Across the U.S., abandoned wells are belching the powerful greenhouse gas. This nonprofit aims to plug them to fight global warming.

TOOLE COUNTY, Mont. — The stench bellows from the 1,500-foot hole in the ground, the remains of a well long ago abandoned by a bankrupt oil company. Despite the well’s rotten-egg smell, the real culprit is methane, and every year this single well spews the potent greenhouse-gas equivalent of roughly 600 cars.

It has been gushing, unchecked, for nearly three decades.

Curtis Shuck calls the well a “super emitter,” one of many in a wheat field not far from the Canadian border, a part of Montana known as the “golden triangle” for its bountiful crops. Aside from the scattered rusty pipes and junked oil tanks, the field is splendid and vast, its horizon interrupted intermittently by power lines and grain bins. On these plains, Shuck says, you can watch your dog run away for a week.

He is a former oil and gas executive who nowadays leads a small nonprofit — the result of a personal epiphany — and is tackling global warming one well at a time. That is the approach of his Well Done Foundation, plugging this and then other orphaned sites and trapping the methane underground. The effort started in Montana in 2019 but will expand to other states before the fall.

“When we’re done, it will be like this well was never here,” Shuck said, standing upwind as cement was pumped hundreds of feet down, through a series of pipes stuck in the 7½-inch-wide hole like a straw in a juice box.

Hundreds of abandoned oil and natural gas wells cover Montana, according to Shuck, and nationally the Environmental Protection Agency estimates that the number exceeds 3 million, which various people view as either way too low or way too high. Either way — and especially when what is escaping from the ground is measured by the metric ton — the math is ugly, the effects profound.

In the short term, methane is markedly more potent than carbon dioxide as a greenhouse gas because of its ability to trap heat. Concentrations of methane in the atmosphere rose more sharply last year than at any time “since systematic measurements began in 1983,” the National Oceanic and Atmospheric Administration reported in April.

Fossil fuel extraction is not the sole source of the problem, but many experts believe that curbing methane’s unchecked emission from oil and gas operations has great potential to slow Earth’s warming. The House weighed in last Friday, voting to restore Obama-era standards, relaxed by the Trump administration, that limit such emissions. President Biden is expected to sign the legislation.

“In combating methane, there are climate benefits to be realized within our lifetimes,” said Emily Connor, a scientist and program manager with the Yale Carbon Containment Lab, who recently visited Toole County to watch Well Done at work.