President Barack Obama and Chinese President Xi Jinping take a walk at the Annenberg Retreat at Sunnylands in Rancho Mirage, California, on June 8, 2013. - 

President Obama and Chinese President Xi Jinping have wrapped up their California summit. The big breakthrough of the summit wasn’t on cybersecurity or trade, but on climate change. The two leaders agreed to reduce use of hydrofluorocarbons.

Hydrofluorocarbons -- or HFC's -- are mostly used in automobile air conditioners, something the car cultures of the U.S. and now China have in droves. HFC's are also hundreds to thousands times more potent greenhouse gases than carbon dioxide.

Durwood Zaelke, president of the Institute for Governance and Sustainable Development, says the agreement by the world’s two largest emitters of these gases to phase them out is significant.

"Reducing the HFC's can provide the single biggest and fastest piece of climate mitigation available to the world through 2020," he says.

That’s when he hopes the new UN climate treaty will go into effect. Zaelke says this new agreement, which could start as early as October, will cut global emissions by the equivalent of 100 billion tons of carbon dioxide. That’s more than ten times what the Kyoto Protocol has cut since it was implemented eight years ago.

And phasing out HFC's, says Zaelke, will be cheap. Low-cost alternatives have already been developed. Good news for the world’s two largest polluters.


Follow Rob Schmitz at @rob_schmitz