China鈥檚 pledge to reach carbon neutrality by 2060 may depend on extracting greenhouse gases from the air at massive scales 鈥� on the order of 2.5 gigatonnes of carbon dioxide per year.
Chinese President Xi Jinping聽announced the聽ambitious target last month at the UN general assembly, saying that the country鈥檚 aim was 鈥渢o have CO2聽emissions peak before 2030鈥�.
To do so would require significant use of negative emissions technologies, such as capturing carbon dioxide directly from the air and the planting of new forests, according to analysis by Shreekar Pradhan at the University of Virginia and his colleagues.
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The researchers used a model that includes projections of future changes to global temperature and atmospheric carbon concentrations.
They simulated four potential trajectories of emissions reductions: a scenario with no climate mitigation policy, used as a reference; one in which only China achieves net zero by 2060; a global net-zero scenario in which all countries achieve overall carbon neutrality by 2060; and a final scenario that limits global warming to 1.5掳颁聽by 2100.
The researchers predicted that the global net-zero scenario will result in about 1.8掳C of warming by 2100.
Although China is now the world鈥檚 biggest carbon emitter, the modelling suggests that if it is alone in achieving net-zero emissions by 2060, the world will remain on course for more than 3掳C of warming over pre-industrial levels by 2100.
The researchers also looked at China鈥檚 path to net zero. They concluded that China will need to make significant use of negative emissions technologies. These include so-called direct air capture that removes carbon dioxide from the atmosphere, an option that isn鈥檛 currently available commercially. Direct air capture may ultimately prove to be expensive to operate. It may never become a commercial option.
鈥淭here is a risk of doing things with the expectation that negative emissions technologies will be realised in future,鈥� says Pradhan.
The priority should be on taking immediate steps to overhaul China鈥檚 energy system, rather than relying on the promise of future carbon-sucking technologies, says Li Shuo at Greenpeace East Asia in China. At present, two-thirds of China鈥檚 power consumption is coal-based.
鈥淭here鈥檚 no way to reconcile a zero-carbon future鈥� with new coal-fired power plants,鈥� says Li. 鈥淲hen we talk about offsets [such as direct air capture], we are actually talking about the very last few miles in a very long journey.鈥�
Frank Jotzo at the Australian National University says at least a modest level of negative emissions approaches will be necessary to reach net zero, both in China and globally.
鈥淭here will be some activities and processes that will have some remaining greenhouse gas emissions even in a world where we devote very great efforts to cut emissions,鈥� he says.
Steel and cement production, for example, are highly carbon intensive.
Jotzo estimates that employing negative carbon emissions technologies to remove in the order of 2.5 gigatonnes annually might cost China hundreds of billions of dollars each year. 鈥淭hat鈥檚 within the realm of the affordable,鈥� he says.
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