Vijayan/Flickr (cc by-nd)
Horseshoe bend of the Colorado River in Arizona.
It's already over-allocated, and the overwhelming scientific consensus is that the Colorado River is going to become more depleted in the decades to come. With a booming population, the river may no longer be able to provide water to the Western states that rely on it. Plus, increased snow melt has caused dust storms, which further accelerate snow melt. That causes plants to sprout earlier, taking up water through their roots. Alex Chadwick reports from a conference in Las Vegas on the consequences of desert development.