Svalbard glacier survived during a warmer past

Her research, just published in Nature Communications Earth and Environment, focuses on the glaciers of Svalbard, and aims to draw parallels between their current response to Arctic warming and wetting, using the past as a reference. As in the early Holocene period around 9500 years ago, when it was kind of similar warming. 

“I was looking at lake sediments and analysing them with different methods to try and figure out how the glaciers reacted to these warming conditions in the past. By analysing lake sediments with various methods, I sought to uncover how these glaciers adapted to past warming trends, providing valuable insights into their potential future changes”, Auer says. She is a PhD Candidate at the Department of Earth Science at UiB. 

To be able to provide the answers to these questions, they chose two lakes on Svalbard. Two so called glacier-fed lakes, receiving meltwater from a big ice cap called Åsgardfonna. The goal was to figure out if the ice cap completely melted during the warmer-than-present early Holocene period, or whether it survived the heat.

“And if the glacier survived, why did it?”. 

Main contributors to sea level rise

Willem van der Bilt is Principal Investigator and supervisor of the project, which is funded by the University og Bergen and the Trond Mohn Research Foundation. He points out why it is important to investigate glaciers, especially in the Arctic.  

“Over the next decades, these glaciers will be the main contributors to global sea lever rise, bigger than the larger ice sheets. The glaciers are a much smaller, but they are far more responsive, so they react almost immediately to a changing climate”, van der Bilt says.  

Therefore, the researchers wants to understand how these glaciers behave in a world that is warmer, but also wetter. The challenge is that climate models are incredibly uncertain about the amount and type of precipitation that will fall in the future Arctic.  

“What we cannot know is whether the precipitation will fall as rain or as snow. As you can imagine, as snowfall, it might help these glaciers melt a bit slower. They are still going to melt, though”, van der Bilt elaborates.  

You can read more about the project PASTFACT here.

Innovative methods

In the project, they used several unconventional methods. They are not brand new, but the way that they have applied them, is quite innovative. First, they used Computed Tomography (CT) scanning, which allowed them to visualize invisible sediment structures. This method provides insights into depositional processes by revealing fine-scale sedimentary features, such as layers left behind by geohazards.

“This was quite helpful. Because it really allows us to diagnose sediment structures in 3D. And in this way, we identified an earthquake deposit. This is actually the first earthquake deposit identified on Svalbard”, Auer says.  

Then they used a statistical method which is called grain size end member modelling analysis (EMMA). In this way, they unmix or separate the different sediment sources, teasing out hidden signals associated with specific processes.  

“You can think of it like identifying ingredients in a smoothie. We unmix the different grain sizes, and each of them reflects a sedimentary process that brought the sediment to the lake,” she explains. This allowed them to disentangle the imprint of glacial melt and run-off – a measure of changes in precipitation. 

Important result

The research on past glacier change goes way back. The basic approach is to use fine-grained glacial flour that is being produced by an eroding glacier and ends up in downstream lakes. Multiple generations of researchers at the Earth Science Department of UiB have worked on this since the late 1900s.  

“We have learned a lot about behavior of glaciers in Norway, and beyond, during the last 10,000 years. Multiple colleagues have added methods to the method toolbox used for this work. It is great to be part of this developing story and add our own approaches, to tease out more information from these records. Stuff that would otherwise be overlooked”.  

Van der Bilt also hopes that scientists in the future will apply this set of tools, so we can learn more about the behavior of glaciers in other parts of the world as well.  

Their findings are exciting. It reveals that Åsgardfonna survived and may have advanced despite warmer conditions, possibly due to enhanced snowfall, driven by sea-ice loss. This suggests that future increases in precipitation could moderate glacier retreat in similar settings. 

A long process

Auer enjoyed the time in the lab learning the new techniques. It is the first paper of her PhD. She has learned a lot, but the publishing process took much longer than she had anticipated.  

“Initially the first round of reviews came through and the journal said that they are interested in publishing it, granted that we made some changes. After this, it took another 8 months before the manuscript was published”. 

Van der Bilt also reacted to several things during the process.  

“One of the reviewers did not just add nuances to the previous review but basically asked us to add a modelling component. As this wasn’t our forte, this was quite a challenge. But it did add a valuable dimension to the work, in the end”, van der Bilt says. 

In that sense, he is glad that the comments are being published along with the paper, so that people can see that the road to publication is long and windy. 

“I encourage readers to check the review reports that are published along with our paper. They are certainly interesting” van der Bilt says.