The World Bank stated that cities should take on a larger role in combating global warming, as they can act more effectively than governments struggling to reach a UN climate agreement. According to Andrew Steer, the special envoy for climate change at the World Bank, the 10 largest cities in the world produce more greenhouse gases than Japan. He suggested reforms, such as changes to carbon markets, to help cities become more environmentally friendly. A World Bank study noted that urban areas, where over half of the world's population resides and which are responsible for two-thirds of greenhouse gas emissions, could contribute to reducing emissions by adopting greener transportation, clean energy, and improved waste recycling practices. Steer emphasized that cities are both a major cause of climate change and a vital part of the solution. The report highlighted the significant economic influence of the world's 50 largest cities, stating that their combined gross domestic product was second only to that of the United States, surpassing China. Tokyo and New York were singled out as having economies larger than Canada or Turkey. The UN climate talks, aiming to reach agreement on measures to combat global warming at a conference in Cancun from Nov. 29 to Dec. 10, were described as challenging due to the diverse opinions of the 194 countries involved. In 2008, over 1,000 US mayors pledged to reduce greenhouse gas emissions in accordance with the UN's Kyoto Protocol, which obligated nearly 40 nations to limit emissions until 2012 but was never ratified by the US. Many of the world's largest cities, including Tokyo, Shanghai, New York, and Buenos Aires, are located near bodies of water, making them vulnerable to floods and rising sea levels. The World Bank is advocating for a revamp of the UN's market mechanism that currently focuses on individual projects in developing countries, such as solar panels in Morocco or hydropower in Honduras, to instead allow for broader, city-wide investments. This reform of the Clean Development Mechanism (CDM) would enable mayors to access funding for a range of initiatives, from flood prevention measures to eco-friendly transportation, without needing approval for each individual project. The CDM currently allows companies to invest in environmentally friendly projects in developing countries and receive credits for reducing emissions. Steer also mentioned that the opinions of urban residents regarding the best places to live were changing. In the past, when there was high industrial air pollution, areas like the east side of London, which were downwind, were inhabited by the poor. However, in the future, it is predicted that the poor will reside in low-lying areas that are at risk of flooding from rivers or rising sea levels.