Analysis of Costs and Time Frame for Reducing CO 2 Emissions by 70% in the U.S. Auto and Energy Sectors by 2050.

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.