We’re seeing new movement toward phasing down the fastest-growing group of greenhouse gases – hydrofluorocarbons, or HFCs. These chemicals are widely used in refrigerators, air conditioners, foam products, and aerosols. And while they don’t stay in the atmosphere long, they can trap 1,000 times or more heat compared to carbon dioxide.

This week, the U.S. Environmental Protection Agency (EPA) proposed new regulations demonstrating its commitment to limiting the use of HFCs domestically. It proposed changes to its significant new alternatives program (SNAP) aimed at expanding the list of acceptable alternatives that minimize impacts on global warming while also restricting the use of HFCs in sectors where alternatives are now available. EPA estimates the proposed rule could avoid up to 11 million metric tons of carbon dioxide equivalent in 2030, which is equal to the energy-related emissions from about one million homes for one year.

Internationally, one sign of growing support for acting on HFCs came this month during the first visit by a U.S. president to Argentina in almost two decades. President Obama and newly elected Argentinian President Mauricio Macri explored opportunities to partner to address global challenges like climate change.

They affirmed their commitment to take action this year to amend the Montreal Protocol to phase down HFCs, which are substitutes for ozone-depleting chlorofluorocarbons (CFCs) that were successfully phased out under the 1989 Montreal Protocol. The two leaders also endorsed the understandings reached at the Dubai Montreal Protocol meeting in November 2015 on financial support for developing countries to implement an HFC phasedown.

A key opportunity will come next week when Montreal Protocol negotiators meet in Geneva to build on the progress made toward reaching agreement this year on an HFC phasedown amendment.

Overcoming challenges

The April meeting will consider a range of issues including: the availability of low global warming alternatives; guidelines for the Multilateral Fund in supporting developing country strategies for reducing HFCs; and legal aspects related to the UN Framework Convention on Climate Change. Among key questions to be addressed:

• Will technologies to help phase down HFCs be available to developing countries?

Developing countries worry that patents will restrict access to HFC alternatives, and whether the Protocol’s Multilateral Fund will help with the transfer of these low-global warming potential technologies. A recent brief by C2ES looks at patent issues in the phaseout of ozone-depleting CFCs by developing countries and the role played by the Multilateral Fund, which provides critical support for developing countries to comply with the treaty.

• How will action to reduce HFCs affect countries in extremely hot climates that, in a warming world, are increasingly dependent on air conditioning?

Cooling a building when it is well over 100 degrees Fahrenheit outside, for instance, is harder than cooling one where it is only 85 F outside. Although parties agree on the importance of phasing down HFCs, a critical concern is whether suitable alternatives are available and have tested well for cooling capacity and energy efficiency under extreme temperatures. One approach being considered is a time-limited exemption for countries that endure extremely high temperatures. A new brief by C2ES examines options for how such an exemption might be structured.

The meeting in Geneva kicks off this year’s treaty negotiations aimed at reaching an HFC phasedown amendment. A positive outcome will help build on the critical political momentum generated by the success of the Paris climate conference at the end of 2015. Unless controlled, emissions of HFCs could nearly triple in the U.S. alone by 2030. Strong international action to reduce HFCs could reduce temperature increases by 0.5 degrees Celsius by the end of the century, a critical contribution to global efforts to limit climate change.