Taylor Hill Takepart.com Yahoo News 4 Sep 15;
Before 38 scientists got together to crunch some seriously big data, it was estimated that there were about 400 billion trees left on Earth. Luckily, the scientists were a few trillion off.
A new review of the world’s forests shows that 3 trillion trees cover the planet—meaning there are 422 trees for every person.
But before you celebrate, the scientists warn that we aren’t out of the woods yet. That’s because there would be way more than 3 trillion trees if it weren’t for humans. The study estimates that since the invention of the axe, the number of trees has fallen by 46 percent.
Today, people are responsible for the loss of 15 billion trees every year, owing to development and agriculture. With around 5 billion new trees sprouting up annually, that’s leaves the world with a 10 billion-tree deficit annually.
At that rate, the planet will be treeless in about 300 years.
“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 video.
Crowther teamed up with scientists from 15 countries to get a clearer picture groups like the United Nations’ Billion Tree Campaign, which wanted a solid baseline figure on tree totals around the world.
Scientists had based the previous 400 billion tree estimate on satellite imagery. But the study, published Wednesday in the journal Nature, combined that imagery with more than 400,000 measurements from on-the-ground studies and government forestry inventories around the world.
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The U.N.’s Plant for the Planet program has planted 14 billion trees in 193 countries in the past eight years. In the wake of the study, the group called for more “afforestation,” which means planting trees where there had been none before.
“It spells out that we need the greatest afforestation effort in human history,” Paulina Sanchez Espinosa, president of Plant for the Planet, said in a statement. “Each tree sequesters 10 kg of CO2 per year, which makes afforestation the cheapest, simplest to implement and the only globally scalable method of carbon capture and storage.”
That type of carbon storage is key to keeping average global temperatures from rising more than 2 degrees Celsius above preindustrial levels. Scientists believe any temperature increase above that would trigger a climate catastrophe.
A study released Tuesday by researchers at Global Forest Watch showed that the planet lost more than 45 million acres of trees in 2014 alone—enough to cover the country of Portugal twice.
The main culprit? Us. Consumer demand for everything from toilet paper, tires, steak, margarine, and even skin cream is leading to massive deforestation—especially in tropical hot spots in Africa and South America.
“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. “This study highlights how much more effort is needed if we are to restore healthy forests worldwide.”
