The world is lagging on efforts to strip carbon dioxide from the atmosphere and buy more time to deal with climate change, a new report warns.
The report is the first comprehensive assessment of efforts to extract and put the greenhouse gas into long-term storage by harnessing natural processes, such as absorption by trees, and emerging technologies.
Carbon dioxide removal, or CDR, is no silver bullet when it comes to climate change and deep emissions cuts remain essential.
But sucking up CO2 for enduring storage on land, in the ocean, in geological formations or in products is akin to a life jacket that will buy time for the transition to net zero emissions.
However, the report has identified a yawning gap between the scale of CDR activities globally and what's needed to meet the Paris climate pact's goals.
About 1300 times more CDR from new technologies - and twice as much from trees and soils - may be necessary to limit warming to well below 2C.
"Scaling up carbon dioxide removal is an urgent priority, as are efforts to rapidly reduce emissions, if we are to meet the temperature goals of the Paris agreement," says lead author Professor Gregory Nemet, from the University of Wisconsin-Madison.
Almost all CDR is occurring via conventional methods that put carbon into storage in the landscape.
Two examples are afforestation - essentially planting trees in areas where there aren't any - and better managing soils to foster carbon absorption and retention.
Novel CDR is everything else including emerging technologies such as direct air capture, which extracts carbon dioxide from the atmosphere for storage in geological formations.
The report estimates 2 gigatonnes of carbon dioxide are being removed from the atmosphere each year.
National pledges under the Paris agreement suggest that will need to hit 2.6 gigatonnes a year by 2030 and 2.9 gigatonnes by 2050.
But the report says few countries have explicit strategies to scale up CDR and novel technologies that will help the world get there remain immature.
Just 0.1 per cent of carbon dioxide that is being removed today involves novel approaches, with the rest taken care of via land reservoirs.
"The next decade is crucial for novel CDR, in particular, since 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," the report warns.
Prof Nemet adds: "We need to start deploying these really novel techs that are at tiny scale now, so they can become developed, de-risked, so that markets can emerge."
Report co-author Dr Annette Cowie, from the climate branch of the NSW Department of Primary Industries, says few countries have specific policies and strategies to scale up CDR.
That's despite the fact CDR can battle climate change on three fronts.
"Firstly, in the near term, by helping to reduce net emissions, secondly by helping to get to this magic point of net zero, and thirdly, after we get to net zero to take more CO2 out of the atmosphere so we're in a net negative situation," she says.
"That's going to be needed on a global scale if we need to overcome an overshoot situation (where) the temperature goes higher than the safe level."
Aaron Tang is a lecturer in climate policy at the Australian National University and says Australia does not have explicit policies to scale up CDR and so far there's no substantive political discussion about it.
But he says the Climate Change Authority could recommend Australia's next Paris pact pledge be split in two - one target for emissions reductions and another for removals.