With negotiations under the Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol) considering limits on hydrofluorocarbons (HFCs) as potent greenhouse gases, this paper examines past transitions during the relatively short, but dynamic history of this international treaty. It focuses on past shifts from chlorofluorocarbons (CFCs) to hydrochlorofluorocarbons (HCFCs) to HFCs, with the goal of identifying lessons that can inform discussions aimed at transitioning from high-global warming potential (high-GWP) HFCs.

At an HFC management workshop organized by the Ozone Secretariat in April 2015, a number of issues were raised about the availability and feasibility of alternatives to HFCs.

• Whether and when alternatives to high-GWP HFCs will be available in adequate quantities, from multiple suppliers, and at reasonable prices;
• Whether patents on the new technologies held by a few companies could limit access to substitutes by other companies, particularly those in Article 5 Parties; and
• Whether the guidelines under the Protocol’s Multilateral Fund would support funding for patents and licensing.

Answers to these questions are of critical concern to the Montreal Protocol Parties as they consider actions to phase down HFCs.