Forests store even more CO2

It has long been known that trees are important carbon stores. Agroecologist Stefan Schwarzer recently referred on Linkedin to new findings that show that the storage capacity of plants is actually a third higher than previously assumed. This discovery is of immense importance for climate protection.

November 2024
Terrestrial photosynthesis inferred from plant carbonyl sulfide uptake. Published: 16 October 2024. nature.com

A new study by scientists at the University of California, Berkeley, shows that plants absorb around 31% more carbon dioxide (CO₂) than previously thought. This discovery emphasises the importance of – above all – tropical rainforests as carbon reservoirs and points to the need to revise models for calculating the carbon cycle in climate forecasts. The study was published in mid-October in the scientific journal Nature.

Neutralisation of the exhaust gases of many millions of petrol-powered vehicles. The study revises the previously assumed terrestrial gross primary production (GPP), i.e. the annual amount of CO₂ bound by photosynthesis. This calculation was made possible by the use of a so-called proxy, in this case in the form of carbonyl sulphide. Carbonyl sulphide behaves similarly to CO₂ and is also absorbed by plants, so it can be used as an indicator of the photosynthesis rate.

Based on the new calculation model, the GPP is now estimated at 157 petagrams of CO₂ per year. One petagram corresponds to one billion tonnes of CO₂, which is equivalent to the annual emissions of around 238 million petrol-powered vehicles. According to the German Federal Environment Agency, there are around 1.04 billion petrol-powered cars worldwide. According to these results, intact tropical forests can therefore absorb many times the amount of car exhaust gases emitted worldwide. They emphasise once again the relevance of intact ecosystems.

Further research needed. The scientists emphasise the need to improve the understanding of photosynthesis and its role in the carbon cycle in climate models. They recommend refining these models in order to better estimate the actual CO₂ binding capacity of plants. Since tropical rainforests are so important for CO₂ storage, measures to preserve and restore these ecosystems could make a crucial contribution to stabilising global CO₂ levels and mitigating the climate crisis. It would be so logical ...