Nov 15, 2023

Forests Can Play a Major Role in Combatting Climate Change, But the World Needs Emissions Cuts First

Sana Pashankar, Bloomberg News

Aerial view of deforestation, near La Paz, Guaviare department, Colombia, on Sunday, July 30, 2023. Ivan Mordisco is a Colombian warlord with a cocaine empire and a bounty on his head. He is also doing more to protect the Amazon rainforest than almost anyone else on Earth. , Bloomberg

(Bloomberg) -- Restoring and protecting forests has the potential to store the equivalent of the annual carbon emissions of 50,000 coal fired-plants, according to a new study.

Forests can play a central role in helping mitigate climate change, owing to their ability to pull carbon dioxide from the atmosphere and store it. The study, published in Nature on Monday, provides a new estimate of how much CO2 could be sequestered by conserving existing forests and revitalizing degraded ones. Carbon storage could reach 226 gigatons, an amount that represents 30% of the world’s total excess carbon.

Investing in forests’ health isn’t an excuse to continue pumping greenhouse gasses into the atmosphere, particularly because the capacity of trees to survive and absorb carbon is significantly threatened by the impacts of an overheating planet. If the world continues on its current emissions track, the ability of trees to absorb CO2 could drop 26% by 2050, according to a previous study.

“There cannot be a choice between nature and decarbonizing, we absolutely must take steps to achieve both simultaneously,” said Tom Crowther, an ecologist at ETH Zurich and author of the new study.

To come up with the new estimate, researchers combined on-the-ground and satellite data to model the total potential forest biomass globally. They incorporated information on soil, carbon, dead wood and litter to estimate the Earth’s total carbon storage potential outside of urban and agricultural areas. The findings indicate that the majority of that potential comes from allowing existing forests to recover, while the remaining comes from restoring forests in areas where they have been removed or fragmented.

But it’s not as simple as planting trees. Large-scale initiatives to do so often involve cultivating massive monoculture plantations, which can be more harmful than helpful as they disturb natural ecosystems and lead to biodiversity loss.

Tree plantations are also less productive at sequestering carbon. A recent study published in Frontiers in Forests and Global Change showed that mixed forests generally store 70% more carbon than their monoculture counterparts. More diverse forests are often better at capturing carbon because they are more resilient to natural disasters, pests and diseases.

“I don't want people to take this information to justify mass plantations, quick carbon offsetting, greenwashing or anything like that,” Crowther said.

How much forests can contribute to curbing climate change is a controversial area of research. The new study’s estimate that forests could capture 226 gigatons of CO2 is much too high, according to Carla Staver, an associate professor of ecology at Yale University. She said the true potential probably falls closer to 25% of that amount. The reason for the discrepancy is because the study’s methodology relies too heavily on regenerating forests in ecosystems that thrive on having open spaces, like savannahs, she argued.

“When you increase the tree component of some of these ecosystems, it means that tree cover increases,” said Staver, who was not involved with the study. “But it also makes it a much less friendly habitat for the types of biodiversity that depend on those ecosystems that historically lived in those places.”

Rather than focusing heavily on restoration, she said conserving existing forests could be more effective at reducing carbon emissions and have a “much more immediate impact.”

The CO2 storage potential associated with forest regeneration could take decades to years to be realized, given the amount of time needed for new trees to grow, according to Sonia Seneviratne, a professor of land-climate dynamics at ETH Zurich’s Institute for Atmospheric and Climate Science who wasn’t involved in the study.

While there are a number of ways to restore forests, the most successful solutions are those that coincide with the economic well-being of local and Indigenous communities, according to Crowther. One example of this type of equitable development can be seen through a payment for environmental services program in Costa Rica. Through this initiative, landowners are given money to undertake activities that improve ecosystem health, allowing both the local economy and nature to flourish. On agroforestry farms in the Maradi region of Niger, farmers reintroduced trees on their land, allowing for the natural regeneration of the ecosystem. The new plant life improved soil conditions and microclimate, increasing crop yields and annual income for farmers by about 20%.

“When nature is the economic choice, it just flies back,” Crowther said.

Even with the carbon-capturing benefits of forest conservation and restoration, both Crowther and Staver stressed the importance of reducing emissions. The danger of these rosy projections of forests’ carbon storage potential is that it allows people and companies to rely on tree planting instead of more sustainable, long-term solutions to climate change, according to Staver.

“Forest conservation does have a contribution, it just isn't enough. We're never going to solve anthropogenic climate change with tree planting,” Staver said.