Microbes in Arctic lakes are fueling a large methane surge

Methane traps more than 25 times as much heat as carbon dioxide over a century, so even modest changes in its release can tilt the climate balance.

Scientists already recognize Arctic and sub‑Arctic lakes as natural methane vents, where gas bubbles up from sediments laid down over millennia. But the exact processes controlling how much is produced and how fast it escapes have remained poorly understood.

Now, a new study led by PhD researcher Marie Bulínová from UiT The Arctic University of Norway offers fresh insight into these dynamics, revealing how lake productivity plays a central role in methane release.

More life, more methane

Bulínová and an international team cored sediments and analyzed pore‑water chemistry in ten lakes scattered across Svalbard and Arctic Scandinavia.

They then modeled how methane diffuses from the mud into the overlying water and, ultimately, into the air. The surprise wasn’t that methane was present – every lake emitted some – but that the same factors consistently drove those emissions.

“We were surprised by how clearly the productivity of the ecosystem was linked to methane production,” Bulínová said.

The researchers found that lakes with thicker mats of algae, more aquatic plants, lush shore vegetation, and shallower depths generated the most methane in their sediments.

Where Arctic methane begins

Across the lakes, production peaked within the upper decimeter of sediment. That thin layer is rich in freshly fallen, easily digestible organic matter and pulsing with microbial activity. Beneath it, older, nutrient‑poor mud yields much less gas.

By combining concentration profiles with mass‑transfer equations, the researchers estimated diffusive fluxes between – 0.46 and 3.1 millimoles of methane per square meter per day.

Those numbers match earlier spot measurements in boreal and Arctic water bodies and are far lower than typical tropical or temperate values. Yet, given the sheer abundance of lakes across high‑latitude landscapes, the regional methane budget remains formidable.

Lakes vary in emissions

When the team compared their data with more than sixty published estimates from lakes worldwide, a striking pattern emerged. Arctic lakes as a group emit less per unit area than tropical ones, but individual northern lakes vary wildly.

“Some release much more methane than others, depending on local factors like vegetation cover, lake shape, or sediment composition,” Bulínová noted.

Machine‑learning models confirmed that climate variables – especially temperature and precipitation – rank alongside primary productivity and basin morphometry as key predictors.

The upshot is that Arctic methane output will not rise evenly. Hot spots will appear where warming and wetter weather most strongly boost in‑lake photosynthesis.

Living lakes drive feedbacks

The findings dovetail with satellite observations of a “greening” Arctic: longer ice‑free seasons and warmer waters spur algae blooms, while shrubs and grasses spread along shorelines.

More plant growth means more organic carbon raining onto lake bottoms, where microbes convert it into methane. That methane, in turn, accelerates warming, potentially creating a feedback loop.

“Our work suggests that increases in ecosystem productivity – something we could think of being positive – can also increase methane release and further accelerate warming,” Bulínová warned.

Arctic methane escapes in many ways

The study focused on diffusion, one of several pathways methane follows from mud to sky. Bubbling, or ebullition, can deliver large, sudden pulses when gas pockets overcome sediment pressure.

Plant stems can vent methane directly, and spring ice‑out may release winter stores in a burst. Accounting for these modes will refine regional budgets.

But diffusion is a baseline flux that operates almost continuously – and scientists can model it more easily across thousands of lakes once they understand the main controls.

Need to study more Arctic lakes

Because each Arctic lake tells a slightly different story, the authors emphasize breadth as well as depth. “That’s why it’s essential to study a wide range of lake types if we want to understand the Arctic’s role in future climate feedbacks,” Bulínová explained.

Their random‑forest approach shows promise for up‑scaling. Feed the algorithm satellite data on lake size, depth, productivity proxies, and local climate, and it can predict methane diffusion with reasonable accuracy.

The same framework could extend to boreal or even temperate basins. This would help Earth‑system models gauge how global lake emissions will shift under various warming scenarios.

What researchers must do next

The study demonstrates that tallying greenhouse gases in the Arctic requires looking beyond thawing permafrost soils to include seemingly placid waters.

Policies aimed at limiting methane rise might need to consider land‑use changes that alter nutrient runoff into lakes or protect certain high‑productivity basins from additional disturbance.

For scientists, the next steps include year‑round monitoring to capture seasonal swings, experiments that manipulate nutrient inputs, and integration of ebullition measurements.

Lakes face a warming future

As climate change redraws the Arctic map, lakes will likely become more productive biological engines. Paradoxically, they may also become more potent methane releasers.

The research led by Bulínová offers a first quantitative framework to anticipate that transformation.

It reminds us that in the delicate dance of climate feedbacks, what looks like a burst of life on a warming tundra can carry an invisible, high‑powered greenhouse cost.

The study is published in the Journal of Geophysical Research: Biogeosciences.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–