Kigali Amendment

• 1. Introduction

  ›

  The Kigali Amendment to the Montreal Protocol is a legal commitment by much of the world to phase down a class of industrial gases. Those gases, hydrofluorocarbons, had been welcomed as a safe replacement for chemicals that were eating holes in the ozone layer. They were safe for the ozone layer. But they proved to be formidable drivers of climate change. The Kigali Amendment was ratified by 171 states and the European Union. It creates binding obligations in international law, not voluntary targets. The path to this agreement runs through decades of science, diplomacy, and an earlier crisis. That crisis is one the world actually managed to solve.

• 2. A Protocol That Worked

  ›

  Paul J. Crutzen, Mario Molina, and F. Sherwood Rowland identified a major problem in 1974. They showed that chlorofluorocarbons, used in refrigerants and cooling systems, were breaking down the stratospheric ozone layer. Their findings set in motion an international response. In 1987, the twenty major CFC producers came together to sign the Montreal Protocol. The treaty entered into force in 1989. All 197 member states of the United Nations eventually ratified it. The Protocol divided its parties into two categories under Article 5, with different compliance schedules for developed and developing countries. That structural choice, designed to account for differing economic conditions, would become the template for the Kigali Amendment.

• 3. The Chemistry of HFCs

  ›

  Many industrial products rely on HFCs, with refrigerants and cooling services representing the largest share of demand. HFCs do not contain chlorine, which means they leave the ozone layer intact. That property made them an appealing substitute for the banned gases. But their effect on the climate proved far more troubling. HFCs filter infrared radiation far more intensely than carbon dioxide does. Carbon dioxide carries a 100-year global warming potential of 1. For HFCs, that value ranges from as low as 12 to as high as 14,800, depending on the specific compound. Their lifespan in the atmosphere is comparatively brief, between ten and twenty years. But within that window, the heat-trapping power far exceeds what carbon dioxide produces. Addressing that warming potential would require a legal framework more differentiated than the world had previously attempted.

• 4. Three Groups, Different Clocks

  ›

  The Kigali Amendment extended the Montreal Protocol's two-category approach into three compliance groups. The economic landscape had shifted substantially since the late 1980s, and the original categories no longer reflected each country's situation. Developed countries, the non-Article 5 parties, committed to reducing HFC consumption to 15% of their baseline by 2036. That baseline is the average of each party's HFC use between 2011 and 2013, plus a buffer of 15% of their HCFC baseline. A second group, which includes China and Brazil, must bring consumption down to 20% of its own baseline by 2045. Their baseline incorporates a larger HCFC buffer of 65%, reflecting a longer overlap with ozone-depleting substances. A third group, which includes India and Saudi Arabia, faces the same 20% target but has until 2047. These countries carry especially high demand for air conditioning due to elevated ambient temperatures. Parties in that category can request a waiver. The qualifying condition is an average monthly temperature above 35 degrees Celsius for at least two months per year, sustained over ten consecutive years. Even within countries that ratified the amendment, the agreement does not always apply uniformly: Greenland is excluded despite Denmark having given its approval.

• 5. The Gains at Stake

  ›

  Full compliance with the Kigali Amendment could prevent more than 80 billion metric tons of carbon dioxide equivalent from entering the atmosphere by 2050. Looking further ahead, the potential benefit grows. A successful phase-down could hold back a full 0.5 degrees Celsius of warming above preindustrial levels by the end of the century. That projection rests on the premise that parties honor the commitments they signed on to. The Montreal Protocol offers a degree of precedent here. All 197 United Nations member states eventually ratified it. The Kigali Amendment now carries that precedent forward, with the first ratifications arriving as early as 2017. Whether those projections are realized will be answered by the temperature record across the decades ahead.