Abstract
AbstractActive subglacial lakes have been identified throughout Antarctica, offering a window into subglacial environments and their impact on ice sheet mass balance. Here we use high‐resolution altimetry measurements from 2010 to 2019 to show that a lake system under the Thwaites Glacier undertook a large episode of activity in 2017, only four years after the system underwent a substantial drainage event. Our observations suggest significant modifications of the drainage system between the two events, with 2017 experiencing greater upstream discharge, faster lake‐to‐lake connectivity, and the transfer of water within a closed system. Measured rates of lake recharge during the inter‐drainage period are 137% larger than modeled estimates, suggesting processes that drive subglacial meltwater production, such as geothermal heat flux or basal friction, are currently underestimated.
Highlights
The vast majority of ice in the Antarctic ice sheet drains from the continent to the ocean through fast-flowing ice streams and glaciers (Rignot et al, 2011)
Active subglacial lakes have been identified throughout Antarctica with satellite altimetry and ice-penetrating radar (Smith et al, 2009; Wright and Siegert, 2012)
2017, four large connected active subglacial lakes were discovered under the Thwaites Glacier from analysis of swath processed CryoSat-2 data, which indicated that the lakes drained simultaneously between June 2013 and January 2014 (Smith et al, 2017)
Summary
The vast majority of ice in the Antarctic ice sheet drains from the continent to the ocean through fast-flowing ice streams and glaciers (Rignot et al, 2011). Active subglacial lakes have been identified throughout Antarctica with satellite altimetry and ice-penetrating radar (Smith et al, 2009; Wright and Siegert, 2012). Observations of surface elevation changes indicate that subglacial lakes are hydraulically connected (Fricker & Scambos, 2009; Wingham et al, 2006), and often exist in groups beneath Antarctic ice streams. Analysis of ice-penetrating radar identified a region of high specularity under the Thwaites glacier, interpreted as evidence of the presence of water in distributed channels at the base of the ice sheet (Schroeder et al, 2013). In. 2017, four large connected active subglacial lakes were discovered under the Thwaites Glacier from analysis of swath processed CryoSat-2 data, which indicated that the lakes drained simultaneously between June 2013 and January 2014 (Smith et al, 2017). The occurrence of two drainage events within a short timeframe allow us to explore the impact of drainage activity on the evolution of the subglacial system, and to quantify sub-glacial melt supply providing rare insights into sub-glacial processes and basal melt generation
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