Researchers from CNRS, France, determined that peat bogs could offset CO2 emissions more than previously thought thanks to their photosynthetic activity, according to a study published in Nature Climate Change.
The team used a computer model to determine how microalgae typically found in bogs could offset up to 14% of future CO2 emissions because they’re capable of photosynthesis. The authors reached this conclusion based on work conducted on in situ experiments and various predictive scenarios established by the IPCC. This is the first time a computer model includes the potential impact of future CO2 emissions done by peatlands on a global scale. This result sheds some light on a part of the terrestrial carbon cycle that has not been assessed until now.
Despite representing only 3% of the Earth’s surface, peatlands contain over 30% of the carbon retained in soils as fossilised organic matter buried deep. This stock is estimated to represent between 500 and 1000 gigatons of carbon, corresponding to 56% and 112% of the total carbon in the Earth’s atmosphere.
Some soil micro-organisms emit small amounts of CO2 through respiration, but most microalgae assimilate it through photosynthesis. The authors suggest that temperature increases will stimulate this microbial photosynthesis and, therefore, enhance the CO2 capture potential of peatlands.
Unfortunately, due to a lack of data, the mechanisms by which soil microalgae capture CO2 have not been incorporated into any climate models until now. However, the authors emphasise its importance and defend that, far from being negligible, this photosynthetic carbon fixation could play a key role in mitigating the impact of climate change in the future. As such, preserving peatlands is crucial to alleviating worsening climate change.
Hamard, S., Planchenault, S., Walcker, R. et al. Microbial photosynthesis mitigates carbon loss from northern peatlands under warming. Nat. Clim. Chang. (2025). https://doi.org/10.1038/s41558-025-02271-8