The Earth has 3 trillion trees, study finds

By Brandon Griggs, CNN

Updated 1841 GMT (0241 HKT) September 4, 2015

A new study led by Yale University estimates the Earth is home to 3 trillion trees -- more than 7 times greater than what was previously believed. But the study also estimates that the globe's tree population has been cut almost in half since the start of human civilization. Research shows that drought, insects and deforestation are decimating forests around the world.
Photos: The world's endangered forests
A new study led by Yale University estimates the Earth is home to 3 trillion trees -- more than 7 times greater than what was previously believed. But the study also estimates that the globe's tree population has been cut almost in half since the start of human civilization. Research shows that drought, insects and deforestation are decimating forests around the world.
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Drought leaves trees more susceptible to disease, like these pines trees near Strawberry Valley in Utah. In the U.S., millions of acres of forest have been damaged by beetles, according to a report by the U.S. Global Change Research Program. Less severe winters and longer summers are allowing beetles to thrive.
Photos: The world's endangered forests
Drought leaves trees more susceptible to disease, like these pines trees near Strawberry Valley in Utah. In the U.S., millions of acres of forest have been damaged by beetles, according to a report by the U.S. Global Change Research Program. Less severe winters and longer summers are allowing beetles to thrive.
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Riberalta, the largest town of Bolivia's Amazon region, is engulfed with fire during September 2005. The Amazon region saw widespread wildfires that turned the rainforest into a carbon source rather than a carbon sink.
Photos: The world's endangered forests
Riberalta, the largest town of Bolivia's Amazon region, is engulfed with fire during September 2005. The Amazon region saw widespread wildfires that turned the rainforest into a carbon source rather than a carbon sink.
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An area of forest in California killed off by pine beetles in 2003.
Photos: The world's endangered forests
An area of forest in California killed off by pine beetles in 2003.
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Forest fires engulfed more than 110,000 hectares across Russia during the summer of 2010. Here, a stand of charred birch and evergreen trees is filled with drifting smoke on the outskirts of the city of Voronezh.
Photos: The world's endangered forests
Forest fires engulfed more than 110,000 hectares across Russia during the summer of 2010. Here, a stand of charred birch and evergreen trees is filled with drifting smoke on the outskirts of the city of Voronezh.
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