Biomass isn't really a solution. We pretty much cultivate all the bits of land which can be cultivated already, and burning biomass puts carbon dioxide back into the atmosphere, which does not help the greenhouse effect.
What we really need to do is remove carbon dioxide from the system - best way I can think of is plant fast growing timber, turn it into paper then instead of recycling the paper, bale it up and sink it in the deep parts of the oceans. That way the cellolose will not decay for millions of years, and so the carbon will be removed from the system.
Note - when a tree is growing it takes in carbon dioxide and releases oxygen. Once it has reached maturity the CO2 it takes in is balanced by the CO2 it produces.
Quack!
GtD.