This is a photo of of an apartment building with rows of window-unit air conditioners installed in the windows.

Credit: Chromatograph on Unsplash

Older air conditioners use chemicals called hydroflourocarbons (HFCs) to cool buildings. Paradoxically, these chemicals are powerful greenhouse gases, causing climate warming if they get into the atmosphere. Recently, 170 countries have agreed to phase out HFCs and use alternatives that don’t cause warming. Making sure that older air conditioners do not leak HFCs and disposing of them safely helps prevent climate change, too.