In this study Dan Tong et. al. used detailed datasets of existing fossil-fuel energy infrastructure in 2018 to estimate regional and sectoral patterns of committed carbon dioxide emissions, the sensitivity of such emissions to assumed operating lifetimes and schedules, and the economic value of the associated infrastructure. From this, they estimate that, if operated as historically, existing infrastructure will cumulatively emit about 658 gigatonnes of carbon dioxide (with a range of 226 to 1,479 gigatonnes carbon dioxide, depending on the lifetimes and utilization rates assumed). 

More than half of these emissions are predicted to come from the electricity sector; infrastructure in China, the USA and the 28 member states of the European Union represents approximately 41 per cent, 9 per cent and 7 per cent of the total, respectively. If built, proposed power plants (planned, permitted or under construction) would emit roughly an extra 188 (range 37–427) gigatonnes carbon dioxide. 

Committed emissions from existing and proposed energy infrastructure (about 846 gigatonnes carbon dioxide) thus represent more than the entire carbon budget that remains if mean warming is to be limited to 1.5 degrees Celsius (°C) with a probability of 66 to 50 per cent (420–580 gigatonnes carbon dioxide), and perhaps two-thirds of the remaining carbon budget if mean warming is to be limited to less than 2 °C (1,170–1,500 gigatonnes carbon dioxide). 

The remaining carbon budget estimates are varied and nuanced, and depend on the climate target and the availability of large-scale negative emissions. Nevertheless, their estimates suggest that little or no new carbon dioxide-emitting infrastructure can be commissioned, and that existing infrastructure may need to be retired early (or be retrofitted with carbon capture and storage technology) in order to meet the Paris Agreement climate goals. Given the asset value per tonne of committed emissions, we suggest that the most cost-effective premature infrastructure retirements will be in the electricity and industry sectors, if non-emitting alternatives are available and affordable.

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