Wood you believe it? Earth has 3 trillion trees
Three trillion. That’s the staggering number of trees on Earth, according to a new tally that astounds even the scientists who compiled it.
Three trillion is three followed by 12 zeroes, which is more than the number of stars in the Milky Way and more than the number of cells in a human brain. If the new sum is accurate — and other scientists say it is — the planet boasts roughly 420 trees for every living person. An earlier count pegged the global tree total at a mere 400 billion, but that study relied on less sophisticated methods.
The gold medal for tree num- bers goes to Russia, which has 642 billion. The USA is fourth with 228 billion, behind Russia, Canada and Brazil, although the USA lags many more countries in tree density.
The figures are published in this week’s Nature.
The total is “astonishing,” said study co-author Thomas Crowther, who did the research as a postdoctoral student at Yale University. When Crowther asked forestry experts to predict the total, they made wildly incorrect guesses, he said in a separate interview. “No one could comprehend the scale of the things we were seeing,” he said.
In a more sobering find, Crowther and his team calculated that roughly 15.3 billion trees are cut down each year, and human- ity has reduced the Earth’s tree population by nearly half since civilization began. Around the world, one of the biggest influences on the number of trees is the corps of humans wielding chain saws and axes.
The scientists didn’t have to count the world’s trees one by one. But they still needed two years, data amassed by thousands of tree huggers and a good chunk of supercomputer time to add up all those oaks and palms and pines. The team combined actual tree counts made in wooded areas with satellite pictures.
By counting actual trees and comparing them to satellite pictures, they learned how to predict the number of trees in places where satellite views were the only source of information.