Representatives of more than 100 countries are joining the Obama administration in backing an “ambitious” worldwide agreement the phase out the use an Earth-warming refrigerant.

Leaders of the countries or allies representing them signed onto a formal declaration Thursday to “strongly support” an amendment to the Montreal Protocol aimed at cutting hydrofluorocarbons (HFCs).

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“Such an amendment is one of the most significant steps the world can take right now to deliver on the goals of the Paris agreement,” the leaders wrote in their declaration. “HFCs are extremely potent greenhouse gases and an amendment to the Montreal Protocol to phase down HFCs could avoid up to 0.5°C of warming by the end of the century.”

HFCs are far less common than carbon dioxide, the most abundant greenhouse gas. But they also have a much higher warming potential than carbon dioxide by volume.

They came into use in refrigeration and air conditioning as a result of the 1987 Montreal Protocol, which sought to cut down on substances that destroyed the ozone layer. Scientists subsequently demonstrated their impact on global warming.

Now parties to the agreement will meet with next week with a goal of cutting HFCs and replacing them with more climate-friendly chemicals.

The Obama administration, which has taken a leading role on the HFC phaseout, hosted the international leaders in New York to sign onto Thursday’s pledge.