Beneath the vast expanse of Antarctica's ice sheet lies a hidden network of subglacial lakes, each playing a crucial role in the dynamics of the region. These lakes, previously unknown to science, have been revealed through the meticulous analysis of satellite data. The findings, published in Nature Communications, highlight 85 new subglacial lakes, significantly expanding our understanding of the subglacial landscape under the White Continent. This discovery not only adds to the growing list of active lakes but also underscores the intricate relationship between these lakes and the flow of the Antarctic Ice Sheet.
The subglacial lakes are nestled deep beneath the ice, with the average thickness of the Antarctic Ice Sheet reaching an astonishing 4,000 meters. Sally Wilson, a glaciologist at the University of Leeds, emphasizes the depth of these lakes, stating, 'The whole column of ice above the lake needs to go somewhere.' This 'blister under the ice sheet' phenomenon is a result of the gentle frictional heating caused by the movement of the ice sheet and the heat emanating from the Earth's interior, preventing the water from freezing.
The research team, led by Wilson, employed satellite data from CryoSat-2, a European Space Agency satellite, to detect changes in the height of the ice surface. By analyzing radar altimetry data collected from 2010 to 2020, they identified 85 regions with significant height changes, indicative of active subglacial lakes. Leigh Stearns, a glaciologist at the University of Pennsylvania, supports this finding, stating, 'There’s really nothing else that could cause the kinds of elevation changes that they’re seeing.'
The study revealed that 50 of the discovered lakes exhibited both filling and draining behavior, with 10 of those lakes completing a full cycle of filling and draining over several years. Interestingly, the researchers found that individual lakes did not always fill and drain to the same level, showcasing a complex pattern of uplift and subsidence. For instance, the Whillans_180 lake in West Antarctica demonstrated a consistent pattern of uplift and subsidence, with the ice above it rising and falling by approximately 5 meters.
Furthermore, the team identified five interconnected regions across Antarctica, where the lakes appeared to be linked. This observation suggests a complex hydrological network beneath the ice sheet, with water moving from one lake to another. Wilson emphasizes the significance of this discovery, stating, 'Identifying the lakes is one thing. But actually tracking the movement of water is an entirely different ball game.'
The impact of these subglacial lakes on the surrounding glaciers is substantial. Water flowing from these lakes can act as a lubricant, potentially accelerating the flow of glaciers and contributing to rising sea levels. Additionally, the freshwater present in these lakes can influence local ocean currents and affect marine life around the ice shelf. Stearns highlights the excitement of this discovery, stating, 'Being able to look at something on the surface to infer what’s happening at the bed is really exciting.'
The success of this research is largely attributed to the availability of archival satellite data, particularly from CryoSat-2, which has far exceeded its expected mission lifetime. Wilson emphasizes the value of long-term records in understanding gradual changes in polar regions, stating, 'We should be putting money and effort into keeping these datasets alive.' This ongoing effort is crucial for advancing our understanding of the complex dynamics beneath the Antarctic Ice Sheet.
