-- How many trees are there on Earth? It's the ultimate estimation game, but a group of Yale researchers believe they have arrived at the most precise answer yet.
There are 3.04 trillion trees on Earth -- nearly eight times as many as was previously thought, according to the study, which was released in the journal Nature. Scientists who worked on the study relied on satellite imagery, forest inventories and supercomputers to help map the number of trees on Earth down to the square-kilometer level.
That's approximately 422 trees for every person on Earth.
"Trees are among the most prominent and critical organisms on Earth, yet we are only recently beginning to comprehend their global extent and distribution," Thomas Crowther, a postdoctoral fellow at the Yale School of Forestry and Environmental Studies and lead author of the study, said in a statement.
The latest count shatters a previous estimate of 400 billion trees worldwide, a number that was arrived at using satellite imagery and estimates of forest area but with no ground-level information.
While Crowther and his team said they were surprised to be dealing with a number in the trillions, it wasn't all good news for Earth's ecosystems. The team estimated the total number of trees has declined 46 percent since the dawn of human civilization, with an estimated 15 billion trees being cut down each year.