www.lesswrong.com/posts/zxXPEtSSSEdwpjopb/we-ve-saved-the-world-before-what-the-...
2 corrections found
The Montreal Protocol banning CFCs, signed 39 years ago today,
This compresses two inaccuracies: the post was published on September 20, 2026, but the Montreal Protocol was signed on September 16, 1987; and the original 1987 Protocol did not ban CFCs outright, but set a phased reduction schedule that was later strengthened.
Full reasoning
Two separate factual details are off here.
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"signed 39 years ago today" is not correct for this post's publication date. The LessWrong page shows the article was published on 20th Sep 2026. The United Nations states that 16 September commemorates "the date of the signing, in 1987, of the Montreal Protocol." So on September 20, 2026, the signing was four days earlier, not "today."
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The original 1987 Montreal Protocol did not itself "ban" CFCs outright. EPA's summary of the treaty says that under the original Montreal Protocol agreement (1987), developed countries had to begin phasing out CFCs in 1993, reaching a 20% reduction by 1994 and a 50% reduction by 1998. EPA separately explains that only later amendments accelerated this to an actual end of CFC production in developed countries by 1996. The UN's ozone page likewise describes the Protocol as setting control measures and timetables for phase-out, not as an immediate outright ban at signing.
So the wording is inaccurate both on the date and on what the 1987 agreement itself did.
3 sources
- We've saved the world before: what the ozone hole teaches us about AI - LessWrong
The page shows the post date as "20th Sep 2026" and contains the sentence: "The Montreal Protocol banning CFCs, signed 39 years ago today..."
- International Day for the Preservation of the Ozone Layer | United Nations
The UN says 16 September commemorates "the date of the signing, in 1987, of the Montreal Protocol on Substances that Deplete the Ozone Layer." It also explains that the Protocol sets timetables for the phase-out of substances.
- International Treaties and Cooperation about the Protection of the Stratospheric Ozone Layer | US EPA
EPA says: "Under the original Montreal Protocol agreement (1987), developed countries were required to begin phasing out CFCs in 1993 and achieve a 20% reduction ... by 1994 and a 50% reduction by 1998." EPA adds that later, in 1992, parties changed the agreement to end production of CFCs by 1996 in developed countries.
is the only treaty that has ever been ratified by every single country in the entire world.
The Montreal Protocol is not the only universally ratified treaty: the Vienna Convention for the Protection of the Ozone Layer also has universal ratification.
Full reasoning
This claim is too broad. The Montreal Protocol does have universal ratification, but it is not the only treaty to achieve that status.
The United Nations' own ozone-day page says that the Vienna Convention and the Montreal Protocol became the first treaties in UN history to achieve universal ratification. UNEP's Ozone Secretariat likewise states that both the 1985 Vienna Convention and the 1987 Montreal Protocol have achieved universal ratification, with 198 Parties each.
So the accurate version is that the Montreal Protocol is one of the universally ratified ozone treaties, not the only treaty ever ratified by every country.
3 sources
- International Day for the Preservation of the Ozone Layer | United Nations
The UN states: "On 16th September 2009, the Vienna Convention and the Montreal Protocol became the first treaties in the history of the United Nations to achieve universal ratification."
- All ratifications | Ozone Secretariat
UNEP's ratification table lists totals of 198 Parties for both the Vienna Convention and the Montreal Protocol as of 10 August 2026.
- Facts and figures on ozone protection | Ozone Secretariat
UNEP says: "The 1985 Vienna Convention for the Protection of the Ozone Layer and its 1987 Montreal Protocol ... Both have achieved universal ratification, with 198 Parties."