Climate: Trump administration prepares to roll back greenhouse gas regulations

In 1970, the U.S. Congress, through the Clean Air Act, empowered the Environmental Protection Agency (EPA) to regulate "air pollution that may reasonably be expected to endanger public health." For decades, the EPA had the authority to regulate toxic pollutants, such as ozone, but not necessarily greenhouse gases (GHGs). However, as scientific knowledge about the role of GHGs in global warming grew, the EPA faced increasing pressure to include them.

The case reached the Supreme Court, which ruled in 2007: greenhouse gases are pollutants, and the EPA must take this into account. As a result, the EPA declared greenhouse gases dangerous to public health in 2009, allowing it to regulate them. The decision, known as an " Endangerment Finding, " thus forms the legal basis for numerous federal regulations aimed at combating global warming .

From rules on car exhausts to those on gas and coal-fired power plants, "all these individual rules go back to the 2009 observation," Meredith Hankins of the NGO Natural Resources Defense Council told AFP.

The "Endangerment Finding" has survived the courts and Donald Trump 's first term. But it has been directly in the Republican's crosshairs since his return to power. "The Trump administration will not sacrifice our nation's prosperity, energy security, and the freedom of our people for an agenda that strangles our industries, our mobility, and consumer choice," Lee Zeldin, Trump's new EPA chief, said in March when he announced a review of the 2009 finding.

His proposal was sent to the White House on June 30 for approval, according to a spokesperson, and a formal announcement is expected soon. The government is expected to argue that the economic cost of the various regulations has been underestimated, while asserting that pollution from American vehicles represents a negligible portion of global greenhouse gas emissions.

Yet transportation is the largest source of emissions in the United States. "If vehicle emissions aren't considered a contributor to climate change, I have a hard time imagining what would be," warns Dena Adler, a law professor at New York University.

Since 1970, U.S. vehicle emissions have exceeded the combined emissions of the nine countries that follow the United States on the list of the most polluting, according to an analysis by the Institute for Policy Integrity.

If the Trump administration does indeed overturn the 2009 Endangerment Finding , it will likely face legal challenges. In March, the EPA planned to rely on a 2024 Supreme Court decision narrowing the scope of federal regulations. But for many legal experts, that doesn't guarantee success in court.

"It's going to take years" to get all the way to the Supreme Court, says environmental law expert Dena Adler. And ruling in favor of the Trump administration would amount to a reversal of precedent: its 2007 decision is the very origin of the "Endangerment Finding."

There, nothing is impossible: the highest court in the country, with a conservative majority, reversed the federal right to abortion in 2022, a 180-degree reversal of a 1973 decision. If the Trump administration succeeds and removes regulations, however, industries will not necessarily change their practices overnight.

Electricity providers, for example, "are not going to make their decisions" on large investments based "on short-term policy changes," says John Tobin-de la Puente, a business professor at Cornell University.