Just as oil shaped politics and conflict across the world in the 20th century, another resource, water, may become the focus of international relations in the 21st. Oscar-winning director Jessica Yu's documentary <em>Last Call at the Oasis </em>examines the possibility of a water crisis in the near future. The companion book, edited by journalist Karl Weber (and published by Public Affairs), collects by essays on the subject by Yu as well as activists, experts and academics. Unlike oil, water is essential to life, and as the human population climbs to unprecedented numbers, what has until now been a more or less finite if renewable supply will be under stress. As many as one billion of the world's seven billion people may already lack access to fresh drinking water. Shortages are already evident in the American southwest and our country's water infrastructure is crumbling or insufficient. <em>Last Call at the Oasis</em> cites Milwaukee as “a world water hub” for research and development into this building block for the Earth's environment.