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Stop Planting Trees, Says Guy Who Inspired World to Plant a Trillion Trees

by Elijah
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In a cavernous theater lit with the green shapes of camels and palms at COP28 in Dubai, ecologist Thomas Crowther, former chief scientific adviser to the United Nations Trillion Trees Campaign, did something he never would have expected just a few years ago: beg ministers of the Environment to stop planting so many trees.

Mass plantations are not the ecological solution they should be, Crowther argued as he took the floor at one of the summit’s ‘Nature Day’ events on December 9. The potential of newly created forests to sequester carbon is often overestimated. They can be harmful to biodiversity. Above all, they are very harmful when used, as is often the case avoid compensation– “as an excuse for not reducing emissions,” Crowther said.

The popularity of planting new trees is – at least in part – a problem of Crowther’s own making. In 2019 his laboratory at ETH Zurich found it that Earth had room for another 1.2 trillion trees, which, the lab’s research suggested, could suck up as much as two-thirds of the carbon that humans have historically emitted into the atmosphere. “This highlights that global tree restoration is our most effective solution to climate change yet,” the study said. Crowther subsequently gave dozens of interviews to that effect.

This seemingly easy climate solution sparked a tree-planting craze among companies and leaders eager to burnish their green credentials without actually cutting their emissions, from Shell to Donald Trump. It also sparked a barrage of criticism from scientists, who claimed the Crowther study had vastly overestimated the land suitable for forest restoration and the amount of carbon it could absorb. (The authors of the study later corrected the article says that restoring trees is only “one of the most effective” solutions and can suck up at most a third of the carbon in the atmosphere, with large uncertainties.)

Crowther, who says his message was misinterpreted, released a more nuanced article last month showing that preserving existing forests could have a bigger impact on the climate than planting trees. He then brought the results to COP28 to end ‘greenwashing’ of the kind his previous research seemed to encourage – that is, using unreliable evidence about the benefits of tree planting as an excuse to keep emitting carbon .

“Ending greenwashing does not mean you have to stop investing in nature,” he says. “It means you’re doing it right. It means distributing wealth to indigenous people, farmers and communities living with biodiversity.”

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