The original protocol introduced the phase-out of chlorofluorocarbons (CFCs) because of the damage they cause to the ozone layer. HCFCs were brought in as an interim measure to replace CFCs in air conditioning, some refrigeration equipment and foams.

HCFCs cause less damage to the ozone layer than CFCs but evidence has been mounting that the chemicals contribute to global warming. While another class of CFC-replacement chemicals, hydrofluorocarbons (HFCs), were included in the Kyoto Protocol that aims to cut greenhouse gas emissions, HCFCs were not.

The new Montreal agreement is to freeze production of HCFCs in 2013 and bring forward the chemicals’ final phase-out date by 10 years. The original Montreal Protocol called for the phase out of HCFCs in 2030 by developed countries and in 2040 by developing nations. As well as reducing greenhouse gas emissions, the accelerated production freeze may speed the recovery of the ozone layer.

“Governments had a golden opportunity to deal with the twin challenges of climate change and protecting the ozone layer and governments took it,” says Achim Steiner, executive director of UNEP. “The precise and final savings in terms of greenhouse gas emissions could amount to several billions of tonnes illustrating the complementarities of international environmental agreements.”

The governments have agreed that sufficient funding will be made available to achieve the measures.