Forks in the Road
Five moments where a different choice was really possible. For each one: what was chosen, what else was on the table at the time, and what we know now. Four of these turned out well. One is still open.
Binding cuts in 1987 vs. waiting for proof
The other option was already signed. The 1985 Vienna Convention set up research and talks but required no cuts, and some countries wanted to stop there until the science was settled. The Montreal Protocol instead asked for a modest 50% cut that could be t
Paying poorer countries vs. a rich-country-only ba
In 1987 poorer countries used few CFCs and had no reason to give up the cheapest coolant available. The 1990 London Amendment created a fund to cover their extra costs. Without it the ban would most likely have moved production rather than ended it, which
Switching CFC to HCFC to HFC vs. waiting for a cle
The switch went through HCFCs, which still harm ozone but less, then to HFCs, which do not harm ozone at all. HFCs fixed the problem the treaty was written to fix, and created one it was not: they are strong greenhouse gases. This is the clearest case her
The HFC fork is the one most worth borrowing from. The treaty measured replacements against the harm it was written to stop, and did not measure them against anything else. A replacement that scores well on the named problem can still be worse overall.
Independent monitoring vs. trusting the paperwork
Making CFC-11 had been banned worldwide since 2010, and the official reports said everyone was complying. The air said otherwise. Emissions rose from 2013, were published in 2018, and were traced to eastern China in 2019. They fell back to pre-2013 levels
26%CFC-11 Emissions Drop, 2018 to 2019 [13]
2yr From Published Detection to Reversal [10] [12]
Exempting feedstocks vs. limiting all production
Ozone-damaging chemicals used as ingredients to make other chemicals were left out of the rules. The reason was an estimate that these uses leaked less than 0.5% of world production in 1990, and that this would fall. It did not. These leaks are now though
Four of these five forks were resolved well. The fifth was resolved on an estimate that turned out to be wrong, and has not been revisited in the 35 years since. That is the one to watch.