Glacier fluctuation and inferred climatology of Langjokull ice cap through the Little Ice Age
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| Authors: | Flowers, GE; Bjornsson, H; Geirsdottir, A; Miller, GH; Clarke, GKC |
| Year: | 2007 |
| Journal: | Quat. Sci. Rev. 26: 2337-2353 Article Link (DOI) |
| Title: | Glacier fluctuation and inferred climatology of Langjokull ice cap through the Little Ice Age |
| Abstract: | Emerging paleoclimate records from proglacial lake Hvitarvatn, central Iceland, suggest that Langjokull ice cap attained its maximum Holocene extent within the last 400 years. With the aim of constructing glaciological models and appropriate model inputs for Holocene simulations of Langjokull, we begin by simulating the evolution of Langjokull through the Little Ice Age to present, a period for which we have some constraint on ice-cap geometry. Using modern measured mass balance distributions (1997-2003) and meteorological data from nearby Hveravellir, we derive a reference precipitation field for the period 1961-1990 over the ice cap. Our simulations suggest Langjokull attained its maximum Little Ice Age volume around 1840 with a second local maximum around 1890. The two outlet glaciers terminating in Hvitarvatn, Norourjokull and Suourjokull, advance slowly into the lake, occupying their maximum lake area in the late 19th century, and retreat comparatively rapidly in the mid- to late 20th century. Simulations of Norourjokull are much more faithful to the geomorphic evidence than are simulations of Suourjokull, potentially suggesting a difference in dynamics between these two glaciers. While only 35% of the Hvitarvatn catchment area is ice-covered, meltwater from Langjokull comprises similar to 70% of the water input to the lake. Two-thirds of this input from the ice cap is transported as groundwater. Simulated glacier-derived discharge to the lake through the Little Ice Age suggests that a sediment concentration of 1.5 kg m(-3) would have resulted in the transport of 1.5 x 10(11) kg of material to the lake over the last 300 years, comparable to the estimated mass of sediment in the most recently deposited sedimentary unit in the lake. (C) 2007 Elsevier Ltd. All rights reserved. |
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