Maybe bio-fuels from the field (plants) are not a longterm option against global warming, because it will increase the international prices of food. Carbon-dioxid should be extracted from atmosphere and split into other chemical components, maybe synthetic oil, in a way this production is not concurrent to food production. Why not reform CO2 or bicarbonate acid (the gaz that is added into the lemonades), into oxygen and coal or oil, either in the desert, or underwater in the sea in large closed-circuit catalyzers? I'm sure that in 15 or 20 years, bio- or nano-technology could do this at commercial level, if commercial interest is sufficient for investment in that type of research. But i'm afraid that interest is not, as long as it's still cheaper and profit-raising to simply take the oil out of the earth, whatever consequences for coming generations.