The technology to pull carbon dioxide out of the air could take all the urgency out of stopping climate change. It may also be unavoidable.
We’re making enormous strides toward a green, decarbonized economy. But we won’t get there fast enough. To save the world from destructive climate change, we need unorthodox solutions.
In 2021, the U.S. shattered records for the amount of renewables added to the grid. Solar power has gotten so cheap that it’s cost-effective even in less-sunny states like Maine or Wisconsin. In warmer climes, it’s cheaper to build new solar and wind plants than to buy fuel for existing gas and coal plants.
We’re moving faster than anyone thought possible just a few years ago. But in spite of this, it won’t be enough.
Humanity took too long to start decarbonizing. Fossil-fuel barons, free-market ideologues and science denialists held back the transition for decades. If we had started twenty years earlier, with even small steps, we’d be on track to meet the Paris Agreement’s 1.5° goal.
Now, even the fastest transition that’s realistically possible won’t spare us from climate change. We have a chance to avoid the worst scenarios, but not to prevent it entirely. The megadrought that’s parching the Sun Belt and massive hurricanes drowning Florida are previews of what we can expect in this more chaotic future.
If we want to stabilize the climate, there’s only one option. Experts largely agree that we need “negative emissions”—ways to pull carbon dioxide out of the atmosphere. The United Nations estimates that we’ll have to remove 10 billion tons annually by 2050. The ways of achieving this go by the name of direct air capture, or DAC.
Trees or tech
The simplest, cheapest way is to plant trees. But that approach will take decades to bear fruit. Worse, it needs land— lots of it—where these new forests can grow. By one estimate, we’d need “three Indias” worth of reforested land to make a dent. And it would have to be left undisturbed, not logged or burned, lest that carbon be released right back into the atmosphere.
Another way is technology that captures carbon dioxide from the air and stores it in geological formations to contain it for the long term. We know this can work: Climeworks, a Swiss company, is already doing it. Their Orca plant in Iceland filters atmospheric CO2 and injects it into basalt rock, where chemical reactions transform it into stable carbonate minerals. According to Climeworks, Orca can capture as much carbon as 200,000 trees in one-thousandth of the space.
This is an energy-intensive process, and obviously it has to be powered with renewable energy, not fossil fuels, for it to help at all. Iceland, with cheap and abundant geothermal power, is an ideal location. The bigger downside of this approach is that, so far, it’s too expensive. Climeworks’ technology costs between $600 and $800 per ton of carbon. Experts believe we’d have to get that down to $100 or less to make it a viable price for mass adoption.
A third approach goes by the name of bioenergy with carbon capture and storage, or BECCS. It proposes that we plant fast-growing vegetation like switchgrass, harvest and burn it for fuel in a biomass plant, and install scrubbers that trap carbon dioxide before it leaves the smokestacks. The advantage of this approach is that CO2 is easier to trap when it’s concentrated in exhaust gas, rather than diluted in the open air. Unfortunately, it has similar space demands to reforestation, and the technology itself is barely beyond the demonstration stage.
Although most experts are resigned to believing that DAC is necessary, there’s a real moral hazard to it. If carbon removal is a reality—or even a distant future possibility—environmentalists fear that oil companies and other polluters will treat it as permission to keep burning fossil fuels. Fighting climate change loses its urgency if we assume our descendants will solve the problem down the road.
However, a bigger issue is the sheer scale of the problem. The Orca plant, currently the world’s largest, captures 4,000 tons of CO2 per year—the same amount humanity emits every three seconds. Its successor, Mammoth, will boost that to 36,000 tons: much bigger, but still insignificant.
President Joe Biden’s infrastructure bill allocated funding for four large next-generation DAC hubs, each capable of capturing 1 million tons per year. Even this is a drop in the bucket next to the 35 billion tons of greenhouse gases that humanity emits each year. To cancel out our emissions, we’ll need thousands of these plants.
This isn’t to say that the situation is hopeless. DAC is very much an experimental technology, and those are most expensive right out of the gate. Every technology has a learning curve, just as solar and wind power did at the beginning. As the technology matures and spreads, it’s reasonable to predict that innovation and economies of scale will drive the price down.
The Inflation Reduction Act sets a generous tax credit for carbon capture, which will spur the creation of entirely new markets. And the increasingly cheap price of renewable energy—dropping to negative during the day in some places—will make carbon capture plants more economically viable.
Cleaning up our mess
If we solve the climate crisis, DAC will be part of the solution, but only part. We shouldn’t view it as a life preserver we can grab to get ourselves out of trouble. Rather, we should treat it as a long-term project: as part of becoming better stewards of the planet, taking responsibility for the damage we’ve done and working to clean it up.
It could take hundreds of years, even thousands; but so be it. We’ve been short-sighted for too long, rarely thinking beyond a few years in advance, foolishly assuming the future will always take care of itself. Humanity would benefit from a more long-term mindset.
And in the long run, there’s no reason we have to be at the mercy of natural cycles. We can control the Earth’s climate, to keep it livable for ourselves and the other species we share the world with.
I can imagine a future civilization with climate control stations across the planet, drawing down and storing greenhouse gases when we want to cool the world, re-emitting them when we want to warm it up. We can keep the climate in a stable Goldilocks zone. We can prevent ice ages, counteract cooling from volcanic eruptions, and cancel out changes in solar radiation.
That’s an awesome responsibility, but it’s not beyond us. We already have the ability to do it. It’s just that until now, we’ve been blundering around, doing it unintentionally and recklessly. What we need is for our wisdom to catch up with our power.