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Carbon Capture Is Not a Climate Savior

The promise of negative emissions is baked into most “net zero” pledges. But putting that into practice is easier said than done.

Algae at the wastewater biofuel system at the San Francisco Public Utilities Commission's Southeast Water Pollution Control Plant (shown here in 2012) capture carbon dioxide and produce biofuel.
Sarah Rice/Getty Images
Algae at the wastewater biofuel system at the San Francisco Public Utilities Commission's Southeast Water Pollution Control Plant (shown here in 2012) capture carbon dioxide and produce biofuel.

In December, the Vatican became one of the latest entities to unveil a plan to reach net-zero emissions by 2050, joining far less pious actors like BP, Shell, and President-elect Joe Biden. Net-zero plans have become all the rage as public concern about the climate crisis has grown. But approving coverage of these wide-ranging announcements rarely question what the “net” of net-zero actually means. 

Meeting climate targets means releasing fewer fumes into the sky, for starters. And those plans include that. But they also include something else. The way they get to “zero” isn’t by cutting all greenhouse gas emissions by mid-century but by sucking carbon dioxide out of the atmosphere afterward through a suite of methods known collectively as “negative emissions.” And there’s a problem with that: Existing “carbon capture” technologies and techniques can today capture only 0.1 percent of global emissions. Banking on them to pick up the slack amounts to a big gamble. It’s not clear these techniques are scalable or that the countries and companies behind net-zero pledges have thought through what trying to scale them would mean.

Talking up carbon capture is good for fossil fuel companies—it makes the next few decades look profitable for them. Companies from ExxonMobil to Shell to Occidental Petroleum have all boasted about investments in carbon capture while continuing to double down on their core business model of finding and digging up as much oil and gas as possible. Whether they’re making meaningful investments in carbon capture is a different matter entirely. Exxon recently nixed its $1 billion investment to store carbon under a gas operation it owns in Wyoming. It moved ahead with a $9 billion expansion of its crude oil drilling operations off the coast of Guyana. All the while, Exxon, like its competitors, continues to advertise its token investments in carbon capture as proof that they’ve enlisted in good faith in the climate fight, despite all evidence to the contrary.

The approach is eerily reminiscent of the climate denial playbook. When companies like Exxon and General Motors funded climate denial, the effect wasn’t to convince the world that more carbon dioxide is a good thing or that the earth just naturally gets really hot sometimes, but it was to muddy the waters, casting enough doubt on the scientific consensus to stymie policymaking that might threaten their profits. Now, such companies’ lavish advertising budgets are being used to spread a new kind of doubt in the face of a new consensus about how to deal with that problem: Phase out fossil fuel use as quickly as possible while phasing in renewables. Negative emissions are one among several vague talking points being thrown out by polluters to suggest that isn’t necessary. What if we could suck up a whole lot of carbon dioxide at some point? What if the timeline for decarbonization could be pushed back as a result? The jury’s still out on how much carbon dioxide we can take out of the atmosphere after 2050, they argue. And renewables can’t yet meet the world’s energy needs. So it’s probably safest to let us keep making the earth hotter while our best researchers work to find a technological fix to this problem that’s just around the corner. 

Here’s the sticky bit: Negative emissions are needed if the world’s governments are indeed serious about keeping warming to “well below” 2 degrees Celsius, per the text of the Paris Agreement. Anything higher than 1.5 degrees may well amount to a death sentence for potentially millions across the global south, and the lack of zero-carbon alternatives on offer in big sectors of the economy mean it’d be all too possible to sail past that threshold in the decades to come. Carbon capture is necessary. But fossil fuel executives are the last people who should get to define how much of it’s needed, what it should look like, and who benefits.

“It’s important to know how many gigatons we can take out of the air and the economic efficiency,” Georgetown University’s Olúfẹ́mi Táíwò, whose research explores the intersections of climate justice and colonialism, told me. In a forthcoming primer on carbon dioxide removal, or CDR, Harvard University researchers Andrew Bergman and Toly Rinberg suggest that around 1 metric gigaton of removal per year, worldwide, is consistent with a pathway toward capping warming at 1.5 degrees Celsius—far less than the 5 to 15 metric gigatons suggested by the models used by the Intergovernmental Panel on Climate Change, or IPCC. 

