OSLO, June 5: From Japan to Jamaica, millions marked World Environment Day on Sunday by planting trees or staging rallies as the United Nations urged better “green” city planning to cope with runaway urban growth.

By 2030, more than 60 per cent 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 said, adding 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 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, organised 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 organised festivals to promote awareness of environmental issues from recycling to tree planting to cleaning up waterways.

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 realise how we need to revolutionise our ways,” said Sanyo Electric Chairman Satoshi Iue after walking down a catwalk in a grey suit and a white stiff-collar shirt — but minus a tie.—Reuters