Cutting emissions that rapidly would require breakneck transitions to new technologies as well as steep reductions in energy demand. That would take unprecedented human behavior changes and efficiency improvements, all of which would be “quite challenging to accomplish in the real world,” says Zeke Hausfather, a contributor to an earlier working group for the latest UN climate report and the climate research lead at Stripe.
Loosening the goal to 2 ˚C would basically provide an additional decade to halve climate pollution, to 29 billion tons of emissions by 2040.
The speed and scale of cuts required in both cases simply isn’t realistic, says Julio Friedmann, chief scientist at Carbon Direct, a research and investment firm focused on carbon removal. Nations will need to do “enormous” levels of carbon removal, he says.
The essential problems: The world has emitted too much already. We haven’t done nearly enough to shift toward cleaner ways of running our economies. And we still don’t have available and affordable ways of fixing certain industries and products, like aviation, maritime shipping, fertilizers, cement, and steel.
The promise of carbon removal is that it can buy nations more time to shift to sustainable practices, and balance out ongoing emissions from sources we don’t know how to replace.
2. We’re going to need to do a whole lot of it
Preventing the planet from warming 2 ˚C, or pulling the climate back from that, could require pulling down billions of tons of carbon dioxide every year.
Models that limited warming to 2 ˚C relied on three main methods of carbon removal: planting trees, restoring forests and adopting similar land management practices, developing and deploying carbon-sucking machines, and relying on plants to produce energy while capturing the emissions, which is known as BECCS. Together, they’d need to remove as much as 17 billion tons of carbon dioxide per year by 2050 and 35 billion by 2100, according to the report.
3. We need a portfolio of carbon removal options
The report stresses that different approaches to carbon removal have very different benefits and challenges.
Nature-based approaches like planting trees and restoring forests, for instance, are the most widely deployed today. But the carbon can go right back into the atmosphere when the plants die or burn up in fires. So these solutions are likely shorter-lived than other methods like geological storage, which locks carbon away underground.
Direct air capture can permanently remove and store away carbon, but the machines are currently limited in scale and expensive, and the technology consumes large amounts of energy and water, the report notes.
The IPCC report’s models lean heavily on BECCS, which is a hybrid of nature-based and technology-based approaches, with some of the benefits of each. BECCS, however, requires vast amounts of land that could compete with the needs of food production, among other challenges.
The report notes a wide variety of other ways to capture carbon dioxide, including ocean-based approaches like using minerals to increase the alkalinity of seawater. But these are largely untested.
4. Scaling up will require funding and policy decisions
The climate panel’s authors stress that achieving high levels of carbon removal is going to take significant research and development to determine the most effective methods, minimize environmental impacts, and rapidly develop major projects in the real world.
“We need all hands on deck to explore a diverse set of options to enact both deep decarbonization and remove carbon dioxide,” wrote Frances Wang, program manager at ClimateWorks Foundation, which funds carbon removal research efforts, in a response to an MIT Technology Review inquiry.
The biggest hurdle to building up a major carbon removal industry is likely to be cost. Who is going to pay the hundreds of billions to trillions of dollars it will run to remove this much carbon dioxide year after year?
The report says that accelerating research and development on carbon removal—and getting businesses to actually do it—will require a “political commitment” from governments. That means enacting policies to mandate or incentivize carbon removal, as well as methods to ensure that the practices are achieving the climate benefits claimed.
If history is any guide, the grim findings of a new IPCC report won’t radically change anything. The world is pumping out about 6 billion more tons of annual emissions than it was when the last major assessment was published, in 2014. But more and more work is happening on carbon removal as the importance of its role in combating climate change becomes ever clearer.