Climate mitigation hope through better soil carbon management


Climate change is a massive problem with the potential to completely reshape the world, both literally (with rising sea levels and melting glaciers) and figuratively (with the way we grow food, or the way that we handle allergies). And while the consequences caused by climate change could be huge, the solutions — transitioning to a completely fossil fuel-free economy, or geoengineering — can often seem equally daunting.

But what if something as simple as the dirt under your feet could help mitigate some of the worst of climate change? The Earth’s soils contain a lot of carbon, and helping to manage and restore them could be a key way to help tackle climate change, according to a recent study in Nature.

The study, published by a group of international scientists, suggests that using “soil-smart” techniques for soil management could sequester as much as four-fifths of the annual emissions released by the burning of fossils fuels. These techniques include planting crops with deep roots, which help keep soil intact and encourage the growth of microbial communities that help trap soil carbon, and using charcoal-based composts. The study also calls for a wider adoption of sustainable agriculture techniques — things like no-till farming, which involves growing crops from year to year without disturbing the soil and has been shown to potentially help soil retain carbon, and organic agriculture, which also has shown some promise in restoring and maintaining soil health.

“In the fight to avoid dangerous climate change in the 21st century we need heavyweight allies,” Dave Reay, a professor at the University of Edinburgh and one of the paper’s co-authors said in a press statement. “One of the most powerful is right beneath our feet. Soils are already huge stores of carbon, and improved management can make them even bigger.”

The Earth’s soils store massive amounts of carbon — more than three times the amount that is in the atmosphere, and four and a half times as much as in all plants and animals.

When soil or the microbes within it are disturbed, however — through things like grassland to farmland conversion, for instance — they can release carbon into the atmosphere, exacerbating climate change.

“If the soil carbon reserve is not managed properly, it can easily overwhelm the atmosphere,” Rattan Lal, director of the Carbon Management and Sequestration Center at Ohio State University, who was not involved with the study, told ThinkProgress last year.

While the study suggests that soil carbon storage could offset as much as 80 percent of the world’s annual emissions, other estimates suggest that the practice could have a smaller impact, helping offset anywhere from 10 to 20 percent of annual emissions. Calculating the potential for soil carbon storage is tricky, because it’s highly dependent on the region and type of soil. As Nathanael Johnson pointed out over at Grist in December, soil carbon storage is a tricky issue mainly because “no one knows how to get soil to increase its carbon uptake consistently and then hold on to all of it.”

To figure out the answer to that question, the study argues that scientists, policy makers, and land users must coordinate their efforts. Many techniques that encourage soil carbon storage either require a shift in traditional farming practices or the purchase of new technology, both of which can be daunting to farmers. The study suggests four ways in which farmers could be convinced to switch to a more “soil-smart” method of agriculture: a cap-and-trade system for soil management, which would effectively pay farmers to sequester carbon; government regulations; payment for adopting better management practices; and supply-chain initiatives, such as a label for crops grown using better soil management techniques.

At the Paris climate talks in December, France launched a new initiative aimed at making soil carbon sequestration a global priority. Dubbed the “40 pour 1000” project, a reference to the 0.4 percent annual increase in soil carbon sequestration needed to offset human emissions, the initiative hopes to initially help seven countries (Vietnam, Nepal, Colombia, Senegal, Ghana, Tanzania, Uganda) scale up their commitments to soil-sequestering agriculture practices.

“The good thing is that no one disagrees that increasing soil carbon is good for agriculture, is good for the environment, good for food security,” Frank Rijsberman, CEO of CGIAR, an agricultural research and development firm involved with the initiative, told ThinkProgress in December. “If we can do it in a stable way, it captures carbon and reduces emissions. It can be a double or triple win.”