Effects of uncertainties in the geothermal heat flux distribution on the Greenland Ice Sheet: An assessment of existing heat flow models

摘要

[1] This study analyzes the uncertainties in the models of the Greenland Ice Sheet (GIS)that arise from ill-constrained geothermal heat flux (GHF) distribution. Within thecontext of dynamic GIS modeling, we consider the following questions: (i) What is thesignificance of the differences between the existing GHF models for the GIS modelingstudies? (ii) How well does the modeled GIS controlled by the GHF models agree with theobservational data? (iii) What are the relative contributions of uncertainties in GHFand climate forcing to the misfit between the observed and modeled present-day GIS?The results of paleoclimatic simulations suggest that differences in the GHF models have amajor effect on the history and resulting present-day state of the GIS. The ice sheet modelcontrolled by any of these GHF forcings reproduces the observed GIS state to only alimited degree and fails to reproduce either the topography or the low basal temperaturesmeasured in southern Greenland. By contrast, the simulation controlled by a simplespatially uniform GHF forcing results in a considerably better fit with the observations,raising questions about the use of the three GHF models within the framework of GISmodeling. Sensitivity tests reveal that the misfit between the modeled and measuredtemperatures in central Greenland is mostly due to inaccurate GHF and Wisconsinprecipitation forcings. The failure of the ice sheet model in southern Greenland, however,is mainly caused by inaccuracies in the surface temperature forcing and the generallyoverestimated GHF values suggested by all GHF models.