# Quantity of new trees needed to compensate all human CO₂ pollution

That trees are the major tools to remove CO₂ from the air is clear, but how many new trees need to be planted to compensate all human CO₂ pollution (6 gigatons / year?)? We should work with standard tree and count a tree in the tropics double since they absorb year round. If yearly net uptake of growing trees is 20kg CO₂ in temperate zones, global average might be 30kg/year. This means that "only" 6 × 10¹² kg ÷ 30 kg = 200 × 10⁹ = 200 bn trees are needed. I say "only" because this means only 10% extra forest, while I was counting on a doubling of global tree cover is needed (and possible).

• I would also like to add that if we were doing a global geoengineering project we should consider that trees sequester different amounts of carbon throughout their life. A fully grown tree does not sequester nearly as much carbon as a growing tree. To maximize the carbon sequestration you would want to plant quick-growing trees, chop them down and bury them in landfills, then keep replanting. Of course, it would be better if we didn't dig up fossilized trees and put them in the atmosphere to begin with... Jan 4, 2016 at 19:24
• Interesting, but where do your figures on absolute and relative uptake come from? Jan 5, 2016 at 15:31
• Thanks replying, I seek this information for 5 years already, but yesterday I googled the subject and spend a few hours, but only found the 20kg with FAO and 15MT per Ha, what could be correct. Extremely confusing and out of date figures are available on google and wiki. Jan 5, 2016 at 22:41
• a few years ago I made an educational puzzle with carbon cycle and found the best figures with Stand-up Economics a UK stage performance on CC. May be science can help me further :-) Jan 5, 2016 at 22:45
• In fact I am talking about class tropical lumber harvested in 10 years and sold (in Africa about \$20,-) for construction. The reason to grow for lumber is to avoid the clearing of old-grown forests Jan 5, 2016 at 22:51