Even more modest targets will require technology that is currently quite expensive, probably in addition to large quantities of land for carbon sinks. The Integrated Assessment Models, or IAMs, used by the IPCC to design net-zero pledges pose deceptively simple answers to this challenge. In assuming a continued annual GDP growth of around 2 percent, year on year, carbon capture technologies that are expensive to deploy now will get cheaper in the future. So long as our future selves and countries are richer, it’ll be cheaper and easier to suck up carbon at evermore impressive scales down the line—more so, say, than phasing out fossil fuels and deploying lots of renewables in the next 20 years. We don’t actually know, though, if societies getting richer means they’ll be able to capture more carbon—particularly given the stubborn fact that GDP and emissions tend to rise together.

Carbon capture, or negative emissions, can mean many different things. So-called “natural climate solutions” involve things like tree planting, grassland and wetland restoration, or (controversially) agriculture-based soil sequestration. The Green New Deal resolution introduced to Congress last year backed this approach, citing the need for “removing greenhouse gases from the atmosphere and reducing pollution by restoring natural ecosystems through proven low-tech solutions that increase soil carbon storage, such as land preservation and afforestation.” But there are other approaches, too. Among the most frequently invoked in climate modeling is Bioenergy with Carbon Capture and Storage, or BECCS. This relies on harvesting new carbon-sucking crops like switchgrass for fuel, then capturing the resulting emissions through machines that filter out emissions from where the power is generated. And in direct air capture, machines that look like air conditioners suck carbon down from the sky and inject it into rock formations or soft drinks, among other uses. 

In some industries, carbon capture makes intuitive sense—for example, in aviation, where sustainable fuel solutions are going to take a while to develop. In others, carbon capture can serve to reduce emissions from activities that should be eliminated outright. A good example of this are so-called “scrubbers” on gas and coal-fired power plants. These lessen the amount of carbon they’re spewing into the atmosphere with the help of a recently bolstered federal tax credit known as 45Q. This isn’t a negative emissions technology, since pollution is still happening. Such poorly targeted subsidies for carbon capture and storage, or CCS, could even extend the life of already uneconomical power stations that should be among the first things phased out as part of any earnest decarbonization agenda.  

“If you’re doing aggressive mitigation, the coal for CCS option essentially falls off the table,” Glen Peters, research director at the Center for International Climate Research, says. “You need both to happen: aggressive mitigation, while starting to figure out the technologies you’ll need for the last 20 to 30 percent.” Despite platitudes from Republicans, former energy secretaries, and even some parts of organized labor about the supposed promise of “clean coal,” no amount of tax credits will change the fact that coal remains a bad investment in just about every sense.  

Innovation is a seductive concept. Given that Republicans are particularly keen on it, investing in negative emissions technology might seem like low-hanging fruit for climate policy in a divided government; just this week, $35 billion in research funding—including roughly $6 billion for carbon capture—made it into the broad spending bill now sitting on Trump’s desk. 

Much of the policy support for negative emissions on offer now, though—and that can garner bipartisan support—tends to take the form of sloppily designed corporate subsidies for polluters like 45Q. The vast majority of the carbon captured on earth today is poured back into extraction. Enhanced Oil Recovery, or EOR, utilizes carbon by injecting it underground to help unearth more fossil fuels from wells. 45Q—created to spur on a domestic carbon capture and storage industry—furnishes generous subsidies on “clean coal” and EOR alike. Unsurprisingly, fossil fuel interests have consistently sought to degrade the reporting requirements for such credits. A 2018 study by Clean Water Action found that just three of the 60 million metric tons worth of 45Q tax credits claimed as of that spring had been reported to the EPA’s verification process.  

“Moving forward, we have to completely change how we’re tackling this type of technology,” Shuchi Talati, a senior policy adviser at Carbon 180, told me. “We really need to have more broad participatory conversations on what infrastructure means for these kinds of projects. Things like carbon dioxide pipelines will be needed at scale. I think having conversations that include labor, environmental justice, and community groups and local governments need to be had at the beginning,” she added, noting the need in particular for international governance. 

“Land use, respecting the rights of indigenous peoples and low-income communities, questions of community benefits agreements, who’s going to get the jobs these projects create ... These are all things we should know. I just don’t think ExxonMobil is going to ask those questions, much less answer them in any kind of serious way,” said Táíwò.

