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Mason professor explains how better fuel efficiency does (and doesn't) fit into global warming discussions

October 3, 2018

James Kinter III

What will be the consequences if Earth warms by an average seven degrees Fahrenheit (about four degrees Celsius) by the end of the century?

It is not a pretty picture, said professor James Kinter III, director of George Mason University’s Center for Ocean-Land-Atmosphere Studies.

Heat waves with daily temperatures of 95 degrees Fahrenheit and higher for longer than a week or two will be more common, Kinter said. Tropical cyclones will not necessarily increase in number but will be more intense and perhaps begin striking farther north in the United States with more regularity. Oceans, which are filling up as ice sheets melt, will also expand as they heat, meaning more rapid sea-level rise.

“It’s an entirely cumulative problem,” Kinter said. “The more carbon dioxide that is in the atmosphere, the more warming there will be. That’s a pretty simple way to look at it. If you want to avoid more warming, you avoid emissions.”

That simple relationship received a spotlight recently in an environmental impact statement issued by the National Highway Traffic Safety Administration, which justified President Trump’s decision to freeze fuel efficiency standards for cars and light trucks built after 2020.

That would countermand Obama administration rules that target fuel efficiency at 41.7 mpg for cars and 31.3 mpg for light trucks by 2020. Those rules also call for car fuel efficiency of 54.5 mpg by 2025.

One argument from the Trump administration is that fuel efficiency increases in the United States, compared to the global scale, would make little difference in slowing global warming and would also cost U.S. consumers and manufacturers money.

“I don’t think there is anything improper about the way they calculated the environmental impact,” Kinter said. “[Fuel efficiency] is a relatively small part of the picture, which includes thousands of coal-fired power plants around the world, industrial generation and deforestation.”

“But the other way to look at it,” Kinter said, “is every time some carbon dioxide puffs out of your tailpipe, you are contributing to global warming.”

Either way, Earth is warming. The question is, by how much?

Kinter pointed out that even if countries agree to extend their commitments of the Paris Agreement on the mitigation of greenhouse gas emissions after its 2030 expiration (Trump pulled the United States out of that agreement), Earth is still expected to warm by 6.3 degrees Fahrenheit by the end of the century, compared to preindustrial levels.

“Basically,” Kinter said, “if you want to avoid dangerous global warming, we should stop emitting [greenhouse gases] tomorrow.”

James Kinter III can be reached at 703-993-5700 or

For more information, contact Damian Cristodero at 703-993-9118 or

About George Mason 

George Mason University is Virginia’s largest public research university. Located near Washington, D.C., Mason enrolls 37,000 students from 130 countries and all 50 states. Mason has grown rapidly over the past half-century and is recognized for its innovation and entrepreneurship, remarkable diversity and commitment to accessibility.