The Potential for Basal Melting Under Summit, Greenland

Abstract

ABSTRACT. The deep-drilling projects at the Summit ice divide will require thermal models to help interpret the paleoclimatic signals in their cores. An analytic, steady-state model predicts basal temperatures within 1°C of the ice melting-point and basal ice no older than 100-400 kyear should melting occur. A two-dimensional, time-dependent temperature model includes the effects of realistic twodimensional ice flow and the temperature and mass-balance patterns of the last two glacial cycles. The model relaxes some assumptions made in one-dimensional studies and produces lower basal temperatures. The basal temperatures are most sensitive to the value of the geothermal heat flux and the mass-balance pattern. If the flux is less than 56 mW m-2 , the bed has likely been frozen throughout the last glacial cycle. The decoupling of the energy and massconservation equations is a significant source of error which can be eliminated only by a fully coupled ice-flow/ heat-flow model.

Oxygen- and Hydrogen-Isotopic Ratios of Water in Precipitation: Beyond Paleothermometry

“…The result is dominance by advection over long distances in the upper half of the ice sheet, with conduction important over short distances and in the lower part. (Note that not all ice masses are as "easy" as central Greenland in this regard; large changes in extent of mountain glaciers and even portions of the Antarctic ice sheet, coupled with large changes in bottom sliding not observed in central Greenland owing to very cold basal conditions there (Firestone et al 1990), complicate interpretations for some other glaciers and ice sheets.) Temperature measurements in boreholes through ice sheets are now available with millikelvin accuracy Cuffey and Clow 1997).…”

Holocene accumulation and ice sheet dynamics in central West Antarctica

“…We use the density profile from the ITASE 00‐1 core to estimate thermal properties in the firn. We calculate an initial steady state temperature profile 250,000 yrs BP using the formulation of Firestone et al [1990], after which the temperature profile evolves in 200‐year time steps. By placing the lower boundary condition effectively at infinity, our results are not sensitive to the boundary condition applied at the base of the bedrock; the 250,000 year model run allows the upper part of the bedrock to adjust to the most recent 100,000 year cycle.…”