Carbon dioxide has been pumped underground and turned rapidly into stone, demonstrating a radical new way to tackle climate change. The unique project promises a cheaper and more secure way of burying CO2 from fossil fuel burning underground, where it cannot warm the planet. Such carbon capture and storage (CCS) is thought to be essential to halting global warming, but existing projects store the CO2 as a gas and concerns about costs and potential leakage have halted some plans.

The new research pumped CO2 into the volcanic rock under Iceland and sped up a natural process where the basalts react with the gas to form carbonate minerals, which make up limestone. The researchers were amazed by how fast all the gas turned into a solid – just two years, compared to the hundreds or thousands of years that had been predicted.

The Iceland project has already been increased in scale to bury 10,000 tonnes of CO2 a year and the basalt rocks used are common around the world, forming the floor of all the oceans and parts of the land too. One potential challenge for the new technique is that it requires large amounts of water: 25 tonnes for each tonne of CO2 buried. But Matter said seawater could be used, which would be in plentiful supply at coastal sites.