WASHINGTON: More than 3 trillion trees exist on Earth – roughly 422 per person – but the total number of trees has plummeted by 46 per cent since the start of human civilisation, according to a new Yale-led study.
The new estimate of more than 3 trillion trees on Earth is about seven and a half times more than some previous estimates of 400 billion.
An international team of researchers mapped tree populations worldwide at the square-kilometre level using a combination of satellite imagery, forest inventories, and supercomputer technologies.
“Trees are among the most prominent and critical organisms on Earth, yet we are only recently beginning to comprehend their global extent and distribution,” said Thomas Crowther, a postdoctoral fellow at the Yale School of Forestry & Environmental Studies (F&ES) and lead author of the study.
The study was inspired by a request by Plant for the Planet, a global youth initiative that leads the United Nations Environment Programme’s ‘Billion Tree Campaign.’
Two years ago the group approached Crowther asking for baseline estimates of tree numbers at regional and global scales so they could better evaluate the contribution of their efforts and set targets for future tree-planting initiatives.
At the time, the only global estimate was just over 400 billion trees worldwide, or about 61 trees for every person on Earth. That prediction was generated using satellite imagery and estimates of forest area, but did not incorporate any information from the ground.
The new study used a combination of approaches to find that there are 3.04 trillion trees – roughly 422 trees per person.
