It could be argued that refrigeration is perhaps one of our best inventions. Keeping food and vaccines fresh for longer, and safe for human consumption has revolutionised our health, wellbeing, and life expectancy. 

Refrigeration is not as new as we might think though. Mankind has been using ice and snow to preserve perishable goods for centuries. Modern refrigeration, as we know it, however, has only been around for about 100 years. From around the late 1800s, scientists started experimenting with the liquefaction and evaporation of gases. But the gases used had wider consequences when used in the home. Ammonia, for example, was highly toxic if leaked, while other refrigerant gases used at the time, such as methyl formate and sulphur dioxide, were poisonous and highly explosive. So, the search was on for a safer alternative. 

From hero to zero…..
By late 1920s, synthetic refrigerants known as chlorofluorocarbons (CFCs) had been developed, making domestic refrigeration far less risky. CFCs seemed perfect for the modern world. They do no damage to land, sea or the air we breathe. They neither react with other substances in the biosphere nor dissolve to pollute the rain, and are non-toxic and non-flammable. Unsurprisingly, their application became more and more widespread. Domestic refrigeration became affordable and spread rapidly. 

But there was a catch. The high stability of CFCs, making them so useful on earth, once released allows them to reach the stratosphere intact. There ultra-violet (UV) radiation breaks down CFCs releasing chlorine atoms that destroy ozone molecules in the “ozone layer”. Chlorines from CFCs can go on to destroy ozone molecules over and over. As fridges became more widespread in our homes, we were blissfully unaware of the damage that these gases were wreaking in the upper atmosphere. But why all the fuss over a damaged ozone layer? 

The ozone layer is a thin layer of gas high up in the stratosphere. It is only about 3 mm thick when brought down to the pressure at ground level, but is a highly effective sun shield, blocking almost all damaging spectrum of the UV radiation from reaching Earth. Depletion of the ozone layer, or even worse, the loss of the ozone layer altogether, would be catastrophic. Exposure to elevated levels of UV radiation would severely impact all living things on Earth: plants, animals, ecosystems and us.

…….to saving the ozone layer…….
Luckily, scientists alerted the world of the dangers posed by CFCs to the ozone layer and the Vienna Convention for the Protection of the Ozone Layer was adopted in 1985. Celebrating its 40th anniversary in 2025, this landmark treaty paved the way for the Montreal Protocol on Substances that Deplete the Ozone Layer adopted two years later in 1987. 

All the countries of the world signed up to the Protocol and agreed to stop using CFCs and instead start using alternative refrigerants such as hydrofluorochlorocarbons (HCFCs) and hydrofluorocarbons (HFCs). To date, 99 per cent of production of ozone-depleting substances has been phased out through the Protocol, and the ozone layer is slowly healing. If countries continue to implement the Montreal Protocol, it is expected that the ozone layer will return to pre-1980 levels by around the mid 2040s and the Antarctic Ozone Hole by around mid 2060s. Problem solved? 

……but that’s not how the story ends

Ozone layer recovery still has a long way to go. The path to full recovery very much depends on countries keeping to their obligations under the Protocol and addressing any new challenges that might impact the ozone layer.

But along this path of recovery came another catch. While HFCs, introduced as substitutes, do not destroy the ozone layer, they are potent greenhouse gases that impact the environment. Some HFCs are over 10,000 times more adept at trapping heat than carbon dioxide. Efforts to save the ozone layer created a new issue that needed to be addressed.

Once again, the parties to the Montreal Protocol listened to the evidence, science and data. While initially noting that HFCs were not ozone depleting and therefore not controlled under the Protocol, the parties nevertheless, considered what they could do about HFCs in the interest of the environment and climate. 

In 2016, the parties agreed to the Kigali Amendment which came into effect on 
1 January 2019. Countries that ratify the Amendment, commit to phasing down the use of HFCs and adopt greener alternative refrigerants. They are also encouraged to adapt to or use more energy efficient cooling technologies. 

While we all want access to fresh and healthy food and vaccines that are safe to consume, it comes at a cost. As the world becomes warmer and prosperity levels have increased, so has the demand for cooling equipment; precisely the equipment that is emitting HFCs and adding to the rising levels of greenhouse gases in our atmosphere. 

Scientists have estimated that full ratification and compliance with the Kigali Amendment could avoid up to 0.5°C of warming by 2100. Combined with improvements in the energy efficiency of equipment, this could potentially double to 1°C by the end of the century. To date, 163 parties (out of 198) have ratified the Amendment. 

On World Refrigeration Day, we want to highlight the importance of the Kigali Amendment as a key driver towards sustainable cooling. Its universal ratification would increase the demand for more skilled technicians, engineers, designers and architects, and boost innovation to improve access to cooling and support livelihoods – a milestone worth aiming for ahead of its 10th anniversary in 2026!