A new robotic submersible could unlock the mysteries of Greenland's underwater glaciers

And transform our grasp of how sea levels rise.
Derya Ozdemir
The glacier Kangerlussuup Sermia in Greenland.University of Texas

They might be the front line of climate change; however, we still don't know much about what's going on at the underwater front of Greenland’s glaciers. A planned robotic dive there could change that and expose some of the mysteries, hopefully revealing just how much these ice rivers will contribute to sea-level rise as a result of human-caused global warming.

The new mission, led by researchers at The University of Texas, is set to launch in midsummer 2023 and will deploy a submersible robot to study three of Greenland’s glaciers: Kangilliup Sermia, Umiammakku Sermiat, and Kangerlussuup Sermia, which are all located on the island's west coast.

Uncharted glacial walls

This is going to be the first time scientists will have a close-up look beneath Greenland's glaciers. The researchers will send a remotely operated submarine called Nereid Under Ice (NUI) to the glaciers' undersides, where they meet the ocean.

To operate in such challenging conditions far from its support ship, the robot has been designed with layers of built-in redundancy, including several thrusters, battery packs, and navigation systems.

Nereid Under Ice was poised to collect samples in a 2019 Arctic Ocean expedition. Source: University of Texas

The submarine will not be looking at the ice itself but at the walls of sand and debris known as moraines that the glacier pushes out ahead of itself as it flows. Moraines transport ice from Greenland's interior to the ocean, acting as a clog to prevent water from running down a drain and they stabilize the ice sheet.

The question that remains, however, is what will happen if the plug is pulled? Understanding sea-level rise as the Arctic melts requires an answer to this question, and to find the answer, the sub will map the moraines' morphology and collect sediment cores, which will allow researchers to better understand how stable the moraines are. The sub will also collect sediment samples from the plume of sediment that comes out from beneath the glacier ice.

"The big uncertainty in Greenland's contribution to sea-level rise is how fast the ice sheet is going to lose mass," explains Ginny Catania, a professor at the University of Texas Jackson School of Geosciences who is leading the voyage, in a statement. "We know how much sea-level is stored in the ice sheet, we know climate is warming and changing the ice sheet, but what we don't know is the rate at which these glaciers will contribute to sea-level rise."

Some scientists have proposed that the impacts of global warming on the sea-level rise could be postponed if some mechanism was utilized to build up these undersea moraines, thereby supporting the Greenland ice sheet, and learning such crucial information could potentially be useful for future geoengineering initiatives.

According to some experts, we could create fake moraines to buy time while the world switches to low-carbon energy sources. And this research will help determine whether or not that notion is viable.

"This is high-risk, high-reward science, but it’s exactly the kind of bold step needed to tackle the pressing and societally relevant questions about climate change and geohazards," stated Demian Saffer, director of the University of Texas Institute for Geophysics. "If it succeeds, it could transform our understanding of sea level rise."