The Antarctic Ice Sheet (AIS) is facing unprecedented changes, with the Thwaites Glacier at its center. A new study reveals how the drainage of subglacial lakes beneath Thwaites Glacier significantly impacts the rate of melting and ice retreat. This melting is mainly driven by the interaction of subglacial freshwater with ocean waters, leading to enhanced ocean melting of the glacier’s ice shelves.
Researchers found during the early months of 2013, seven extensive subglacial lakes began to drain, discharging around 7.22 ± 0.26 km3 of water over approximately one year. The peak discharge occurred between late August and early September of 2013, with rates reaching 630 m3 per second—substantially higher than typical rates observed previously.
The impact of this event was significant, as the buoyant plume formed by the discharged freshwater temporarily increased ocean melting rates under Thwaites Glacier. Observations highlighted the mean melt rates nearly doubled during this period, from 17.5 ± 0.7 m per year to 31.0 ± 0.7 m per year, with maximum melt experienced under the Thwaites Western Ice Tongue sector.
These findings are part of broader concerns surrounding the stability of the AIS, which contributed approximately 7.4 ± 1.5 mm of sea level rise from 1992 to 2020, with projections indicating the potential for continued acceleration. The Thwaites Glacier, renowned for its vulnerability, has become a focal point as scientists study the dynamics of ice-shelf melting and its global effects on sea level rise.
While traditional models have focused on ocean warming and increased melt, the role of subglacial water systems has remained less understood, particularly their dual-nature of potentially providing stabilizing influences or triggering rapid loss. With models simulating the effects of continuous subglacial discharge showing enhancements up to 70% more basal melting compared to steady-state scenarios, the complexity of these interactions becomes clear.
Between 2014 and 2017, Thwaites’ grounding line experienced surface lowering of up to 80 m, compounded by substantial basal melting rates reaching 200 m per year. Such changes raise alarms about the glacier’s potential for irreversible retreat with significant consequences for global sea levels.
Following the drainage event, researchers observed notable changes, including the formation of polynyas—open water regions among sea ice—approximately 20 km offshore from the grounding line. These environmental shifts correlate with increased ocean heat at the surface, resulting from the interplay of discharged meltwater.
The results suggest the dynamics of subglacial water flow could provide fresh insights on physical changes occurring within the West Antarctic region. These findings highlight the necessity for continued monitoring of the Thwaites Glacier, especially as it may serve as an indicator of broader changes within the Antarctic Ice Sheet.
Despite the drastic changes within the region, scientists caution against predicting outcomes too hastily. This study shines light on the complex interplay of subglacial hydrology and ocean dynamics but leaves open questions about the future stability of Thwaites Glacier and its contributions to sea-level rise.
Future research must unravel these interactions to anticipate how similar melting patterns may emerge elsewhere across Antarctica, shaping the forecast of our planet's changing climate.