Governments will address the law of unintended consequences when they meet this week to revise a global treaty and try to eliminate the use of a group of greenhouse gases used in fridges, inhalers and air conditioners.



Hydrofluorocarbons (HFCs) were hailed as the answer to the hole in the ozone layer which appeared over Antarctica in the 1980s because they replaced hundreds of chemical substances widely used in aerosols which depleted the thin layer of ozone which protects the Earth from harmful rays of the sun.

One hundred and ninety-seven countries signed the historic 1987 agreement which phased out chlorofluorocarbons (CFCs) and similar hydrochlorofluoro carbons (HCFCs) and has seen gradual closure of the two polar ozone holes.

But concern has been mounting at how their substitute is undermining the landmark Paris climate agreement and could hamper attempts to keep global warming below dangerous levels.



“The use of hydrofluorocarbons is growing. Already, the HFCs used in refrigerators, air conditioners, inhalers ... are emitting a gigaton of CO2-equivalent pollution into the atmosphere annually. If that sounds like a lot; it is. It’s equivalent to the emissions from nearly 300 coal-fired power plants every single year,” the US secretary of state, John Kerry, told a UN meeting on the Montreal protocol earlier this year.

“An HFC phasedown amendment is a critical piece of the climate puzzle,” he added.

HFC use is increasing rapidly, driven by sales of fridges and air conditioning especially in fast-growing developing countries.

Researchers at the US government’s Lawrence Berkeley National Laboratory have calculated that 700m air-conditioning units, all using HFCs, are likely to be installed worldwide by 2030 and 1.6bn by 2050, it says.

The UN’s climate change body, the IPCC, has projected that global air-conditioning energy demand will grow 33-fold from 300 terawatt-hours (TWh) in 2000 to more than 10,000TWh in 2100, with most of the growth coming in developing economies.

Countries meeting in Kigali, Rwanda, this week will be asked to approve an amendment to the Montreal protocol. This would cover HFCs and, over time, eliminate the manufacture of the chemicals and, potentially reduce global temperatures by an around 0.5C by 2100.

A fast phasedown of the factory-made HFCs could avoid the equivalent of as much as 200bn tonnes of CO2 by 2050, according to a study published in Atmospheric Chemistry and Physics.

But negotiations will be tough. Rich countries want the chemicals phased out within 5-10 years, but developing countries led by China and India have argued for a date closer to 2031 which, they say, will give their chemical industries time to adapt.

But because HFC alternatives, including natural refrigerants such as CO2, and hydrocarbons, already exist, there is no technical reason why HFC reductions cannot be achieved quickly and inexpensively, say scientists and environmentalists.

G7 countries have committed to provide additional funding to help developing countries implement an HFC amendment and last month a group of philanthropists pledged $53m to help.

“It is in everyone’s interests to phase out HFCs as soon as possible,” said Gaby Drinkwater, Christian Aid’s policy officer. “As people in developing countries seek more air conditioners and refrigerators, a heavy expansion of HFCs could deal a significant blow to the ambition of the Paris agreement and set back any progress made on keeping global warming to 2C.”

However, environmentalists with a long memory say that governments could have easily avoided the release of tens of billions of tons of HFC chemicals if they had listened to scientists in the 1980s.

“HFCs were always known to have the potential to increase global warming. We solved the ozone problem of ozone but governments chose not to address the climate-changing potential of their substitutes even though they knew about it,” said Dr Robin Russell-Jones, former director of the skin tumour unit at the St John’s Institute of Dermatology in London.

“If it takes over a quarter of a century to fix a simple technological problem, then what chance is there for the world community to solve global warming?” he added.

In 1989, he wrote in one of Britain’s leading medical journals, the Lancet: “Most scientists want to see the Montreal protocol widened to include substitutes like HCFC22. If uncontrolled [they] will be adding 15% to the global warming effect of carbon dioxide by the year 2030.”