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Subglacial lake

Satellite image of subglacial Lake Vostok in Antarctica. Image credit: NASA

A subglacial lake is a lake that is found under a glacier, typically beneath an ice cap or ice sheet. Subglacial lakes form at the boundary between ice and the underlying bedrock, where liquid water can exist above the lower melting point of ice under high pressure.[1][2] Over time, the overlying ice gradually melts at a rate of a few millimeters per year.[3] Meltwater flows from regions of high to low hydraulic pressure under the ice and pools, creating a body of liquid water that can be isolated from the external environment for millions of years.[1][4]

Since the first discoveries of subglacial lakes under the Antarctic Ice Sheet, more than 400 subglacial lakes have been discovered in Antarctica, beneath the Greenland Ice Sheet, and under Iceland's Vatnajökull ice cap.[5][6][7] Subglacial lakes contain a substantial proportion of Earth's liquid freshwater, with the volume of Antarctic subglacial lakes alone estimated to be about 10,000 km3, or about 15% of all liquid freshwater on Earth.[8]

As ecosystems isolated from Earth's atmosphere, subglacial lakes are influenced by interactions between ice, water, sediments, and organisms. They contain active biological communities of extremophilic microbes that are adapted to cold, low-nutrient conditions and facilitate biogeochemical cycles independent of energy inputs from the sun.[9] Subglacial lakes and their inhabitants are of particular interest in the field of astrobiology and the search for extraterrestrial life.[10][11]

  1. ^ a b Palmer, Steven J.; Dowdeswell, Julian A.; Christoffersen, Poul; Young, Duncan A.; Blankenship, Donald D.; Greenbaum, Jamin S.; Benham, Toby; Bamber, Jonathan; Siegert, Martin J. (2013-12-16). "Greenland subglacial lakes detected by radar: GREENLAND SUBGLACIAL LAKES DISCOVERED". Geophysical Research Letters. 40 (23): 6154–6159. Bibcode:2013GeoRL..40.6154P. doi:10.1002/2013GL058383. hdl:10871/30231. S2CID 55286616.
  2. ^ Siegert, Martin John; Kennicutt, Mahlon C. (2018-09-12). "Governance of the Exploration of Subglacial Antarctica". Frontiers in Environmental Science. 6: 103. doi:10.3389/fenvs.2018.00103. hdl:10044/1/63886. ISSN 2296-665X.
  3. ^ Le Brocq, Anne M.; Ross, Neil; Griggs, Jennifer A.; Bingham, Robert G.; Corr, Hugh F. J.; Ferraccioli, Fausto; Jenkins, Adrian; Jordan, Tom A.; Payne, Antony J.; Rippin, David M.; Siegert, Martin J. (2013). "Evidence from ice shelves for channelized meltwater flow beneath the Antarctic Ice Sheet". Nature Geoscience. 6 (11): 945–948. Bibcode:2013NatGe...6..945L. doi:10.1038/ngeo1977. ISSN 1752-0908.
  4. ^ Drewry, D (1983). "Antarctica: Glaciological and Geophysical Folio". University of Cambridge, Scott Polar Research Institute. 2.
  5. ^ Davies, Bethan. "Antarctic Glaciers". AntarcticGlaciers.org. Retrieved 2019-12-16.
  6. ^ Bowling, J. S.; Livingstone, S. J.; Sole, A. J.; Chu, W. (2019-06-26). "Distribution and dynamics of Greenland subglacial lakes". Nature Communications. 10 (1): 2810. Bibcode:2019NatCo..10.2810B. doi:10.1038/s41467-019-10821-w. ISSN 2041-1723. PMC 6594964. PMID 31243282.
  7. ^ Björnsson, Helgi (2003-02-01). "Subglacial lakes and jökulhlaups in Iceland". Global and Planetary Change. Subglacial Lakes: A Planetary Perspective. 35 (3): 255–271. Bibcode:2003GPC....35..255B. doi:10.1016/S0921-8181(02)00130-3. ISSN 0921-8181.
  8. ^ Dowdeswell, Julian A; Siegert, Martin J (February 2003). "The physiography of modern Antarctic subglacial lakes". Global and Planetary Change. 35 (3–4): 221–236. Bibcode:2003GPC....35..221D. doi:10.1016/S0921-8181(02)00128-5.
  9. ^ Christner, Brent (2008). Bacteria in Subglacial Environments. Heidelberg, Berlin: Springer-Verlag. pp. 51–71.
  10. ^ Petit, Jean Robert; Alekhina, Irina; Bulat, Sergey (2005), Gargaud, Muriel; Barbier, Bernard; Martin, Hervé; Reisse, Jacques (eds.), "Lake Vostok, Antarctica: Exploring a Subglacial Lake and Searching for Life in an Extreme Environment", Lectures in Astrobiology: Volume I, Advances in Astrobiology and Biogeophysics, Springer Berlin Heidelberg, pp. 227–288, Bibcode:2005leas.book..227P, doi:10.1007/10913406_8, ISBN 978-3-540-26229-9
  11. ^ Rampelotto, Pabulo Henrique (2010). "Resistance of Microorganisms to Extreme Environmental Conditions and Its Contribution to Astrobiology". Sustainability. 2 (6): 1602–1623. Bibcode:2010Sust....2.1602R. doi:10.3390/su2061602.
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