Source: Time

By Justin Worland

More than 170 countries agreed early Saturday morning to limit emissions of key climate change-causing pollutants found in air conditioners, a significant step in the international effort to keep global warming from reaching catastrophic levels.

The deal reached in Kigali, Rwanda, comes after years of wrangling over HFCs—short for hydrofluorocarbons—and could on its own prevent a 0.5°C (0.9°F) rise in temperature by 2100. Scientists say such an achievement could be crucial to the goal laid out in last year’s Paris Agreement of holding global temperature rise below 2°C (3.6°F) by 2100.

Total global HFC emissions—most commonly from air conditioners and refrigerators—are far less significant contributors to climate change than the aggregate emission of other greenhouse gases like carbon dioxide and methane. But HFCs are thousands of times more potent than carbon dioxide on a pound-per-pound basis, making them an obvious target for international efforts to combat climate change.

“Adopting an ambitious amendment to phase down the use and production of hydrofluorocarbons—or HFCs—is likely the single most important step that we could take at this moment to limit the warming of our planet,” Secretary of State John Kerry said in Kigali, in remarksbefore the passage of the agreement.

This week’s accord formally comes an amendment to the Montreal Protocol, an agreement crafted in 1989 to protect the ozone layer. The Montreal Protocol required countries to phase out chlorofluorocarbon—or CFC—from use in refrigerators, air conditioners and other uses because it depleted the ozone layer. Most manufacturers replaced CFC with HFCs—leading to a different, if related problem.

Now, countries party to the agreement will have to follow one of three timetables to peak and then reduce their use of HFCs. Developed countries will need to freeze their HFC production and use in 2019 with immediate reductions to follow immediately after that. Some developing countries, including China, Brazil and more than 100 more, agreed to peak their HFC use in 2024. And other developing countries agreed to freeze use in 2028. That last group includes many countries like India, Pakistan and the Gulf States, where expanded access to air conditioning could save lives due to sweltering heat.

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