The Earth Has 3 Trillion Trees

That's more than previously thought, but fewer than there once was

Banyan Tree
Giant banyan tree in Haleakala National Park. ML Harris/Getty Images

The calculations are in and a recent study has revealed some rather shocking results regarding the number of trees on the planet.

According to researchers at Yale University, there are 3 trillion trees on Earth at any given moment.

That's 3,000,000,000,000. Whew!

It's 7.5 times more trees than previously thought! And that adds up to roughly 422 trees for every person on the planet.

Pretty good, right?

Unfortunately, researchers also estimate that it is only half the number of trees that were on the planet before humans came along.

So just how did they come up with those numbers? A team of international researchers from 15 countries used satellite imagery, tree surveys, and supercomputer technologies to map tree populations around the world - down the square kilometer. The results are the most comprehensive count of the world's trees that has ever been undertaken. You can check out all of the data over at the journal Nature.

The study was inspired by the global youth organization Plant for the Planet - a group that aims to plant trees around the world to reduce the effects of climate change. They asked researchers at Yale for the estimated global population of trees. At the time, researchers thought there were about 400 billion trees on the planet - that's 61 trees per person. 

But researchers knew that this was just a ballpark guess as it used satellite imagery and forest area estimates but it did not incorporate any hard data from the ground.

 Thomas Crowther, a postdoctoral fellow at the Yale School of Forestry and Environmental Studies and lead author of the study put together a team that studied tree populations using not only satellites but also tree-density information through national forest inventories and tree counts that had been verified at the ground level.

 

Through their inventories, researchers were also able to confirm that the largest forest areas in the world are in the tropics. Roughly 43 percent of the world's trees can be found in this area. The locations with the highest densities of trees were the sub-arctic regions of Russia, Scandinavia and North America.

Researchers hope that this inventory - and the new data regarding the number of trees in the world - will result in improved information about the role and importance of the world's trees - particularly when it comes to biodiversity and carbon storage.

But they also think that it serves as a warning about the effects that human populations have already had on the world's trees. Deforestation, habitat loss, and poor forest-management practices result in the loss of over 15 billion trees each year, according to the study. This affects not only the number of trees on the planet, but also the diversity.

The study noted that tree density and diversity drops drastically as the number of humans on the planet increases. Natural factors such as drought, flooding, and insect infestations also play a role in the loss of forest density and diversity.

"We've nearly halved the number of trees on the planet, and we've seen the impacts on climate and human health as a result," Crowther said in a statement released by Yale.

"This study highlights how much more effort is needed if we are to restore healthy forests worldwide."