Carbon dioxide removal: The tech that's dividing climate scientists

Carbon capture technology could be a key tool in tackling global heating. But could it also damagingly shift research focus away from renewables?

- Fiona Harvey

For some scientists, they are the inevitable next stage of staving off the existential threat of climate chaos. For others, they should not even be talked about.

Carbon dioxide removal (CDR) technologies, which provide a means of sucking carbon out of the atmosphere, are one of the hottest, and most controversial, areas of climate research.

The debate over whether and how to develop CDR has been ignited by the release in March of the final section of the comprehensive review of climate science by the Intergovernmental Panel on Climate Change (IPCC). The report found that ways of capturing and storing carbon dioxide, though expensive, may play a role in trying to keep global temperatures within safe bounds.

But scientists and policymakers are divided. Some say the technology must be the priority for research. Others urge caution, and warn against putting faith in untested technology before we have even fully deployed the reliable low-carbon technologies we already have, such as renewable energy.

John Kerry, the US special presidential envoy for climate, talked of his concerns. "Some scientists suggest it's possible there could be an overshoot [of global temperatures, beyond the limit of 1.5C above pre-industrial levels that governments are targeting] and you could clawback, so to speak; you have technologies and other things that allow you to come back. The danger with that... is that according to the science, and the best scientists in the world, we may be at or past several tipping points that they have been warning us about for some time."

The former UK government chief scientific adviser Sir David King strenuously disagrees. He believes CDR of many kinds will be needed, along with the means to "repair" the climate, such as by refreezing the ice caps, because the world is almost certain to overshoot the global target limit of 1.5C above pre-industrial levels.