MILAN, May 12 (Thomson Reuters Foundation) - Vast tracts of land previously considered barren are actually covered by forests "hiding in plain sight", scientists said on Friday, a discovery that could help the fight against climate change and desertification.
An international team of researchers led by the U.N. Food and Agriculture Organization (FAO) used new technology to analyse high-resolution images from Google Earth and map forest coverage in drylands worldwide.
They found that trees like baobab and acacia shade 467 million more hectares of land than previously thought - an area roughly equal to half the size of the United States - increasing estimates of global forest cover by at least nine percent.
The discovery allows for more accurate assessments of how much greenhouse gases are absorbed from the atmosphere by the world's vegetation, FAO experts said.
"Drylands absorb more carbon than we thought and they can actually help mitigate climate change," Eva Muller, director of FAO's forestry policy and resources division told the Thomson Reuters Foundation by phone.
The analysis, published in journal Science, would also help forestry experts better identify areas suitable for restoring trees and vegetation in a bid to slow down desertification, added Jean-Francois Bastin, one of the study's authors.
In Africa only, some 60 million people could be forced to leave their homes within five years and two thirds of arable land could be lost by 2025 as land progressively turns into desert, according to the United Nations.
Bastin said the new estimate of forest coverage was calculated using a data collection tool named Collect Earth, which enabled researchers to analyse Google Earth satellite images with a resolution of less than one meter.
"This allowed us to visually see and almost count the trees," he said.
Earlier studies used lower definition images with a resolution of 30 to 250 meters that made it difficult to distinguish trees from soil in semi-arid areas where vegetation is sparse, he said.
Thanks to the new method "hidden" forests were found on every continent, with the largest concentrations in sub-Saharan Africa, the Mediterranean, India, Australia, South America, Canada and Russia, the study said.
Reporting by Umberto Bacchi @UmbertoBacchi, editing by Ros Russell.
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