Carbon dioxide removal projects, wrote Táíwò, Talati, and several other researchers across disciplines in a recent paper in One Earth, need to be evaluated “on a case-specific basis rather than just as abstract technologies.” In a country where rural, mostly white landowners can still stymie vital wind farm and transmission line projects, comparatively little attention is paid to potential resistance to negative emissions. Removing just a single metric gigaton of carbon per year would require a land area bigger than Texas. Stabilizing temperatures at the same level through BECCS alone, per many IAMs, is estimated to require a landmass five times the size of India. And a recent Nature Climate Change study finds that relying primarily on more “natural” negative emissions to stabilize warming at 1.5 degrees could trigger a five-fold increase in staple food crop price. 

Already, troubling patterns have emerged. As Táíwò has pointed out, Africa—where land ownership is increasingly concentrated—now accounts for 75 percent of the land pledged under the “Bonn Challenge” to restore 350 million hectares of forest. Having the “net” of “net-zero” pledges happen out of sight and out of mind for global north countries could see the dynamics of capturing carbon look a lot like those that were erected to dig it out of the ground. Making matters worse is the fact that decades of multilateral programs, from REDD+ to the Bonn Challenge, have treated large swathes of the global south as an inexhaustible carbon sink. Having contributed just 3 percent of global emissions since 1751, Táíwò says, it’s “absurd that the African continent should have to deal with the land use costs of carbon removal.” 

“Carbon removal in particular is one of the most direct forms of climate reparations,” he added. “Global north countries taking on carbon removal is obviously not exhaustive of their responsibilities from a justice perspective, but in a lot of ways is the most direct thing they can do conceptually speaking.” A more just approach would be for global north countries to fund carbon removal and site much of it in their own backyards.

But while less land-use intensive, direct-air capture technologies have their own feasibility and affordability issues. For one, they depend on an enormous amount of electricity; if the grid powering DAC is still carbon-intensive, its carbon savings look a lot more ambiguous. And if such technologies are patented by private companies, onerous intellectual property statutes could make it virtually impossible for them to proliferate widely, particularly to low- and middle-income countries that lack the capacity to pay the rents that might be demanded by patent holders. Wealthy countries’ recent refusals to waive intellectual property rights for publicly funded Covid-19 vaccines, Táíwò notes, could offer a preview for how IP rules may stymie a new generation of life-saving technologies. 

True negative emissions—mostly, capturing carbon and keeping it buried—aren’t neatly compatible with the profit motive. Even if captured carbon is used to make building materials, acknowledging that negative emissions are critical to ward off climate catastrophe means making sure that installing them quickly doesn’t depend on their ability to turn a profit. Lavishing private companies with subsidies and tax incentives, that is, will only go so far. Instead, we might need to treat carbon like sewage, as science fiction writer Kim Stanley Robinson recently proposed: an essential but basically boring public service that nobody expects to get rich off of unless there’s something illicit happening. 

As fossil fuel companies look to capture the field of captured carbon with schemes for EOR and pernicious academic funding, there’s a dire need for democratic governance models for carbon dioxide removal that prioritize equity and emissions reductions over shareholders. Environmental sociologist Holly Jean Buck argues that carbon capture could fall under the mandate of nationalized fossil fuel companies, which could keep union workers on the payroll as they build out the vast amount of infrastructure needed to store carbon. As the One Earth paper coauthored by Buck also notes, “We might need to stretch our imaginations to envision economic and political futures in which CDR fits into the world we want rather than delaying or undermining it.”

The proliferation of net-zero plans in 2020 is clearly good news insofar as it indicates that governments are now taking the climate crisis more seriously. But they also belie the need for concrete plans to reduce emissions much sooner. “The scenarios are performative in a sense that they show us one way but not all the ways to 1.5 or 2 degrees,” Glen Peters explained. Earlier climate models, he said, were designed around stabilizing atmospheric concentrations of carbon dioxide, say around 450 or 550 parts per million. “But many models couldn’t get to this,” he said. “So what they did is change that target to only apply in 2100, so you could go over and come back down. All the models could do this if they used BECCS.” Such models can be useful reference points but don’t need to dictate what’s possible. 

If stabilizing temperatures at “well below” 2 degrees is the goal, the task for the next decade at least is straightforward: electrify everything, build lots of renewables, and rapidly phase out fossil fuels. Federal research into how to capture carbon at scale is a necessary complement to reducing the amount of work those processes will have to do. But carbon capture will always be a complement—never a substitute.