President Trump speaks about the U.S. role in the Paris climate change accord in the Rose Garden of the White House. (Andrew Harnik/AP)

Carbon-cutting efforts in the United States may be more resilient to Trump administration policies than expected, according to a new study. But under even one term for President Trump, the nation will still fall behind on an ambitious Obama-era plan for reducing emissions over the next few decades.

Despite the Trump administration’s large-scale rollback of environmental policies, and the president’s withdrawal from the Paris climate agreement, U.S. emissions are likely to remain relatively flat over the next few years, according to research published last week in the journal Climate Policy. Researchers at North Carolina State University argue that market forces are likely to bolster the expansion of clean energy and other emissions-cutting efforts, particularly in the electricity sector, against changes in federal policy.

Even so, the paper estimates that by 2050 a single Trump term could lead to the release of 12 billion more metric tons of carbon dioxide than would have been emitted under the Obama administration’s long-term plan for cutting emissions, a detailed proposal known as the Mid-Century Strategy for Deep Decarbonization released at the end of President Barack Obama’s final term. If Trump is elected to a second term, his policies would release an additional 20 billion metric tons of carbon dioxide. That’s equivalent to more than half a year’s worth of carbon emissions across the globe.

The Mid-Century Strategy aimed to bring U.S. emissions down to 80 percent below their 2005 levels by the year 2050. The plan was meant to build upon the nation’s pledge under the Paris climate agreement, a short-term target of cutting U.S. emissions by 26 percent to 28 percent below their 2005 levels by the year 2025. As The Washington Post’s Chris Mooney reported in November, the Obama-era strategy’s long-term climate effects would be tantamount to the impact of suddenly removing all vehicles from U.S. roads.

But if emissions remain flat under the Trump administration, this means that any subsequent administrations that want to meet the same climate goals outlined under the Obama-era strategy would have to introduce policies that cut carbon emissions at an even faster rate than the Obama plan.

The authors make a good case for why U.S. emissions are likely to remain flat under President Trump,” said Marc Hafstead, an environmental economist and research fellow at the nonprofit Resources for the Future, who was not involved with the analysis. “While the administration’s policies will prevent further declines in emissions in the next four to eight years, market forces and aggressive state policies — in California, for example — make it equally unlikely emissions will increase in the near term.”

The authors examined five sectors that contribute to greenhouse gas emissions — electricity, land use, buildings and infrastructure, transportation and non-carbon dioxide emissions sources such as methane — to analyze how vulnerable they may be to changes in federal climate policies. They found that, given the future outlook for U.S. coal mining, the electricity sector is likely the most stable.

Despite repeated promises from the Trump administration to revitalize the declining coal industry, the expansion of cheaper natural gas and renewables such as wind and solar is likely to prevent that from happening, the authors note. Even in the absence of the Clean Power Plan, the Obama administration’s flagship effort to reduce carbon emissions from the electricity sector, “it’s hard to imagine a big coal rebound,” said Harrison Fell, an environmental economist at N.C. State and one of the new paper’s authors.

With the coal industry in decline, the authors write, greenhouse gas emissions from the electricity sector are “unlikely to increase dramatically in the near-term, and may even continue to see small declines.”  

The other sectors the researchers studied may carry slightly more uncertainty, Fell said, although the analysis suggests they’re also unlikely to see steep increases in emissions over the next few years.

So far, the Trump administration has not made major changes in land-use policies, for example, and researchers suggest that “it is reasonable to assume that recent trends — modest but decreasing gains in carbon sequestration — continue in the short-term absent federal leadership.”

Trump has threatened to cut funds for federal energy efficiency programs for buildings and appliances, but those measures would need approval from Congress. The report notes that total energy consumption from buildings in the residential, commercial and industrial sectors has remained largely flat over the past decade and is unlikely to change without major federal action.

And attempts from both Congress and the Trump administration to roll back Obama-era rules aimed at reducing methane emissions have so far been unsuccessful.

As for the transportation sector, the authors do note a risk that the Trump administration may try to revise or overturn Obama-era fuel economy standards for vehicles. The Republican-controlled Congress could also target the federal Renewable Fuel Standard, which requires gasoline to contain certain percentages of biofuel. Both measures could lead to a modest increase in greenhouse gas emissions.

On the other hand, Fell said, Trump has expressed a strong interest in aggressive infrastructure projects, including road-building, which could mute the effects of the looser fuel standards.

“It’s hard to imagine that they could do big things, at least in road infrastructure, without revisiting perhaps a gasoline tax increase,” Fell said. A gasoline tax could motivate people to buy more fuel-efficient vehicles and drive less, he said, reducing transportation-sector emissions.

State and local efforts could also help buffer the affects of new federal emissions policies, Fell said.

Environmental economist Hafstead noted that the Obama-era strategy “is just one potential pathway to deep decarbonization” and that there was substantial uncertainty about how the United States would ultimately meet those goals. And because we’re unsure which policies would have been key to achieving those results, Hafstead said, there’s also uncertainty over which Trump policies are likely to have the greatest effect on long-term U.S. emissions.

Still, assuming emissions do stay flat for the next four to eight years, the nation will definitely emerge from a Trump presidency behind on its former climate goals.

Meeting the Obama administration’s goals would have required an annual reduction in emissions of at least 117 million metric tons of carbon dioxide starting in 2017. After a four-year Trump term, and assuming another two-year lag for the next administration’s policies to kick into effect, meeting the same goals by 2050 would require an annual reduction of 142 million metric tons. If Trump continues those policies for a second term, the United States would need an annual reduction of 165 million metric tons of carbon dioxide under the Obama-era strategy.

In other words, the longer the hold on federal climate action lasts, the more work must be done by future administrations to meet those 2050 targets, the authors write, noting that “even a pause on an otherwise declining emissions trajectory shifts the burden to later years and increases the risk associated with uncertain climate impacts.”