UNITED NATIONS — Hydrofluorocarbons. It’s a mouthful of a name for a chemical that keeps the turkey frozen in our refrigerators and also heats up the planet.

Now, a landmark international agreement to eliminate HFCs, as the chemicals are better known, is poised to come into effect. On Friday, Sweden became the 20th country to ratify the treaty, joining a diverse group that includes North Korea and Norway. That meets the threshold for the agreement to enter into force at the earliest possible date, according to the treaty: January 1, 2019.

It requires every country in the world to phase out the use of HFCs, compounds that are regarded as a sort of greenhouse gas on steroids, able to trap much more heat in the atmosphere than carbon dioxide.

The agreement was reached, after seven painstaking years of negotiations, in October 2016 in Kigali, the capital of Rwanda. Known as the Kigali Amendment to the Montreal Protocol, it required 20 countries to ratify it in order to go into effect — just in time for a global meeting on a broader treaty designed to protect the ozone layer, which starts next week in Montreal.