Changing the Way We Farm Could Help Stop Climate Change

When the Soviet Union collapsed in the early 1990s, 112.4 million acres of farmland were abandoned as the country’s collectivized farming system collapsed along with it. Over the next 20 years, that land became one of the largest areas in the world to sequester carbon. The region, known as a carbon sink, is equal to between 10 and 20 percent of the sequestration action of Russia’s woodlands, which include vast tracts of boreal forests. Every year, the former farmland absorbs 42.6 million metric tons of carbon, or about 10 percent of Russia’s fossil fuel emissions.

And according to a new paper looking at “climate-smart soils” published in the journal Nature on Wednesday, the world’s farmland could help to reduce greenhouse gas emissions by between 50 and 80 percent.

“Certain land management practices can add more plant material to soils as well as hold more of that organic matter in the soil for a longer time and thus build up the storage of that carbon in the soil,” coauthor Pete Smith, a professor of soils and global change at the University of Aberdeen in Scotland, told Climate Central. No-till farming, applying biochar to fields, and changing the types of crops and how they’re grown can all help to increase the uptake of carbon in agricultural soil.

But getting enough farmers to engage in such practices—which can require technology and capital that isn’t readily available to many—is a challenge. “There are ways to both maintain high production as well as build soil carbon and reduce other greenhouse gases, but in many cases that means some additional work and/or costs to the farmers, so a key issue is to incentivize them to do so,” Smith said.

While 80 is the grand upper end of potential offsets, the study puts likely sequestration rates at between 10 and 20 percent of human-caused global emissions. According to the paper, the slow release of carbon from soil currently accounts for 37 percent of greenhouse gases.

There’s some debate as to whether even achieving a 10 percent reduction in emissions through changes in soil management is even possible, however. The post-USSR sink, which was described in a 2014 study published in the journal Global Change Biology, reveals both the promise and limitations of using farmland as a hedge against climate change. While it shows just how much carbon farmland can sequester, creating the circumstances for the sink took a massive social, political, and economic upheaval—something that can’t readily be re-created on hundreds of millions of acres of farmland around the globe.

According to Phil Williamson, science coordinator at the U.K.-based Natural Environment Research Council, it’s nearly impossible to enact carbon-capturing soil management on the scale required to make a significant dent in emissions. In a commentary published by Nature in February, he argued that applying black biochar (a type of charcoal) to millions of acres of farmland would decrease its reflectivity, “increasing the Earth’s heat absorption significantly.”

Silicate rocks can also be used like biochar to increase the carbon-capture capability of soils. But in order to decrease emissions by 12 percent, Williamson estimated that between 1 and 5 kilograms of material would have to be applied annually to every square meter of farmland across between 15 and 45 percent of the entire planet.

A worldwide undertaking on such a scale may indeed be impossible, but upping the carbon-capture potential on farmland around the world certainly would not hurt. As such, the authors recommend a series of policy changes that could help “climate-smart” soil management become more common around the world, including a cap-and-trade system, subsidies that encourage carbon-capturing land management, and increasing consumer demand for food products grown with negative carbon emissions.

“If we can do this,” Smith told Climate Central, “we can complement efforts in other sectors to stabilize the climate and deliver on the Paris agreement.”