Some NET technologies can be costly, controversial and many are still in the early phase of testing. However, other NETs are ready to be deployed at scale, this includes land management practices that store more carbon in agricultural soils and forests. However, there’s no way those methods alone could ever capture enough carbon to keep Earth’s temperature from rising another degree.
Other more technological solutions need more research. This includes technologies that mimic natural rock weathering practices on a vastly accelerated time scale. Although there are prototypes of air capture machines that suck carbon out of the atmosphere and store it underground, the technology is unproven.
Even under the most optimistic scenarios the transition from fossil fuels to clean sources of energy like renewables will take time and if we are to have a shot at keeping global temperatures below the upper threshold limit GHG emissions will need to be prevented from reaching the atmosphere. According to the IPCC and almost all climate models, cutting CO2 emissions over the next few decades won't be enough to stop climate change.
"It's not a question of 'Maybe we'll need negative emissions technologies or maybe we can prevent more CO2 from going into the air’" Erin Burns, a senior policy advisor at the think tank Third Way, told Business Insider. "We are at a point where we need all of those things." As explained by Kate Gordon, a fellow at Columbia University’s Center on Global Energy Policy, "We need to be committed to it today, because we know from all the modeling that's happening that this is not an if question, it's a when question."
A study from the National Academies of Sciences, Engineering, and Medicine recently estimated that to meet climate targets, the world will need to remove as much as 10 gigatons of CO2 from the atmosphere each year by mid-century. The study suggests NETs have an unlimited capacity for reducing carbon levels in the atmosphere. The study supports investments in technologies that filter out CO2 molecules from the air. This involves materials that naturally attract and bind with carbon. That carbon would then get concentrated and stored, perhaps by injecting it into pores in deep underground rock.
As reported by the Guardian, Bill Hare of Climate Analytics, a science and policy institute thinks NETs are essential despite the concerns raised by Corinne Le Quéré, director of the Tyndall Centre for Climate Change Research at the University of East Anglia. Efforts to store captured carbon underground are "showing no progress … and even backwards steps in some cases", said Le Quéré.
"[I]f you’re really concerned about coral reefs, biodiversity [and] food production in very poor regions, we’re going to have to deploy negative emission technology at scale," said Hare, adding, "I don’t think we can have confidence that anything else can do this...we will need geoengineering by the mid-2030s to have a chance at the [1.5C] goal".
The costs of such technologies are sometimes put forward as a constraint, however there is reason to believe that technological advancements can reduce costs. As we research and scale these technologies the price can be expected to decline substantially and as we ebb ever closer to tipping points the costs may become secondary to survival.
"[T]he world no longer has the luxury of waiting for emission reduction strategies to do the job alone. Far from being a Plan B, NETs must be a critical part of Plan A, and embracing them sooner rather than later makes economic sense," said Nat Keohane the Senior Vice President of EDF's Climate program. "Because the marginal costs of emission reductions rise as more emissions are cut, it will be cheaper to deploy NETs at the same time as emission reduction technologies rather than waiting to exhaust those options first."
There is justifiable concern that investments in NETs will diminish the pressure to quickly cut emissions. We cannot afford to ignore proven approaches, such as improving energy efficiency, promoting cleaner transport, eating less meat and scaling up renewable energies. While emissions reduction must remain a dedicated focus of international attention, we will also need to invest billions to develop and scale NET technologies.
The University of Tasmania professor Pete Strutton offered the following succinct warning: "There is no way for Earth to stay below 3 C without large-scale emissions capture and storage, in addition to massive emissions reduction," he said . "Governments and individuals need to act swiftly." The key challenge is quickly scaling NETs and to do this government support is key..
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