Estimated read time: 2-3 minutes
This archived news story is available only for your personal, non-commercial use. Information in the story may be outdated or superseded by additional information. Reading or replaying the story in its archived form does not constitute a republication of the story.
WASHINGTON (AP) — It would be hard enough to count all of the trees in a forest. Imagine counting all of the trees on Earth.
It may not be an exact count, bur scientists have an answer. They say more than 3 million trees now grow on Earth -- seven times more than scientists previously thought.
But the number is also trillions fewer than there used to be.
The counting began after a youth group set out to plant a billion trees. A Yale forestry researcher, Thomas Crowther, was asked if planting that many trees would do anything to fight climate change, since trees capture and store carbon dioxide.
Crowther said he first had to figure out how many trees are on Earth. The number -- 3.04 trillion -- appears in a study today in the journal Nature.
The previous estimate was 400 billion. And that rough count was based on satellite images.
Crowther and his colleagues used more than 400,000 ground-based measurements along with satellite data and computer models to get a more accurate number.
But the computer models also estimate that before human civilization, Earth had about 5.6 trillion trees.
Crowther finds that 15 billion trees are cut down each year by people, while 5 billion are planted. That's a loss of 10 billion trees a year -- and at that rate, all of Earth's trees will be gone in about 300 years.
%@AP Links
APPHOTO WX101: FILE - In this July 25, 2014 file photo, vegetation grows among trees burned by the Rim Fire, near Groveland, Calif. More than 3 trillion trees now grow on Earth, more than seven times greater than scientists previously thought. But it's also trillions fewer than there used to be, a new study concludes. (AP Photo/Rich Pedroncelli, File) (25 Jul 2014)
<<APPHOTO WX101 (07/25/14)££
Copyright © The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
