Scientists push for crash program to scrub carbon from air

WASHINGTON — With time running out to avoid dangerous global warming, the nation’s leading scientific body on Wednesday urged the federal government to begin a research program focused on developing technologies that can remove vast quantities of carbon dioxide from the atmosphere in order to help slow climate change.

The 369-page report, written by a panel of the National Academies of Sciences, Engineering and Medicine, underscores an important shift. For decades, experts said that nations could prevent large temperature increases mainly by reducing reliance on fossil fuels and moving to cleaner sources like solar, wind and nuclear power.

But at this point, nations have delayed so long in cutting their carbon dioxide emissions that even a breakneck shift toward clean energy would most likely not be enough. According to a landmark scientific report issued by the United Nations this month, taking out a big chunk of the carbon dioxide already loaded into the atmosphere may be necessary to avoid significant further warming, even though researchers haven’t yet figured out how to do so economically, or at sufficient scale.

And we’ll have to do it fast. To meet the climate goals laid out under the Paris Agreement, humanity may have to start removing around 10 billion tons of carbon dioxide from the air each year by midcentury, in addition to reducing industrial emissions, said Stephen Pacala, a Princeton climate scientist who led the panel. That’s nearly as much carbon as all the world’s forests and soils currently absorb each year.

“Midcentury is not very far away,” Mr. Pacala said. “To develop the technologies and scale up to 10 billion tons a year is a frightful endeavor, something that would really require a lot of activity. So the time would have to be now.”

The panel’s members conceded that the Trump administration may not find the climate change argument compelling, since the president has disavowed the Paris Agreement. But, Mr. Pacala said, it’s likely that other countries will be interested in carbon removal. The United States could take a leading role in developing technologies that could be worth many billions of dollars.

There are plenty of ideas for carbon removal kicking around. Countries could plant more trees that pull carbon dioxide out of the air and lock it in their wood. Farmers could adopt techniques, such as no-till agriculture, that would keep more carbon trapped in the soil. A few companies are building “direct air capture” plants that use chemical agents to scrub trace amounts of carbon dioxide from the air, allowing them to sell the gas to industrial customers or bury it underground.

But, the National Academies panel warned, many of these methods are still unproven or face serious limitations. There’s only so much land available to plant new trees. Scientists are still unsure how much carbon can realistically be stored in agricultural soils. And direct air capture plants are still too expensive for mass deployment.