Mud reveals surprising find about Greenland ice streams | Polarjournal

Researchers of the EastGRIP project, a 14-nations research project on ice core drilling on the Greenland ice sheet, recently made a significant discovery: ice streams flow as a single block into the oceans, sliding on mud rather than on water. This discovery will have a significant impact on modelling ice sheet dynamics in the light of climate change. Sara Kirstine Hald has visited the researchers in their mobile camp and reports on the findings.

Ice, ice and more ice. Everywhere you turn, there is ice as far as the eye can see. We are in the middle of the ice sheet. In the middle of nowhere.

… and yet, scattered across the mass of ice a pile of red tents, a row of poles with fluttering flags, a handful of snowmobiles and a large, angular dome appear. Together, these entities make up a mobile research station, which constitutes the framework for the international research project EastGRIP – East Greenland Ice-Core Project, that has just had a significant breakthrough.

Since 2016, interrupted only by the pandemic, EastGRIP has been drilling through the 2,670 meters of ice that surrounds the base. And on the day before our visit, they succeeded; for the first time ever, scientists managed to reach the bottom of a so-called ice stream. Their findings may provide new insights into the climate of the past – and the future.

The EastGRIP research base is situated currently at the 75th parallel. Map: Google Maps via Arctic Hub

The ice sheet is a journal of the planet’s climate

Drilling through almost three kilometers of ice is quite the feat, but why do it? What is in it for us?

The simple answer is knowledge. And lots of it.

Looking at ice cores can tell us a lot of things. For example, the specific ice core of the EastGRIP project can tell us about the earth’s climate and evolution over the past 120,000 years.

The information is found, among other things, in impurities and air bubbles in the ice, which when analyzed can reveal the composition of the atmosphere at a given time. The sulphate content in the ice sheet can be traced to volcanic eruptions, just as scientists can track changes in the ice corresponding to the industrial development.

The ice cores contain a wealth of information that can help us understand the past, and, in particular, the climate of the past. At the same time, the findings at EastGRIP point to the future.

The ice core drilling takes place in an underground – or “under-snow” – drilling hall. (Photo: Sara Kirstine Hald)

Newfound knowledge about ice streams

The EastGRIP ice core measuring 2,670 meters was drilled in an ice stream – i.e., ice that flows faster than the surrounding ice sheet and calves into the fjords, where it becomes icebergs. The ice stream thus account for a large part of the ice loss occurring in Greenland. Just about half, actually. Still, not much was known about them – until now.

The day before our visit, the researchers reached all the way through the ice and hit… mud.

“We could see that the entire ice stream flows on a layer of mud at the bottom. This was not known before,” says Professor Dorthe Dahl-Jensen, who leads the research at EastGRIP.

This wet mud has been hidden under the 120,000-year-old ice of Greenland. (Photo: Sara Kirstine Hald)

The theory is that the wet mud acts as quicksand, enabling the large block of ice to slide smoothly across the bedrock. So, you have to imagine a large block of ice breaking away from the rest of the ice sheet and sliding towards the fjords on mudflats.

“Until now, it was thought that ice streams had shifts down through the ice, but at EastGRIP we have seen that the entire mass – totaling 2,670 meters of ice – flows as a single block at a speed of 58 meters per year,” says Dorthe Dahl-Jensen.

She calls the finding ‘exceptional’ and has no doubts about its significance: “It will change climate models because it changes our basic understanding of how ice moves,” says Dorthe Dahl-Jensen.

The discovery of mud has given researchers new knowledge about how the ice stream moves. Hear Dorthe Dahl-Jensen talk about this in the video

The ice core gives us a better idea of future sea level rise

The global sea level is rising, partly due to human-caused climate change. Ice loss from the Greenland ice sheet, including ice streams, contributes significantly to these increases.

The findings from EastGRIP not only provide us with new knowledge about the ebb and flow of ice streams. It also gives us new knowledge about the source of half of Greenland’s ice loss, which leads to sea level rise all over the world.

Concretely, the new knowledge may contribute to more accurate forecasts of future sea level rise.

“The fact that the ice does not shift, but slides like a block on mud, is going to improve sea level predictions in the future with the help of modified models,” says Dorthe Dahl-Jensen.

“Until now, it was thought that ice flows had shifts down through the ice, but at EastGRIP we have seen that the entire mass – totaling 2,670 meters of ice – flows as a single block at a speed of 58 meters per year.”

Professor Dorte Dahl-Jensen, Head of EastGRIP research project

We can future-proof Venice, Copenhagen and Miami

Although new knowledge about ice streams does not allow us to stop sea level rise, it does make it possible to prepare for them. For example, rising water levels can and, indeed, should be kept in mind in new construction projects. Now, initiatives can be launched to protect vulnerable cities and coasts.

The whole point of predicting sea level rise is that it allows us to prepare for it. If we know roughly how the sea level will rise in the coming decades, we are better equipped to future-proof the numerous cities, areas and countries that will be affected by the increased water volumes.

Cities such as Venice, Copenhagen and Miami, to name just a few, are affected by sea-level rise. As are numerous Asian countries such as Vietnam, Bangladesh, and India. The more accurate forecasts of the sea level rise, the better chances are of protecting these areas.

Wondering why the mud isn’t frozen solid? Dorthe Dahl-Jensen explains why in the video.

The ice streams have a direct impact on Greenland’s fisheries

The new knowledge from EastGRIP is important in a global perspective. Locally, in Greenland, it can also prove to be of great importance because the ice streams supply the sea around Greenland with nutrients that are essential to fisheries.

By learning more about the ice streams and their future, we can also learn more about the future of the fisheries around Greenland. At the same time, the loss of ice from the ice sheet naturally affects Greenlandic waters into which the ice from the ice streams is bound to end up. The findings can therefore have an impact both locally in Greenland and on the rest of the world.

The analyses of the ice cores will start in the autumn of 2023, and it is estimated that the results will be ready within a year.

Sara Kirstine Hald, Arctic Hub

More information on EastGRIP can be found here: Website EastGRIP

Arctic Hub is responsible for disseminating research about Greenland to audiences outside of academia. Articles are published here as part of a partnership with PolarJournal.

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