Preface Martin J. Siegert1 , John C. Priscu2 , Irina A. Alekhina3 ,

Jemma L. Wadham4 and W. Berry Lyons5 1 Grantham Institute, Department of Earth Science and Engineering,

Preface Cite this article: Siegert MJ, Priscu JC, Alekhina IA, Wadham JL, Lyons WB. 2016 Preface. Phil. Trans. R. Soc. A 374: 20150145. Accepted: 5 May 2015 One contribution of 17 to a Theo Murphy meeting issue ‘Antarctic subglacial lake exploration: first results and future plans’. Subject Areas: biogeochemistry, geophysics, glaciology, ocean engineering Keywords: Antarctic, subglacial, lakes, extreme environments Author for correspondence: Martin J. Siegert e-mail: [email protected]

Imperial College London, South Kensington, London, UK 2 Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA 3 Arctic and Antarctic Research Institute, St Petersburg, Russia 4 School of Geographical Sciences, University of Bristol, Bristol, UK 5 School of Earth Sciences, Ohio State University, Columbus, OH, USA It has been 20 years since Subglacial Lake Vostok was introduced as one of our planet’s top five largest lakes. Authors of this decisive work hypothesized that this subglacial system harbours a unique microbial community that evolved in isolation over millions of years, and holds ancient records of past ice sheet and climate change. Shortly after the seminal paper on Vostok, records of 77 other subglacial lakes were published, revealing the diverse hydraulic and geomorphic nature of Antarctic subglacial lakes. Testing scientific hypotheses about these systems is possible only through direct measurement and sampling of the lake water and sediment, and subsequent experimental and laboratory analyses. In 2000, the Scientific Committee on Antarctic Research (SCAR) commissioned a scientific research programme to promote and coordinate the exploration of subglacial lakes, including the important issues of sample cleanliness and environmental stewardship. The Committee met its goals in 2009 and the programme ended. In large part due to this Committee’s work, several national Antarctic subglacial exploration programmes were developed, and the formation of a code of conduct into subglacial access was accepted at the Antarctic Treaty Consultative Meeting in 2011. We now know that over 400 subglacial lakes exist across the Antarctic continent, and that many of these lakes, known as ‘active’ lakes, regularly discharge and receive water to/from the subglacial system. Importantly, data have revealed that the flow of ice is affected by the modulating effect of subglacial lakes on basal hydrology. In 20 years, the notion of the Antarctic continent as a frozen and lifeless place has been transformed by the discovery of dynamic and extensive drainage systems at its base.

2015 The Author(s) Published by the Royal Society. All rights reserved.

2 ......................................................... Phil. Trans. R. Soc. A 374: 20150145

Following studies on more than 200 m of ‘accreted lake ice’, Russian scientists penetrated the surface waters of the southern extreme end of Lake Vostok in February 2012, using the existing ice coring equipment. Surface water was allowed to enter the borehole and freeze during the ensuing winter. Subsequent coring efforts returned a portion of this frozen lake water to the surface. The lake was accessed for a second time in January 2015, and lake water froze again within the borehole, allowing future coring and sample retrieval. In December 2012, a British attempt to reach Lake Ellsworth, a deep water lake at the centre of West Antarctica, was halted when their clean deep access hot water drill experienced technical difficulties. A month later, US scientists successfully used clean hot water drilling to enter and sample Subglacial Lake Whillans, a shallow ‘active’ lake at the edge of West Antarctica. Results from the Whillans study revealed that a thriving microbial ecosystem existed in the lake water and sediments. With a first phase of subglacial exploration now complete, 60 researchers from 12 nations gathered in the UK Royal Society’s Chicheley Hall on 30–31 March 2015 to discuss first results and to plan future work. This meeting was held within the same time frame as SCAR’s 20-year horizon scanning exercise, which identified the top 80 questions driving international scientific ambition in Antarctic science and how they may be addressed. Hence, the meeting had a unique opportunity to take the experience from the last 20 years to guide scientific development over the next two decades. Open discussion identified the following three priorities for future research: (i) that technology for clean, reliable deep-ice access and subsequent in situ data acquisition is a fundamental prerequisite for subglacial lake exploration, (ii) that a variety of subglacial environments be considered for exploration to obtain a holistic view of subglacial biodiversity and crosscorrelation of climate records held within these lakes, and (iii) that international cooperation be considered as essential for scientific and logistical optimization, allowing the sharing of equipment and samples. Targets for future exploration include deep water lakes with long hydraulic retention times at the ice sheet centre and ‘active’ lakes closer to the margin that are known to influence ice sheet flow. We now have an excellent understanding of how to cleanly access and sample subglacial lakes, including Lake Vostok. Importantly, the international community now has in its possession clean access drills and a variety of instrumentation packages and sampling technologies to directly measure and sample subglacial lakes in the future. By continuing the international dialogue established by SCAR, and by concentrating on the priorities for programme development listed above, it is entirely feasible that Lake Vostok can be explored thoroughly by 2025, making the 2015 discussion at Chicheley Hall, detailed within the papers of this issue, a pivotal moment in the history of subglacial exploration. We began the meeting with a round of applause in appreciation of our colleague and friend, Dr Alberto Behar, who died on 10 January 2015 when the light aircraft he was piloting crashed in Los Angeles. Alberto was involved in subglacial lakes research for nearly 20 years and, through his expertise in robotics and sensors, contributed greatly to investigation of life in extreme environments.


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