US President Joe Biden's administration is slashing the domestic production and use of hydrofluorocarbons, the highly potent greenhouse gases commonly used in refrigerators and air conditioners.
The super-pollutants, known as HFCs, can be hundreds to thousands times more potent than carbon dioxide at trapping heat in the atmosphere, exacerbating the climate crisis.
New rules unveiled by the Environmental Protection Agency (EPA) on Thursday are intended to decrease US production and use of HFCs by 85 per cent over the next 15 years, part of a global phase-out designed to slow global warming.
The rules "are expected to reduce emissions by the equivalent of 4.5 billion metric tons of carbon dioxide by 2050," White House national climate advisor Gina McCarthy told reporters.
"That's as much as three entire years of emissions from our power sector."
Last year, Congress passed a law targeting HFCs with support from both Democrats and Republicans.
EPA Administrator Michael Regan said the phase-down is backed by a coalition of industry groups that see it as an opportunity to “supercharge” American leadership on domestic manufacturing and production of alternative refrigerants.
The industry has long been shifting to the use of alternative refrigerants and pushed for a federal standard to avoid a patchwork of state laws and regulations.
“This action reaffirms what President Biden always says — that when he thinks about climate, he thinks about jobs,” Mr Regan said, echoing a Biden refrain about climate change.
If similar reductions are implemented worldwide, it can prevent up to 0.5°C of planetary heating by the end of this century, Mr Regan said.
A pandemic relief and spending bill passed by Congress last December directs the EPA to sharply reduce production and use of HFCs.
The measure won wide support and was hailed as the most significant climate change law in at least a decade.
The Paris climate accord of 2015 calls for the world to hold warming to 1.5°C to avert a future filled with extreme weather events, desertification, mass species extinction and food insecurity.
HFCs were not always considered bad news.
They were first introduced in the 1990s, before their powerful heat-trapping properties were understood, to replace chlorofluorocarbons (CFCs) that had been found to erode the ozone layer.
