A Yale scientist said he thinks he’s pinned down how many trees are on Earth—3 trillion.
If he’s right, that means there are more than 400 trees for every human being alive.
Unlike other tree population surveys that rely on satellite imagery, this count by Thomas Crowther, a post doc associate at Yale’s School of Forestry and Environmental Studies, actually relied on “ground-source” information.
Basically, people. Crowther and his team capitalized on the fact that many countries now produce detailed forest inventories.
"All of the information that went into our models was generated from people standing on the ground counting numbers of trees in a given area,” he told NPR. “And so we could relate this information to what the satellites are telling us."
The team put data from 400,000 forest plots into a computer, which then came to its huge conclusion.
This is one of the first and, Crowther hopes, most accurate global tree surveys done to date. Previous population counts based on satellite imagery are not all that common, and the ones that exist are not reliable, according to NPR.
The new study suggests that the world has lost about half of its trees since the days before mankind. The number of trees lost per year because of humans is around 15 billion, according to NPR.
