As the "Rio+20" United Nations Conference on Sustainable Development gets underway in Brazil this week with presidents and prime ministers gathering to negotiate ways to halt climate change, Oakland is playing a role.

Oakland Mayor Jean Quan is in Rio de Janeiro and spoke Tuesday at the invitation of the U.S. State Department about what cities can do and what Oakland has been doing to reduce greenhouse gas emissions and promote environmental justice.

Quan spoke about the Oakland Shines energy efficiency program for businesses, about Oakland’s Energy and Climate Action Plan as "one of the most aggressive" in the nation and about innovation started by Oakland-based companies including Sungevity and Solar Mosaic, which aim to make solar energy affordable to more people.

Addressing an audience at the U.S. Center at the Ri0+20 summit, and listened to in Oakland over live video stream over the web, Quan also said that working to solve poverty and solve climate change do not have to be separate goals. 

"I think we will not have sustainability unless we include everyone - and that includes particularly the low-income communities whether in Brazil or the United States," she said in her talk, watched from a live stream over the Internet. 

 Quan was the only mayor on a panel entitled "Cities: Where the Rubber Meets the Road" organized by the U.S. State Department in its U.S Center program. She joined the Chair of the White House Council on Environmental Quality Nancy Sutley and Sonoma County Supervisor and recent president of the national association of counties, Valerie Brown.

The same week that Oakland's mayor spoke at this international climate meeting, the U.S. Conference of Mayor's awarded Oakland with an "honorable mention" in its Climate Protection Honorable Mention list in Grand Rapids, Mich. Secondly, Oakland was ranked the fifth greenest city in America by Corporate Knights magazine. Two Oakland businesses, Solar Mosaic and BrightSource Energy, last week also shined a light on the city when they won SunShot Challenge grants from the U.S. Department of Energy for their work in driving down the cost of solar power. Solar Mosaic developed a crowd-source funding platform for solar installation financing and BrightSource is developing large-scale solar farm technologies and power sources. 

That the UN conference even included a panel with such a title holding up cities reflects a widening belief that it may be cities, local governments, new business innovations and actions by people that ultimately have some effect in stemming climate change rather than national governments or international treaties. After years of successive United Nations climate meetings in Cancun, Mexico; Copenhagen, Denmark; and elsewhere, national governments have had little progress in agreeing to treaties. 

"Rio+20 is a historic chance to move away from business-as-usual and end environmental destruction, reduce poverty, jumpstart the green economy and chart a course to a sustainable future. But the outlook is bleak," wrote Kathleen Rogers, the chief executive of Earth Day Network, which has an international membership on Huffington Post.

Rio+20 is so-named because it has been 20 years since the 1992 U.N conference on the environment in Rio at which some 90 nations committed to take steps to halt environmental degradation. Key world players, including the United States would not sign on to those commitments and so over time, few other countries adhered to them. The Rio+20 conference is expected to include leaders of 115 nations and representatives from some 50,000 non-governmental agencies.

Kent Portney, author of Taking Sustainable Cities Seriously and professor at Tuft's University, said in an introduction to the Knight Corporation list of the greenest cities in the United States that cities may be the answer. 

"In discussions about climate change and our deteriorating environment, it’s often said that cities – not international organizations, nations or states – are best positioned to put us on a more sustainable path. Indeed, American cities have already laid the groundwork for the pathway to a national green economy."

The National Resource Defense Council Director of Global Strategy Jacob Scherr wrote after participating in Rio+20 preparatory meetings at the United Nations, "We are struck by the lack of urgency and energy in the formal discussions."

Rio+20 might turn out to be the biggest United Nations meeting in history but at similar meetings in recent years in Cancun, Mexico and Copenhagen, Denmark, little progress was made to create binding agreements on policies that would in fact reduce climate change.