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Peatlands' carbon capture potential increases with rising temperatures

According to a predictive model developed by a CNRS researcher and his European colleagues, the microalgae present in peat bogs could offset up to 14% of future CO₂ emissions, thanks to their photosynthetic activity. This conclusion was reached by basing the work on in situ experiments and the various predictive scenarios established by the IPCC.

It is the first model to quantify the potential compensation of future CO₂ emissions by peatlands on a global scale. This result lifts the veil on a currently ambiguous section of the terrestrial carbon cycle and its alterations by anthropogenic climate change. The associated study is in Nature Climate Change.

Representing just 3% of the Earth's land surface, peatlands contain over 30% of the carbon retained in soils in the form of fossilized organic matter at depth. It is estimated that this stock represents between 500 and 1,000 gigatons of carbon, corresponding to 56% and 112% of the total carbon present in the Earth's atmosphere.

While some soil micro-organisms emit CO₂ through respiration, microalgae assimilate it, notably through photosynthesis. Any increase in temperature will stimulate this microbial photosynthesis, enhancing the CO₂ capture potential of peatlands.

Regrettably, due to a lack of data, the mechanisms by which soil microalgae capture CO₂ have not been incorporated into any climate projections to date. However, far from being negligible, this photosynthetic carbon fixation could mitigate the impact of climate change in the future.

Further work is needed—on this and other carbon assimilation processes carried out by the micro-organisms in peat bogs—to fully quantify the potential of these ecosystems as carbon sinks and improve accuracy. Nevertheless, preserving peatlands and reducing global CO₂ emissions are still the best way of mitigating worsening climate change.