By Valerie Volcovici
WASHINGTON (Reuters) - Leaders attending the Group of 20 summit of the world's biggest economies in St. Petersburg, Russia, agreed on Friday to phase down the use of certain potent greenhouse gases known to damage the climate.
The White House cited the agreement to cooperate on phasing down the use of hydrofluorocarbons (HFCs), gases used in refrigerators, air conditioners and some industrial equipment, as one of the "most significant agreements" of the summit.
"This commitment marks an important step forward toward addressing HFCs - highly potent greenhouse gases that are rapidly increasing in use - through the proven mechanism of the Montreal Protocol," the White House said in a fact sheet.
Addressing HFCs also has climate benefits and can reduce as much as 90 billion tonnes of carbon dioxide (CO2) equivalent between now and 2050, the White House said.
The Montreal Protocol is an international treaty established in 1987 that targets the production of various substances known to deplete the earth's ozone layer. The specifics of the agreement will be discussed at the next meeting of the protocol in October in Bangkok.
Separately, China and the United States, the world's top greenhouse gas emitters, agreed to take new steps on an HFC phasedown following there June agreement to cooperate.
The two countries agreed to set up a contact group to explore specific issues such as financial and technology support for developing countries under the Montreal Protocol, an step that marked the start of formal use of the protocol to phase down HFCs.
John Podesta, chairman of the liberal think tank Center for American Progress, said the U.S.-China move was a milestone in "stepping outside of the historically deadlocked U.N. climate negotiations to tackle HFCs."
President Barack Obama's climate action plan, announced in June, calls on the U.S. to show international leadership on climate change.
Part of the effort involves the United States working with countries to push to include HFCs within the Montreal Protocol.
The administration has also called on countries to stop investing in coal-fired power plants overseas as part of its international climate strategy.
On the eve of the G-20 summit on Wednesday five Scandinavian countries backed Obama's call to end the financing of overseas coal plants.
(Reporting by Valerie Volcovici, editing by Ros Krasny and Jackie Frank)