The Rocky Mountain Institute is quite possibly the most effective environmental think-tank in the world. Under the leadership of Amory and Hunter Lovins, RMI has pioneered key work in energy efficiency, sustainable product design, hypercars and green building.
Now they're turning their attention to water.
You already know that we're expected to see massive shortages of fresh water in the next century, made worse by climate change and pollution - shortages which could lead to wars, ecological collapses and mass migrations of refuges. What you may not know is that some of the world's smartest water experts think these shortages is avoidable, if we change our approach.
The approach they're championing is a "soft path.". The ideas are deceptively simple: decentralize water systems, use green infrastructural systems (like those designed at Ocean Arks) to reclaim and reuse run-off and gray water, manage water demand more effectively, and distribute the best, most water-efficient technologies available as widely as possible. The differences these approaches could make are dramatically illustrated in this set of scenarios RMI commissioned (large PDF file).