Can we suck carbon dioxide out of the air to tackle the Irn-Bru shortage?

A host of CO2-removal projects are under way, from trapping carbon in the ground to forcing it out of seawater. But we should manage expectations.

By Stuart Ritchie

Illustration by Thomas Kuhlenbeck / Ikon Images

They’re the most chilling words a true Scotsman can hear: “Irn-Bru production under threat”. But we heard them last week: due to the UK’s carbon dioxide shortage, stocks of Scotland’s “other national drink” might run dangerously low.

Of course, we know where we can find abundant carbon dioxide – far too much, in fact: the atmosphere. It’s just floating around up there. If we could somehow get it down, there would be nothing to stop us having all the fizzy drinks we could want. Oh, and I suppose it might also be helpful in the small matter of stopping climate change.

It turns out that this isn’t just a fantasy. The idea of “carbon dioxide removal” is increasingly mainstream, having been mentioned in the recent Intergovernmental Panel on Climate Change report as an integral part of the worldwide strategy to keep global warming below 1.5°C. And we can’t do that if we don’t actively remove CO₂ from the air.

We should, though, bear in mind that “removal” of CO₂ can mean different things – some of them old-fashioned, such as planting trees, which are the ultimate carbon-converter machines. The fancier, hi-tech options – ones that, for instance, pass air through a set of chemicals that scrub it of CO₂ then store the carbon elsewhere – are less certain prospects. It is also worth noting that removal of CO₂ is usually considered separate from “carbon capture and storage”, where equipment attached to, say, a chimney on a coal-fired power station removes some portion of the CO₂ that’s produced before it gets into the environment. The CO₂ is then turned into a liquid and stored deep underground where it can’t have a greenhouse gas effect.

The UK government is funding a variety of CO₂-removal projects: a heat-driven one attached to the Sizewell C nuclear plant; some that attempt to trap carbon in the ground using a kind of charcoal called biochar; and one that forces CO₂ out of seawater so that the water can absorb even more of it from the air. Clearly the government has gone for a diverse portfolio: some of these technologies, all of which start relatively small-scale, likely won’t go anywhere, or won’t be cost-effective. But if one works… just imagine the potential.

It’s not all government funding, either. There are big bucks available from private sources for anyone who comes up with a carbon-removal idea that works. The payments company Stripe is funding innovative technologies including a plant in Iceland that opened earlier this month. The tech entrepreneur Elon Musk has put up $100m – apparently the “largest incentive prize in history” – for anyone who can show how to remove a net 1,000 tons of CO₂ from the atmosphere per year and who can also show a credible plan to remove gigatons in future.

But we should be careful with our expectations. A few years ago I read about a kind of E coli bacterium that had been genetically modified to eat CO₂ out of the air. As soon as I heard that such a thing existed, a seductive part of my brain began to tell me: “It’s in hand! This will fix climate change! You don’t need to worry!” But early, often over-hyped stories of scientific discoveries can gloss over the caveats – one of which, in this case, was that the process to create the bacteria produced more CO₂ than it consumed.

Over-exuberance about new technologies is also a poor incentive for politicians who, short-termist as they tend to be, might put off taking larger steps to deal with climate change right now if they are convinced that a planet-saving technology is just around the corner. If the technology doesn’t materialise, we’ll end up in a worse position than if we’d never heard of it in the first place.

That’s not to gainsay the impressive progress we’re making. It’s simply that, before we reduce our anxiety levels about climate change, the technology needs to show some results.

Tempering our expectations about carbon removal will help us understand that it’s only going to play a partial role in our fight against climate change. And that’s OK. In the same way that wearing a mask (or even getting a vaccine) doesn’t remove your risk of catching Covid-19 100 per cent, we shouldn’t expect that a technology like carbon removal is the answer to global warming. It being an answer, alongside cutting emissions and all the rest, is good enough. Advocates of carbon-removal argue that it comes into its own when we consider how difficult – and in some cases unjust – it might be to fully decarbonise our economy in the short timespan we have available.

I’m sad to report that, as I was reading through the proposals for carbon-removal technology, I couldn’t find any that mentioned outputs to the carbonated-drinks industry (many of them propose storing the CO₂ underground, as with the carbon-capture methods, or using it to make chemicals). We might have to find other ways around the looming Irn-Bru crisis. But in terms of climate change, as long as we’re realistic about how much we want the technology to do, we’ve a lot of reasons to be optimistic.