Global urbanization: can ecologists identify a sustainable way forward?

The year 2007 was the first year in which more than half of humanity lived in cities. Over the next 25 years, the world will see the addition of nearly one million km2 of urban area, occurring in tens of thousands of cities around the globe. The form these new neighborhoods take will affect our planet's ecology profoundly. Here, I highlight the connection between urban form and ecosystem service generation and consumption. I also discuss how urban form controls energy use, and hence oil security and climate change. I argue that only by directly addressing the implications of urban growth as a research subject will ecologists meet their responsibility to provide a foundation for a sustainable biosphere, a mandate of the Ecological Society of America.