With the urgent need to dramatically shrink human use of fossil carbon fuels, the role of cities has become central. Human populations are projected to become 60% urban this century, an unprecedented change for humanity. For a city of 10 million people, over 6,000 tons of food has to be imported every day, traveling an average of 1,000 miles. Material flows to support mega cities are poorly quantified, but vast. How will cities in the Anthropocene evolve? Can we supply large cities with what they need in a fossil carbon restricted world? This conceptual talk proposes that cities maybe far more constrained in determining their future than is hoped for and that to develop strategies for a post-fossil carbon world, the commonly accepted future of urbanization needs to be questioned and examined.