Indeed, while there is some evidence that soil carbon can be rebuilt on degraded land, the technique requires putting so much nitrogen in the soil that the technique may not be viable in some places, he said. Additionally, many regenerative farmers discover that after a few years of no-till farming, their yields begin to fall. Searchinger said better options for achieving natural carbon sequestration at scale would be to focus on reducing deforestation and preserving peat lands.

“It’s not the most useful thing to do in agriculture,” Searchinger said. While carbon farming would be helpful, he said the bigger agricultural climate issue is methane from livestock, something that might be addressed with feed additives.

At its most basic, carbon farming is about leaving the ground alone. Simply plowing and tilling fields can disturb soil’s natural structure, releasing stored carbon into the atmosphere and displacing insects and microbes necessary for healthy soil. No-till farming creates fields that are better at acting like a sponge to absorb both water and carbon.

Gore’s home state Tennessee leads the U.S. in no-till farming, with more than 78% of its farmland managed that way, versus 37% for the U.S., according to the Soil Health Institute. On his farm, some 10,000 trees have been planted to increase soil carbon. Small groups of cattle and sheep are rotated to graze in different areas, adding natural fertilizer to soils. The farm uses compost and cover crops to keep the soil healthy, rather than for their profit potential.

Regenerative farming has more costs than traditional methods, especially upfront. Only about 108 million acres cross the U.S. are using some regenerative practices, according to Project Drawdown, a climate research group (as of 2012, the government said there were 914 million acres of farmland in America). The group estimates it would cost about $57 billion to convert another 1 billion acres by 2050, but that some 23.15 gigatons of CO2 could be sucked out of the atmosphere by doing so.

While not a solution to the climate crisis by itself, Lal told the audience at Gore’s farm that regenerative farming could be, at the very least, “a bridge to the future.”

Planting the same cash crops each year without rotating them tends to deplete nutrients from soil. Regenerative farming, meanwhile, results in more nutrient dense-crops. But most farmers don’t have any incentive to change what they are doing, because staples like wheat, rice, soybeans and corn are usually covered by federally-subsidized U.S. crop insurance—a $100 billion industry which currently guarantees that more than 290 million acres of U.S. farmland deliver returns for farmers regardless of the harvest.

“For most people, this is a very new idea,” said Will Rodger, director of policy communications at the American Farm Bureau Federation. “We’re certainly aware that carbon can be stored in the soil, but farmers have very narrow margins. Many of our members are looking very closely at it, but the question is how to make it a business.”

The U.S. Farmers & Ranchers Alliance proposed earlier this year that lenders find more creative financing models to help farmers employ regenerative practices. A study published this month in Nature Climate Change found that deploying land sector strategies like carbon farming, as well as food waste reduction and increasing plant-based diets, could turn farming into a net absorber of carbon as soon as 2050.

Gore predicts that popular adoption of regenerative farming will someday take hold the same way residential solar and electric vehicles have caught on. “Farmers are doing this because they think it’s better for them,” Gore said. “I look for signs of hope.”