But a third option may have just become feasible. For a long time, people have dreamed about technology that would allow carbon to be pulled out of the air and stored in the ground or recycled into fuel. Now, a team of Harvard scientists is claiming they have a much cheaper way to do this.
The scientists, led by David Keith — who has also formed a company called Carbon Engineering to commercialise his invention — have been testing technology at a pilot facility in Canada for years. Their claim — which some other experts find believable — is that they can remove carbon dioxide from the atmosphere much more cheaply than previous approaches, with greater cost reductions still to come.
Direct air capture is a crucial piece of the puzzle in lowering carbon levels. There’s really no other way to get rid of the carbon that’s already in the atmosphere, other than waiting the decades or centuries it takes to go away on its own. This technology will help humanity go beyond simply avoiding further damage to the planet’s environment, and fix some of the damage we have already caused.
Also, direct air capture is a way to do deep decarbonisation without waiting for renewables to become dirt-cheap. On the margin, emissions reduction — through energy efficiency, reforestation and renewable energy — is still cheaper than pulling carbon out of the air. But deep decarbonisation — reducing emissions not by a small percent, but by large amounts — would still be extremely expensive, which is why no one is doing it yet.
However, unlike emissions reduction, direct air capture’s economic costs probably don’t balloon — building 100 carbon-capture facilities should be more or less 100 times as expensive as building one. The inventors of the new technique estimate that if costs continue to fall as they expect, they could capture all the carbon the world emits for only 5% of global economic output.
Those predictions are probably overly rosy. And 5% of global output is still trillions of dollars. A much more realistic scenario is for nations to use carbon removal as a supplement to renewable energy and energy efficiency. Even spending 1% of global GDP would require a huge commitment by many industrial nations; and developed countries would probably be asked to foot more of the bill, having already emitted a lot of carbon in the past. There will be many political sticking points.
But carbon capture is now at least moving out of the realm of science fiction and into the realm of the possible. Stopping climate change will still require a large, global, co-ordinated effort, combining carbon taxes (or similar policies, such as cap-and-trade), continued advances in renewable energy, and government-funded carbon capture. But thanks to the magic of human innovation, we will be able to save the planet while also preserving our modern industrial society and keeping the engine of economic growth humming.