Antarctic subglacial hydrology: an overview of current knowledge and forthcoming scientific challenges

Flood-carved landforms across the deglaciated terrain of Victoria Land, East Antarctica, provide convincing geomorphological evidence for the existence of subglacial drainage networks beneath the Antarctic Ice Sheets, and motivate research into the inaccessible environment beneath the current ice sheet. Unlike at temperate glaciers, and more recently Arctic glaciers, where numerous researchers have explicitly studied “subglacial hydrology,” the acquisition of knowledge about subglacial hydrology in Antarctica has often been a side effect of geophysical and remote-sensing programmes targeted at multiple objectives. Through this research, however, we are steadily building an understanding of Antarctic subglacial hydrology, and this article presents an overview of the current state of knowledge. We first contextualise the discussion by introducing how our conceptualisation of subglacial hydrological behaviour has been developed at temperate and Arctic glaciers, but is less mature in the Antarctic, where our knowledge of subglacial-melt generation and variability, in particular, remain poorly constrained. We overview the discovery and progressive understanding of subglacial lake systems, whereby recent geophysical and remote-sensing observations have shown us that many lakes, once thought to be isolated and stable, form part of a highly dynamic network of subglacial drainage beneath the ice sheet. We then discuss some of the latest findings concerning subglacial water flows other than those directly concerned with lakes. Such water flows have potentially significant impacts on ice-stream dynamics, ice-sheet mass-balance, and supplies of water to the ocean potentially affecting circulation and nutrient productivity. We close by identifying some of the grand challenges that lie ahead for improving our understanding of these processes further.