Under President Donald Trump, the US Environmental Protection Agency is seeking to overturn its own 2009 "Endangerment Finding," which acknowledges that heat-trapping emissions are endangering public health and welfare.

It has long served as the legal basis for numerous federal regulations like emissions standards.

Lee Zeldin, the current EPA head, has said the standard -- which was upheld by the Supreme Court -- was based on flawed reasoning and caused economic harm.

But the letter said that "as climate scientists, public health experts, and economists, we can attest to the indisputable scientific evidence of human-caused climate change, its harmful impacts on people's health and well-being, and the devastating costs it is imposing."

"This explicit attempt to undermine or weaken these findings, as well as the critical regulations linked to them, is contrary to science and the public interest," it added.

The letter delivered by the Union of Concerned Scientists also skewered a recent report commissioned by the Trump-era US Department of Energy, reiterating criticism that the report is inaccurate, contradictory and a mischaracterization of data.

"The scientific evidence on human-caused climate change and its consequences was unequivocal in 2009 and, since that time, has become even more dire and compelling," read Tuesday's letter.

"We urge you to stop dismantling critical climate regulations and evading the EPA's responsibility by pushing disinformation about climate science and impacts," the signatories continued.

"Instead, we call on you to act with urgency to help address this pressing challenge by limiting heat-trapping emissions.

"People across the nation are relying on the EPA to fulfill its mission to protect public health and the environment."