Hidden under miles of thick ice, very little is known about groundwater, however it plays an important role in how fast the ice sheet moves to the sea, as it creates less friction between the ice and the bedrock.
When runoff comes out of the ice and comes into contact with the warm ocean waters, it also has the potential to increase ice melting and affect global sea levels, according to scientists.
The new study found that the melting rate at the base of the ice sheet was underestimated by 150%.
Experts analyzed data from the European Space Agency’s (ESA) CyroSat satellite a decade ago and were surprised to find that the lakes beneath the Thwaites Glacier – a vast frozen stretch the size of Britain – have drained and reloaded. in rapid succession – in 2013 and in 2017.
The study, led by researchers in Edinburgh, estimates that the flow rate reached a maximum of about 500 cubic meters per second – about eight times faster than the speed of the River Thames as it flows into the North Sea.
I used CryoSat to show a period of lake activity just four years after the previous drainage event in 2013. But what’s interesting about this second drainage event is how different it is from the first, with a faster transfer. of water and an increased discharge of water. Our observations highlight that there were potentially significant changes in the subglacial system between these two events.
Principal Author, School of GeoSciences, University of Edinburgh
The relatively short time required to recharge the lakes between the two drainage events provides scientists with an unprecedented estimate of the melting rate at the base of the ice sheet.
By comparing the rates with the modeled estimates, the team found that previous models underestimated basal melting by almost 150%.
The discovery will help glaciologists reevaluate models and improve predictions about how the ice sheet might behave in the future.
What happens under the ice sheet is essential for how it reacts to changes in the atmosphere and ocean around Antarctica and yet it is hidden from view by miles of ice, which makes it very difficult to observe. This movement of water gives us a look at where the water is and how fast it moves in the system. Together, they are essential information about the nature of the subglacial environment and the processes of the hydrological network under the ice sheet. These findings provide key information that can help us design how the ice sheet adds to sea level as it responds to climate change.
Dr. Noel Gourmelen
Reader, School of GeoSciences, University of Edinburgh
Dr. Gourmelen added that it is important to continue to monitor such remote regions for long periods of time. The planned CRISTAL mission, which is part of the European Copernicus expansion program, will be crucial to ensure the continuity and expansion of current capabilities to study the entire ice sheet in space, he said.
About 120 km wide, Thwaites is the largest glacier on Earth and one of the most fragile in Antarctica.
Thwaites International Glacial Collaboration and ESA’s 4D Antarctica programs were created to continuously monitor the entire Antarctic ice sheet using ice sheet simulation and space observations.
The project brings together several years of research from different teams to form a new comprehensive assessment of the hydrological processes of the Antarctic ice sheet – from the lithosphere and subglacial environment to the surface melting process. This will certainly help to establish a solid scientific basis for the future development of an Antarctic Digital Twin.
ESA Head of Earth Observation Science Department – Overseeing 4D Antarctica Project
The paper, published in Geophysical Research Letters, was funded by the European Space Agency’s 4DAntarctica project and the PROPHET project, a component of the Glacier Thwaites International Collaboration (ITGC), supported by the US National Science Foundation and the UK’s Natural Environment Research Council. United.