In 1985, three British scientists published a paper in the journal Nature that revealed there was a large hole in the ozone layer above the Antarctic. The research sent shockwaves around the world. The ozone layer shields the planet from the sun’s harmful ultraviolet radiation and its loss would decimate life on Earth.
The crisis led to the Montreal Protocol, a landmark global agreement that has put the ozone layer on the path to recovery. But the Protocol also has the potential to do something else: slow climate change. By implementing its key obligations, countries could prevent what experts call a massive amount of global warming, key at a time when the planet’s temperature is going through the roof.
“The Montreal Protocol has helped protect the world from the sun’s deadly ultraviolet radiation,” said Megumi Seki, Executive Secretary of the Ozone Secretariat administered by the United Nations Environment Programme (UNEP). “It is also helping us combat another catastrophe.”
Here’s a closer look at the Montreal Protocol and how it’s countering climate change.
What exactly is the ozone layer?
Located 15–35 km above the Earth’s surface, the ozone layer acts as a shield, protecting humans, animals and plants from harmful ultraviolet (UV) radiation from the sun, in particular UV-B. Without the ozone layer, the Earth would be a very different place: crops would fail, and humans would be blighted by everything from cataracts to skin cancer.
What has the Montreal Protocol done?
The accord has led to the phase out of 99 per cent of ozone-depleting substances, including chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). These refrigerants were once commonly found in fridges, air conditioners, foams, spray cans and fire extinguishers. Their demise has put the ozone layer on the road to recovery; scientists estimate it will return to pre-1980s levels by 2066.
How is the Montreal Protocol tackling climate change?
Most ozone-depleting substances also contribute to global warming. By reining in these substances and protecting carbon sinks, like forests, from damaging ultraviolet radiation, the protocol is expected to prevent about 0.5°C to 1°C of warming by the end of the century.
But that’s not the end of the story. CFCs and HCFCs, have been largely replaced by hydrofluorocarbons (HFCs). Although harmless to the ozone layer, HFCs are potent greenhouse gases. Some are thousands of times more adept at trapping heat than carbon dioxide, the most common greenhouse gas, says Seki.
Adopted in 2016, the Montreal Protocol’s Kigali Amendment aims to gradually reduce HFC production over the next 30 years. So far, 162 states and the European Union have ratified the treaty.
What effect could the Kigali Amendment have on global warming?
Eliminating HFCs could prevent up to 0.5°C of planetary heating by the end of the century. Seki says that could make a big difference in the trajectory of climate change. “For every fraction of a degree the Earth warms, the impacts of climate change – from droughts to wildfires, to superstorms – become more severe,” she says.
According to UNEP’s latest Emissions Gap Report, a 0.5°C temperature rise would increase the frequency and severity of heat extremes, heavy rainfall events and regional droughts.
Energy efficiency is also a pillar of the global effort to implement the Kigali Amendment. As nations phase down HFCs, they are also working to transition to cooling equipment that uses less electricity, helping to lower the greenhouse gas emissions associated with power generation.
Does the Kigali Amendment support other efforts to limit greenhouse gas emissions?
Yes. HFCs, also fall under the Paris Agreement, which aims to limit global warming to well below 2°C this century. The amendment also serves as the foundation of voluntary initiatives like the Global Cooling Pledge. Launched in 2023 it aims to reduce cooling-related emissions by more than two-thirds and dramatically improve the efficiency of air conditioners while also promoting passive cooling solutions.
What is UNEP doing in this area?
UNEP hosts the Secretariat of the Montreal Protocol and the Multilateral Fund for the Implementation of the Montreal Protocol. The fund is helping 144 developing countries to phase out ozone-depleting substances, phase-down HFCs and at the same time, improve the energy efficiency of cooling. Meanwhile, UNEP through its OzonAction programme, strengthens the capacity of developing nations and industry to implement the Montreal Protocol.
Finally, the UNEP-convened Climate and Clean Air Coalition supports action on super climate pollutants, like HFCs, including through partnerships and by funding transformative projects at the global, regional and country levels.
What needs to happen next to harness the full cooling potential of the Kigali Amendment?
The amendment needs to be fully ratified by all parties to the Montreal Protocol; so far, 163 of the 198 parties have done so. Seki says universal ratification and full implementation of the amendment is key to maximizing its contribution to reducing global temperature rise. As well, energy efficiency improvements, which should take place amid the phase down of HFCs, are crucial for meeting a rapidly increasing demand for cooling while minimizing further warming of the planet.
The Montreal Protocol Ozone Secretariat based in Nairobi, Kenya, housed within the United Nations Environment Programme (UNEP) is the administrative office for two important ozone protection treaties/agreements: the Vienna Convention for the Protection of the Ozone Layer and the Montreal Protocol on Substances that Deplete the Ozone Layer. Both play a major role in safeguarding the ozone layer, an invisible shield around the Earth that protects all living things from the effects of the sun’s harmful ultraviolet (UV) radiation. Through the Protocol’s Kigali Amendment adopted in 2016, countries that ratify the Amendment are helping to cool the planet. By phasing down hydrofluorocarbons (HFCs) - potent climate-warming refrigerants – this will avoid an estimated 0.5°C of warming by 2100. Combined with improvements in energy efficiency of equipment in the cooling sector, this could be doubled, making the Kigali Amendment a powerful climate action tool.
