The informal summit between the presidents of China and the United States last week yielded one very one important climate-related agreement.  After years of opposing international efforts to restrict hydrofluorocarbons (HFCs – a potent family of greenhouse gases), China has now agreed to cooperate with the United States and most other nations in moving forward to phase down the use of these chemicals under the Montreal Protocol.

The Montreal Protocol is the international treaty agreed to in 1987 that restricts the production and use of ozone-depleting substances with the goal of restoring the earth’s protective ozone layer. Widely hailed as the most successful international environmental treaty, it has been ratified by all 197 states. While not its primary objective, the treaty has also played an important role in reducing greenhouse gas emissions and now appears on track to play an even larger role.

Chlorofluorocarbons  (CFCs) were the first and most significant ozone-depleting substances phased out under the treaty.  In addition to being potent ozone depleters, these compounds have global warming potentials roughly 11,000 times that of carbon dioxide.  One analysis suggests that by phasing out CFCs, the Montreal Protocol slowed the increase in global warming by 5 to 6 times the amount that would have been achieved by the reductions in carbon dioxide and other greenhouse gases called for by the Kyoto Protocol.

But the phase-out of CFCs led to the development and expanded use of HFCs as substitutes for CFCs in refrigeration, foam, aerosol propellants and other applications.  HFCs do not deplete the ozone layer, but do contribute to climate change with a global warming potential 1,400 times that of carbon dioxide.

HFCs, with an atmospheric lifetime of only 14 years, are referred to as a short-lived climate pollutant. In a recent brief, C2ES laid out a strategy for slowing the rate of near-term climate change by reducing HFCs and other short-lived climate pollutants, such as methane and black carbon.

The United States, Mexico and other nations have tried for the past four years to get agreement under the Montreal Protocol to phase down HFCs. They contribute about 1 percent of total global warming, but with expanded use worldwide, could account for as much as 20 percent by 2050. While more than 100 nations have voiced support for amending the Montreal Protocol to include restrictions on HFCs, China, India, Brazil and a few other nations have blocked progress.  The Parties to the Montreal Protocol will reconvene later this month to begin discussing this and other issues. With China’s cooperation, the prospects for adding a new chapter in climate protection under the Montreal Protocol have considerably improved.