This key scientific finding underpins US climate action. Now Trump is being urged to ignore it

As President Trump’s attack on the climate continues, the US is considering repealing an important scientific finding that underpins the country’s climate action. 

According to the Washington Post, Environmental Protection Agency (EPA) Administrator Lee Zeldin has urged the White House to strike down the 2009 ‘Endangerment Finding.’ 

This finding determines that greenhouse gas emissions are a risk to public health, and gives the EPA a legal foundation for regulations to limit planet-warming pollution. 

Why does the EPA want to repeal this key climate finding?

On day one of Trump’s second presidency, he signed a slew of executive orders. This included EO 14154, also known as ‘Unleashing American Energy.’ Buried in the 20-page document is an instruction to the EPA Administrator which tasked him with reviewing the “legality and continuing applicability of” the Endangerment Finding. 

It gave Zeldin 30 days to submit recommendations to the head of the White House budget office, Russell Vought. 

The executive order effectively asked the EPA and other agencies to determine whether climate change is a hoax, as Trump has claimed many times in the past. A month on, Administrator Zeldin appears to have made his decision.

“I challenged Lee Zeldin to his face on the endangerment finding,” Senator Ed Markey posted on social media. “I knew he wouldn’t stand up to Trump's fossil fuel donors. If this admin wants to say that climate-fueled hurricanes, wildfires and droughts aren't a danger to our country, the admin itself is a danger to our country.”

In the wake of the planet’s hottest year on record and multiple climate-related disasters in the US, there is almost certainly going to be some opposition to this move. 

According to NOAA’s National Centers for Environmental Information (NCEI), in 2024 there were 27 individual weather and climate disasters in the US, causing at least $1 billion in damages. These disasters, it says, were responsible for at least 568 fatalities and cost the US $182.7 billion.

“Targeting the Endangerment Finding is extreme, dangerous, and puts important benefits at risk,” says Peter Zalzal, special projects director and lead attorney at the Environmental Defense Fund. “It also goes well beyond anything the first Trump administration undertook.”

What is the Endangerment Finding?

In 2007, the US Supreme Court ruled that greenhouse gases are air pollutants under the country’s Clean Air Act. It asked the EPA to make a science-based decision on whether they were a danger to public health. Two years later, the EPA issued the Endangerment Finding, which read:

“The Administrator finds that the current and projected concentrations of the six key well-mixed greenhouse gases—carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6)—in the atmosphere threaten the public health and welfare of current and future generations.”

This finding has formed the bedrock of the Clean Air Act and 15 years of greenhouse gas reduction in the US. Under this act, the EPA is legally obliged to limit the emissions of any air pollutant that may reasonably be anticipated to endanger public health or welfare.

The finding is backed by a vast amount of scientific data and evidence that climate pollution harms human health. It has been reaffirmed in the US Supreme Court multiple times and provides the foundation for the EPA to protect people from climate-changing pollution. 

Since it was established, the scientific evidence has only become stronger. National Climate Assessments conducted in 2018 and 2023 confirmed that climate change resulting from greenhouse gas emissions causes extensive harm throughout the country.

“It’s no surprise that this anti-science, pro-fossil fuel administration wants to go after the Endangerment Finding,” says Rachel Cleetus, policy director at the Union of Concerned Scientists. “This blatant attempt to do an end-run around scientific evidence deserves to fail.”

Can President Trump dismantle the Endangerment Finding?

Dismantling the Endangerment Finding will be difficult but not impossible. The wealth of scientific evidence on which the finding is based would need to be discredited, and robust, compelling evidence to the contrary presented.

Given the overwhelming consensus on climate change and its risks, discrediting this key ruling with science will be a near-impossible task. Beyond that, the EPA would need to go through a lengthy rulemaking process, including public comments, reviews, and legal justifications, which could take years.

Rather than directly dismantling the Endangerment Finding, the Trump administration may decide to take a more indirect approach to weakening laws about air pollution. The EPA could be instructed, for example, to interpret the finding in such a way that it minimises regulatory burden. 

There is a precedent for this. During Trump’s first term, he weakened the Endangerment Finding by instructing the EPA to roll back regulations based on it. This meant the finding was never directly repealed, but became ineffective in regulatory terms. 

In practice, this saw a reinterpretation of the EPA’s regulatory authority, allowing the administration to replace the Obama-era Clean Power Plan with the Affordable Clean Energy Rule. This new rule significantly reduced federal restrictions on coal power plants.

Now, with a key piece of scientific evidence at risk, it seems the White House is once again weighing how far it is willing to go to attack the foundational science that underpins climate action in the US. If the Endangerment Rule is weakened or repealed, it could open the floodgates to an array of climate-damaging activities.