His climate research uncovers potential Arctic futures

When Jan Karlsson started researching climate effects on lakes in 1998, the field was new and untested. There was a lack of important knowledge, such as the fact that lakes and rivers emit greenhouse gases, and the authorities' environmental monitoring of mountain lakes was based on incorrect information.

Since then, Jan Karlsson's research team has worked hard to show how Arctic aquatic ecosystems function. Their figures, along with those from other researchers, are now included in major climate models and give us more accurate scenarios for the future, such as effects of fossil fuel emissions on the climate.

If the carbon inside the permafrost starts to be released, some of it will flow into lakes and rivers and be decomposed into greenhouse gases

The numerous lakes in the Arctic play a significant role in the overall health of our planet. Here in the Arctic, warming is happening several times faster than elsewhere and the consequences are escalating.

“There is a lot of permafrost in the Arctic and if the carbon in it starts to be released, we have shown that some of it will flow into lakes and rivers and be decomposed into greenhouse gases that are released into the atmosphere. This is what we call a positive feedback that reinforces the greenhouse effect,” says Jan Karlsson, professor at the Department of Ecology and Environmental Science at Umeå University.

Spends a lot of time in the mountains

He speaks from Abisko in an interview conducted via Teams. It is late summer and this time of year Jan Karlsson spends a lot of time at CIRC, the Climate Impacts Research Centre, where he is director. The research center is part of Umeå University. The center engages in interdisciplinary research, facing both national and international exchanges on the impacts of climate changes on Arctic ecosystems.

The work involves collecting and analyzing samples from lakes, streams and rivers.

ImageMattias Pettersson

Jan Karlsson primarily focuses on lakes and running water (river and streams); how the climate affects the production of algae, bacteria, plankton and fish, and how lakes store carbon in sediment and release it into the atmosphere in the form of the greenhouse gases carbon dioxide and methane.

“I do this mainly by studying how lakes in different climates, such as cold tundra lakes versus warmer forest lakes, function. Based on this, we can make predictions about what will happen if the temperature rises,” says Jan Karlsson.

He employs comparative studies along natural climate gradients, which means that in the absence of historical data from a specific lake, the same type of lake is studied at a different altitude where the temperature is different. Likewise, the researchers seeks to understand how changes in precipitation levels affect systems by contrasting data from Abisko – located in the rain shadow and among Sweden's driest places – with data from the border to Norway, which is one of the wettest places. Karlsson and his research team are currently working hard on the latter.

A well-functioning ecosystem is important for both tourism and the locals. Jan Karlsson tries to ensure that his research results are put into practice and benefit society.

ImageMattias Pettersson

Sees the effects with his own eyes

A normal working day in the field involves a long hike in the mountains. The backpack often contains a rubber boat, bottles and measuring equipment for the lake studies. The researchers collect water and sediment samples and download data from equipment that has been deployed. Once back home, the samples are examined in the lab, then the bag is packed for a new day and a new lake.

“We work all year round, but especially from late winter to fall. From April to October we sample almost every week,” says Jan Karlsson.

For himself, much of his time is spent on planning and administration. But on the days he is out in the mountains, the impact of the climate is already evident. Comparing with hundred-year-old photos from Abisko, one can see that the tree line has shifted about 40 meters uphill. Karlsson notices that skiing has become more challenging and that trees are being stripped of their leaves by the mountain birch moth, a caterpillar that thrives in milder winters.

Torneträsk at Abisko Natural Science Station.

ImageAnna Lawrence

The increase in temperature has meant that the active layer in the ground, which does not consist of permafrost, has increased from about half a meter to up to one meter in the last 30 years. The ground is sinking, becoming wetter and more difficult to walk on.

“This may seem trivial, but for large areas of the Arctic it is extremely important. It is a very big question what happens to the carbon in the soil if it starts to break down and release carbon dioxide and methane. This is the subject of extensive studies both at CIRC and internationally,” says Jan Karlsson.

The Arctic char was gone

They also anticipate changes in plant and animal life.

“When we arrived at a lake known for its Arctic char specially adapted to cold water, we found only pike upon sampling. This is a fish species that is expected to move further up the mountain when it gets warmer. You also hear from local people that there are changes in fish communities. Isolated cases cannot be linked to the climate, but it is something that is likely to become more common in the future.”

Well-functioning ecosystems are important not only for the natural environment but also for the local population and tourism. Collaborating with the county administrative boards, Jan Karlsson's research has contributed knowledge that leads to better monitoring and management of the lakes in the mountains.

Like many researchers, Jan Karlsson is driven by intense curiosity. He wants to find out more, but also to ensure that his work is useful.

“We have so much knowledge that we feel we have to share. A lot of the textbooks are still wrong about how these systems work. We see that there is so much more to do. It is important that we get out methods that can be used by authorities, for example,” he says.

Abisko is a small dot on the world map and a metropolis for global climate research. Every time Jan Karlsson takes a coffee break, he meets researchers from many different countries. They study different systems but are so interdependent that working together is invaluable. Through CIRC, he has established connections and built networks globally.

Received a donation

Two years ago, CIRC received a donation of SEK 2 million from a private individual.

“We will build a unique infrastructure inviting researchers worldwide to collaborate. We are waiting for some permits, but there will probably be an area around the research station where you can conduct unique experiments on the terrestrial environment, for example by manipulating the water supply.”

They have also started building a database and methodology to work with remote sensing and geographic information systems (GIS).

“This will have a huge impact on the quality of the research and create opportunities for innovative research. We are extremely grateful for that money,” says Jan Karlsson.