An area the size of the United States could be restored as forests with the potential of erasing nearly 100 years of carbon emissions, according to the first ever study to determine how many trees the Earth could support.

Published today in Science, "The global tree restoration potential” report found that there is enough suitable land to increase the world’s forest cover by one-third without affecting existing cities or agriculture. However, the amount of suitable land area diminishes as global temperatures rise. Even if global warming is limited to 1.5 degrees Celsius, the area available for forest restoration could be reduced by a fifth by 2050 because it would be too warm for some tropical forests.

“Our study shows clearly