http://www.blogyoulikeahurricane.com/2007/04/what-if-everyone-actually-planted-tree.html
"The average tree absorbs somewhere around 4.5 kg of carbon dioxide per year. That may not sound like a lot. But if everyone on the planet planted a tree on Earth Day, there would be six billion more trees tomorrow than there was yesterday. Those trees would remove roughly 27 Million metric tons of carbon dioxide from the atmosphere annually."
"The average tree absorbs somewhere around 4.5 kg of carbon dioxide per year. That may not sound like a lot. But if everyone on the planet planted a tree on Earth Day, there would be six billion more trees tomorrow than there was yesterday. Those trees would remove roughly 27 Million metric tons of carbon dioxide from the atmosphere annually."