‘I’ve never said we should plant a trillion trees’: what ecopreneur Thomas Crowther did next

The ecologist admits messing up' in the past, but says his Restor project will be a Google Maps of biodiversity', showing the impact of restoration - from a forest to your own back garden

Listen to our podcast: Can we really solve the climate crisis by planting trees? - part one

Thomas Crowther understands more than most the danger of simple, optimistic messages about combating the climate crisis. In July 2019, the British ecologist co-authored a study estimating that Earth had space for an extra trillion trees on land not used for agriculture or settlement. Its implications were intoxicatingly hopeful. By restoring forests in an area roughly the size of China, the press release accompanying the paper suggested two-thirds of all emissions from human activities still present in the atmosphere could be removed.

The study, led by Jean-Francois Bastin, a postdoctoral researcher at Crowther's lab in ETH Zurich, Switzerland, was the second most featured climate paper in the media in 2019, according to one analysis. It inspired the World Economic Forum's (WEF) One Trillion Trees Initiative, launched last year after Salesforce billionaire Marc Benioff read the paper on the recommendation of Al Gore, the former US vice-president. The Time magazine owner told everyone he could about the research: chief executives, friends and world leaders, even convincing climate sceptic Donald Trump to back the WEF initiative with a multibillion tree commitment.