Subglacial water storage and drainage beneath the Fennoscandian and Barents Sea ice sheets

Abstract

Subglacial hydrology modulates how ice sheets flow, respond to climate, and deliver meltwater, sediment and nutrients to proglacial and marine environments. Here, we investigate the development of subglacial lakes and drainage networks beneath the Fennoscandian and Barents Sea ice sheets over the Late Weichselian. Utilizing an established coupled climate/ice flow model, we calculate highresolution, spatio-temporal changes in subglacial hydraulic potential from ice sheet build-up (~37 ka BP) to complete deglaciation (~10 ka BP). Our analysis predicts up to 3,500 potential subglacial lakes, the largest of which was 658 km 2 , and over 70% of which had surface areas <10 km 2 , comparable with subglacial lake-size distributions beneath the Antarctic Ice Sheet. Asynchronous evolution of the Fennoscandian Ice Sheet into the flatter relief of northeast Europe affected patterns of subglacial drainage, with up to 100 km 3 more water impounded within subglacial lakes during ice build-up compared to retreat. Furthermore, we observe frequent fill/drain cycles within clusters of subglacial lakes at the onset zones and margins of ice streams that would have affected their dynamics. Our results resonate with mapping of large subglacial channel networks indicative of highdischarge meltwater drainage through the Gulf of Bothnia and central Barents Sea. By tracking the migration of meltwater drainage outlets during deglaciation, we constrain locations most susceptible to focussed discharge, including the western continental shelf-break where subglacial sediment delivery led to the development of major trough-mouth fans. Maps of hydraulic potential minima that persist throughout the Late Weichselian reveal potential sites for preserved subglacial lake sediments, thereby defining useful targets for further field-investigation.

Groundwater Flow Under a Paleo‐Ice Stream of the Scandinavian Ice Sheet and Its Implications for the Formation of Stargard Drumlin Field, NW Poland

“…Besides the generally fine‐grained nature of the Odra lobe substratum (model layer 2), meltwater storage at the ice/bed interface would have been facilitated by relatively high basal melting rates as the area lies in the zone of positive geothermal heat anomaly (Szuman et al, ). Ubiquitous meltwater at the ice/bed interface in the study area would be consistent with the study by Shackleton et al (), suggesting that the OPIS area and its up‐ice continuation was one major route of subglacial water drainage during the Last Glacial Maximum.…”

Past water flow beneath Pine Island and Thwaites glaciers, West Antarctica

“…Meltwater features, similar to the channels in Pine Island Bay, have been mapped and modelled beneath other former ice sheets such as the Fennoscandian and Barents Sea ice sheets (Greenwood et al, 2016(Greenwood et al, , 2017Bjarnadóttir et al, 2017;Shackleton et al, 2018), the Laurentide Ice Sheet (Bretz, 1923(Bretz, , 1969Livingstone et al, 2013aLivingstone et al, , 2016Livingstone and Clark, 2016), and the British-Irish Ice Sheet (Sissons, 1958;Clark et al, 2004;Greenwood et al, 2007).…”

Glacial erosion: status and outlook

“…(Here, we do not further consider eskers and the nature of the drainage feeding them, but progress has been rapid (e.g. Shackleton and others, 2018; Hewitt and Creyts, 2019), and they surely deserve further attention. )…”