Carbon-sucking technologies 'limited'

Technologies to capture carbon emissions from the atmosphere have "limited realistic potential" to help avoid dangerous climate change, scientists warn.

Emerging plans to curb climate change by sucking excess emissions out of the atmosphere rely on technologies that have "limited realistic potential" to work, at least in coming decades, scientists say.

So-called "negative emissions" technologies - including capturing emissions from the air and storing them underground, or planting much more of the world's land to trees - are unlikely to significantly help hold the line on climate change, they warn.

Suggestions that the measures could help keep global temperature increases to under 2 degrees Celsius - the target set in the Paris Agreement on climate change - "appear optimistic" and cannot compensate for inadequate emissions cuts, a report from the European Academies Science Advisory Council (EASAC) notes.

"We cannot trust technology to come to the rescue," warned Michael Norton, a science and engineering professor at the Tokyo Institute of Technology. Instead, "we need to reduce our emissions as rapidly as possible."

With efforts to cut the use of fossil fuels falling short of what is needed, a growing number of scientists and engineers believe efforts to capture climate pollution already emitted will be necessary to hold warming to relatively safe levels.

Scientists have proposed a range of ideas to do that, from fertilising the ocean with iron to help it absorb more carbon dioxide, to planting many more carbon-absorbing trees.

About 87 per cent of science models that show a path to holding world temperature hikes to below 2 degrees Celsius rely on such technologies, said Gideon Henderson, a geochemist at the British Royal Society and chair of a group of UK scientists and engineers looking at the technologies.

The problem, he and other scientists said on Wednesday at a discussion in London, is that much of the needed technology is still untested, not commercially viable, likely to lead to other risks or simply not possible at the scale needed.