S. Fred Singer, a physicist whose efforts to refute established climate science earned him the enmity of experts, died on April 6 at a nursing facility in Rockville, Md. He was 95.

His death was confirmed by Rochelle Lieberman, a cousin.

Even as evidence of the human causes of climate change and its risks to the planet coalesced into a scientific certainty, Dr. Singer argued that the threat of climate change was overblown, that efforts to blunt its effects would cause grievous economic damage, and that the effects of global warming would be largely beneficial.

“Not only was Fred among the first atmospheric experts to publicly question the validity of climate models, but as it became more and more politically incorrect to criticize the models, Fred was unmoved,” said Steven J. Milloy, a climate-change denialist who served on President Trump’s transition team for the Environmental Protection Agency. “He doubled and tripled down on substantive criticism of the models, putting his scientific view ahead of the risks to his stellar career and reputation.”

But most climate experts saw a humbug.

Dr. Singer was a focus of the book “Merchants of Doubt” (2010), which examined how tobacco and other industries promoted a small group of scientists who worked to muddy the truth on climate change and other environmental risks, including secondhand smoke, asbestos and acid rain. He was one of those, the book’s authors, Naomi Oreskes and Erik M. Conway, wrote, who “used their scientific credentials to present themselves as authorities” and “used their authority to try to discredit any science they didn’t like.”