Topography and ice sheet growth

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Abstract
This paper uses a numerical ice sheet model to investigate the role of topography in influencing ice sheet growth. The model is applied to the maritime, mid‐latitude uplands of Scotland and relies on a series of assumptions about mass balance, topography, and ice flow. It is driven by an imposed pattern of temperature change. The model is able to predict effectively the extent and thickness of the Loch Lomond ice sheet, using a palaeotemperature curve based on Coleoptera assemblages.A series of experiments with a stepped, constant July air temperature depression suggests that in Scotland a change in excess of −3·0°C is necessary to initiate ice sheet growth; that steady state ice caps build up at changes of −3 to − 6·5°C; and that large ice sheets build up at changes of more than − 6·625°C. The bifurcation revealed by the last two types of behaviour is the result of topography. Both the vertical amplitude and the spatial distribution of bedrock basins and ridges are important in determining the pattern, rate, and extent of ice sheet growth. The implication is that topography plays an important role in determining the dynamics of ice sheet growth.