July 24, 2021

They warn of the uselessness of using forests to cool the climate

They warn of the uselessness of using forests to cool the climate


Managing European forests to cool the climate by improving, for example, their ability to sequester carbon has very little impact on the global climate and yet reduces their contribution of wood, according to a study published today in the journal "Nature".

The researcher Aude Valade, of the Center for Ecoplógica Research and Forest Applications (CREAF-UAB), who has participated in this study, has recommended making a forest management aimed at maintaining ecological, social and cultural environmental services, and not to cool the planet , as planned to comply with the Paris Agreement.

This agreement included the commitment to manage forests in a sustainable manner as a strategy to slow down global warming, making them more active, growing more and needing more CO2 from the atmosphere to make photosynthesis.

According to what was believed until now, if the forests absorb more CO2, the levels of this gas in the atmosphere will decrease or, at least, they will be maintained.

Nevertheless, this new study reveals that managing European forests for this purpose does not have clear effects on climate.

The international research team in which Aude Valade has participated has improved a complex model to calculate the amount of carbon, energy and water that is trapped or released according to the type of forest management that is done.

Through this model, they have compared three forest management strategies that represent the different visions of forest management that are carried out to mitigate climate change in Europe and has concluded that no option allows achieving the three goals while they have been raised to stop climate change: maximize carbon sequestration, increase sunlight that forests reflect into space and reduce surface temperature.

Valade has explained that a management aimed at capturing the maximum carbon in the atmosphere would require converting deciduous forests into coniferous ones and increasing the proportion of forests without management.

With this computational model, the team has calculated that with this option they would be able to remove 7 Petagrams (one Petagram are one billion tons) of carbon from the atmosphere by the year 2100, more than double than if we manage as it is now.

"If we focus only on these terms it is obvious that removing that amount of carbon from the atmosphere could cool the environment, but if we change the deciduous trees for conifers we can improve the capacity to sequester CO2, but this too can change the microclimate of the forest, change wind speed, humidity, cloud formation and albedo, that is, the percentage of radiation that a forest is capable of absorbing according to the color of its surface, "Valade warned.

Thus, according to the study, forest management would have parallel consequences beyond carbon sequestration that would "heat up" the environment and that they would leave the counter practically at zero, neither colder nor warmer.

"In addition, we would have 12% less wood production, depending on the model," the researcher warned.

On the other hand, according to the work, a management aimed at cooling the surface of the Earth, which would require converting coniferous forests into deciduous forests and increasing the proportion of forests managed as scrubland, would give a small cooling of 0.3ºC in spring in Scandinavia and in the Alps, but the effect would not be strong enough to be felt globally, and would be an option that would reduce the available wood by 25%.

Research shows that sustainable forest management provides some climate benefits, but modest and local, so the authors suggest that forestry management in Europe in the coming decades does not prioritize the effects on climate, but the adaptation of forests to climate change so that they are able to continue providing ecological, social and cultural services and goods.

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