Neal R. Peirce: Greater global sustainability starts with "bottom-up approaches." 


New York City Mayor Michael Bloomberg presses the point even more forcefully. Speaking at an event at U.N. headquarters on Dec. 15, Bloomberg championed a major role for cities at Rio plus 20, specifically including mayors on national delegations.


Even as national and global efforts to curb greenhouse gas emissions have faltered, Bloomberg said, cities across continents have moved aggressively to the "forefront of climate change action." And that matters hugely, he suggested, since burning of carbon fuels by cities not only accounts for an overwhelming 70 percent of global greenhouse emissions, but "clogs our city streets, pollutes our air, harms the health and shortens the lives of the people we serve."


The mayor, who also chairs the C40 Cities Climate Leadership Group, noted New York's pacesetting "PlanNYC" -- the "greenprint" for his city's future. But he pointed as well to significant carbon reduction efforts in such cities as Lagos, Buenos Aires, Jakarta, Johannesburg, Hong Kong, Berlin and Seoul.