Last Saturday afternoon in a second-floor auditorium at San Francisco’s Metreon, the feel-good moments just kept on coming. The audience burst into spontaneous applause when the formidable Bianca Jagger declared that the Bush administration is part and parcel of the “military-petroleum complex,” not just its government facilitator. People obeyed when Salvadoran indigenous activist Marta Benavides insisted everyone take three deep breaths (“in through the nose, out through the mouth, always”) before she began explaining how racism feeds environmental degradation.

As the event entered its third hour, San Francisco State University urban and environmental studies professor Raquel Rivera Pinderhughes urged attendees to stretch and “take care” of themselves. Then Pinderhughes, the last speaker on the Social Equity panel at the United Nations’ World Environment Day event, got down to business.

“I don’t really care what happens this week,” she said. “I care about what happens afterward. We have to hold the mayors’ feet to the fire and make sure they follow through on what they’re promising.”

The conference was attended by mayors from 50 cities around the world. Where past UN environment celebrations have focused on sustainability (the 1992 Rio de Janeiro Earth Summit is the best-known), acid rain, desertification and the oceans, this year’s focus was on the world’s cities.

What the mayors are promising is considerable progress in the area of urban sustainability. On Sunday, the fifth and final day of the UN’s annual meeting on the environment, the mayors signed the Urban Environmental Accords, a set of 21 targets adding up to a “clean, healthy and safe environment for all members of our society.”

The goals are ambitious, and the mayors represent a huge constituency—meaning if they honor their commitments, it will have a measurable global impact.  

The targets are stringent. They include:

• Cutting greenhouse gas emissions by 25 percent by 2030.

• Reducing waste sent to landfills by 20 percent by 2012.

• Ensuring there’s a park and affordable public transportation within a quarter-mile of every city resident by 2015.

• Adopting high-density, mixed-use urban planning principles.

• Maintaining trees to cover at least 50 percent of available sidewalk space by 2012.

• Ensuring 20 percent of all city facilities and schools serve locally grown and organic food by 2012.

• Making sure all citizens have access to safe drinking water by 2015.

The goal is for cities to pick three of the 21 actions to focus on each year, with an evaluation coming at the end of seven years.

It sounds like another feel-good moment in the making, but in many parts of the world, urban sustainability is a matter of grave consequence. Mayors are feeling the heat of world migration patterns, which increasingly lead to city gates.

The UN estimates that by 2007, half of the world’s 6.5 billion people will live in cities, up from 30 percent in 1950. By 2030, city-dwellers will make up 60 percent of the world’s population. If cities are not prepared to accommodate this massive influx in an orderly way, the UN projects that by 2050, three billion of the world’s nine billion inhabitants will wind up in slums—crowded settlements just beyond city limits where people live without clean water, sewage or public services. These are places like the favelas of Brazil and the slums of Nairobi, which are as unkind to their human inhabitants as they are to the surrounding territories.

This is why the signatories to Sunday’s accord include the mayors of Delhi, Calcutta, Buenos Aires, Rio de Janeiro, Shanghai, Jakarta and Dhaka, all among the world’s 20 biggest cities, all in developing nations. Other signatories include Moscow, London, Melbourne, Sydney, San Francisco and Seattle. As the new UN atlas One Planet, Many People shows in page after page of satellite imagery, the cities of industrialized nations have a profound environmental impact too, through drained waterways and changed landscapes.

“The battle for sustainable development, for delivering a more environmentally stable, just and healthier world, is going to be largely won and lost in our cities,” said UN Environment Program chief Klaus Toepfer at Sunday’s ceremony, where he presided along with House Minority Leader Nancy Pelosi (D-SF).

There’s a little-red-hen feel to all this, as if fed-up mayors are tired of waiting around for sluggish national governments to act and are taking matters into their own hands. This was highlighted on the first day of the meeting, when Gov. Arnold Schwarzenegger announced goals for reducing California’s greenhouse emissions. In sharp contrast to the Bush administration, which couldn’t stomach the thought of reducing emissions to 5 percent below 1990 levels per the requirements of the Kyoto Protocol, Schwarzenegger is aiming for 80 percent below 1990 levels by 2050.

The organizers of this year’s World Environment Day were capitalizing on frustration with national leadership when they chose the theme. Cities, the organizers hope, can make a decisive end-run around recalcitrant national capitals.

As the event’s official Web site says, “Mayors are emerging as the most powerful and flexible agents of change.  They are able to respond quickly to environmental issues and are uniquely accountable to their citizens. Their enormous purchasing power is shaping markets…their visionary solutions provide inspiration and serve as models to all sectors of society.”

It’s just like the bumper sticker says: Think globally, act locally.