We still use lumber, if it isn't locally harvested we buy it from another part of the world, outsourcing those externalities and throwing in all the extra costs of shipping, labor overhead for the various middlemen, customs, etc.
My point isn't that we're screwed and should just chop down forests because we're damned if we do and damned if we don't. But saving one forest won't fix anything by itself and could very well make things worse if we don't do it by simply reducing the number of resources we consume. Paying someone else to own the externalities will never help.