This is a summary of an essay published in Foreign Affairs.
A wave of destructive hurricanes, heat spells and wildfires has ravaged communities across the United States over the past year – bringing new urgency to the need for climate action, as both scientists and citizens are able to connect these extreme events to a warming Earth.
Time is of the essence, but it's not too late to solve the global climate crisis. A decade of extraordinary innovation has made a greening of the global economy not just feasible, but likely. Now a whole new arsenal is emerging in the fight against climate change: negative emission technologies.
Alongside aggressive action to cut emissions, these technologies will be crucial to reaching "net zero" carbon emissions – the point where any climate pollution we add to the atmosphere is balanced by what we take out. The U.S. must reach this goal by 2050, with the world as a whole reaching net zero as soon as possible thereafter, if we are to stabilize our atmosphere.
$1 billion – just to research it
NETs are different from conventional approaches to climate mitigation because rather than seeking to reduce the amount of greenhouse gases we've emitted into the atmosphere, they focus on removing carbon dioxide that's already there.
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Some NETs are ready to be deployed today, including land management practices that store more carbon in agricultural soils and forests. Others are at the pilot stage – like direct air capture machines that suck carbon out of the sky and store it underground. And then there are some on the horizon, such as technologies that mimic natural rock weathering practices on a vastly accelerated time scale.
A key challenge is getting to scale. The National Academies of Sciences, Engineering, and Medicine recently estimated that to meet its climate targets, the world will need to remove as much as 10 gigatons of CO2 from the atmosphere each year by mid-century – nearly twice the current annual emissions in the U.S. from burning fossil fuels.
The report recommends as much as $1 billion annually in U.S. government funding for research on NETs.
Airlines could pave the way for NETs
We've long known that pricing emissions through a carbon tax or an emissions trading system creates an economic incentive for cheaper, faster ways to cut pollution. Valuing negative emissions – through tax rebates or tradeable credits for removal – would spur countless more entrepreneurs to join the hunt for NETs.
Standing in the way of those incentives is the lack of a global market for carbon credits. But progress on that front is coming from an unlikely place: aviation.
Airlines, which account for about 2 percent of global carbon emissions today and are set to triple or quadruple such pollution by mid-century, have agreed to cap the CO2 emissions from international flights at 2020 levels with the help of a global carbon credit program.
A pot of gold will await companies that cut or remove aviation carbon emissions.
Done right, this program – the Carbon Offsetting and Reduction Scheme for International Aviation, or "CORSIA" – could catalyze a global carbon market that drives investment in low-carbon fuels and technologies such as NETs.
Over the first 15 years of CORSIA, demand for aviation credits is estimated to reach between 2.5 billion and 3 billion tons – roughly equal to the greenhouse gas emissions the U.S. power and manufacturing sectors release annually.
With this new demand, there is a good possibility that a pot of gold will await companies that develop technologies to cut or remove aviation carbon emissions. CORSIA could also spur investment in NETs to make cleaner jet fuel, for example by producing fuel from waste or biomass through processes that, on balance, absorb more carbon than they emit.
Carbon removal must be part of Plan A
Scientists and activists have historically tended to regard negative emission technologies as a fallback option, to be held in reserve in case other efforts fail. Many fear that jumping ahead and spending billions to suck carbon from the sky or to develop massive forest carbon sinks will distract from the critical need to cut pollution.
But the 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.
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.
Many NETs are ready to be deployed at scale today, and they could help make the difference between limiting warming to bearable levels, and failing to do so. Thanks to the emerging global carbon market for aviation, we may soon be on our way.
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