Swiss university study: forests could capture even more CO2

On a global scale, trees could absorb 328 gigatonnes of CO2 more than they currently do, without any human influence. Keystone / Peter Klaunzer

According to a study by the federal technology institute ETH Zurich, the reforestation and restoration of existing forest areas around the world would make it possible to sequester an additional 226 gigatonnes of carbon. This corresponds to more than six times the global CO2 emissions in 2022.

An international team of researchers, under the direction of the federal technology institute ETH Zurich, obtained this result by analysing satellite data and associating it with ground measurements. The study was published on Wednesday in the specialised journal Nature.

On a global scale, trees could absorb 328 gigatonnes of CO2 more than they currently do, without any human influence. By way of comparison, 36.8 gigatonnes of CO2 will have been emitted in the world by 2022, according to the International Energy Agency (AIE).

Land use conflicts

However, of these 328 gigatonnes, 102 gigatonnes are located on areas currently used for agriculture or densely populated. The remaining 226 gigatonnes could be used with “a minimum of conflicts of use of the soil”, according to the researchers.

A portion of this potential (61%) can be realised by restoring degraded land and a small portion (39%) by rebuilding.

“We must take measures to put an end to deforestation,” declared Tom Crowther, from the ETH, during a presentation of the study to the media.

Practical difficulties

However, the researchers emphasise that measures to reduce CO2 emissions are still necessary despite this important potential. “If we continue to emit as much carbon as we did in the past, fires, fires and other extreme events will continue to threaten the global forestry system and limit its potential contribution,” added Tom Crowther.

Independent researchers also point out that this potential cannot be fully exploited. The study conducted by the ETH does not take into account the time needed to realise this potential, said Markus Reichstein of the Max Planck Institute of Biochemistry in Jena (Germany). The potential calculated in the study “suggests more than what is possible within a limited time”.

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