To clear the air, go underground

The big challenge of global warming needs big ideas to mitigate it. Two well-known ways to bury carbon dioxide in the ground keep looking like an important part of the solution.

Nati Harnik/AP/File
Farmer Don Bloss examines a tall sorghum plant in his field in Pawnee City, Neb.

Trying to remove heat-trapping gases from Earth’s atmosphere to halt global warming is a huge undertaking. But big challenges can provoke big solutions. A recent proposal even suggested one of the most radical ideas so far: Forget about reducing carbon dioxide. Instead, just push Earth’s orbit 50% farther out from the sun, about where Mars is and where solar heating would be less intense. Problem solved.

A big idea no doubt, but hardly practical.  Meanwhile two much more down-to-earth big ideas to cut global warming are gaining momentum. Pulling carbon dioxide from the atmosphere into the soil through reforestation and improved farming techniques could be a powerful duo. Neither idea is new, but the thinking about how best to carry out these concepts keeps being refined as more research is done.

Farming techniques such as rotating crops, not turning soil over when planting, and using cover crops to restore soil quality help whatever is planted do what it does naturally: take carbon dioxide from the air and fix it in the soil. The Rodale Institute, a nonprofit research group, has forecast that, in theory, 100% of today’s worldwide carbon emissions could be captured this way.

Among the challenges standing in the way is the need to give farmers a financial incentive to change their methods. That likely means funding the effort through carbon offsets – creating a market where carbon-emitting industries must pay to have farmers fix carbon in soils. It also means finding ways to measure how much carbon is actually being captured so its value can be established.

Preserving large swaths of forested land around the world has long been seen as an important climate-saving technique. Trees also suck carbon dioxide out of the air and store it in the ground. Efforts to combat further deforestation as well as reforest degraded land are crucial, say environmental groups such as The Nature Conservancy. 

Letting degraded land naturally return to forest, rather than replanting trees, may often be the best way to go. That lets nature choose the species that will flourish in that particular region. Some 7.7 million square miles of degraded forest, about twice the size of Canada, could be restored in this fashion, the World Resources Institute estimates.

Changing farming techniques and regrowing forests to take carbon dioxide out of the air can’t replace efforts to cut emissions. Reducing the use of fossil fuels through techniques such as generating more energy from sun and wind remains crucial. 

But these two approaches do show that the campaign against global warming needs to take place on many fronts, from lowering the amount of carbon dioxide going into the atmosphere to pulling more back out of it.

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