This paper in the October 2008 issue of the journal 'Environment and Urbanization' suggests that the contribution of cities to global anthropogenic greenhouse gas emissions is often overstated.

Many sources suggest that cities are responsible for 75-80% of all such emissions but, as demonstrated by statistics drawn from the IPCC's Fourth Assessment Report, this considerably understates the contributions from agriculture and deforestation and from heavy industries, fossil-fuelled power stations and high consumption households that are not located in cities.

The paper adds that the potential for cities to help address climate change is being overlooked because of this error, including measures such as the promotion of walking, cycling, public transport and building designs that require much less energy for heating and cooling. The paper is available to download for free for a limited time online (http://eau.sagepub.com/current.dtl ).