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The rollback of the fuel efficiency standards, they found, would add about 450 million tons of CO2 or its equivalent; the withdrawal of California’s waiver, if it were upheld, would add about 570 million tons more, mostly by slowing the switch to electric vehicles. The weaker methane rules would contribute 640 million tons.
With a few more odds and ends, the Rhodium analysts arrived at their bottom line: The Trump Administration’s actions could add a total of at least 1.8 billion tons of extra CO2 to the atmosphere by 2035.
That’s about 30 percent of what the U.S. emitted in a single year, 2019.
The effects of replacing the Clean Power Plan with ACE would make that number bigger, but the magnitude of the effect isn’t certain. And Larsen stresses that there were many more ineffable changes made that were difficult or impossible to quantify, so the number is likely to be a low-end estimate.
Subramanian says it’s important to know that “nothing was permanently lost, in terms of the regulatory framework for environmental policy. Everything [the Trump Administration] has done on the regulatory front is reversible.”
The real question, he says, is how long it will take a Biden administration to reverse course again and “affirmatively push the needle on climate action,” and to get the emissions trend going firmly the right direction.
In search of lost time
Since U.S. emissions reached their all-time high in 2007, they’ve generally trended downward. In 2018, they rose to about 5.9 billion metric tons, according to Rhodium, before falling again in 2019 to 5.7 billion metric tons, about the same as in 2017. In 2020 they’re falling sharply again—but only because the pandemic partially shut down the economy and people aren’t travelling or commuting nearly as much.
Yet scientists agree that emissions must fall rapidly and sustainably, in the U.S. and elsewhere. “We have only a finite amount of carbon that we can emit,” says Kirstin Zickfeld, a climate scientist at Simon Fraser University in British Columbia, “and we have blown through most of it.”
The exact amount left in that “carbon budget,” and how it should be split up among countries, are hotly debated topics. But, says Zickfeld, a simple way to look at the issue goes like this. To have a 50/50 chance of keeping the planet from warming beyond 2.7 degrees Fahrenheit (1.5 degrees Celsius)—the most ambitious goal set by the Paris Agreement—the world should limit itself to emitting less than about 500 billion more tons of carbon dioxide in total.
At the rate we’re all emitting—globally, about 36 billion tons of fossil carbon dioxide a year—that budget will be exhausted in just over 12 years. The challenge is to get to “net zero” emissions before the budget is spent.
Larsen did a rough calculation to illustrate how the Trump Administration has affected that challenge in the U.S., where President-elect Joe Biden has now embraced the net-zero goal. If after 2016 the country had wanted to steer toward that goal and comply with the Paris Agreement, it would have needed “to keep up emission reductions between 2025-2030 of 4.4 percent per year to stay on track for net zero by 2050,” Larsen wrote in an email.
But, after the Trump rollbacks, she writes, “we’ll have to hit 5.4 percent reductions each year on average between 2025-2030 to stay on track.”
Each year where progress isn’t happening makes the cuts required deeper and the ultimate goal harder to hit. Many experts regard the time wasted as the biggest loss of the last four years.
Ben Sanderson, a climate scientist at France’s CERFACS research center, and a colleague recently looked at how delaying climate action affects the economic cost of addressing it.
“As you get closer to the [1.5C target], it’s getting exponentially more expensive with each passing day,” he says. “We really are right on the cusp of that being impossible.”
“To me, what hasn’t happened over the last four years is much more important than what has happened,” says Noah Kaufman, a climate policy expert at Columbia University. “The more you delay, either the more costly those policies will become to implement, or the alternative is that you just won’t achieve as much with them. That’s the impact of the Trump years.”
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