Inaugural lecture: 'Slip-sliding away?' - Professor Andrew Sole

Earth’s ice sheets are one of the key indicators of climate change. Climate warming causes faster melting of the ice sheet surface, forming networks of striking azure streams, rivers and lakes. When these meltwater networks intersect surface crevasses, meltwater is transferred to the ice base where it becomes highly pressurised, causing acceleration of the overlying ice. Despite this clear link between meltwater supply and ice flow speed, long-term records show that ice tends to decelerate during years with greater surface melting, and that exceptionally large pulses of meltwater to the ice base – caused by the rapid drainage of surface lakes, for example – lead to multiyear reductions of ice motion.
 

When this meltwater completes its journey through the ice sheet, it emerges at the base of kilometre-thick glaciers where they flow into the surrounding ocean. The meltwater thermally erodes the underside of these glaciers and weakens protective sea ice, leading to glacier recession and enhanced production of icebergs. Melting of these icebergs might be expected to cool the ocean, and thus curtail glacier recession, yet modelling studies show that it enhances transport of warm water from the open ocean towards glaciers. In this lecture, I will explain these apparent contradictions through an exploration of my research into ice sheet dynamics over the past 18 years.