The World Bank emphasized that cities have a crucial role to play in the fight against global warming, as they can act more quickly and effectively than governments struggling to reach a consensus on a UN climate agreement. Andrew Steer, the World Bank's special envoy for climate change, pointed out that the top 10 biggest cities in the world collectively emit more greenhouse gases than Japan. He recommended reforms, such as changes to carbon markets, to help cities become more environmentally friendly. According to a World Bank study, urban areas, which are home to just over half of the global population and account for two-thirds of greenhouse gas emissions, could contribute to combating climate change by adopting greener transportation, clean energy, and improved waste recycling practices. Steer emphasized that cities are both a major contributor to climate change and a key potential solution to addressing it. They possess significant economic influence, with the report indicating that the world's 50 largest cities collectively have a gross domestic product second only to the United States, surpassing China. Tokyo and New York were highlighted as having economies larger than that of Canada or Turkey. Achieving consensus among 194 countries can be challenging, as seen in the UN climate talks aiming to reach agreements on measures to address global warming. In 2008, over 1,000 US mayors committed to reducing greenhouse gas emissions in alignment with the UN's Kyoto Protocol, which binds nearly 40 nations to emission reductions until 2012 but was never approved by the US government. Sea levels are a growing concern for many major cities around the world, including Tokyo, Shanghai, New York, and Buenos Aires, which are located near coasts or rivers. The World Bank is in favor of revamping the UN market mechanism that currently promotes investments in individual projects in developing nations, such as solar panels in Morocco or hydropower in Honduras, to a broader, city-wide scale. This reform of the UN's Clean Development Mechanism (CDM) would enable mayors to receive funding for a range of projects, from flood barriers to hydrogen-powered buses, without needing approval for each individual project. The CDM allows companies to invest in green projects in developing nations and receive credits for reducing emissions in their home countries. Steer also mentioned that city residents' opinions on the ideal living location were changing. In the past, when industrial pollution was a major issue, poorer individuals tended to live in areas like the east side of London that were affected by the pollution. However, in the future, it is predicted that the poor will reside in low-lying areas that are vulnerable to river flooding or sea level rise.