One of the most difficult dichotomies in climate change mitigation is that between the relatively short window for emissions reductions-the IPCC believes that world carbon emissions must peak within the next 6-11 years-and the long development times for many emissions control technologies, such as mass-market hydrogen or carbon capture and storage. This puts significant pressure on discovering processes which can provide immediate mitigation effects. This past weekend, the Financial Times investigated one potential tool: biochar.

“Biochar,” also known as “agrichar,” is simply charcoal: biomass heated at very high temperatures in the absence of oxygen. This charcoal becomes important in the battle against climate change in concert with one of the planet’s largest carbon sinks: the soil. Soil holds huge amounts of carbon, mostly in the form of decomposing plants. That carbon, however, is largely unstable-disturbing the soil, such as when a farmer plows his fields, causes a release of that carbon into the atmosphere. The instability of soil as a carbon sink presents a series of problems. Land use changes, especially towards agricultural uses, have the potential to release huge amounts of carbon into the atmosphere. This potential creates one of the most complicated-and controversial-issues in the biofuel industry: how should indirect land use changes be included in calculations of the emissions avoided by increased use of biofuels? At an even deeper level, there are questions as to whether the effects of these land use changes on atmospheric carbon can even be accurately modeled.

Biochar, however, provides a relatively stable way to lock carbon into soils. Charcoal stabilizes carbon, leaving it relatively resistant to breakdown. Beyond this stabilization effect, however, biochar has other significant beneficial effects. Particularly exciting, are its effects on soil fertility: some studies have found that it is comparable to chemical fertilizers in its ability to increase crop yields. Biochar therefore provides multiple effects; not only does it lock up carbon that might have been released into the atmosphere, it also prevents the emissions of other power greenhouse gasses: nitrous oxide, produced by nitrogen-based fertilizers, and methane, produced by crop waste left to rot in the fields. Also, because biochar can be made from crop waste-like any biological material-it has the potential to reduce any possible impacts from land use changes.

A number of entities have noticed the potential of biochar; at the recent international negotiations in Poznan, the U.N. Convention to Combat Desertification suggested that biochar production be included in the Clean Development Mechanism. Some scientists estimate that as much as 10% of total carbon emissions could be sequestered by the application of biochar around the world. While the technology to create biochar exists right now (and has existed for hundreds of years), creating biochar at a scale to effect the global climate would require significant effort; to even sequester 0.2 billion tons of carbon annually (2% of global emissions), would require the conversion of 27% of global crop waste to biochar.

Even with the potential challenges of biochar production, it still stands as one of the most significant quick-acting climate change mitigation tools. Academic programs, based out of Cornell University and Edinburgh, are researching ways to more efficiently produce and use biochar, while a number of companies have already begun to develop biochar as an economically viable resource.

“The world is in a race against time, with scientists estimating that major climate tipping points could be passed within a decade,” said Durwood Zaelke, President of the Institute for Governance & Sustainable Development. “It is imperative we take immediate and aggressive action on climate change through ‘fast-action’ mitigation strategies, in addition to reducing CO₂ emissions. Biochar is a fast-action strategy that can be expanded now and will bring near-term mitigation in addition to major agricultural benefits.”

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