Since the start of human civilisation the total number of trees has on Earth has almost halved, according to the latest research.

There are about 3.04 trillion trees in the world today, according to the research published in the journal Nature. That's about 422 per person. 

The study looked at more than 400,000 measured tree density estimates from every continent except Antarctica to produce a comprehensive global map of forest tree density. The scientists estimate that the number of trees removed each year is more than 15 billion.

"Trees are among the most prominent and critical organisms on Earth, yet we are only recently beginning to comprehend their global extent and distribution," says Thomas Crowther, a postdoctoral fellow at the Yale School of Forestry and Environmental Studies in the US and lead author of the study.

"They store huge amounts of carbon, are essential for the cycling of nutrients, for water and air quality, and for countless human services. Yet you ask people to estimate, within an order of magnitude, how many trees there are and they don't know where to begin. I don't know what I would have guessed, but I was certainly surprised to find that we were talking about trillions."

The study was inspired by a request by Plant for the Planet, a global youth initiative.

The group approached Crowther asking for baseline estimates of tree numbers at regional and global scales so they could better evaluate their efforts and set targets for tree-planting.

At the time, the only global estimate was more than 400 billion trees worldwide, or about 61 trees for every person on Earth. That prediction was generated using satellite imagery.

This article was originally published by Business Insider.

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