Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

Nearly 200 nations have reached a deal to limit the use of greenhouse gases far more powerful than carbon dioxide in a major effort to fight climate change.

The talks on hydrofluorocarbons, or HFCs, have been called the first test of global will since the historic Paris Agreement to cut carbon emissions was reached last year. HFCs are described as the world's fastest-growing climate pollutant and are used in air conditioners and refrigerators.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

The agreement announced Saturday morning, after all-night negotiations, caps and reduces the use of HFCs in a gradual process beginning in 2019 with action by developed countries including the United States, the world's second worst polluter. More than 100 developing countries, including China, the world's top carbon emitter, will start taking action in 2024.

A small group of countries including India, Pakistan and some Gulf states pushed for and secured a later start in 2029, saying their economies need more time to grow. That's two years earlier than India, the world's third worst polluter, had first proposed.

Environmental groups had hoped that the deal could reduce global warming by a half-degree Celsius by the end of this century. This agreement gets about 90 percent of the way there, said Durwood Zaelke, president of the Institute for Governance and Sustainable Development.

Zaelke's group said this is the "largest temperature reduction ever achieved by a single agreement."

The new agreement is "equal to stopping the entire world's fossil-fuel CO2 emissions for more than two years," David Doniger, climate and clean air program director with the Natural Resources Defense Council, said in a statement.

Experts said they hope that market forces will help speed up the limits agreed to in the deal.

"Compromises had to be made, but 85 percent of developing countries have committed to the early schedule starting 2024, which is a very significant achievement," Clare Perry, UK Climate Campaign Leader with the Environmental Investigation Agency, said in a statement.