On June 5, mayors and civic leaders from around the globe closed the United Nations World Environment Day (WED) summit in San Francisco by signing the Urban Environmental Accords. Media buzzed, hailing the day as historic: Putting a pen to the green declaration, the mayors pledged to put sustainability on the forefront of civic agendas.

The Accords focus on seven issues: energy, waste reduction, urban design, urban nature, transportation, environmental health, and water. Clarifying each are three actions. Waste reduction, for example, includes the action: 'Establish a policy to achieve zero waste to landfills and incinerators by 2040.' Timetables for the 21 actions range from immediately implementable change -- such as new policies or programs -- to decades-long projects. The Accords challenge cities to achieve as many of the 21 actions as possible before WED 2012.

The WED website explains that the Accords are the product of a yearlong collaboration among cities, the International Council for Local Environmental Initiatives, and the UN Environment Programme, as well as businesses, nonprofits, and educational institutions. Leading up to the signing, the five-day summit -- built around the theme 'Green Cities' -- provided a torrent of programming to educate and excite participants. As Utne magazine Associate Editor Leif Utne reported in his blog from the summit, 'There's so much going on -- literally hundreds of events all over San Francisco -- that it's like drinking through a firehose just trying to take it all in.'

Leading on the civic level, mayors appear uniquely poised to shoulder the Accords' responsibility. Planet Drum founder Peter Berg points out on the organization's website: 'The most significant cultural change for our species in the last 15,000 years is taking place in this decade. Homo sapiens is becoming an urban species.' As urban centers grow, so do the opportunities to enact concentrated change. In the San Francisco Examiner's coverage of the WED summit, Vancouver City Councilor David Cadman reflects, 'When you understand that 50 percent of the world's population lives in cities, and when you understand that cities consume 75 percent of the world's resources and occupy 2 percent of the land mass, then if cities change, the world changes.'