The Earth’s capacity for safely storing carbon might be 10 times smaller than previously predicted, limiting its impact as a tool against the climate crisis, according to a new study.
Recent estimates, published in Nature, indicate that, at its full potential, carbon capture could only cut global warming by 0.7°C, far lower than the 6°C that was previously estimated.
Carbon capture and storage (CCS) is a process whereby carbon dioxide (CO2) is captured from the environment or industry, transported, and stored deep underground, so it can’t contribute towards greenhouse gas emissions.
The paper warns that many sites once considered suitable for carbon capture and storage (CCS) may actually be too risky. Potential problems such as leaks, earthquakes and water contamination could rule out large numbers of these locations.
The scientists in this study began their research by analysing underground rock formations, mapping areas where carbon could be stored deep under the surface. The scientists concluded that, realistically, carbon capture could only store around 1,460 billion tons of CO2 – about 10 times smaller than previous estimates.
“Carbon storage is often portrayed as a way out of the climate crisis,” said lead author Matthew Gidden, senior researcher at IIASA and the University of Maryland, USA. “Our findings make clear that it is a limited tool.
“With current trends suggesting warming up to 3°C this century, using all of the safe geological storage wouldn’t even get us back to 2°C.”
Coauthor Joeri Rogelj, senior research scholar at IIASA and director of research at the Grantham Institute, added that carbon storage should no longer be considered an unlimited solution to save the climate.
“Instead, geological storage space needs to be thought of as a scarce resource that should be managed responsibly to allow a safe climate future for humanity,” he said. “It should be used to halt and reverse global warming and not be wasted on offsetting ongoing and avoidable CO2 pollution.”
The scientists also considered which countries should bear more of the burden for climate storage, noting that fossil fuel producing countries – such as the US, Russia, China, Brazil and Australia – could make use of their depleted oil and gas reservoirs.
“This is not just a technical issue,” said coauthor Siddharth Joshi, research scholar at IIASA. “It is about justice across generations and across nations.
“Countries that have historically contributed the most to emissions also have the most practical storage space available and must show leadership in using this resource responsibly.”
Among scientists not involved with this research, there has been debate about the accuracy of this paper’s figures, and what they mean for the future of carbon storage in efforts to tackle the climate crisis.
But Prof Carrie Lear, a climate scientist at Cardiff University who was not involved in this research, said the finite nature of carbon storage means we should focus efforts on cutting fossil fuels.
“There is no single solution to climate mitigation,” said Lear. “It is like a pie made up of many slices.
“This new study shows that the CCS slice is much smaller than we thought. That means the fossil fuel reduction slice just got bigger and also more urgent.”
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