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Secrets of the ice

There is still so much we don’t know about the earth. One of the blind spots can be found in northeast Greenland, and it is relevant to climate change and the marine environment. An AU-led research project will now generate valuable knowledge about the region by using a new and unique data set collected during a successful expedition.

2021.07.05 | Rasmus Rørbæk

The sun may be setting on the inland ice sheet as we know it, but we still need to understand how the area around north-east Greenland has evolved over time in order to assess any possible changes caused by anthropogenic climate change. This work can now begin under the leadership of a geology professor from Aarhus. (Photo: Colourbox)

The sun may be setting on the inland ice sheet as we know it, but we still need to understand how the area around north-east Greenland has evolved over time in order to assess any possible changes caused by anthropogenic climate change. This work can now begin under the leadership of a geology professor from Aarhus. (Photo: Colourbox)

One of the globe's 'coronary arteries' is located on the western side of the Fram Strait in the North Atlantic Ocean. It’s a focal point for calving of the inland ice sheet, where the heat exchange between the North Atlantic and the Arctic Ocean drives the circulation of the world’s oceans.

Changes to the area’s climate, marine environment and geology have been registered, but it hasn’t been possible to date these changes to see if similar changes have taken place at other points in time. We therefore don’t know how unusual the current changes are or what conditions are "normal" for the area. For that matter, we’re not even sure if it’s possible for the area to go back to “normal” if anthropogenic climate change is stopped.

A Danish research project is now poised to benefit from a new unique dataset and can begin the difficult task of identifying the underlying mechanisms and conditions that have governed the area for thousands of years. If the project is successful, new and important knowledge could be gained on the effect climate change has on sea conditions and the melting of the Greenland inland ice.

The project is headed by professor Marit-Solveig Seidenkrantz from the Department of Geoscience at Aarhus University.

"Northeast Greenland plays a key role in a number of dynamics in the region, including ocean currents, sea ice, topography of the seabed and, not least, climate change. The region is home to some of the large glaciers that together account for 16% of the inland ice melt-off of freshwater into the Arctic Ocean. At the same time, the Fram Strait is the primary channel of water discharge into the Arctic Ocean," explains Marit-Solveig Seidenkrantz.

In other words, it’s a crucial area that is responsible for transporting up to 85% of sea ice and 50% of freshwater from the Arctic region into the Atlantic Ocean via the eastern Greenlandic sea current. The interplay between the different temperatures and water types drives sea currents and contributes to the global climate. However, the effect of the interaction between the Atlantic Ocean and the water from east Greenland is still unknown.

Jackpot

In 2017, Marit-Solveig Seidenkrantz headed NorthGreen2017, a 5,576-kilometre-long expedition onboard the Danish research vessel "Dana". The expedition turned out to be a big success, collecting over 100 metres of core drilling, sediment and water samples from a number of test stations in the area and a large number of seismic profiles from an otherwise impassable area thanks to fortuitous ice and weather conditions along the way.

It was a veritable jackpot for the research team, who can now begin to build up knowledge and understanding through an interdisciplinary and large-scale research collaboration named "GreenShelf", financed by the Independent Research Fund Denmark.

"GreenShelf will not only give us a significantly better understanding of the past and present oceanography, climate and geology of this distant region of the globe. The project will also provide valuable insight into the processes that impact the Greenlandic inland ice and the climate of the North Atlantic region, including Denmark. This research may also improve the methods that underpin climate models, and thereby improve the directives and regulations that will help alleviate the impact of climate change on the region," says Marit-Solveig Seidenkrantz.

Floating changes

Climate change plays a major role in the region, which is particularly noticeable through the drastic decrease in sea ice and the increased melting of inland ice. This means changes in the factors that influence the extent and pace of climate change.

One of the main factors behind the rapid warming of the Arctic is that the ice's ability to reflect the sun's energy, the albedo effect, is affected by the melting; because the ice is less white. This will impact how much heat the Earth's surface absorbs. The sea ice is believed to reduce the melting of the inland ice due to the sea ice’s own albedo effect and its ability to "protect" the inland ice from the heat.

The sea ice also impacts ocean dynamics as the ice cover creates the so-called deep-water formation, i.e. the sinking of the upper water masses into deeper layers, which drives the circulation of the oceans. Very simply put, this circulation ensures that sea currents flow and transport energy and food around the globe in a circuit known as thermohaline circulation. This circulation is of crucial importance to the climate of the entire planet.

However, the melting of the sea ice means an increased influx of fresh water into the ocean, which, in turn, dilutes salt water in the upper layers and thereby interferes with the mechanism that causes sea layers to mix, and which will ultimately slow the circulation of the sea currents.

New knowledge, old normal

In recent years, measurements and satellite missions have shown a drastic decline of sea ice. The disappearance of the ice has been linked to global warming, but the melting has been far greater than the models predicted.

Therefore, one of the goals of the research project is to gain a necessary insight into the accuracy of sea ice models in relation to nature's own rhythm, i.e. what is normal and how changes can be linked to the changes in sea currents. This can be done with the help of the collected samples from the region, as they can help us look further back in time than has previously been possible.

"We don't really know how the many factors interact over a longer period of time. We have data from satellite missions dating back to 1978, which has provided a better overview of, among other things, mass balance and albedo, but there is little information prior to that. This is where GreenShelf can contribute with a more far-reaching timeline," says Marit-Solveig Seidenkrantz, “GreenShelf is divided into five working groups, each of which will explore a number of factors by analysing the collected samples. For the first time ever, we’ll have a concrete point of departure and a tangible historical understanding of the pre-industrial dynamics in northeast Greenland and the North Atlantic region."

Contact:

Professor Marit-Solveig Seidenkrantz,

Department of Geoscience,

Aarhus University,

Tel. no.: +45 27 78 28 97

Email: mss@geo.au.dk

Department of Geoscience, Sustainability