A United Nations-led panel of scientists delivered a grim prognosis this week: The planet is, on average, 2 degrees Fahrenheit hotter than it was in the last century, and even if we magically halted all emissions tomorrow, humanity has spewed enough carbon dioxide into the atmosphere to lock in dangerous climate effects for the next 30 years.
Avoiding climate catastrophe at this point would require removing carbon from the atmosphere. The Earth naturally absorbs carbon when plants and algae photosynthesize. But the long-awaited report from the U.N.’s Intergovernmental Panel on Climate Change, a consortium of scientists representing virtually every country, makes clear that averting catastrophe now will require us to develop measurable, surefire ways to suck CO2 from the air and return it to the ground.
Many of the tools scientists say we’ll most likely need, however, are nascent. And this approach has been controversial among environmentalists, who fear that fossil fuel interests would have policymakers focus on draining atmospheric CO2 so the pumping and burning of oil and gas can continue.
But carbon removal experts say the new U.N. report should put to rest the idea that cutting emissions alone will be sufficient to forestall disaster.
“We will fail to hit 1.5 degrees without CO2 removal,” said Julio Friedmann, a senior research scholar at Columbia University’s Center on Global Energy Policy, referring to the threshold beyond which climate change is forecast to be devastating. “That’s it. That’s just math.”
An Alphabet Soup Of Carbon Sucking
The IPCC isn’t scheduled to release its projections showing what policy pathways countries can take to rapidly cut emissions until next March.
But the various approaches to cleaning up centuries’ worth of accumulated carbon will likely rely on a suite of options, ranging from mixing rocks into soil to help capture carbon to two technologies best known by their acronyms: bioenergy with carbon capture and storage, or BECCS, and direct air capture, or DAC.
An example of BECCS would be a facility that grows trees, which suck carbon dioxide from the atmosphere via photosynthesis before they are harvested and burned to produce energy. Instead of venting that smoke back into the atmosphere, technology captures the CO2 from smokestacks and pumps it underground. DAC technology, on the other hand, mostly looks like giant fans that vacuum carbon from the sky, attach it to calcium particles via a chemical reaction, and inject the captured substance back into the Earth.
Both technologies work, at least on a small scale. But they carry serious drawbacks. To remove significant sums of carbon at scale with BECCS would require huge areas of land and vast amounts of water, competing for space with food crops, natural habitats and human homes ― all of which are expected to face added stress as the world continues to heat up.
And DAC, at least in its present form, is expensive. The Swiss startup Climeworks, one of the world’s most advanced DAC companies, pegs the costs per metric ton of carbon it removes at between $500 and $600. That’s largely because the technology requires loads of energy. A 2019 study in the journal Nature Communications found that DAC, at scale, would consume a full quarter of global energy supplies by 2100. At a moment when the world is struggling to replace fossil fuels with zero-carbon alternatives, the very concept of DAC seems to skeptics like taking out a loan to pay down a debt.
Improving By Trying
The land-use issues facing BECCS may remain challenging. Given current constraints on land use and infrastructure to carry captured carbon from the source to storage areas, the United States could remove only 100 metric tons of CO2 per year using BECCS, a 2018 study in the Proceedings of the National Academy of Sciences estimated. That’s equal to just one year’s worth of emissions reductions from converting coal plants to natural gas.
Studies into what’s called “enhanced weathering,” where mixing certain types of crushed rock dust into soil pulls carbon into the ground, remain relatively few. The Department of Energy issued a call for more research last October. One paper, published last summer by the University of Sheffield, suggested the technique could pull 2 gigatons of carbon per year at scale, equal to more than 500 coal plants’ annual emissions.
But DAC deployed at scale around the world could remove up to 5 gigatons of carbon dioxide from the atmosphere per year, a 2018 study in Environmental Research Letters found. That’s equal to the annual emissions of all the coal-fired power plants in China and India combined.
The cavernous geology under much of the U.S., particularly in regions most ravaged by centuries of fossil fuel extraction such as Appalachia, means the country has enormous potential to store captured carbon. The U.S. Geological Survey’s first comprehensive assessment of the country’s storage potential pegged the mean figure at about 3,000 gigatons.
The cost remains a big hurdle. But early pilot-scale projects indicate the price per metric ton of carbon removed could drop to somewhere between $94 and $232. By 2040, that number could fall below $60 per ton, a 2019 paper in the journal Joule estimated. Those price decreases, however, depend on subsidies and other policies making a DAC supply chain profitable enough to be worth building.
