MacArthur fellow Peter Gleick, 50, is a leading water expert and president of the Pacific Institute, in Oakland, California, and edits The World's Water: The Biennial Report on Freshwater Resources.

"The fact that this is the 21st century and we've failed to meet basic human needs for water is the most appalling problem facing us. It's our most egregious failure. We're not living in a world where our demand for resources has to go up inexorably. Clean water is finite, but it's renewable if we're careful. The problem is that we don't use it properly and don't plan our systems properly. If we did, there would be enough to meet everyone's needs. We give it inadequate attention, inadequate funding, and—all too often—incompetent governance. It's a problem of will and commitment. I originally came to the subject through an interest in energy issues, but I'm drawn to water now because it's so critical to everything we care about: the environment, prosperity, family life. If any other environmental problem is more connected to all aspects of our lives, it would be hard to imagine what that is."