United Airlines is investing in a venture that doesn’t make airplanes, transport passengers, or ring up frequent flier miles on the company’s credit cards. And, even as it posts losses stemming from the coronavirus pandemic, United is providing millions of dollars to that venture, which has no direct ties to aviation and may not make any money.

It is backing carbon capture, the nascent technology designed to suck carbon dioxide from the atmosphere.

United Airlines is the first major U.S. air carrier to take a step toward trying to remove some of the greenhouse gases spewed by it and every other airline — pollution that is driving up global temperatures.

For United, it's an alluring project. Governments, particularly in Europe, are beginning to crack down on emissions from airlines. Last month, the Environmental Protection Agency for the first time regulated greenhouse gas emissions from commercial aircraft, although environmental groups say the rules are so lax as to not make a difference. United is increasingly focused on its voluntary goal of net-zero emissions by 2050 — good publicity at a time of growing alarm about climate change.

But it may also be placing an early bet that carbon capture technology could — with the help of federal tax credits — prove profitable as the globe races for ways to cut the pollution that threatens the planet.

"This crisis will end," United chief executive Scott Kirby wrote on Medium last month, referring to the pandemic. "That's why we're keeping our focus on another crisis that will force all of us to change our behavior in far more dramatic ways than the pandemic ever did: the crisis of a changing climate. The longer we wait, the more drastic those changes will have to be."

United has declined to say how much it is investing.

Steve Oldham, chief executive of Carbon Engineering, which has developed carbon capture technology, said United is taking an unusual approach to decarbonization. “When most are thinking they have to stop emissions, here you have a very credible company with a real need saying that the best way of dealing with emissions is removing them,” he said.

A lot is at stake. If global airlines were lumped together as one country, they would rank among the world's top five or six emitters of carbon dioxide, according to the International Energy Agency. Aviation accounts for 3.5% of the planet's man-made greenhouse gas emissions, a recent Manchester Metropolitan University study says. At high altitudes, the planes leave behind contrails of carbon dioxide, nitrogen oxide, water vapor and soot.

When it comes to commercial aviation, there are no low-carbon alternatives. In the summer, a small white-and-red all-electric-powered Cessna e-Caravan flew safely in the air over Washington state — for only 28 minutes. The plane had room for nine, but only the pilot was on board. Solar-powered flights are even less practical.

"The aviation sector is one of the hardest to decarbonize," Oldham said. "Planes require fuel and burn a lot of fuel. At high altitude, the impact of those carbon emissions is greater than if they were released on the surface."

So United says it will become a partner in 1PointFive, a joint venture designed to finance and deploy a large-scale direct air capture plant. The firm, formed in August by a subsidiary of Occidental Petroleum and Rusheen Capital Management, will use technology created by Carbon Engineering.

1PointFive refers to the U.N. goal of limiting the average increase in global temperature to 1.5 degrees Celsius compared with preindustrial times. Constraining global warming to that level could avert the most catastrophic fallout from climate change, scientists say. The company will build its first plant somewhere in the Texas Permian Basin, an area rich in shale crude oil and natural gas.

Occidental, the biggest oil and gas operator in the Permian, will take the carbon dioxide from the air and pump it into old wells to extract more oil. Legislation gives firms a $35-a-barrel tax credit for this capture and use. Occidental will leave the carbon dioxide underground; it has said it has enough geologic storage capacity to bury 28 years' worth of U.S. emissions.

But extracting more oil from underground doesn't please climate activists, although the money will help 1PointFive cover Carbon Engineering's estimated cost of $100 for each ton of carbon dioxide captured.

"It's not a new business model. It's just thinking about carbon as an asset, not a waste product," said Jim McDermott, cofounder and managing partner of Rusheen. 1PointFive plans to ultimately build 27 plants, he said.

Even with that ambition, scale remains a problem. United has improved its fuel efficiency by more than 45% since 1990, the year often used as a benchmark for climate-oriented energy savings. It has added aerodynamic fins on wing tips, used only one engine when taxiing on runways and bought planes that weigh less.

But the number of travelers has soared, and airline fuel consumption has gone up. The federal Energy Information Administration estimates that jet fuel demand will more than double to 230 billion gallons in 2050.

Each carbon capture plant will take up about 100 acres and capture 1 million tons, equivalent to the work of more than 40 million trees. To put that into perspective, worldwide emissions are 40 gigatons. Offsetting that would require 40,000 carbon capture plants.

It's a daunting number, though Oldham says that it's no more than the number of power and industrial plants around the world. And it would be a major jobs program. In his campaign position paper, President-elect Joe Biden said he would "double down" on federal investments and tax incentives to bring carbon capture technology to market.

Time, however, is pressing. United aircraft burned 3.56 billion gallons of fuel in 2019, generating 34.4 million metric tons of carbon dioxide and equivalent greenhouse gases, the company said. It is one of the nation's four largest carriers, with an approximately 15% market share.