During the last few years, I have read a fair bit about biochar, a substance generated by burning biomass in a low oxygen environment. Because this charcoal is rich in carbon dioxide (CO2), making it could somewhat draw down the amount of CO2 in the atmosphere. There are also claims that it can make soil more fertile, playing a similar role to the ‘terra pretta’ that apparently makes some Amazonian lands more productive than average.
There are certainly people who make exaggerated claims about what biochar production could achieve. While it might be adequate to generate one small ‘wedge’ in net greenhouse gas emission reductions, it does not seem plausible that it can be a major part of the solution. George Monbiot has been especially critical of those who have hailed it as a solution in itself.
While not a miracle cure, biochar may have some promise, and deserves to be looked into as part of the process of building a low- (eventually zero-) carbon global society.