Sorry edd but we do need trees and other plants to keep the Co2 balance in the atmosphere we find so pleasant. Rising Co2 levels may well save us from the next ice age (only a mere 50,000 years away so keep an eye on that one) but we could end up instead with an atmosphere similar to the Cambrian which would be unpleasant to say the least.....that's only 3% more Co2 in the mix than we have now. More trees please.