‘Large gap’ in carbon dioxide removal needed to curtail global warming

‘Innovation in CDR has expanded dramatically in past two years’

Current levels of carbon dioxide removal (CDR) from the atmosphere by conventional methods such as afforestation and novel technologies make it impossible to meet critical Paris Agreement climate targets including net-zero emissions, according to a global assessment.

The first independent evaluation of CDR — also known as “negative emissions” — concludes it an essential requirement in decarbonising economies alongside rapidly reducing emissions, if the Paris temperature goal to limit warming to below 2 degrees and pursue efforts to achieve 1.5 degrees are going to be met.

Almost all current CDR comes from conventional methods on land, such as planting trees and managing soils, 20 CDR experts led by the University of Oxford’s Smith School of Enterprise and Environment found.

Conventional CDR levels need to double in 1.5 pathways and increase by about 50 per cent in 2 degrees pathways by 2050 compared to 2020 levels, it suggests.


The study published on Thursday indicates 99.9 per cent of current CDR is from conventional methods such as planting trees with the remainder from novel methods such as biochar, a residue from the disposal of biomass; bioenergy with carbon capture and storage, and direct air capture with carbon capture and storage.

Through CDR, CO2 is captured from the air and stored durably on land, in the ocean, in geological formations or in products. Closing “the CDR gap” requires rapid growth of new CDR technologies, by a factor of 1,300 on average by 2050, it concludes.

“To limit warming to 2 degrees or lower, we need to accelerate emissions reductions. But the findings are clear: we also need to increase carbon removal, too, by restoring and enhancing ecosystems and rapidly scaling up new CDR methods,” says report author Dr Steve Smith of the University of Oxford.

“Many new methods are emerging with potential. Rather than focusing on one or two options we should encourage a portfolio so that we get to net zero quickly without over-relying on any one method,” he said.

CDR was not a silver bullet, as pathways limiting warming to 2 degrees or lower require deep emissions cuts in addition to, not in place of, CDR, he underlined, while dependence on CDR could be limited by reducing emissions fast and using energy more efficiently.

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While research, innovation and public awareness of CDR have expanded, closing the CDR gap requires urgent and comprehensive policy support by governments. “The amount of CDR deployment required in the second half of the century will only be feasible if we see substantial new deployment in the next 10 years,” he said.

“Given the orders of magnitude the CDR industry needs to grow by mid-century to limit warming, there is an urgent need for comprehensive policy support to spur growth,” said Prof Gregory Nemet of the University of Wisconsin-Madison.

“CDR is not something we could do, but something we absolutely have to do to reach the Paris Agreement temperature goal,” said Dr Oliver Geden of the German Institute for International and Security Affairs. “More than 120 national governments have a net-zero emissions target, which implies using CDR, but few governments have actionable plans for developing it.”

Dr Jan Minx from the Mercator Research Institute on Global Commons and Climate Change in Berlin said the state of CDR research, development and policy lags behind where needed – similar to renewables 25 years ago. “Good decisions and accelerated progress in the field of CDR require adequate data.”

Speaking at a briefing, Dr Smith said CDR was entirely feasible and in some instances could be regarded as “the oil industry in reverse”. Storage capacity in the North Sea could be deployed using the same transport and storage network and capture CO2 from fossil fuel production, cement manufacturing and biomass.

CO2 in many ways is a waste problem, he added, so it had to be reduced and the equivalent of a sewerage system put in place.

Dr Emily Cox of CO2RE at the University of Oxford acknowledged there were moral hazard issues with CDR. Emission reductions must always come first “and you cannot put all your eggs in the CDR baskets”, she said.

With reservations among the public about using CDR at scale, options had to be part of a two-way conversation on decarbonisation, she added.

Kevin O'Sullivan

Kevin O'Sullivan

Kevin O'Sullivan is Environment and Science Editor and former editor of The Irish Times