New paper explores major opportunities under the Montreal Protocol to reduce ozone and climate super-pollutants

A new paper published this week outlines significant greenhouse gas mitigation opportunities under the global ozone treaty – the Montreal Protocol.

The paper in the Journal of Integrative Environmental Sciences (JIES) — written by Environmental Investigation Agency (EIA) climate campaigners from its UK and US offices — highlights the important role of the 1987 Montreal Protocol in phasing out 99% of ozone-depleting substances (ODS).

Since ODS are also harmful greenhouse gases, action taken under the Protocol has avoided as much as 2.5°C warming by the end of the century.

The treaty is now primarily concerned with reducing climate-damaging hydrofluorocarbons (HFCs), which have been widely adopted as alternatives to ODS, especially as refrigerants in cooling appliances. HFCs are the fastest growing greenhouse gases, but the Kigali Amendment to the Montreal Protocol, agreed in 2016, seeks to reduce their production and consumption by up to 85% by 2045.

However, a range of significant ODS and other fluorochemical greenhouse gas emissions that are unreported, unaccounted for and, in several cases, unexpected point to challenges for the Montreal Protocol. Their primary sources are feedstocks, by-products and intermediates in fluorochemical production processes which are not currently controlled.

The paper estimates that these avoidable emissions amount to almost 870 million tonnes of carbon-dioxide equivalent per year, higher than the 2022 annual emissions of Germany, Canada or Mexico.

Lead author and EIA UK Climate Campaign Leader Clare Perry said: “The Montreal Protocol is well known as the most successful environmental treaty, but it can and must do much more. What began as the ozone treaty can achieve some important climate mitigation, which we need now more than ever. This treaty has delivered time and again and it is simply a question of whether the political will of the Parties to the Montreal Protocol is there to do more.”

EIA US Climate Campaign Director Avipsa Mahapatra said: “The Intergovernmental Panel on Climate Change warns that our current trajectory is insufficient to cap warming at 1.5 degrees. The Montreal Protocol must ensure deep, sustained and accelerated emissions cuts through strengthened monitoring, reporting and enforcement of fluorochemical emissions and establishing a global framework to recover and destroy these super-pollutants from old equipment and products.”

The authors suggest a number of areas where strengthened controls under the Montreal Protocol can reduce fluorochemical greenhouse gas emissions, namely:

  • strengthening monitoring, reporting, verification and enforcement to enhance compliance
  • placing obligations on fluorochemical producers to minimise emissions of feedstocks, intermediates, process agents and byproducts
  • developing a global framework to recover and destroy ODS and HFCs in ‘banks’ of old equipment and products
  • addressing nitrous oxide (N2O) emissions from industrial processes – N2O is currently the most significant ODS in the world and the third most prevalent greenhouse gas
  • accelerating the global HFC phase-down under the Montreal Protocol through an adjustment to the Kigali Amendment.


Perry, C., Nickson, T., Starr, C., Grabiel, T., Geoghegan, S., Porter, B., Mahapatra, A., Walravens, F. (2024). More to offer from the Montreal protocol: how the ozone treaty can secure further significant greenhouse gas emission reductions in the future. Journal of Integrative Environmental Sciences, 21(1).