The Gary Null Blog

Freshwater is fundamental for maintaining human health, agricultural production, economic activity, and critical ecosystem functions. But as populations and economies grow, new constraints on water resources are appearing, raising questions about ultimate limits to water availability. Such resource questions are not new. The specter of "peak oil" -- a peaking and then decline in oil production -- has long been predicted and debated. A recent paper in the Proceedings of the National Academy of Sciences [1] I wrote with a colleague, Meena Palaniappan, offers three concepts of "peak water:" peak renewable water, peak nonrenewable water, and peak ecological water. And it looks like the U.S. has passed all three points.