REMOVING CARBON DIOXIDE RESOLUTELY : RESEARCH

Businesses have got going to explore ways to pull greenhouse gases from the air despite risks.

Using technology to suck carbon dioxide  out of the sky has long been dismissed as an impractical way to fight climate change - physically possible but far too expensive to be of much use.

But ass the global warming accelerates and society continues to emit greenhouse gases at a dangerous rate, the idea is gaining support from a surprising source : large companies facing pressure to act on climate.

A growing number of corporations are pouring money into so-called engineered carbon removal - for example using giant fans to pull carbon dioxide from the air and trap it. The companies say these techniques, by offsetting emissions they can't otherwise cut, may be the only way to fulfill lofty ''net zero'' pledges.

Occidental Petroleum and United Airlines are investing in a large ''direct air capture'' plant in Texas that will use fans and chemical agents to scrub carbon dioxide from the sky and inject it underground.

Stripe and Shopify, two e-commerce companies, have each begun spending at least $1 million per year on start-ups working on carbon removal techniques, such as sequestering the gas in concrete for buildings.

Microsoft will soon announce detailed plans to to pay to remove one million tons of carbon dioxide.

The United Nations- backed Intergovernmental Panel on Climate Change has said nations may need to remove between 100 billion and 1 trillion tons of carbon dioxide from the atmosphere this century to avert the worst effects of climate change - far more than can be absorbed by simply planting more trees.

But many carbon removal technologies remain too expensive for widespread use, often costing $600 or more per ton of carbon.

The hope companies say, is that early investments can help drive down prices to something more palatable - say, $100 per ton or less, much as investments in wind and solar have made those energy sources cheaper over time.

But there are risks, too. As more companies pledge to zero out their emissions by 2050, some experts warn that they could hide behind the uncertain promise of removing carbon later to avoid cutting emissions deeply today.

''Carbon removal shouldn't be seen as get-out-of-jail-free-card,'' said Jennifer Wilcox, a leading expert on the technology at the University of Pennsylvania.

''It has a role to play, particularly for sectors that are very difficult to decarbonize, but it shouldn't be an excuse for everyone to keep emitting greenhouse gases indefinitely.''

The research publishing continues to part 2. The World Students Society thanks authors Brad Plumer and Christopher Flavelle.