Dynamic/thermodynamic simulations of Laurentide ice-sheet instabilityR. GREVE and D. R. MacAYEAL AbstractA crucial element of several leading theories of Laurentide ice sheet instability (i.e., Heinrich events and advance/retreat cycles of the southern margin) is the evolution of melting conditions at the subglacial bed. Despite the great importance basal-temperature conditions play in these theories, relatively little has been done to test their physical plausibility. We thus undertake a numerical model study of the ice sheet temperature field along an important transect which extends from the lobate southern margin of the Laurentide ice sheet to the iceberg-calving front at the terminus of Hudson Strait. Our experiments illustrate the influence of important aspects of ice sheet thermodynamics on ice-sheet instability, including horizontal advection and the development of an internal temperate-ice reservoir. Free oscillations of the basal temperature and ice thickness in Hudson Strait are possible under a restricted range of parameters elucidated by the model. These free oscillations may provide a basis for understanding ice-sheet instability, e.g., Heinrich events, with time scales in the range of 1.000-10.000 years. Annals of Glaciology, 23, 328-335 (1996).
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