US ratifies major international climate treaty - wait, what?

Hardly anybody noticed and very few news outlets bothered to report it, but the US Senate ratified a major international climate treaty this week.

The Senate finally joined 137 other countries (including Canada) in ratifying the Kigali Amendment to the Montreal Protocol (what? and what?). Montreal Protocol on Substances that Deplete the Ozone Layer dates back to 1987, and was the international agreement to eliminate chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) that had been found to be destroying the ozone layer. It was one of the stand-out international environmental agreements of the 20th century. The Kigali Amendment dates from 2016, and calls for the phasing out of hydrofluorocarbons (HFCs). HFCs have been widely used as replacements for the banned CFCs and HCFCs and, while they have next to no impact on ozone, they are potent greenhouse gases, hence the Kigali Amendment.

The US Senate voted to ratify it with bipartisan support (48 Democrats and 21 Republicans). Probably the main reason such a major ratification attracted such little media attention is the fact that the US has actually been effectively complying with the treaty since December 2020, even without having ratified it, when the US Congress passed stringent targets for eliminating HFCs as part of an otherwise lame COVID stimulus bill. 

By some calculations, this is expected to eliminate the equivalent of 900 million metric tons of carbon dioxide (for context, this is more emissions than Germany produces in a year) by 3036, so yes, this is a big deal climate-wise, not so much the ratification, but the 2020 legislation that hardly anyone remembers. The ratification, however, is important too, as it keeps the legal regime underpinning the agreement strong for the future. Now, the three largest producers and consumers of HFCs - USA, China and India - have all ratified the Amendment.

Between this and the climate change elements of the poorly-named Inflation Reduction Act (which I have commented on elsewhere), the Biden administration could be said to be presiding over a mini golden age of climate change policy-making. Long may it last.