As hard as it may seem to utter "charcoal" and "green" in the same sentence (go on, give it a try), Johannes Lehmann and his colleagues would have you believe that charcoal, or as it's known by researchers in the field, "biochar," is the next big thing in the fight against global warming. In essence, Lehmann, an associate professor of crops and soil sciences at Cornell University, proposes that biochar, which is produced when biomass is baked in the absence of oxygen through a process called pyrolysis, be buried, or "sequestered," in the soil as an alternative approach to tackling climate change.
Results from his research indicate that not only does biochar sequestration keep carbon dioxide from reaching the atmosphere; it actually extracts the greenhouse gas and helps decrease atmospheric concentrations. Although burning wood waste or ethanol made out of corn is considered "carbon neutral" because the carbon dioxide released in the process will be reabsorbed by other plants (i.e. no net gain or loss barring the effects of deforestation and soil depletion), sequestration is considered a "carbon negative" process since there will be an actual net decrease in the carbon dioxide concentrations.
In an article he published in the latest issue of the journal Nature, Lehmann wrote that "Our calculations suggest that emissions reductions can be 12 to 84 per cent greater if biochar is put back into the soil instead of being burned to offset fossil-fuel use."
While not a new process (Lehman says its use goes back hundreds of years to the Amazon Basin), interest in biochar didn't pick up steam until just recently as the increasing focus on global warming by the world community pushed scientists and policymakers to find new, viable solutions. "Three years ago (biochar) was not considered (for sequestration), but now people are starting to. It's gaining momentum," he says.
Lehmann and his colleagues suggest that biochar could be mixed with topsoil in farming to remove the carbon from the crop's lifecycle, an effect that, when magnified over several countries, would result in a sharp reduction of atmospheric carbon. They argue that the technology is already available and that the pyrolysis process, which also produces biofuel in the form of bio-oil, could make biochar use an economically attractive proposition. "The biophysical benefits are now clearly spelled out and far enough advanced that economists can help to find opportunities to make it work," Lehmann said in a recent interview.