"Doomsday Glacier" exposed to more warm water than expected

Scientists have obtained data from beneath the Thwaites Glacier, also known as the “Doomsday Glacier,” for the very first time. The experts found that the glacier is exposed to a larger supply of warm water than what was expected, which raises new concerns about its stability. 

The study was made possible with the help of the unmanned submersible vehicle Ran, which made its way underneath the Thwaites glacier front. The submarine was used to measure the strength, temperature, salinity, and oxygen content of the ocean currents under the glacier.

“This was Ran’s first venture to polar regions and her exploration of the waters under the ice shelf was much more successful than we had dared to hope,” said Professor Karen Heywood of the University of East Anglia. “We plan to build on these exciting findings with further missions under the ice next year.”

According to study lead author Professor Anna Wåhlin of the University of Gothenburg, the biggest uncertainty in forecasts of global sea level rise is the future evolution of the West Antarctic Ice Sheet.

Currently, the ice sheet in West Antarctica contributes about ten percent of the overall rate of sea level rise. At the same time, this ice sheet holds the most potential for increasing the rate of sea level rise because of the rapid changes taking place in the Thwaites Glacier.

Due to its location and shape, Thwaites is particularly sensitive to warm and salty ocean currents. The glacier is challenging to study because it is usually blocked by thick sea ice and many icebergs. 

The researchers used the data from RAN to map the ocean currents underneath the floating part of the glacier. They discovered that there is a deep connection to the east through which water flows from Pine Island Bay – a connection that was previously thought to be blocked by an underwater ridge.

The experts also measured heat transport in one of the three channels that push warm water toward Thwaites from the north. 

“The channels for warm water to access and attack Thwaites weren’t known to us before the research. Using sonars on the ship, nested with very high-resolution ocean mapping from Ran, we were able to find that there are distinct paths that water takes in and out of the ice shelf cavity, influenced by the geometry of the ocean floor,” explained Dr. Alastair of the University of Southern Florida.

The team found variations in salinity, temperature, and oxygen content under the glacier which indicate that this is an area where different water masses meet and mix with each other.

The observations show warm water approaching from all sides on pinning points – critical locations where the ice is connected to the seabed and give stability to the ice shelf. 

“This work highlights that how and where warm water impacts Thwaites Glacier is influenced by the shape of the seafloor and the ice-shelf base as well as the properties of the water itself. The successful integration of new seafloor survey data and observations of water properties from the Ran missions shows the benefits of the multidisciplinary ethos within the International Thwaites Glacier Collaboration,” said Dr. Rob Larter of the British Antarctic Survey.

“The good news is that we are now, for the first time, collecting data that is necessary to model the dynamics of Thwaite’s glacier. This data will help us better calculate ice melting in the future. With the help of new technology, we can improve the models and reduce the great uncertainty that now prevails around global sea level variations.” said Professor Wåhlin.

The study is published in the journal Science Advances.

—

By Chrissy Sexton, Earth.com Staff Writer