Smithsonian.com

A "bathtub ring" is left around Lake Mead, a Colorado River reservoir, as water levels fall (courtesy of flickr user loop_oh)

First, check out my story on the Colorado River in the October issue of Smithsonian:

From its source high in the Rocky Mountains, the Colorado River channels water south nearly 1,500 miles, over falls, through deserts and canyons, to the lush wetlands of a vast delta in Mexico and into the Gulf of California.

That is, it did so for six million years….

The river has become a perfect symbol of what happens when we ask too much of a limited resource: it disappears. In fact, the Colorado no longer regularly reaches the sea.

But the Colorado River isn’t the only waterway that humans have manipulated to such a great—and devastating—degree. A new study published in today’s Nature reports that nearly 80 percent of the world’s population is facing threats to freshwater security because of damage to riverways caused by stressors like pollution, dams, agriculture and invasive species.

The list of regions most under threat is long and includes: much of the United States, Europe and central Asia; the Middle East, the Indian subcontinent and the eastern half of China; and desert belts in both the northern and southern hemispheres. “A strikingly small fraction of the world’s rivers remain unaffected by humans,” the scientists wrote. Those areas tend to be remote and unsettled.

The threat goes beyond the issue of freshwater availability. The researchers found that what humans are doing to river ecosystems has put thousands of species at risk and endangered the biodiversity of 65 percent of the habitats associated with the world’s rivers.

I sometimes feel like a broken record here. Yesterday, it was the message that a fifth of plant species are threatened with extinction. Earlier, a prediction that one in five lizard species could be extinct by 2080. Scientists keep showing us how we are messing up the world around us and how that is harming us. In the most recent study, they’re even kind enough to give us suggestions on how to prevent the worst from happening—better land use mangement and irrigation are a couple of examples—and explain that this would save money in the long term. But can we change our fate? I don’t know.