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, U.N. Secretary-General Kofi Annan said. Growth poses huge problems ranging from clean water supplies to trash collection.

Members of World Wildlife Foundation (WWF) place a giant faucet near the 'Christ the Redeemer' statue, at Corcovado mountain, to commemorate the World Environment Day in Rio de Janeiro, Brazil, Sunday, June 5, 2005. (AP Photo/Renzo Gostoli)

"Already, one of every three urban dwellers lives in a slum," Annan said in a statement. "Let us create green cities," he said, adding the U.N. 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 U.N.'s World Environment Day. The 2005 theme is "greener" planning for cities, many of them hit by air pollution, fouled rivers and poor sanitation.

In San Francisco, the main host of the 2005 event, mayors from more than 50 cities including Shanghai, Kabul, Buenos Aires, Sydney, Phnom Penh, Jakarta, Rome and Istanbul planned to sign up for a scheme setting new green standards for cities.

Cities would be ranked from zero to four stars according to compliance with a set of 21 targets. And around the world, from Australia to Zimbabwe, activists staged rallies, cleaned up litter, organized poetry competitions or planted trees.

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 revolutionise 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 staged protests against plans to build new gas-fired power plants, saying they would mean too much pollution and add to greenhouse gas emissions.

GLOBAL WARMING

The San Francisco meeting would set goals including a cut in emissions by cities of heat-trapping carbon dioxide (CO2) gas from cars, factories and power plants by 25 percent by 2030.

That is more ambitious than under the U.N.'s Kyoto protocol, which seeks to cut emissions from developed nations by 5.2 percent below 1990 levels by 2008-12.

"Cities are prolific users of natural resources and generators of waste. They produce most of the greenhouse gases that are causing global climate change," Annan said.

Other targets for the cities will include ensuring residents would not have to walk more than 500 meters (550 yards) in 2015 to reach public transport or an open space.

And in London, the environment ministry admitted that Britain's year-long presidency of the club of the world's top eight industrial nations -- focused on slowing global warming and helping Africa -- would emit a lot of hot air.

"The total carbon dioxide emissions associated with the G8 presidency will amount to 4,000 tonnes ... roughly equivalent to the emissions generated by the electricity and gas used in 800 average homes over a year," it said in a statement.

With reporting by David Fogarty in Singapore, Jeremy Lovell in London, George Nishiyama in Tokyo, Anis Ahmed in Dhaka and Tamora Vidaillet in Beijing

© Copyright 2005 Reuters Ltd.

###