Scientists have proposed all kinds of complicated—and probably dangerous—ways to take carbon pollution out of the atmosphere or mitigate its effect. But there's actually a far simpler geo-engineering technique available to us: improving soil quality.
"Improving soil" doesn't have quite the same ring as, say, pumping sulphur into the air to block out the sun. Yet soil is known to be highly effective at storing carbon, because the Earth has been doing it for millions of years. Just the first meter of soil contains 1,500 gigatons of organic carbon, or three times as much carbon as there is in the atmosphere. If we could restore more carbon to the world's soil—it's lost 50% to 70% of its carbon content since we started land cultivation—we could put a huge dent in the climate change problem, say researchers and campaigners.
Carbon sequestration is vital because even if we reduce the current level of CO2 emissions, we're still left with all the carbon already in circulation. That in itself is enough to cause 1,000 years of climate change, studies show. Either we develop our own machines to do that, or we look to forests and oceans.
"We need to focus on the carbon dioxide supply into the atmosphere, but we really need to focus on the demand side as well," says Larry Kopald, co-founder of The Carbon Underground, a nonprofit that's advocates for soil carbon storage. "We have to put the CO2 back into a sink where it's demanded and where it is useful, and improve the reabsorption of the carbon that is already out there."
Constant plowing causes erosion, allowing soil content to flow into waterways or be blown away. And climate change itself exacerbates soil carbon loss, recent research has shown.
The alternative is so-called "carbon agriculture" which includes no-till farming (where you grow things year to year without disturbing the soil), cover crops (which help spur microbial activity in the soil) and "holistic management"—a grazing technique popularized by biologist Allan Savory. (Savory's TED talk, where he offers a solution to desertification and climate change, has been viewed 3.2 million times).
The Carbon Underground is calling for policies that reinvigorate the 3.5 billion acres of grasslands in the world, many of which are degraded. "The largest immediate available opportunity to put carbon back into the ground is focusing on that huge quantity of grasslands where we can restore photosynthetic activity to put carbon back into the soil," says Tom Newmark, another founder of the group.
A growing number of farmers are using such techniques, including the ranchers in a recent film produced by Peter Byck. It shows how, by grazing animals for short intensive periods, grasslands maintain a diversity of plants, plants retain more water, and farmers regenerate their soils. Ultimately, that helps the plants take in CO2 and send carbon down to their roots and into microbes into the soil, Byck says.
Kopald says there's a strong pent-up demand among farmers to move away from practices based around intensive tillage and heavy inputs, but not necessarily the money and resources available to make the switch. Not yet anyway.
"If we took the subsidies that go to fossil fuels today and put that into the restoration of soil, we would deal with climate change within a generation. Easily," he says.