The 1.5 – 2 C path is still possible but requires a dramatic and rapid shift. The U.S. is the largest cumulative emitter of greenhouse gases, and the electric and auto industries account for nearly half of the country’s annual output. Fossil fuel combustion accounts for 95 percent of those industries’ emissions.
Sarang D. Supekar, Steven J. Skerlos. Analysis of Costs and Time Frame for Reducing CO2 Emissions by 70% in the U.S. Auto and Energy Sectors by 2050. Environmental Science & Technology, 2017; 51 (19): 10932 DOI: 10.1021/acs.est.7b01295
Rate of change, why earlier action is necessary
A new study from the University of Michigan underscores the urgency of reducing greenhouse gas emissions — from both environmental and economic perspectives. For the U.S.’s most energy-hungry sectors — automotive and electricity — the study identifies timetables for action, after which the researchers say it will be too late to stave off a climate tipping point; the longer the nation waits, the more expensive it will be to move to cleaner technologies in those sectors — a finding that runs contrary to conventional economic thought because prices of solar, wind and battery technologies are rapidly falling. “If we do not act to reduce greenhouse gas emissions forcefully prior to the 2020 election, costs ?to reduce emissions at a magnitude and timing consistent with averting dangerous human interference with the climate will skyrocket,” said Steven Skerlos, U-M professor of mechanical engineering. “That will only make the inevitable shift to renewable energy less effective in maintaining a stable climate system throughout the lives of children already born.” Using a custom, state-of-the-art model of these sectors, the researchers showed that the window for initiating additional climate action would close between 2023 and 2025 for the automotive sector and between 2023 and 2026 for the electric sector.
“That’s true under even the most optimistic assumptions for clean technology advancements in vehicles and power plants,” said study lead author Sarang Supekar, a mechanical engineering postdoctoral fellow at U-M. “At some point, likely by 2023, you actually can’t build the newer, cleaner power plants fast enough or sell enough fuel-efficient cars fast enough to be able to achieve the 70-percent target,” Skerlos said. Added Supekar, “The year-on-year emission reduction rate in such dramatic technology turnovers will exceed 5 percent after about 2020, which makes the 70-percent target infeasible for all practical purposes.” The analysis found no evidence to justify delaying climate action in the name of reducing technological costs, even under the most dramatic cost decline scenarios; in fact, the study found that waiting another four years to initiate measures on track with the 70 percent target would take the total cost for both sectors from about $38 billion a year to $65 billion a year..”The point is, regardless of whether the cost of climate action today is $38 billion or $100 billion, this cost will rise sharply in three to four years from now.”(Sarang D. Supekar, Steven J. Skerlos. Analysis of Costs and Time Frame for Reducing CO2 Emissions by 70% in the U.S. Auto and Energy Sectors by 2050. Environmental Science & Technology, 2017; 51 (19): 10932 DOI: 10.1021/acs.est.7b01295)