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Committed emissions from existing energy infrastructure jeopardize 1.5 °C climate target

Dan Tong, Qiang Zhang, Yixuan Zheng, Ken Caldeira, Christine Shearer, Chaopeng Hong, Yue Qin, and Steven J. Davis · Nature 572, 373-377 · 2019

Key finding. Existing fossil-fuel energy infrastructure will cumulatively emit about 658 gigatonnes of CO2 if operated as it has been historically, with a range of 226 to 1,479 GtCO2 depending on assumed lifetimes and utilization rates; proposed power plants would add roughly a further 188 GtCO2.

A stacked area chart of committed annual CO2 emissions in gigatonnes per year from 2018 to about 2070, broken down by sector. Electricity is the largest band at 358 gigatonnes cumulative, followed by industry at 162 and road transport at 48, with smaller bands for other transport, residential, commercial, and other energy. A pale outer envelope labelled Proposed adds a further 188 gigatonnes. Total emissions decline steadily to zero by around 2060.
Committed emissions from infrastructure already built, by sector, if each asset runs its historical lifetime. Electricity dominates the total; the pale envelope shows how much power plants that were merely proposed would add on top. Figure 1 from Tong et al. (2019), Nature 572, 373-377. Reproduced under author reuse rights. Extracted from the published PDF and resized for web display.

What question did this research address?

Nine years after the idea of committed emissions was introduced, the stock of fossil-fuel infrastructure had grown substantially and the temperature target under discussion had tightened from 2 °C to 1.5 °C.

This paper asked what the world's existing energy infrastructure, as it actually stood in 2018, has already committed us to — and how much more would be committed if the power plants currently planned, permitted, or under construction are in fact built.

What did we find?

The estimate is built from detailed datasets of the fossil-fuel energy infrastructure actually in place in 2018, rather than from scenarios, and is resolved by region and by sector.

More than half of the committed emissions come from the electricity sector alone.

The geographic concentration is high. Infrastructure in China accounts for roughly 41 per cent of the total, the United States about 9 per cent, and the 28 member states of the European Union about 7 per cent.

Power plants that were planned, permitted, or under construction would, if built, emit an additional 188 GtCO2, with a range of 37 to 427 GtCO2.

The sensitivity of the total to assumed operating lifetimes and schedules is large, which means the commitment is not fixed — retiring plants earlier or running them less materially changes the outcome.

Why does it matter?

The comparison with the earlier assessment is the point. In 2010 the infrastructure then existing was consistent with staying below 2 °C; by 2018 the infrastructure existing and proposed was enough to jeopardize 1.5 °C. The commitment grew because building continued.

Because the total depends strongly on lifetimes and utilization, the finding identifies a lever that does not require any new technology — operating existing assets for less time, or less intensively, reduces committed emissions directly.

Citation

Dan Tong, Qiang Zhang, Yixuan Zheng, Ken Caldeira, Christine Shearer, Chaopeng Hong, Yue Qin, and Steven J. Davis (2019). Committed emissions from existing energy infrastructure jeopardize 1.5 °C climate target. Nature 572, 373-377.

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