Climate change negotiators from more than 170 nations have agreed to begin limiting heat-trapping greenhouse gases known as HFCs, often used in air conditioners and refrigerators.
The legally binding accord, agreed upon in the Rwandan capital Kigali on Saturday, was celebrated as the biggest environmental success since last year's Paris climate deal, which aims to limit the global temperature rise to 2 degrees Celsius.
"It's a huge step forward," said US Secretary of State John Kerry, who participated in the talks.
"This will allow us to reduce global warming by half a degree Celsius."
Hydrochlorofluorocarbons (HFCs) have been used for years as a substitute for chlorofluorocarbons (CFCs), which were once found in aerosol spray cans as well as insulation and packing materials.
CFCs were a primary cause of the hole in Earth's ozone and were eventually banned under the 1987 Montreal Protocol.
Negotiators meeting in Kigali agreed on Saturday to an amendment to the Montreal Protocol that would also curb the use of HFCs, which have a limited impact on the ozone but are a major contributor to global warming.
"We've moved from Paris pledges to concrete action," said Durwood Zaelke, president of international research organization Institute for Governance and Sustainable Development.
The HFC amendment could be easily and cheaply implemented, said UN Environmental Programme executive director Erik Solheim, calling the accord "one of the lowest hanging fruits in the arsenal of climate change".
"The Kigali amendment is the most significant climate mitigation step the world has ever taken," said Rwanda's natural resources minister, Vincent Biruta.
Timetables were established in Kigali for a drawdown of HFCs for both developed and developing countries.
Developed countries agreed to begin phasing them out in 2019. More than 100 developing countries - including China, Brazil and South Africa - will be given until 2024 to freeze their use of HFCs and then begin a gradual reduction.
A few states, such as India and Pakistan, agreed to slower HFC deadlines.
Many countries had already been working to towards a reduction in HFCs, which experts say cause 100 to 1000 times more damage than carbon dioxide.
