World will probably warm beyond the...

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near-term ambition,” which entails rapid reductions in carbon dioxide emissions from all sectors of the energy system, immediately and through 2030.

If countries uphold their nationally determined contributions through 2030 and follow a 2 percent minimum decarbonization rate, for example, global carbon dioxide levels would not reach net zero this century.

Taking the most ambitious path outlined, however, could bring net-zero carbon dioxide emissions by 2057. Such a path, the authors write, is marked by “rapid transformations throughout the global energy system” and the scaling up of “low-carbon technologies like renewables, nuclear energy, as well as carbon capture and storage.” “The technologies that help us get to zero emissions include renewables, hydrogen, electric cars, and so on. Of course those are important players,” said Iyer. “Another important piece of the puzzle is the technologies that can remove carbon dioxide from the atmosphere, like direct air capture or nature-based solutions.”

The most ambitious scenarios outlined in their work are meant to be illustrative of the pathways on offer. But the central takeaway remains clear throughout all modeled scenarios: if 1.5 degrees is to be reattained sooner after we warm past it, more ambitious climate pledges must come.

This work was supported by the U.S. Environmental Protection Agency.