Some of the world’s largest cities are being asked to publicly disclose what their carbon footprints are in a global effort led by a diverse group of organisations.

The Carbon Disclosure Project, which has been tracking greenhouse gas emissions of large businesses since 2000, recently sent questionnaires to the 40 largest cities in the world as part of a new initiative called CDP Cities. Those cities — which include Beijing, Delhi, Karachi, London, Mexico City, Moscow, Mumbai, New York, Shanghai and Tokyo — have until Jan. 31, 2011, to respond. The CDP plans to release the findings based on those questionnaires next May.

Besides data on carbon emissions, other questions the CDP is seeking answers to:

• Who’s the highest-level city official in charge of climate change?
• Has the city identified the physical risks it faces from climate change?
• Could global warming bring any benefits to the city?
• Does the city have plans for reducing greenhouse gas emissions and responding to the effects of climate change?

The new initiative was actually prompted by a group of cities themselves. Several municipalities contacted the CDP in 2008 to ask whether they could disclose their greenhouse gas emissions in the same way in which corporations do. The result of that inquiry was a CDP pilot programme involving 18 US cities that concluded such reporting could benefit cities as well as businesses.

“Cities are at the forefront of our global response to climate change,” states a report — “The Case for Carbon Disclosure” — written for the CDP by Accenture. “Cities consume approximately 60-80% of the world’s energy production. Experts differ in their analysis of the overall contribution of cities to greenhouse gas emissions but estimates show urban areas could be responsible for up to 80% of total emissions. It is not unusual for the largest cities to produce emissions that exceed those of medium-sized countries.”

The report continues, “However, city officials often lack the data required to understand both their key sources of emissions and the impact of their low-carbon initiatives. Identifying the major risks and opportunities of climate change can also be challenging for many cities.”

A common platform such as the one used by the CDP could help cities get better data to identify those risks and opportunities, the report finds.

Many of the cities being asked to respond to the new questionnaire have already undertaken aggressive steps to reduce emissions and improve sustainability. London, New York and Chicago, for example, already take inventories of their emissions, although each uses a different approach that makes it hard to compare one to the other. The CDP effort is aimed at making it easier to compare apples to apples, whether it’s the Big Apple (New York), the Big Durian (Jakarta) or the Big Chilli (Bangkok).

• Carbon emissions hit new high: ‘As if financial crisis never happened’
• World’s engineers to politicians: We can cut carbon now, so do it
• Is VW really the Darth Vader of automakers?
• Clock’s ticking: Carbon emissions must peak by 2015
• Why you can’t judge a country by its carbon emissions
• Carbon and energy cuts: Are we trying hard enough?
• Countdown to Copenhagen: Is there hope for change?
• How to cut carbon? Take our poll, earn chance to win prizes
• Cutting transport’s carbon footprint will take tech revolution
• Habit changes could cut as much carbon as France produces