Glacier change in northern Sweden from AD 500: a simple geometric model of Storglaciären

• Published in: Journal of Glaciology
• Main Authors: Raper, S. C. В., Briffa, K. R., Wigley, Т. M. L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1996
• Subjects: Earth-Surface Processes; Storglaciären; Fennoscandia; Journal of Glaciology; Northern Sweden
• Online Access: http://dx.doi.org/10.1017/s0022143000004196; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000004196

Abstract A simple geometric model of glacier volume is derived. The model is based on the assumption that the net mass balance averaged over the glacier surface is related to the summer temperature and winter accumulation at a representative height on the glacier. This height varies with time as climate changes, in ways that are determined by the geometry of the glacier surface. Expressions are derived for the equilibrium glacier volume ( V eq ) as a function of summer temperature and winter accumulation and for the glacier-response time ( τ ) as a function of volume. The model is used to reconstruct the volume of Storglaciären over the period AD 500–1992. Measured net mass-balance data for Storglaciren (1946–92) are used to estimate the model parameters. For the summer temperature forcing, the long tree-ring-based temperature reconstruction for northern Fennoscandia is used to extend a temperature record near the glacier back to AD 500. For the past accumulation forcing, a range of assumptions is tested. The results show that the prime cause of the decrease in volume of Storglaciären between 1946 and 1992 was relatively low accumulation over 1946–89 as opposed to warm temperatures as previously supposed. Reconstructed volume changes agree well with geomorphological evidence. Where differences occur, deductions can be made about past accumulation. For example, the maximum reconstructed glacier volume is associated with the cold period from 1580 to 1740 but relatively low accumulation probably limited the volume to values not much larger than that achieved around 1916.