The world needs to heavily invest in efforts to remove long-lived carbon dioxide from the atmosphere, as well as rapidly reduce greenhouse gas emissions.
This is the chief finding of an independent report drawing on the expertise of 26 international researchers, who say all scenarios laid out by the Intergovernmental Panel on Climate Change will require decades of concerted carbon removal if the world is to avoid the two-degree ceiling target of the Paris Agreement.
Substantial scale up of both conventional carbon removal methods – like reforestation – and innovative, novel technologies, is required.
Unfortunately, the carbon dioxide removal sector is, in the view of the report, at roughly the same point the renewables sector was at the end of last century: promising but in need of major investment to be ‘Paris effective’.
Reforestation – the creation of new forests – and the integration of new vegetation into agricultural land, are typically the first port-of-call for carbon capture. These methods could sequester up to 10 gigatonnes of carbon dioxide a year in 2050.
But right now, conventional methods would account for 2,000 megatonnes of carbon capture annually.
It overshadows innovative capture technology though, which accounts for just two megatonnes, or less than 0.1%, of carbon capture.
“This illustrates a need for massive scale up,” says one of the report’s lead authors Gregory Nemet from University of Wisconsin-Madison.
“The scale up is even bigger on the novel CDR [carbon dioxide removal] because it’s starting from such a small base of only about 1-2 million tonnes a year, and we’re talking about getting up to gigatons in the next 30 years.
“27 years from now, we need to scale up novel CDR by a factor of 1300 and we have to, in fact, increase by a factor of 30 by 2030. So that’s the big challenge.”
That big gap needs to close quickly
Three scenarios relevant to the Paris Climate Agreement – emphasising either renewable energy, carbon removal or reduction in carbon use – highlight the divide between ambition and requirement.
Conventional means are only included in national pledges to remove around 2,600 megatonnes of carbon annually until decade’s end, but in each scenario, current carbon removal mechanisms will fall significantly short in helping to meet the Paris target.
The immediate opportunity is in expanding the use of forest-based capture methods.
“The biggest potentials amongst the most ready technologies [are] the tree planting, soil carbon and biochar,” says Dr Annette Cowie, an adjunct professor at the University of New England’s school of environmental and rural science.
Soil carbon sequestration is a biological process where improvements in land management allow CO2 to be captured and stored in soils, which in turn improves their quality, resilience and productivity. But while it’s a relatively cheap form of carbon removal, the expense of measuring hard-to-see carbon in soils is an important consideration for government’s regulating offset schemes, which recompense proponents of such projects.
Biochar is a residue (like charcoal and other carbon products) produced by the slow heating of organic materials. But whereas soil carbon is a mature form of carbon removal, biochar production is only just beginning to realise its commercial potential in Australia.
“Building soil organic matter is always a good thing to do, it’s good for agriculture and the environment, so there’s no reason not to do that. But there are barriers to, for example, developing schemes to give carbon credits to farmers for soil carbon.
“The methods have all got pros and cons, and we need to be looking at all of them.”
Time to ramp up
Investment and development of novel technologies is seen as essential to deplete excess carbon.
These include technologies that directly capture and store air carbon, treat oceans with alkaline materials to reduce acidity, redisperse marine nutrients, directly removing carbon and using bioenergy in the process of sequestration.
But nations around the world, including Australia, are still at the start line when it comes to implementing new carbon removal technology.
Aaron Tang from ANU’s Fenner School of the Environment and Society says there’s a slim silver lining in Australia’s adoption of climate targets in law, but there’s still a distance to go before it begins the physical removal of carbon.
While existing policy and credit schemes offer incentives to implement carbon sequestration projects, these aren’t yet at a scale sufficient to achieve the removal required.
“We’re not really where we want to be,” Tang says.
“We don’t’ really have explicit policy to scale up CDR… we don’t have even have a substantive political and policy discussion underway in Australia just yet… but I think Australian carbon removal policy is very much on the horizon.”
The solution to making deep carbon cuts lies, according to the report, in pairing both removal and reduction strategies.
“One of the main takeaways from this report is we should really be thinking about a portfolio of solutions,” says Nemet. “It’s a portfolio because we’re really focussed on emissions reductions and then we’re adding conventional CDR, and then we’re scaling up and eventually adding novel CDR
Matthew Agius is a science writer for Cosmos Magazine.
Read science facts, not fiction...
There’s never been a more important time to explain the facts, cherish evidence-based knowledge and to showcase the latest scientific, technological and engineering breakthroughs. Cosmos is published by The Royal Institution of Australia, a charity dedicated to connecting people with the world of science. Financial contributions, however big or small, help us provide access to trusted science information at a time when the world needs it most. Please support us by making a donation or purchasing a subscription today.