The Kigali Amendment to the Montreal Protocol turns 10 today. It agreed to phase down hydrofluorocarbons, or HFCs, which had become common refrigerants after countries moved away from chemicals, like chlorofluorocarbons (CFCs), that destroyed the ozone layer.The amendment is expected to prevent up to 0.5°C of warming by 2100. Yet at its 10th anniversary, the world is getting hotter, demand for cooling, expectedly, is rising rapidly, and the machines that provide it can themselves add to warming.India will confront this problem at unusual scale. What Kigali does next may therefore matter as much as what it has already achieved.The Montreal Protocol was agreed in 1987 to phase out CFCs and other chemicals that damage the ozone layer. This layer shields the Earth from harmful ultraviolet radiation. Countries have since eliminated nearly 99% of the controlled ozone-depleting substances, and the layer is recovering.Also Read | Kigali Amendment: Ozone pact in climate fightHydrofluorocarbons, or HFCs, became common substitutes in refrigeration and air-conditioning because they do not deplete ozone. These chemicals act as refrigerants, carrying heat out of the space being cooled. If they escape, many have hundreds or thousands of times the warming impact of carbon dioxide over a century, weight for weight.As the use of HFCs grew, the Federated States of Micronesia and Mauritius proposed bringing them under the Protocol in 2009.Governments adopted the amendment in Kigali, Rwanda, on October 15, 2016; it entered into force in January 2019. It sets binding schedules for reducing HFC production and consumption, with developing countries given longer to comply. Limited use can continue after the reductions, which is why the agreement calls for a “phase-down”.Story continues below this adHow much warming could it prevent?Full implementation could avoid about 0.3°C to 0.5°C of global warming by 2100, according to the UN-backed scientific assessment of ozone depletion. That is the difference between projected temperatures with the HFC controls and those without them. Even a fraction of a degree matters when the Paris Agreement seeks to keep warming well below 2°C and pursue a limit of 1.5°C above pre-industrial levels.Why has cooling become central to Kigali’s next decade?Cooling contributes to warming in two ways. Refrigerants can escape into the atmosphere, while the electricity used to run the equipment causes emissions wherever fossil fuels supply the power. Switching to a refrigerant with a lower warming impact addresses the first problem. A more efficient machine reduces the second.Manufacturers changing refrigerants often need to redesign their equipment. Improving efficiency during that redesign can reduce electricity use for the lifetime of the appliance. The UN Environment Programme and the International Energy Agency estimate that combining the HFC transition with better cooling efficiency could roughly double the climate benefit.Also Read | Ozone hole, filling up now: What this means for climate actionFor India, the electricity savings would be substantial. Cooling already accounts for slightly more than a tenth of annual electricity demand, according to the IEA. On hot summer nights, air-conditioners can account for as much as a third of power consumption. Under current policies, India’s cooling demand is projected to more than double by 2035.What must India do under Kigali?Story continues below this adIndia ratified the amendment in 2021 and must freeze HFC production and consumption in 2028. This caps them at an agreed baseline. The first cut, of 10% below that baseline, is due in 2032; reductions reach 85% in 2047.The limits are calculated according to the gases’ warming impact.Equipment bought before the first cuts may remain in use well into the 2030s. Its efficiency will determine how much households pay to run it and how much extra generating capacity the country needs. That gives India a reason to improve appliance standards before the treaty’s deadlines arrive.Those standards also matter for imports. Equipment that cannot meet efficiency requirements in one market may find buyers in another with weaker rules. An appliance with a low purchase price can leave its owner with years of unnecessarily high electricity bills.What remains to be done after 10 years?Story continues below this adKigali has yet to achieve universal participation: 175 parties had joined by early October.Gases already inside equipment need attention too. They can leak during servicing or escape when an appliance is scrapped. Recovering refrigerants for reuse, or destroying them safely when reuse is impractical, reduces emissions that restrictions on new production cannot prevent.Governments revived the Friends of the Kigali Amendment coalition in New York on September 23 to support this work. Backed by the Climate and Clean Air Coalition, the group is seeking wider participation and more finance for implementation. It will also work with industry to improve access to efficient cooling equipment and strengthen refrigerant recovery.Who pays for the transition in developing countries?The Montreal Protocol’s Multilateral Fund helps meet the agreed additional costs of compliance. Established in 1990 and operating since 1991, it receives contributions from developed countries to help poorer countries change technologies. Its support includes converting factories and training the people who service cooling equipment.Story continues below this adThe Fund estimates that its work helped developing countries avoid emissions equivalent to about 50 billion tonnes of carbon dioxide between 1995 and 2021. Against that estimated benefit, its spending amounted to about seven US cents per tonne. That calculation covers the Fund’s own expenditure; the economies making the transition also bear costs.The same financing arrangement supports the HFC phase-down. For Indian manufacturers, access to funding and suitable technology will affect the cost of changing production while demand for their products continues to grow.Why has the Montreal Protocol been effective?The original agreement set a limited target: a 50% reduction in major CFCs. Governments subsequently tightened the controls and brought more chemicals under the treaty as alternatives became available. Mostafa Tolba, the former UN environment chief who helped negotiate it, described this as “start and strengthen”.Binding schedules gave manufacturers a reason to invest in substitutes, with some certainty about when markets for the old chemicals would shrink. Expert panels assessed the available technologies so that later decisions could reflect what industry was able to do. Developing countries received longer timetables, supported by the Fund.Story continues below this adThis allowed governments to revise the agreement without renegotiating its basic bargain. Kigali drew on the same institutions when the growing use of HFCs required another change in refrigerants.Could a parallel approach work for other short-lived climate pollutants?The four main short-lived climate pollutants, or SLCPs, are methane, black carbon, HFCs and tropospheric, or ground-level, ozone. Often called super pollutants, they have strong warming effects and generally remain in the atmosphere for much less time than carbon dioxide. Reducing them can therefore slow warming relatively quickly, alongside the carbon dioxide cuts needed to limit warming over the longer term.Also Read | Can India cool down without heating up? Experts Explain why sustainability is keyKigali already addresses HFCs. Methane from oil and gas operations is one candidate that could be addressed by a new agreement inspired by the Montreal Protocol’s approach. (Note, natural gas is mostly methane.) Methane remains in the atmosphere for about 12 years and has a strong warming effect during that time. Cutting its emissions can slow warming over the next few decades, alongside the carbon dioxide reductions needed to limit warming over the longer term.Story continues below this adMany oil and gas emissions can be prevented with existing equipment. Repairing a leaking pipeline, for example, keeps methane out of the atmosphere and preserves gas that can be sold. The Montreal Protocol could provide a model for a binding international agreement to cut methane emissions from oil and gas operations.The 27 member states of the European Union already have an international methane agreement that requires energy companies to measure methane emissions and repair leaks. It also restricts routine releases and burning of gas, and is phasing in requirements for imports. Such rules could provide a basis for an expanded agreement between major producers and buyers.Other sources of the short-lived superpollutants would need different rules. In India, measures to reduce methane from cattle have to account for small farmers’ incomes and food production. Black carbon, the soot produced by incomplete combustion, requires action on sources such as diesel engines and household cooking fuels. The case for agreements covering particular sectors rests on these differences: each can set obligations suited to the sources of pollution and provide support for those who must comply.Durwood Zaelke is President of the Institute for Governance & Sustainable Development (IGSD). Zerin Osho is Director of its India Programme.