CHICAGO, Oct. 13 (Xinhua) -- A new study of the University of Michigan (UM) indicates that climate action window may close as early as 2023, and it is urgent to reduce greenhouse gas emissions.

UM researchers found that steps outlined in the Clean Power Plan, proposed to be repealed by Donald Trump administration, as well as in the 2016 Paris climate accord, would not have been enough to meet the goal of keeping global temperatures increase to two degrees Celsius by the end of this century.

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 UM.

To arrive at the findings, UM researchers calculated the future greenhouse gas contributions of the auto and power industries based on two approaches going forward: "business as usual" and "climate action." Their calculations relied on the lowest-cost technologies in each sector.

In the "business as usual" scenario, the auto industry followed its current rate of vehicle diversification-utilizing efficient internal combustion, electric and hybrid models, and the power sector utilized mostly natural gas and renewable plants. In the "climate action" scenario, those sectors relied on a greater percentage of cleaner automotive and power technologies to meet the climate goals of Intergovernmental Panel on Climate Change (IPCC).

"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," said Steven Skerlos, UM professor of mechanical engineering.

"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," Supekar added.

The study found no evidence to justify delaying climate action in the name of reducing technological costs, even under the most optimistic trajectories for improvement in fuels efficiencies, demand, and technology costs in the U.S. auto and electric sectors.

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 dollars a year to 65 billion dollars a year.

For the most energy-hungry sectors in the United States, 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 IPCC has determined that in order to keep Earth's average temperature from rising more than 2 degrees Celsius above pre-industrial times by the end of the century, global greenhouse gas emissions must be reduced between 40 percent and 70 percent by 2050. 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.

The study has been published in Environmental Science and Technology.