For Climate, Protecting Forests Is Way Better Than Planting Trees

At Cop26 in 2021, world leaders pledged to halt and reverse deforestation by the end of this decade, although data shows that countries are currently off track. Brazil, Colombia and Indonesia are among nations making progress, however. The researchers said meeting this target, along with making good on UN climate and biodiversity agreements, was crucial to forests reaching their full potential.

“Conserving forests, ending deforestation and empowering people who live in association with those forests has the power to capture 61 percent of our potential. That’s huge. It’s potentially reframing forest conservation. It’s no longer avoided emissions, it’s massive carbon drawdown, too,” said Tom Crowther, the head of the Crowther Lab at ETH Zurich. He said thousands of different project and schemes were needed to preserve and revive forests.

“It can be achieved by millions of local communities, Indigenous communities, farmers and foresters who promote biodiversity. It could be agroforestry for cacao, coffee or banana, natural regeneration, rewilding or creating habitat corridors. They’re successful when nature becomes the economic choice. It’s not easy but it’s doable.”

The research follows a controversial 2019 paper on the potential of forests to mitigate the climate crisis, which was also co-authored by Crowther, that provoked intense scientific debate among forest ecologists. The researcher inspired corporate action on forests and was credited with Donald Trump’s support for tree-planting schemes.

But several scientists felt that potential for nature to help meet climate goals had been overstated and the paper advocated for the creation of mass tree-planting, driving greenwashing concerns.

Simon Lewis, a professor of Global Change Science at University College London who was a leading critic of the 2019 paper, said the new estimate was much more reasonable and conservative.

“There is a lot of spin and bluster about what trees can do for the environment. To cut through this always ask: What is the amount of carbon taken up by a hectare of land, and over what time period, he said. “The spin on what trees can do for the climate will no doubt continue. But there is still only a finite amount of land to dedicate to forests, and ability of trees to sequester carbon is limited. The reality is that we need to slash fossil fuel emissions, end deforestation, and restore ecosystems to stabilise the climate in line with the Paris agreement.”

Crowther acknowledged that he had been overzealous in the messaging around the 2019 paper.

“When I spoke to the media as an excitable 30-year-old, I said, guys, restoration has this incredible potential. And I was naive to the fact that to nonecologists, that sounds like you’re saying tree planting has incredible potential,” he said.

“The fact that it was so much carbon I think gave people the idea that [the study] was suggesting that tree planting could be an alternative to cutting emissions, which categorically cannot be.”