The Trillion Tree Solution

"Scientists examined areas around the globe where we could reforest and figured out that, even after you exclude agricultural and urban lands, we have room for another 1 trillion trees. For reference, the planet currently has about 3 trillion -- which is only about half of what existed before human civilization. What's more, adding back 1 trillion trees, it's calculated, could capture up to 25% of global annual carbon emissions...."
"The Trillion Tree Solution" by Michael Brune / Sierra Club