Major cities are getting a bad rap for the disproportionately high greenhouse gases they emit even though their per capita emissions are often a fraction of the national average, a new report said on Monday.

Published by the International Institute for Environment and Development, the report found that urban residents generate substantially lower greenhouse gas emissions, which scientists blame for global warming, than people elsewhere in the country.

Although the concentration of people, enterprises, vehicles and waste in cities is often seen as a 'problem', high densities and large population concentrations can also bring a variety of advantages for ... environmental management, said the report.

The report brought together the findings of several studies published in the past 13 years to determine if cities have a disproportionately negative effect on global emissions.

The real climate change culprits are not the cities themselves but the high consumption lifestyles of people living across these wealthy countries, said report author David Dodman.

He analyzed the per capita emissions from major cities in Europe, Asia, North America and South America.

According to the report, London emitted 44.3 million tons of CO2 in 2006, or 8 percent of the national total.

With a population of around 7 million, per capita emissions in London were only 6.18 tons per person, or 55 percent of the UK's 2004 average of 11.19 tons.

In the United States, New York City had emissions of 58.3 million tons in 2005, or around 7.1 tons per person. U.S. per capita levels were more than triple at 23.92 tons in 2004.

The report noted the density of New York's buildings, the smaller-than-average dwelling sizes and the reliance on public transportation as reasons for the large difference.

Washington DC's per capita emissions of 19.7 tons were closer to the national average due to a high number of government office buildings versus a small metropolitan population, the report said.

Brazil's Sao Paulo and Rio de Janeiro, the only two South American cities analyzed, both had substantially lower per capita emissions due to the country's widespread deforestation and large amounts of livestock.

PRODUCTION VERSUS CONSUMPTION

The report analyzed only the emissions emitted directly by a city rather than those generated by the production of the goods consumed by its residents.

Production-oriented centers like Beijing and Shanghai, which house many factories outsourced by rich countries, were the only cities with higher per capita emissions than the national average.

Many polluting and carbon-intensive manufacturing processes are no longer located in Europe or North America, sited elsewhere in the world to take advantage of lower labor costs and less rigorous environmental enforcement, the report said.

Anna Tibaijuka, executive director of UN-Habitat, said in a presentation last week that cities emit 50-60 percent of greenhouse gases, rising to 80 percent if you include the indirect emissions generated by city-dwellers.

She said more than half of the world's population now lives in cities but they consume 75 percent of global energy.

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