Widespread movement of meltwater onto and across Antarctic ice shelves

• Published in: Nature (London) 2017-04, Vol.544 (7650), p.349-352
• Main Authors: Kingslake, Jonathan, Ely, Jeremy C., Das, Indrani, Bell, Robin E.
• Format: Article
• Language: English
• Subjects: 704/106/125; 704/106/694/1108; Aerial photography; Glaciers; Humanities and Social Sciences; Hydrology; Ice; Ice shelves; letter; Meltwater; multidisciplinary; Science; Sea level
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature22049

Surface water and its drainage across the surface of Antarctic ice is shown to be widespread, large-scale and to have persisted for decades. Meltwater mediates ice-shelf stability Melt ponds and streams form across Antarctica, but their full extent and the duration of their existence have remained unclear. Now, Jonathan Kingslake et al . show that surface drainage systems, including interconnected ponds and streams, have existed for decades as far as 85° S and up to 1,300 metres elevation. They show that surface water can be transported more than 100 kilometres, creating pond networks almost 80 kilometres long. Although the implications of the findings for ice-sheet dynamics are not explored, the study demonstrates that surface water drainage is more extensive than previously thought, and is probably a persistent feature of the Antarctic Ice Sheet. Elsewhere in this issue, Robin Bell et al . report on the influence of surface meltwater on Antarctic ice-shelf stability and find that it might not be a universally destructive force as was previously thought. Surface meltwater drains across ice sheets, forming melt ponds that can trigger ice-shelf collapse 1 , 2 , acceleration of grounded ice flow and increased sea-level rise 3 , 4 , 5 . Numerical models of the Antarctic Ice Sheet that incorporate meltwater’s impact on ice shelves, but ignore the movement of water across the ice surface, predict a metre of global sea-level rise this century 5 in response to atmospheric warming 6 . To understand the impact of water moving across the ice surface a broad quantification of surface meltwater and its drainage is needed. Yet, despite extensive research in Greenland 7 , 8 , 9 , 10 and observations of individual drainage systems in Antarctica 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , we have little understanding of Antarctic-wide surface hydrology or how it will evolve. Here we show widespread drainage of meltwater across the surface of the ice sheet through surface streams and ponds (hereafter ‘surface drainage’) as far south as 85° S and as high as 1,300 metres above sea level. Our findings are based on satellite imagery from 1973 onwards and aerial photography from 1947 onwards. Surface drainage has persisted for decades, transporting water up to 120 kilometres from grounded ice onto and across ice shelves, feeding vast melt ponds up to 80 kilometres long. Large-scale surface drainage could deliver water to areas of ice shelves vulnerable to collapse, as melt rates in