HFC leakage from air conditioners alone will raise the global average temperature by 0.5 a degree Celsius by mid-century. When all the world's government are pledged to stop the warming before it reaches plus 2 degrees C, and we are already well past plus 1 degree C, an extra 0.5 a degree is a lot.
So we needed another miracle like the Montreal Protocol " and now we have it.
On October 15, in Kigali in Rwanda, almost 200 countries signed an agreement to curb the use of HFCs, with United States Secretary of State John Kerry calling it "the single most important step we could take at this moment to limit the warming of our planet".
Well, yes it is ... but you are probably noticing a pattern in all this. It's not so much that we keep getting it wrong, it's the time it takes to put it right - a century so far, and we'll still be at it for at least another 30 years before all the HFCs are out of the system.
When you read the fine print of the Kigali amendment, it turns out that the US (the second-biggest HFC polluter), the European Union, and some other rich countries will have to achieve their first 10 per cent cut in HFC production by 2019, but the schedule for further cuts is not clearly defined, apart from the fact that they must be down 85 per cent by 2036 (that's 20 years from now).
India, Pakistan and most of the Middle Eastern countries don't even have to freeze production until 2028, and their target date for getting to 85 per cent cuts in production is 2047. At a rough guess, global HFC production will peak some time in the late 2020s, and will be back down to the current level by the mid-2030s.
Countries don't know how to negotiate any other way - nobody gives anything away if they don't absolutely have to. But if you want to despair, go right ahead. The pace of the political process does not match the speed with which the threat is growing. We have to do much better than this if we are to avoid crashing through the plus 2 degree limit and tumbling into runaway warming.
We are not ready to make those deals yet, but when we finally are we will have one small consolation. This deal has been far easier to make because it is an amendment to the 1987 Montreal Protocol. The more treaties we have on climate matters now, however imperfect they may be, the faster we will be able to move when we finally do take fright.
-Gwynne Dyer is an independent journalist whose articles are published in 45 countries