The Biden administration gave out $12 million in funding to research DAC in June. The infrastructure package currently making its way through Congress would earmark another $3.5 billion to set up regional DAC hubs, mirroring a policy recently pioneered by the British government.
The primary federal policy creating a market for DAC, at this point, is the 45Q tax credit, which allows companies using carbon capture technology to write off captured CO2 to the tune of between $12 and $32 per metric ton, depending on what happens with the captured gas. The tax credit pays about $20 per metric ton for CO2 used in oil drilling, which means some of the earliest U.S. investments in DAC are by oil giants like Occidental Petroleum.
“We will fail to hit 1.5 degrees without CO2 removal. That’s it. That’s just math.”
Proposals to raise the payout for carbon that’s captured and stored underground to somewhere closer to $120 per ton are likely to make it into one of the final federal bills to fund infrastructure.
State and regional policies could also be a boon. As yet, California’s low-fuel standard remains the world’s only major carbon-trading market that explicitly values DAC projects. Expanding others, such Canada’s carbon-trading market, could provide the technology another boost.
A ‘False Solution’ No Longer?
Opposition to carbon removal technologies has grown as policies to support them gain momentum. Last month, more than 500 community groups and environmental advocates signed on to a letter to Biden and congressional leaders urging them against enacting new policies to promote carbon capture technology, including DAC.
The criticism echoed long-standing concerns among environmentalists that carbon removal technology is mostly a means for polluters who oppose eliminating emissions altogether to make it hard or impossible to design policies to do so.
“Artificial carbon removal is largely a sideshow when it comes to climate change,” Jonathan Foley, the climate scientist who runs the advocacy group Project Drawdown, wrote in a recent blog post. “At best, it may eventually grow into a minor solution. At worst, it’s a distraction from reducing emissions — and plays right into the fossil fuel industry’s hands.”
But the latest IPCC report shows “that is wrong,” said Michael Thompson, a research fellow at American University’s Institute for Carbon Removal Law and Policy.
“Carbon removal has to be part of the real work ahead, and I sincerely hope this report will help bring closure to that debate,” he said, adding that the political stigma has prevented progressive advocates from even engaging in discussions about how best to design policies to govern these technologies.
“I hope this will be a wake-up call to climate justice groups that they need to come to the table and be part of this process, if not dominate the process on what carbon removal will be,” Thompson said.
The vast majority of American voters reported having heard “very little” or “nothing at all” about carbon removal technologies in a May survey by the progressive pollster and think tank Data for Progress. About 44% of respondents admitted they didn’t know enough about the tools to say whether they held favorable or unfavorable opinions. Perhaps unsurprisingly, the preferred carbon removal solution of environmentalists ― planting new trees and protecting existing forests ― enjoyed the most popularity, with over 70% of people in support.
Trees and so-called nature-based solutions should be part of any mix of carbon removal policies. But Celina Scott-Buechler, the fellow at Data for Progress who wrote a paper for the think tank on what a progressive carbon removal policy could look like, pointed to recent wildfires in Oregon that torched woodlands set aside to store carbon.
“As forest fires continue to rage and as other natural disasters continue to become stronger and less predictable, there needs to be a broad enough portfolio of carbon removal options such that we are not relying on plots of land that just end up burning,” she said. “The progressive environmental movement has decided that, with renewable energy, these technologies are good and we should be pushing for as much deployment as possible. But these other areas of newer technological advancement are still mistrusted.”
Making it more profitable to suck carbon from the air and store it underground than to use it for oil drilling is likely key to building trust in the technology, and tax credit increases like those proposed for 45Q could be a promising first step, Thompson said.
Noah Deich, president of the carbon removal advocacy group Carbon180, compared the current state of the technology to that of solar and wind when the first major IPCC assessment of climate science came out 31 years ago.
“Back in 1990, the report was telling us that, of course, solar and wind are not ready to displace the fossil economy, but if we had started really really investing in those technologies then and started to limit the expansion of fossil fuels, we could have scaled those solutions much more quickly and we’d be in a much less dire situation today,” Deich said. “That’s the same story we’re hearing today for carbon removal. Fortunately we have time ― we just don’t have that much time.”
Friedmann, the Columbia research scholar, compared carbon concentrations in the atmosphere to a ship taking on water, meaning carbon removal technology offers a way to escape to safety. The big IPCC report due out in March, he said, will tell us “whether we need 10 lifeboats or 50 lifeboats.”
“What we know now is we need lifeboats,” Friedmann said.