Cities have proven to be crucial to the process of achieving global sustainability initiatives, from the Paris Climate Agreement to the New Urban Agenda. As areas dense with exploding populations and large carbon footprints, cities benefit from policies that aim to reduce pollution and protect the environment. If the situation demands it, local urban governments may make the choice to chart their own courses. Cities don't sign international treaties, and Garcetti's pledge to maintain the treaty was political, not legislative. But there is power in numbers, and more than ever, cities are coming together to unite behind common goals. For example, the Mayors National Climate Action Agenda commits U.S. mayors to working together to strengthen local efforts for reducing greenhouse gas emissions. The C40 Cities Climate Leadership Group is a network of the world's megacities committed to addressing climate change. It's groundbreaking that cities are coming together to rally for their causes, but the more important aspect is that national governments are actually listening. This interesting shift of power represents the high status that cities currently have on the world stage, and the power they have to influence environmental, political and economic issues. As the world becomes increasingly urban, local governments taking the lead on global initiatives may be the key to achieving global sustainability.