13:11.
The planet currently has half the trees, compared to when human civilization began. This amount represents a trillion trees, or about 442 per human being, an amount eight times higher than originally estimated by the researchers.
A team of experts from 15 countries coordinated by Yale University in the United States resorted to the old technique of counting per head and cutting edge satellite technology for what they present as the Census fuller trees ever made.
“I do not know what we had anticipated, but certainly I was surprised to learn that we were talking about trillions,” he said lead author of the study, Thomas Crowther, forestry school studies . and environment of Yale (Connecticut)
Along with the unexpected finding came bad news: The study reveals that the number of trees has halved since the beginning of human civilization.
And the rate of deforestation continues unabated: we are currently cutting down 15,000 million per year of the total of three trillion (a trillion equals one million billion, ie one followed by 18 zeroes).
The researchers turned to satellite imagery to determine how climate, topography, vegetation, soil conditions and human activities affect forest density.
After developing models to estimate the number of trees at the level of each region, experts then made a map of the 3 trillion trees present on the planet.
“The highest density of trees was found in boreal forests in the subarctic regions of Russia, Scandinavia and North America, “Yale said in a statement.
“But the most extensive wooded areas,” says, “are in the tropics, where it is 43 percent of the trees in the world”
-. We cut half –
The team’s calculations revealed that all the impacts of human activity is by far the most affect the number of trees, mainly due to deforestation for land use for other purposes, such as agriculture, livestock and mining.
There was a decrease of 46 percent of the number of trees since humans started deforesting their environment.
“The density of trees usually plummets as the population increases” human, says the study.
“Practically we have halved the amount of trees present on the planet, affecting the climate and human health, “ Crowther said. The study notes additional efforts needed to restore forest health around the world.
In addition to being a source of oxygen, fuel, shelter, trees store large amounts of carbon, which should be released contribute to climate change.
Simon Lewis of the University College London, who was not involved in the study, said it is the first on the trees with global reach.
– Quantity or quality? –
“A plantation of small trees of the same species and is not the same as an area of Amazon forest intact, with fewer but larger trees and different species “ said Lewis.
To measure the carbon storage capacity requires more than just counting trees, he adds, since there is more in a small number of large trees that in many small .
The report was published at a time when representatives of 195 countries are negotiating in Bonn (Germany) to pave the way for a global agreement in December to allow combating the greenhouse effect and climate change it generates.
The same day, the World Resources Institute (WRI) US released a study on deforestation, also based on satellite observations, which highlighted the regression of tropical forests worldwide, the Gran Chaco to Madagascar, to West Africa or Cambodia.
Last year the world lost 18 million hectares of forest, more than half in the tropics, according to WRI.
(FIN) AFP / MPM
Posted: 09/02/2015
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