Using a least-cost optimization framework, it is shown that unless emissions reductions beyond those already in place begin at the latest by 2025 (±2 years) for the U.S. automotive sector, and by 2026 (−3 years) for the U.S. electric sector, 2050 targets to achieve necessary within-sector preventative CO₂ emissions reductions of 70% or more relative to 2010 will be infeasible. The analysis finds no evidence to justify delaying climate action in the name of reducing technological costs. Even without considering social and environmental damage costs, delaying aggressive climate action does not reduce CO₂ abatement costs even under the most optimistic trajectories for improvements in fuel efficiencies, demand, and technology costs in the U.S. auto and electric sectors. In fact, the abatement cost for both sectors is found to increase sharply with every year of delay beyond 2020. When further considering reasonable limits to technology turnover, retirements, and new capacity additions, these costs would be higher, and the feasible time frame for initiating successful climate action on the 70% by 2050 target would be shorter, perhaps having passed already. The analysis also reveals that optimistic business-as-usual scenarios in the U.S. will, conservatively, release 79–108 billion metric tons of CO₂. This could represent up to 13% of humanity’s remaining carbon budget through 2050.

中文翻译：

---

到2050年将美国汽车和能源行业的CO ₂排放量减少70％的成本和时间表分析

使用最低成本的优化框架，结果表明，除非美国汽车行业的减排量最迟于2025年（±2年）开始，并且美国电力行业的减排量最迟在2026年（−3年）开始，到2050年实现部门内预防性CO ₂排放量相对于2010年减少70％或更多的目标将是不可行的。分析发现没有证据证明以降低技术成本为名而推迟采取气候行动。即使不考虑社会和环境损害成本，延迟积极的气候行动也不会减少CO ₂甚至在美国汽车和电力部门改善燃油效率，需求和技术成本的最乐观轨迹下，减排成本也是如此。实际上，随着2020年以后每年的延迟，这两个部门的减排成本都会急剧增加。当进一步考虑技术营业额，退休和新增产能的合理限制时，这些成本将会更高，并且可行的时间表是在2050年达到70％的目标上发起成功的气候行动的过程可能会更短，也许已经通过了。该分析还显示，保守地，美国乐观的照常情景将释放79-1080亿公吨的CO ₂。到2050年，这可能占人类剩余碳预算的13％。