Re: @AC 13:00
Carbon-capture is extremely feasible. The plant you need to accomplish it is called, er, a plant. Every year the atmospheric CO2 concentration cycles by about 15ppm (average concentration is now 380ppm). This is because the mass of deciduous vegetation in the Northern hemisphere is greater than that in the Southern hemisphere. This tells you that if we could prevent all decay of fallen leaves, we would probably remove all CO2 from the atmosphere in less than 20 years! (Not, of course, a good idea to go this far).
So: genetically engineer or breed a common crop plant to grow more root than it needs, and to surround parts of its roots with something that will protect the root from decay for a long time after the plant dies (ie, is harvested). Interestingly, Wheat naturally does this to some extent. Its roots excrete tiny silica nodules, and the root inside the nodule does not decay for millennia. Some varieties of wheat do it much more than others. To start with, grow only those varieties. Selective breeding may well further increase the effect 10, even 100-fold. (Think of how we've shrunk a wolf into a Yorkshire terrier). GM might do a lot better still.
Or we could coppice lots of forest, and instead of burning the biomass for power, process it into a form of cellulose that's highly resistant to microbial attack and dump it into a deep ocean trench (from where nature will subduct it into the Earth's core). Such a form (nanocrystalline cellulose) does exist, and in fact has a lot of promise as a replacement for oil-based plastics.