Mayors from around the globe gathered for the United Nations World Environment Day Conference in San Francisco on Sunday to sign a 21-step international treaty that aims to help the world's cities become more environmentally friendly. Among its provisions, the "Urban Environmental Accords" calls for increased use of public transportation and drastic cuts in the amount of trash sent to landfills. They also call for increasing access to safe drinking water, with a goal of access for all by 2015. Mayors participating in the event came from Zurich, Istanbul, Melbourne, Seattle and dozens of other cities. Much of the conference focused on global warming and what mayors can do to curb emissions of "greenhouse gases" such as carbon dioxide that trap heat in the Earth's atmosphere.
