Cities around the world have also begun to take climate change seriously, many in response to the direct threat they face.

WASHINGTON, D.C.:

If global development priorities are not reassessed to account for massive urban poverty, well over half of the 1.1 billion projected to join the world's population between now and 2030 may live in under-serviced slums, according to State of the World 2007: Our Urban Future, released January 10 by the Worldwatch Institute. Additionally, while cities cover only 0.4 percent of the earth's surface, they generate the bulk of the world's carbon emissions, making cities key to alleviating the climate crisis, notes the report.

As recently as a century ago, the vast majority of the world's people lived in rural areas, but by sometime next year more than half of all people will live in urban areas. Over 60 million people - roughly the population of France - are now added to the planet's burgeoning cities and suburbs each year, mostly in low-income urban settlements in developing countries.

Unplanned and chaotic urbanisation is taking a huge toll on human health and the quality of the environment, contributing to social, ecological, and economic instability in many countries. Of the three billion urban dwellers today, one billion live in 'slums', defined as areas where people cannot secure key necessities such as clean water, a nearby toilet, or durable housing. An estimated 1.6 million urban residents die each year due to lack of clean water and sanitation as a result.

The Commission for Africa has identified urbanisation as the second greatest challenge confronting the world's most rapidly urbanising continent, after HIV/AIDS. Only about 35 per cent of Africa's population is urban, but it is predicted that this figure will jump to 50 percent by 2030.

State of the World 2007 also described how community groups and local governments have emerged as pioneers of groundbreaking policies to address both poverty and environmental concerns, in some cases surpassing the efforts of their national governments. "The task of saving the world's modern cities might seem hopeless - except that it is already happening," said Christopher Flavin, president of the Worldwatch Institute. "Necessities from food to energy are increasingly being produced by urban pioneers inside city limits."

Cities around the world have also begun to take climate change seriously, many in response to the direct threat they face. Of the 33 cities projected to have at least eight million residents by 2015 at least 21 are coastal cities that will have to contend with sea-level rise from climate change.

In the United States, over 300 cities - home to more than 51 million Americans - have joined the U.S. Mayors' Climate Protection Agreement, committing to reducing their emissions and lobbying the federal government for a national climate policy. Chicago, for example, has negotiated with a private utility to provide 20 per cent of the city government's electricity from renewable sources by 2010, and aims to become 'the most environmentally friendly city in America'. Not to be outdone, New York mayor Michael Bloomberg recently announced plans for his city to become the nation's leader in reducing greenhouse gas emissions.

While no single set of 'best practices' would enable all cities to successfully address the challenges of poverty and environmental degradation, State of the World 2007 focuses on areas where urban leadership can have benefits for the planet and human development. These include providing water and sanitation services to the urban poor, bolstering urban farming, and improving public transportation. Additionally, the report recommends devoting more resources to information - gathering on urban issues so that city, national, and international entities can better assess development priorities.

The Worldwatch Institute is an independent research organisation based in Washington, D.C. that works on energy, resource, and environment issues. The State of the World Report is published annually.