Successful environmental treaties have a peculiar disadvantage: the disasters they prevent never become news. The Montreal Protocol, agreed in 1987, put the ozone layer on the path to recovery. It has also helped avert a much hotter planet. Yet its capacity to do more remains underused, just when governments are starved for actionable ideas to slow warming.
On October 15, the Kigali Amendment to that treaty turns 10. The anniversary demands attention for reasons extending far beyond its storied achievements in regulating harmful chemicals. Montreal shows that countries can agree to binding obligations and help poorer economies meet them. It also shows how to strengthen those obligations as better technologies become available. The next decade should put that experience to greater use.
For those with more salt in their hair than pepper, the treaty’s primary achievement remains vividly familiar. Chemicals used in products from aerosol sprays to refrigeration to insulating foams were destroying the ozone layer that shields life from harmful ultraviolet radiation. Countries have since phased out nearly 99 percent of banned ozone-destroying substances. If current policies hold, as history suggests they will, ozone will return to 1980 levels by around 2040 across most of the world, with Antarctica following around 2066.
The Montreal Protocol’s second achievement is less widely appreciated. Many of the banned chemicals were also powerful greenhouse gases, a threat Indian scientist Veerabhadran Ramanathan identified in 1975. Removing them prevented enormous additional warming. Healing the ozone shield also protected the ability of plants and soils to store carbon, which greater ultraviolet exposure would have damaged. Together, these effects could avert roughly 2.5°C of additional warming by the end of this century compared with a world without the binding ozone controls. That is a measure of the catastrophe avoided.
In 2006, over a long lunch in Cairo, Mostafa Tolba, the Egyptian scientist and former UN environment chief who helped forge the treaty, gave one of us a useful explanation for its success. Montreal was a “start and strengthen” agreement. It began with limited cuts. Experience built confidence, allowing governments to adopt more demanding obligations.
That approach had effective institutions behind it. Scientific panels assessed the danger and experts examined substitutes. Binding schedules gave industry the confidence to invest. Developing countries received more time, alongside financial assistance through the Multilateral Fund. The bargain recognised that an obligation becomes credible when countries have the means to fulfil it. Success depended on sustained work after the agreement was signed.
When some chemicals introduced as replacements—hydrofluorocarbons or HFCs—spared the ozone layer but warmed the atmosphere, governments applied Montreal’s logic and brought them under the treaty. Full implementation of the resulting Kigali Amendment could avoid up to 0.5°C of warming by 2100, proving that a framework designed for one atmospheric crisis could be retooled to tackle another.
The urgency now lies in how quickly such gains can be secured. Cutting shortlived pollutants such as HFCs, methane and black carbon soot, however, can slow warming quickly over the next few decades. For farmers and other Indians who earn their living outdoors, slowing the rise in temperature over the next decade is an immediate economic as well as health concern.
There is an immediate opportunity to further strengthen the Montreal Protocol. Governments revived the Friends of the Kigali Amendment in New York on September 23. When they return to Kigali in November, they should agree to a replenishment of the Multilateral Fund for 2027-29 that continues to enable developing countries to meet their obligations and move faster where feasible.
This financial support is critical: manufacturers need affordable access to replacement technologies, while technicians require training and equipment to prevent refrigerants from escaping during servicing or disposal. The 20-plus countries still outside the amendment should join as soon as possible.
The timing of these negotiations is particularly critical for India, which ratified Kigali in 2021 and faces an HFC production and consumption freeze starting in 2028, with the first reduction due in 2032. These dates give industry time to prepare. Investment decisions taken now will determine how much equipment needs replacing later. India should use the negotiations to secure finance and access to technology that make earlier progress affordable, while helping domestic manufacturers supply the next generation of equipment. Montreal’s record supports a fundamental Indian demand: greater ambition must come with the means to deliver it.
The treaty’s wider lesson should now be applied to methane. The International Energy Agency estimates that existing technologies could eliminate about threequarters of methane emissions from oil and gas operations. A substantial share of those reductions would cost little or nothing because the captured gas can be sold. Much of this involves stopping the waste of a saleable fuel, as natural gas is mostly methane. Governments should negotiate a binding agreement for that sector, requiring companies to measure emissions and repair leaks, with enforceable limits on routine venting and flaring. India is well-positioned to help shape a sectoral agreement on methane. Good climate diplomacy should pursue reductions where they can be made quickly and fairly.
(Views are personal)
Durwood Zaelke
President, Institute for Governance & Sustainable Development
Zerin Osho
Director, India Programme, Institute for Governance & Sustainable Development