- Per the IPCC, it would mean emissions falling to net-zero by roughly mid-century.
What they did: The new paper in the peer-reviewed journal Nature compares future emissions from infrastructure — power plants, vehicles, industrial plants and more — against the estimated remaining "carbon budget" for staying within 1.5°C and 2°C.
What they found: Projected cumulative emissions from existing infrastructure, roughly 658 gigatonnes, are much higher than the estimated remaining 1.5°C budget.
That's what you can see in the chart above, which shows that even expected lifetime CO2 from infrastructure and vehicles already in use are enough to surpass 1.5°C of warming.
- “There’s a lot of aspirational talk about the 1.5 target, and I think that’s all good, but there are some sobering realities if we wanted to meet that target,” co-author Steven Davis of UC Irvine tells me.
- A substantial amount of these "committed" future emissions are from relatively young coal-fired power fleets in China and India.
- Davis notes the findings are conservative. The paper doesn't include emissions from fossil fuel extraction and deforestation.
The bottom line: Any shot at 1.5°C likely means shutting down lots of power plants before the end of their roughly 40-year lifetimes.
- "[U]nless compensated by negative emissions technologies or retrofitted with carbon capture and storage, 1.5 °C carbon budgets allow for no new emitting infrastructure and require substantial changes to the lifetime or operation of already existing energy infrastructure," the paper states.
Threat level: Additional emissions from power plants that are planned or under construction already make staying within 2°C (the less ambitious Paris target) difficult to achieve.
- Emissions from existing infrastructure and proposed plants could consume two-thirds of the emissions budget for staying within 2°C, the report states.
What they're saying: Rutgers University climate scientist Robert Kopp, who was not part of the study, tells me the results are consistent with what's expected from energy forecast models, but notes the paper is "based on empirical data analyzed in a fairly transparent fashion."
"It emphasizes the radical transformations necessary to stabilize global temperature in the 1.5-2.0°C range: basically, an end to new construction of fossil fuel-based electric and industrial infrastructure, and — especially for 1.5°C — an acceleration of the retirement of existing infrastructure."
Go deeper: The climate stakes of speedy delivery
