The question, posed by Chris Coldwell of Lancaster to The Guardian’s long-running Notes and Queries series, is deceptively simple: if every vehicle on Earth had its tyres inflated with carbon dioxide rather than ordinary air, would it make any meaningful dent in the amount of CO2 in the atmosphere? Readers responded with calculations, chemistry, and no small amount of scepticism. The short answer, by near-universal consensus, is no — and the long answer reveals just how ambitious any carbon-storage scheme must be to compete with the scale of human emissions.
The maths simply do not add up
Several readers reached for their calculators. DrLBlack estimated that an inflated tyre holds roughly 14g of air. Because CO2 is about 50% denser than air, a tyre pumped full of the gas would contain around 21g — or 105g per standard four-wheeled car. Multiplied across the world’s fleet of nearly 1.5 billion vehicles, that gives a grand total of approximately 157,700 tonnes of CO2 sequestered in rubber.
To put that in perspective, global CO2 emissions in 2025 clocked in at 38.1 billion tonnes — roughly 100,000 tonnes every single minute. The entire global tyre store would offset emissions for about 95 seconds.
KP8900 proposed a more useful comparison: how much land would rewilding need to match that storage figure? Using a benchmark of 400 tonnes of carbon absorbed per hectare per year, fellow commenter mill1806 crunched the numbers. “Either thousands of hectares or thousands of years,” they wrote — a sobering figure that still falls “well, well short of current emissions.”
Tyres leak, and CO2 seeps faster
Beyond the scale problem lies a more practical headache. Randomusername222 asked the obvious follow-up: are we expecting these tyres to remain pressurised for geological time? The damage caused by a single generation of fossil fuel use, they pointed out, will linger in the environment for tens of thousands of years. A tyre that goes flat after a few thousand miles of motorway driving has, in carbon terms, achieved precisely nothing.
PolyphonicPoly highlighted a further technical wrinkle: CO2 escapes through rubber significantly faster than the nitrogen in ordinary air. Drivers would find themselves topping up constantly or driving on soft tyres — bad for safety and worse for fuel efficiency. Worse still, compressed CO2 combines with any trace moisture to form carbonic acid, which corrodes metal components. Store enough pressurised CO2 in billions of vehicles and forecourts across the world, and you have created a corrosion and safety problem on an industrial scale.
As FrankieandDexy put it bluntly: “There would be little or no point in using an esoteric gas in pressurised cylinders, particularly in the hands of unskilled operators on petrol station forecourts.”
The hidden cost of capture and storage
A handful of readers pushed the thought experiment further. TotallyTukTuk wondered whether captured CO2 could be split into elemental carbon and oxygen, arguing that solid carbon is far easier to store long-term. Canyoudoso floated the idea of recombining CO2 with green hydrogen to produce synthetic methane, which could feed into the gas grid.
Randomusername222 was quick to invoke the laws of thermodynamics. Any electricity spent electrolysing water and synthesising methane, they noted, would equal or exceed the energy originally released by burning natural gas. A heat pump, by contrast, delivers four units of heat for every unit of electricity consumed. Even a humble electric fan heater, they calculated, would be many times cheaper than synthetic methane.
Pointy_Haired_Boss, Mark of Cambridgeshire, and Alan Webb all reached similar conclusions: the cost of capturing, compressing, transporting, and storing CO2 specifically for tyre inflation would be astronomical — and entirely pointless, given that punctures, replacements, and scrapped vehicles would eventually release the gas back into the atmosphere.
What actually works?
Readers were largely united on what should replace the idea. Bubble CO2 through algae, trap it in basalt, convert it to bicarbonate and pump it into the ocean, urged king_tubby. Plant a tree each day. Restore kelp forests. Educate more girls. Make voting compulsory. The suggestions were varied, but the underlying message was consistent: the planet’s carbon problem demands solutions measured in gigatonnes, not the contents of a tyre.
Rockyrex offered two pieces of personal advice that require no infrastructure at all: stop buying from the livestock industry, and stop buying airline tickets. “There really is no sustainable future which includes the mass-production livestock industry,” they wrote, “and the mass aviation industry is very unlikely to be able to produce enough non-fossil aviation fuel within the timeframe required.”
Jupiterblue and Drspeedy both championed tree-planting as the more natural — and more effective — carbon store. Alan Webb went further, arguing that electric cars are not the silver bullet their advocates claim. “We need much better public transport,” he wrote, “not more expensive little boxes that degrade the environment.”
And finally, EddieChorepost provided the answer nobody was looking for: “It wouldn’t help the environment if you filled your tyres with nitrous oxide, but it would be funny if they burst.”
Why it Matters
The exchange illuminates a truth climate communicators have long struggled to convey: the scale of human carbon emissions is so vast that almost any individual intervention — no matter how imaginative — becomes meaningless without systemic change. Filling every tyre on Earth with CO2 would offset less than two minutes of global emissions. The real solutions, readers argued, are unglamorous and structural: rewilding land, decarbonising heating, reforming transport, and rethinking the industries we fund with our spending. As king_tubby put it, locking CO2 into tyres is “a very short-term, fanciful solution.” The conversation is a useful reminder that the climate crisis demands ambition measured not in tyre-loads, but in gigatonnes — and a willingness to change the systems, not just the wheel.
