Peatlands, long valued as one of the planet's most efficient natural carbon stores, can shift into carbon emitters far more quickly than previously assumed, according to a new field experiment conducted in a Minnesota bog. Researchers built ten large open-top chambers around sections of the peatland and warmed the plots by up to 9 degrees Celsius over three years. Every warmed plot switched from accumulating carbon to releasing it, demonstrating that even modest temperature increases can disrupt the delicate balance that keeps vast amounts of carbon locked in waterlogged soils.
The transition occurred even with warming of about four degrees Fahrenheit, a level well within the range projected for many northern regions under future climate scenarios. The observed carbon losses were significantly faster than the rates at which these ecosystems historically accumulated carbon, suggesting that once peatlands begin to degrade, they may release stored carbon on a timescale that matters for current and near-term atmospheric carbon dioxide levels. The findings carry direct implications for global climate models, which often treat peatlands as reliable carbon sinks over long periods.
Peatlands cover only about three percent of the Earth's land surface but hold roughly one-third of all soil carbon, an amount comparable to the carbon contained in the atmosphere or in all terrestrial vegetation. Most of that carbon has been built up over thousands of years as plant material decomposes slowly in cold, water-saturated conditions. When temperatures rise, microbial activity accelerates, breaking down organic matter and releasing carbon dioxide and methane into the air. The Minnesota experiment provides some of the clearest experimental evidence yet that this process can begin quickly and intensify with sustained warmth.
The research team constructed the chambers to enclose natural bog vegetation and soil while allowing rain, wind, and sunlight to pass through, creating conditions close to real-world warming. Over the three-year study period, the warmed plots consistently lost more carbon than they gained, reversing the net balance that defines a healthy peatland. The speed of the shift surprised the researchers, who had expected a longer lag before the ecosystems tipped from sink to source.
These results are particularly relevant for the vast peatlands of the northern hemisphere, including those across Canada, Scandinavia, and Siberia, where permafrost thaw and rising air temperatures are already altering landscapes. If widespread peatland degradation follows the pattern observed in Minnesota, the additional carbon released could accelerate climate change in a feedback loop that is not fully captured in current forecasting tools. The study underscores the need to refine climate models to account for the rapid response of peatland carbon stores to warming and to consider peatland protection as part of broader climate mitigation strategies.
