CDP Cities provides a platform for cities to measure, manage and disclose their environmental data. More than 500 cities are now measuring and disclosing environmental data annually. The potential and need for this program is enormous since over 56% of the world's population now live in cities. CDP Cities provides a global platform based upon a simple questionnaire that allows city governments to disclose their greenhouse gas emission data publicly. One of the greatest values of the annual report, first released in June 2011, is to city leaders who can identify peers who are addressing similar risks and issues with new and innovative strategies for reducing carbon emissions and for mitigating risk from climate change.