US says CO2 emissions aren’t harmful – climate science shows otherwise

The Trump administration is attempting to end the US government’s ability to regulate greenhouse gas emissions by arguing they do not pose a danger to people. This is part of a strategy to roll back restrictions on power plants and vehicles, which the administration argues slow economic growth. But this legal argument is weak in light of the huge body of climate science that clearly shows rising concentrations of greenhouse gases do pose a threat.

“It’s a nutty argument and it doesn’t hold up,” says David Doniger at the Natural Resources Defense Council, an environmental advocacy group that plans to sue the administration over the change.

The legal debate rests on a 2009 determination by the US Environmental Protection Agency (EPA) which found greenhouse gases emitted by power plants and vehicles in the US pose a danger to people. Known as the “Endangerment Finding”, the rule gives the agency authority to regulate these emissions, which together account for about half of the US total. Rules put in place since then have helped slash emissions from cars and trucks, made them more fuel efficient and formed an important part of past administrations’ efforts to reduce power plant emissions.

On 29 July, Lee Zeldin, the administrator of the EPA, announced the agency would seek to repeal the Endangerment Finding, calling the move “the largest deregulatory action in the history of the United States”. However, before this change can go into effect, the agency has to publicly explain the decision, as well as defend it in the lawsuits already being prepared against it.

In a draft of the new rule, the EPA makes clear its rationale will depend in part on arguing rising concentrations of greenhouse gases in the atmosphere don’t pose a large enough danger to people to justify reducing emissions. This goes against the basic conclusions reached by climate science bodies like the Intergovernmental Panel on Climate Change, as well as several US National Climate Assessments and the EPA itself, which found in 2009 the evidence that greenhouse gases endanger people was “strong and clear”.

“I think they’re trying to throw all the spaghetti at the wall and see what sticks,” says Doniger. “They’re coming with old theories and new theories. They’re all quite flimsy.”

The evidence greenhouse gases endanger health has only strengthened in the past few decades, according to a 2018 study that reassessed the rationale for the Endangerment Finding 10 years on. Today, climate scientists have even more proven tools to determine whether climate change has impacted a particular extreme event. They can even link greenhouse gas emissions from a particular source to damages from a particular extreme heat event.

In order to challenge this consensus view, the EPA rule relies heavily on the findings of a draft report produced by the Department of Energy and released alongside it. The 151-page report, written by five well-known skeptics of mainstream climate science, recognises carbon dioxide is a greenhouse gas that drives global warming, but it casts doubt on how damaging this will be for the US, and discusses the benefits of more CO2 in the air, such as its fertilising effect on plants.

While many of the individual parts of the report are narrowly true and supported by climate science, other researchers say the report is fatally flawed, because it fails to address research that doesn’t support its overall conclusions. For instance, while it is true raised levels of CO2 boost plant growth, the report doesn’t mention that rising temperatures are expected to overwhelm this effect, with damaging consequences for agriculture and ecosystems.

“They sift through data to find the few examples that support their narrative while systematically ignoring the much larger body of evidence that contradicts it,” says Andrew Dessler at Texas A&M University.

“I’m a bit surprised that the government put out something like this as an official publication,” says Zeke Hausfather at Berkeley Earth, a research non-profit in California. “It reads like a blog post – a somewhat scattershot collection of oft-debunked skeptic claims, studies taken out of context, or cherry-picked examples that are not representative of broader climate science research findings.”

Hausfather, who is cited numerous times in the DOE report, calls it a “farce”, saying it would not pass any standard peer-review process. He contrasts the process of producing this report, written by five authors over several months, with the National Climate Assessment that was in the process of being written over years by hundreds of authors, all of whom were recently dismissed by the Trump administration.

“This notion that there’s no societal cost to these emissions is a totally fallacious and tired argument,” says Justin Mankin at Dartmouth College in New Hampshire. In 2025, following the two warmest years on record and associated extremes, “what’s patently clear is that the impacts from global warming are far larger than what we understood in 2009”, he says.