Environment

Earth Has Lost Half Its Trees to Humans

A new global census of all the trees on Earth estimates that more than 3 trillion call this "pale blue dot" home. But the total number of trees on the planet has dropped by almost 50 percent since human civilization began.

The study is billed as the most accurate inventory of Earth's tree population to date, revealing that there are 3.04 trillion trees, which is roughly equivalent to 422 trees for every person on the planet. Researchers used satellite images, forest inventories and supercomputing technologies to calculate the number of trees on Earth. The new estimate found about 7.5 times more trees than were included in previous assessments, the scientists said.

The researchers also used projected maps of current and historic forest cover, which were provided by the United Nations Environment Programme, to estimate how much tree loss has occurred over time. They found that the total number of trees on Earth has fallen by close to 46 percent since civilization began.

The study also found that the areas with the highest density of trees are in the subarctic regions of Russia, Scandinavia and North America. The largest forested areas, however, are located in the tropics, which play host to 43 percent of the world's trees, the scientists said.

Human activity is the main reason for the disappearance of trees, primarily through deforestation, land-use changes and forest-management practices, the researchers said. These effects combined contribute to the loss of 15 billion trees worldwide every year, the scientists added.