Rising temperatures trigger chain reaction in northern Greenland
September 9, 2026
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Written by Ulla Abildtrup
Written by Ulla Abildtrup
Researchers are measuring much higher nutrient concentrations off Greenland’s Sermeq Kujalleq glacier than just a few years ago. The nutrients are increasing levels of phytoplankton, which could make Disko Bay far more productive in terms of shrimp, mussels and fish, says Professor of Marine Biology Per Juel Hansen.
The Arctic Station’s research vessel Porsild cuts through the water off Qeqertarsuaq. On board, researchers are heading out to collect seawater samples.
There is nothing unusual at the surface of the sea, but major changes are taking place deeper below.
“We have been collecting data around Qeqertarsuaq for more than 100 years. The temperature of the surface water has not changed, but the temperature at the seabed has risen by two degrees since the late 1990s,” says Per Juel Hansen, Professor of Marine Biology at the University of Copenhagen.
The research vessel Porsild belongs to the Arctic Station at the University of Copenhagen and is used, among other things, to collect water samples. Photo: Ulla Abildtrup.
One consequence of these changes is that it is no longer possible to walk across the ice between Qeqertarsuaq and Ilulissat during the winter, as it was until 1997.
The higher temperature in the seabed is due to an increased flow of Atlantic water from the south. The reason why the surface water temperatures have not increased is likely due to the outflow of ice and meltwater from the glaciers into the Disko area, according to the professor.
Captain David Brandt slows the vessel and adjusts the rudder slightly to keep a safe distance from a small iceberg.
As part of the MarinBasis Disko project, researchers measure temperatures and collect samples 8-9 months of the year, in all kinds of weather. Today, however, there is not a cloud in the sky. Fulmars glide elegantly on the wind just above the surface of the sea.
The captain brings the vessel to a stop, and a probe is lowered 320 meters into the ocean.
“We collect water samples at seven depths – 1, 10, 20, 50, 100, 200 and 300 meters – and transfer them to containers and sample bottles to analyze nutrients and the composition of microscopic algae and animals. We also collect plankton samples at different depths.”
In May and August, the researchers sail all the way around Disko Island, measuring temperature and salinity, and collect water samples to measure nutrient concentrations. The trip takes about five days, depending on the weather.
Today is just a short three-hour trip before captain David Brandt and deckhand Eli Martinsen set course for the harbor in Qeqertarsuaq.
Major changes in the ocean
Climate change is happening rapidly in northern Greenland, and higher temperatures are changing marine life, says Professor Per Juel Hansen.
“Over the past 2-3 years, we have measured high nutrient concentrations off the Sermeq Kujalleq glacier. Phytoplankton, which we normally only find in spring, are now present in abundance throughout the summer.”
“The increased amount of nutrients in the surface water allows the algae to grow much faster when they reach the light. Algae provide food for the animals higher up in the food chain, so these phytoplankton blooms make Disko Bay enormously productive in terms of shrimp, mussels and fish,” – Per Juel Hansen.
The explanation lies in increased melting from the glacier, which is Greenland’s largest and one of the most ice-productive glaciers in the world.
“When the ice melts in the ocean, the freshwater helps draw nutrients up from the seabed, stimulating photosynthesis. In addition, icebergs stir the water column as they calve and are transported further into the bay. The increased amount of nutrients in the surface water allows the algae to grow much faster when they reach the light. Algae provide food for the animals higher up in the food chain, so these phytoplankton blooms make Disko Bay enormously productive in terms of shrimp, mussels and fish,” says Per Juel Hansen.
Researchers frequently collect water samples near Qeqertarsuaq on Disko Island. Photo: Ulla Abildtrup.
Every year, the Greenland Institute of Natural Resources studies shrimp, halibut, cod, and other fish in Disko Bay. But the latest data shows no big changes in the amount of these fish and shrimp.
“The recorded increase in plankton could theoretically have a positive effect. However, since plankton is initially part of the diet of smaller larvae, any positive effect on fisheries would only show 5-7 years later,” the department writes to Arctic Hub.
Per Juel Hansen also estimates that it could take 5-7 years before an effect on fisheries would materialize, depending on whether the change persists.
“The impact of melting glaciers on marine life is currently much greater than we had expected. Qeqertarsuaq is far way from Sermeq Kujalleq, yet the change is happening there as well.”
“In the longer term, the question is what happens when the glaciers run out of ice. The glaciers will retreat, bringing an end to the mixing of seawater that they currently cause. This will lower the plankton production and sedimentation and, in the longer term, possibly lower fish production and therefore reduced fisheries,” says Per Juel Hansen.
“However, preliminary data from Sermeq Kujalleq suggest that it will probably take several 100 years before the glacier terminates on land rather than in the sea, as it does today.”
There is therefore no imminent threat to the roughly 50 full-time hunters and fishers in Disko Bay area or to the fish-processing plants in Ilulissat and Qeqertarsuaq.
More precise measurements
Measurements have been carried out on land, at sea and in the atmosphere around Arctic Station since 1906. The station is the oldest in Greenland and one of the oldest of its kind anywhere in the Northern Hemisphere.
Because of these long time series, the data are of great interest to researchers around the world, says Thomas Friborg, Professor at the University of Copenhagen’s Department of Geosciences and Natural Resource Management and Chair of the Arctic Station Board.
“Unfortunately, much of the historical data has not been digitized and is therefore not as readily accessible to researchers around the world. We would like to change that, but it requires funding that we do not currently have.”
“Fortunately, our new measurements are becoming increasingly precise, enabling researchers to develop better predictions of the impacts of climate change,” says Thomas Friborg.
Some of the measurements come from the Greenland Ecosystem Monitoring programme, which has collected data on the long-term impacts of climate change since 1995.
“The amplified warming at the poles is four times stronger than elsewhere on the planet, and temperatures in the Arctic have risen by an average of four degrees compared with the late 19th century. Because the Earth’s climate system is interconnected, knowledge about developments in the Arctic is an important piece of the puzzle in understanding what may happen to the climate worldwide,” the professor emphasizes.
The level of interest can be seen, among other things, in the fact that measurements from Arctic Station are frequently downloaded by researchers around the world and form the basis of new scientific publications.
Global warming is progressing faster at the poles than anywhere else on the planet. Temperatures in the Arctic have risen by four degrees compared with the late 19th century. Photo: Ulla Abildtrup.
Besides getting warmer, researchers have also seen more rain and snow, and more frequent thaw.
“We are now experiencing thawing in February and March, which is unusual. In 2022, there was also an exceptional amount of rain during the summer and autumn, and a landslide destroyed a bridge near Qeqertarsuaq. But it is too early to determine whether these are lasting changes,” he says.
Thomas Friborg is currently particularly interested in the relationship between thawing permafrost and greenhouse gas emissions.
“When Greenland’s dry landscapes thaw, they release large amounts of carbon dioxide and methane. But rising temperatures combined with released nitrogen also create better growing conditions for vegetation. Plants absorb more carbon and can therefore help store greenhouse gases.”
“So we are interested in understanding the balance between these two components – thawing permafrost and increasing vegetation – and what it means for greenhouse gases and, consequently, global warming,” says Thomas Friborg.