) in the total mass balance. The persistence of a basal temperate zone characteristic for this polythermal glacier depends largely on its contribution. Accelerated glacier retreat since the early nineties seems directly related to the increase in ELA and the sudden reduction in AAR due to the fact that a large lower elevation cirque – previously an important accumulation area – became part of the ablation zone.

Highlights

McCall Glacier is situated at 69◦18 N, 143◦48 W, in the northeastern part of the Brooks Range, Alaska
Results demonstrate that a key factor in determining the glacier retreat history is the importance of internal accumulation (>50%) in the total mass balance
McCall Glacier is considered as a good indicator for climate change in the Arctic (Nolan et al, 2005), situated in an area sensitive to climate change (IPCC, 2007)

Summary

Introduction

McCall Glacier is situated at 69◦18 N, 143◦48 W, in the northeastern part of the Brooks Range, Alaska. The glacier has been studied extensively, from IGY (1957–1958) onwards through to the International Hydrological Decade (1969–1972) and the mid 1990s to present. These studies have shown that McCall Glacier has been losing mass for decades, accelerating over the last 10 to 20 years (Rabus et al, 1995; Nolan et al, 2005). It seems that this well-studied glacier is representative of the other large glaciers of its region (Rabus and Echelmeyer, 1998). McCall Glacier is considered as a good indicator for climate change in the Arctic (Nolan et al, 2005), situated in an area sensitive to climate change (IPCC, 2007)

Objectives

Findings

Discussion

Conclusion