The most consequential impact of Trump’s climate policies? Wasted time.

We added a lot of carbon dioxide to the atmosphere during the Trump years, but the biggest loss was failing to make forward progress, experts say.

For decades, climate experts have warned that delaying action to limit global warming would make the problem more dangerous and harder to solve. So how much impact did four years of delay under President Donald J. Trump actually have?

On the total amount of extra carbon dioxide added to the atmosphere in the past few years, surprisingly little, says Leah Stokes, a climate policy expert at the University of California, Santa Barbara. But the bigger cost was to slow down progress that was being made. Climate and economic costs of creating a future with fewer fossil fuels are increasing steeply each year, so an extra four years on hold, at least in the United States, puts even more pressure on future leaders.

“It’s not just that we’ve been moving in the wrong direction, but also we haven’t been moving in the right direction,” Stokes says.

What policies mattered most?

During his campaign in 2016, Trump had already announced his skepticism of climate change. After he took office in 2017, his administration made decision after decision that slowed or deprioritized climate action. It rolled back policies that helped mitigate warming, relaxed regulations for climate polluters, approved the Keystone XL pipeline, left the Paris Agreement, and more.

In early 2017, for example, Trump told the EPA to dismantle the Clean Power Plan, an Obama-era policy that aimed to reduce carbon emissions from the power sector to 32 percent below 2005 levels by 2030. That plan would have avoided about 70 million tons of emissions by this year and over 400 million tons by 2030.

Instead, the EPA replaced the Clean Power Plan with the Affordable Clean Energy (ACE) rule, which set no national emissions goals, allowing states to decide how to regulate emissions from power plants. The agency estimated that its rule would have resulted in only 11 million tons less CO2 in the atmosphere by 2030—about a year’s worth of Rhode Island’s emissions, based on 2017 numbers.

Similarly, the administration weakened vehicle fuel efficiency standards, finalizing rules with new, less ambitious goals in March 2020. The changes wouldn’t have large impacts in the immediate future but would slow down the transition to more efficient cars and trucks. So would the administration’s withdrawal of a waiver allowing California to set stricter vehicle emission standards—an action that is still being challenged in court.

The administration also changed rules about how much methane, a super-potent greenhouse gas, could be emitted as a byproduct of oil and gas drilling and from landfills. EPA estimates that its new rules, finalized in 2020, will result in an extra 850,000 tons of methane added to the atmosphere by 2030, though some experts think this is an underestimate. Methane is a much more powerful warming agent than carbon dioxide in the short-term, meaning its impacts could have a strong influence in the near future.

Many other rules were weakened and many subtler signals sent that favored the fossil fuel economy. “There are so many things they did, and each individual decision doesn’t quite rise up to the surface as a big fossil emissions impact,” says Narayan Subramanian, a climate policy expert and fellow at Data for Progress and the University of California, Berkeley “But they have a kind of collective impact.”

How big an impact?


Quantifying the impacts of these policy changes is difficult, says Kate Larsen, an analyst at the Rhodium Group, in part because future emissions will also be affected by other things like the weather (cold winters drive emissions up) and economic trends (a shift toward renewables is occurring even without policy nudges).

But Larsen and her colleagues tried anyway: They estimated how much carbon dioxide Trump’s most significant moves might add to the atmosphere by 2035.

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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