The Montreal Protocol has not only served to protect the ozone layer, it also has provided a certain degree of climate protection. However, this positive effect on climate may be reduced or lost completely if the use of hydrofluorocarbons (HFCs) as substitutes for ozone-depleting substances continues to increase. The climate benefits could be preserved if appropriate alternatives would be chosen to meet the growing global demand for HFCs in refrigeration, air-conditioning and foam production systems. This is the conclusion of a study led by the RIVMNational Institute for Public Health and the Environment and published in the scientific journal Science.

The Montreal Protocol has not only served to protect the ozone layer, it also has provided a certain degree of climate protection. However, this positive effect on climate may be reduced or lost completely if the use of hydrofluorocarbons (HFCs) as substitutes for ozone-depleting substances continues to increase. The climate benefits could be preserved if appropriate alternatives would be chosen to meet the growing global demand for HFCs in refrigeration, air-conditioning and foam production systems. This is the conclusion of a study led by the RIVMNational Institute for Public Health and the Environment and published in the scientific journal Science.

What are HFCs?

HFCs increasingly are being used in applications that traditionally used ozone-depleting substances (CFCs and HCFCs), such as in refrigeration and air conditioning equipment, as blowing agents for foams, and in aerosol sprays. As most of these ozone-depleting substances are potent greenhouse gases, their reduced application has also had the added benefit of providing a certain degree of climate protection. However, although HFCs do not destroy the ozone layer, they are, in fact, potent greenhouse gases.

HFCs and climate forcing

The current contribution of HFCs to climate forcing is less than 1% of the total forcing caused by all greenhouse gases. However, this contribution is rapidly increasing and could become 14% to 27% of the increase in CO2 forcing from 2010 to 2050. The increase in the use of HFCs can be directly attributed to the Montreal Protocol, and, hence, the related effect on climate change may be viewed as an unintended side effect of this Protocol.

Maintaining the climate benefit

Future climate forcing effects of HFC use could be reduced by selecting appropriate alternatives. In several sectors, alternatives are already in commercial use, such as in fibre insulation materials and dry powder asthma inhalers, and as hydrocarbons, ammonia and CO2 in some refrigeration systems. HFCs have been included in the Kyoto Protocol. However, at the last UNUnited Nations  climate conference held in Durban, in 2011, it was decided that new climate commitments will come into effect only from 2020 onwards. This leaves an eight-year gap, without a climate treaty involving legally binding global measures to reduce potential climate effects of HFCs and other greenhouse gases. Therefore, several countries have proposed that HFCs also be included in the Montreal Protocol, as a way of preserving the positive effect on climate from phasing out ozone-depleting substances. To date, however, no such agreement has been reached.

Article in Science: Guus J. M. Velders, A. R. Ravishankara, Melanie K. Miller, Mario J. Molina, Joseph Alcamo, John S. Daniel, David W. Fahey, Stephen A. Montzka, Stefan Reimann, Preserving Montreal Protocol climate benefits by limiting HFCs.

Link to the article on the Science website (http://www.sciencemag.org/lookup/doi/10.1126/science.1216414).