LONDON -- The world's cities are mushrooming at the rate of around 1 million people a week as the planet's population heads toward 9 billion people by 2050 from 7 billion now.

Urban areas are set to sprawl over an extra area equivalent to most of Europe within 20 years, yet little is being done to prepare for the major challenges that expansion will bring, scientists said Tuesday.

Already more than half the world's population is urbanized -- a fraction, they said, that would surge to some two-thirds by midcentury if current projections hold true. "Re-engineering cities is urgently needed for global sustainability," Shobhakar Dhakal, director of Tokyo's Global Carbon Project, said during the second day of the Planet Under Pressure conference.

Rehabilitation was a major theme of the meeting, held in the former industrial wasteland of east London's docklands area, adjacent to the site of the new stadium for this year's Olympic Games. Conferees learned that more than 70 percent of climate-changing carbon dioxide emissions are generated in cities, with emissions set to hit 36.5 billion metric tons in 2030 from 25 billion in 2010 and 15 billion in 1990.

But most cities around the world were neither planned for nor intended to hold the vast numbers of people they are projected to house, with, in many cases, aging water, sewage, power and transport systems already struggling to cope.

While a century ago there were fewer than 20 cities holding more than 1 million people, there are now around 450, of which at least 10 have a population of more than 10 million.

'The North American suburb has gone global'
"The way cities have grown since World War II is neither socially or environmentally sustainable, and the environmental cost of ongoing urban sprawl is too great to continue," Yale University's Karen Seto said at the conference, which runs through Thursday.

"The planet cannot afford not to urbanize. People everywhere, however, have increasingly embraced Western styles of architecture and urbanization which are resource-intense and often not adapted to local climates," she said. "The North American suburb has gone global, and car-dependent urban developments are more and more the norm."

The scientists called for a range of critical actions, including better urban planning, improved health monitoring, congestion charging to regulate road usage, smart power grids to balance power demand and supply, and more integrated green spaces to act as urban lungs. They also called for better water supply, drainage and waste treatment and the rehabilitation of urban rivers that could help improve sustainability and lifestyle.

Some among the 2,800 participants said such actions could also have hidden dividends of actually improving public health through cleaner air and the incentive to take more exercise in the new open spaces.

"We have the unique opportunity now to plan for a coming explosion of urbanization in order to decrease pressure on ecosystems, improve the livelihoods of billions of people, and avoid the occurrence of major global environmental problems and disasters," said Roberto Sanchez-Rodriguez, professor emeritus of environmental studies at the University of California, Riverside. "That process cannot wait."

A need to rethink resource movement
Sybil Seitzinger, director of the International Geosphere-Biosphere Programme, a science research program founded in 1987 and sponsored by the International Council for Science, said it is crucial that cities see themselves in a planetary context whose responsibilities do not end at the city limits.

"Everything being brought into the city from outside -- food, water, products and energy -- needs to be sourced sustainably. We need to rethink the resource flow to cities," she said.

Also at the conference Tuesday, a major alliance of science, research and United Nations bodies launched a 10-year initiative -- Future Earth Research for Global Sustainability -- to commence next year to coordinate scientific research into the major social and environmental challenges from climate change as they emerge over coming years. It will be officially launched at the Rio+20 meeting in Rio de Janeiro in June.

And while the meeting was frank about the major problems facing the planet while being relatively upbeat about solving at least some of them, one side session also showed the darker side of global deliberations with a look at some of the options being offered by intentionally manipulating the Earth's climate through geoengineering from dumping iron filings into the ocean to seeding clouds and pumping "designer particles" into the stratosphere.

The session concluded that while the likelihood of imminent intentional geoengineering was very slim, the possibility of it being used at some point in the future could not be ruled out.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500