Representatives of nearly 200 nations agreed Saturday morning to a binding deal to phase out use of a potent greenhouse gas category used in air conditioning and refrigeration.

The deal to cut hydrofluorocarbons (HFCs), reached in the early morning hours in Kigali, Rwanda, is projected to avoid 0.5 degrees Celsius (0.9 degrees Fahrenheit) of global warming by 2100.

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HFCs are about 10,000 times more potent by volume as a greenhouse gas than carbon dioxide, the most plentiful greenhouse gas. Because HFCs stay in the atmosphere for only a short amount of time, cutting their use is predicted to have a relatively fast impact on warming.

But the deal, which is formally an amendment to the 1989 Montreal Protocol on the ozone, could increase the costs of air conditioning and refrigeration, putting it out of reach for some in developing nations.

It is binding to the countries signing it, unlike last year’s Paris agreement, whose emissions cuts are voluntary. Nonetheless, as an amendment to a previous treaty, it does not require separate Senate ratification.

The deal relied heavily on leadership on the issue over recent years from the U.S., Canada and Mexico.

“Today’s agreement caps off a critical ten days in our global efforts to combat climate change,” President Obama said in a statement on the negotiations in Rwanda.

“In addition to today’s amendment, countries last week crossed the threshold for the Paris agreement to enter into force and reached a deal to constrain international aviation emissions,” he said.

“Together, these steps show that, while diplomacy is never easy, we can work together to leave our children a planet that is safer, more prosperous, more secure, and more free than the one that was left for us.”

Secretary of State John Kerry John Forbes KerryThe Memo: Warning signs flash for Trump on debates Divided country, divided church TV ads favored Biden 2-1 in past month MORE called the deal “likely the single most important step we could take at this moment to limit the warming of our planet and limit the warming for generations to come,” according to the New York Times.

“It is the biggest thing we can do in one giant swoop,” he said.

“While we have seen many significant successes under President Obama’s leadership in fighting climate change, this day will unquestionably be remembered as one of the most important in our effort to save the one planet we have,” added Gina McCarthy Regina (Gina) McCarthyFormer EPA chiefs endorse Biden, criticize agency direction under Trump OVERNIGHT ENERGY: Energy Department proposes showerhead standards rollback after Trump complaints | Interior memo scaling back bird protections is 'contrary to law,' court rules | Former EPA chiefs call for agency 'reset' Former EPA chiefs call for agency 'reset' MORE, head of the Environmental Protection Agency (EPA) and leader of the U.S. delegation to the talks.

“It is truly an exciting time for all of us who have worked so hard to achieve this new level of success, and as head of the U.S. delegation, I could not be more delighted with the outcome of the negotiations and our collective resolve,” she said.

The Saturday breakthrough came after a significant rift among major nations emerged late in the week.

India and some other developing nations wanted a slower phaseout of HFCs for the poorest countries, while the United States wanted a faster timeline that nonetheless gave poor countries more time, according to environmental and development groups monitoring the talks.

“It was a shame that India and a handful of other countries chose a slower time frame for phasing down HFCs but the bulk of nations, including China, have seen the benefits of going for a quicker reduction,” Benson Ireri, a senior policy adviser at Christian Aid, said in a statement.

But India reached an agreement on the differences by Friday.

Manoj Kumar Singh, India's joint secretary at the Ministry of Environment, Forest and Climate Change, told Reuters that with implementation of the deal starting in 2024, India believes it will be acceptable.

Phasing out HFCs worldwide is expected to cost billions of dollars, though different governments have come to different conclusions about the exact cost.

Environmentalists and the air conditioning industry alike cheered the deal.

“This amendment to the Montreal Protocol is the single most important measure the global community could take to limit global warming in the short-term,” said Andrew Light, a senior fellow at the World Resources Institute and former State Department official.

“Because HFCs are thousands of times more potent as a warming agent than carbon dioxide, a successful phase down can avoid up to a half a degree Celsius of global warming by the end of this century,” he said.

“While the freeze dates and step down levels are ambitious, the [air conditioning and refrigeration] industry is confident we can meet them and continue to provide quality, innovative, energy efficient products and equipment for the benefit of the world’s citizens,” Stephen Yurek, president of the United States-based Air Conditioning, Heating and Refrigeration Institute, said in a statement.

The deal follows recent major developments on international agreements to fight climate change. The Paris agreement earlier this month reached the threshold to take force in November, and the United Nations’s International Civil Aviation Organization agreed to an emissions trading system for international commercial flights.

The HFC deal requires the EPA to write domestic regulations to implement it.