Abstract

At the Earth's surface, heat fluxes from the interior(1) are generally insignificant compared with those from the Sun and atmosphere(2), except in areas permanently blanketed by ice. Modelling studies show that geothermal heat flux influences the internal thermal structure of ice sheets and the distribution of basal melt water(3), and it should be taken into account in planning deep ice drilling campaigns and climate reconstructions(4). Here we use a coupled ice-lithosphere model driven by climate and show that the oldest and thickest part of the Greenland Ice Sheet is strongly influenced by heat flow from the deep Earth. We find that the geothermal heat flux in central Greenland increases from west to east due to thinning of the lithosphere, which is only about 25-66% as thick as is typical for terrains of early Proterozoic age(5). Complex interactions between geothermal heat flow and glaciation-induced thermal perturbations in the upper crust over glacial cycles lead to strong regional variations in basal ice conditions, with areas of rapid basal melting adjoining areas of extremely cold basal ice. Our findings demonstrate the role that the structure of the solid Earth plays in the dynamics of surface processes.