A colleague described Minnesota to Vanessa Czeszynski as “the Norway of the United States.” That comparison points to cultural connections, to be sure, but it also speaks to scientifically relevant similarities, as it turns out.
“Both regions are rich in freshwater systems shaped by cold climates, seasonal mixing, and growing pressures from climate change,” says Czeszynski, an Ecology, Evolution, and Behavior Ph.D. student, advised by Professor Jim Cotner. “My research focuses on greenhouse gases and microbial processes in Minnesota lakes, and Norway provides a uniquely valuable comparison.”
Czeszynski is in Norway this year as a Fulbright Scholar. She is exploring the culture while doing research at the University of Oslo that builds on her studies of Minnesota lakes, including Deming Lake in Itasca State Park. By doing research in both places, she hopes to add to our understanding of how lakes worldwide contribute to the global carbon cycle.
What has your experience in Norway been like so far?
One of the biggest highlights has been assisting with sampling at an alpine research center in Finse. This site has a long history of annual sampling, which has been essential for understanding how glacial retreat is shaping lakes, landscapes, biogeochemistry, and microbial communities. The work was demanding at times, with long hikes and challenging weather, but it was incredibly rewarding to be part of a collaborative team in such a unique environment.
Seeing the glacier up close was especially impactful — it not only reminded me of Earth’s origins and the massive ice sheets that once covered this region, but also made me reflect on the reality of glacial retreat and what it means for the future.
I feel grateful to have experienced this landscape while the glacier is still present.
The microbial communities you are studying are in lakes that you describe as “early Earth analogs.” Can you explain what that means?
The microbial community played a vital role in the early evolution of life on Earth, particularly methanogens — microbes that produce methane as a byproduct of their metabolic processes. Methanogens are among the oldest life forms, evolving when Earth's atmosphere lacked oxygen and the Sun was fainter than it is today. The methane produced by these early microbes accumulated in the oceans and atmosphere, acting as a greenhouse gas that warmed the planet.
As the Earth's environment evolved, so did microbial metabolisms. The rise of photoferrotrophs — microbes that use sunlight and iron to produce biomolecules — marked a significant evolutionary step. This process not only provided a new way for life to use solar energy, but also played a critical role in shaping the Earth’s biogeochemical cycles, or how elements move through living organisms, geological structures, like rocks and soil, and chemical processes.
Freshwaters are "hot spots" that play an important role in global biogeochemical cycling. These cycles ensure that vital nutrients are continuously recycled and available for use by all forms of life. Most lakes in Norway are considered “holomictic,” meaning that they stratify with less dense, warmer water at the surface in summer and colder, denser water underneath it, and then mix in the fall when the water cools. A similar phenomenon can occur in winter if ice forms on a lake.
When lakes mix, it replenishes oxygen and releases greenhouse gases that have accumulated in the bottom waters. However, some lakes in Norway and many other parts of the world are "meromictic,” meaning they never completely mix due to unique morphological or chemical properties. Because of this, the deep waters of these lakes are typically high in greenhouse gases, like carbon dioxide and methane, and anoxic (meaning no oxygen is present). Scientists theorize that these were also the conditions of water bodies on early Earth, making these neomictic lakes “early Earth analogs.”
How does it connect with research you’ve done in Minnesota?
Some lakes in both Minnesota and Norway are meromictic due to natural causes such as depth, shape, or geology, while others in both regions are increasingly influenced by road salt and other environmental changes. This makes them powerful systems for comparison.
Natural meromixis (lack of complete mixing) in lakes provides an analog for early Earth conditions, where permanently stratified, anoxic bottom waters supported diverse microbial metabolisms. At the same time, salt-driven meromixis in both Norway and Minnesota represents a growing modern phenomenon, where road salt inputs stabilize stratification, prevent full mixing, and drive oxygen depletion and methane buildup.
By applying metagenomic approaches to microbial communities in the deepest waters of these lakes, I can investigate how microbes regulate carbon cycling and greenhouse gas production under both natural and anthropogenic meromixis. Linking these insights across regions will help reveal how microbial processes shape methane dynamics in the past, present, and future.
