The accords call for 21 actions aimed at putting cities on a path to greener, cleaner, healthier environments for their current residents and the estimated 1 million people moving to cities each week.

They covered energy, waste reduction, urban design, urban nature, transportation, environmental health, and water improvement programs to be implemented by mayors and delegates from cities like Jakarta, London, Seattle, Rio de Janeiro, Lausanne, and Calcutta.

Among the goals to develop global "Green Cities," the programs seek to reduce greenhouse gas emissions by 25 percent by 2030, set a policy of zero waste going to landfills and incinerators by 2040, ensure public parks within a half mile of every city resident by 2015, and safe drinking water for all by 2015.

The San Francisco event wound up a day of conferences, concerts, art shows, tours, films, parades, tree plantings and cleanup drives in cities around the world, all focusing on building momentum for environmental change.

CROWDED CITIES

By 2030, more than 60 percent of the world's population will live in cities, up from almost half now and just a third in 1950, UN Secretary-General Kofi Annan said. Growth poses huge problems ranging from clean water supplies to trash collection.

"Already, one of every three urban dwellers lives in a slum," Annan said in a statement. "Let us create green cities."

He added the UN goal of halving poverty by 2015 would not be met unless city planning was less haphazard.

Activists mark June 5, the date of the first environmental summit in Stockholm in 1972, as the UN's World Environment Day. The 2005 theme was "greener" planning for cities, many of them hit by air pollution, fouled rivers and poor sanitation.

Elsewhere on Sunday, millions of people from Japan to Jamaica marked World Environment Day by planting trees or staging rallies as the United Nations urged better "green" city planning to cope with runaway urban growth.

In China, home to a fifth of humanity, the 2005 focus was to curb noise and clean up fouled water, air and rubbish in urban areas, Pan Yue, vice minister of the State Environmental Protection Administration, told Chinese Central Television.

In Australia, green groups and local councils organized festivals to promote awareness of environmental issues from recycling to tree planting to cleaning up waterways.

COOL FASHION

In Greece, the port of Zakynthos banned cars for the day and allowed free public transport, while tree planting took place along the Sri Lankan coast -- devastated by the Dec. 26 tsunami -- in Kenya and at Ocho Rios on the Caribbean island of Jamaica.

Among events in Japan, a fashion show encouraged workers to dress less formally in summer to help cut air conditioning bills and save energy under a government-sponsored "Cool Biz" drive.

"By trying on these clothes, it helps ... raise awareness of environmental issues and help realize how we need to revolutionize our ways," said Sanyo Electric Chairman Satoshi Iue after walking down a catwalk in a gray suit and a white stiff-collar shirt -- but minus a tie.

In Norway, a youth group protested plans to build new gas-fired power plants, saying they would mean too much pollution and add to greenhouse gas emissions. (Reporting by Alister Doyle in Oslo, Leonard Anderson in San Francisco and Sarah Tippit in Los Angeles.)