The World in 2050_ Four Forces Shaping Civilization's Northern Future - Laurence C. Smith [63]
Looking ahead to the next forty years, it’s not hard to see where the big pressure points lie. Joseph Alcamo directs a research institute at the University of Kassel dedicated to exploring different possible futures for humanity’s water supply. To do this they built WaterGAP,265 a sophisticated computer model incorporating not only climate change and population projections but also other factors like income, electricity production, water-use efficiency, and others. WaterGAP is thus a powerful tool for simulating a range of possible outcomes depending on the choices we make.
A typical, “middle-of-the road” WaterGAP scenario is shown here for 2050.266 Regardless of how the WaterGAP model parameters are twiddled, the big picture is clear: The areas where human populations will be most water-stressed are the same areas where they are water-stressed now, but worse. From this model and others, we see that by midcentury the Mediterranean, southwestern North America, north and south Africa, the Middle East, central Asia and India, northern China, Australia, Chile, and eastern Brazil will be facing even tougher water-supply challenges than they do today. One model even projects the eventual disappearance of the Jordan River and the Fertile Crescent267—the slow, convulsing death of agriculture in the very cradle of its birth.
Computer models like these aren’t built and run in a vacuum. They are built and tuned using whatever real-world data scientists can get their hands on. Take, for example, the western United States. In Kansas, falling water tables from groundwater mining is already drying up the streams that refill four federal reservoirs; another in Oklahoma is now bone-dry. These past observed trends, together with reasonable expectations of climate change, suggest that over half of the region’s surface water supply will be gone by 2050.268 Kevin Mulligan’s projection of the remaining life of the southern Ogallala Aquifer requires no climate models at all—it simply subtracts how much water we are currently pumping from what’s left in the ground, then counts down the remaining years until the water is gone.
In the United States, the gravest threat of all is to the Colorado River system, the aorta of water and hydropower for twenty-seven million users in seven states and Mexico. It supplies the cities of Los Angeles, Las Vegas, Tucson, and Phoenix. It irrigates over three million acres of highly productive farmland. Global climate models almost unanimously project that human-induced climate change will reduce Colorado River flows by 10%-30%269 and already, its water is heavily oversubscribed.
More water is legally promised to the Colorado’s various shareholders than actually flows in the river.270 Its left and right ventricles are Lake Mead and Lake Powell, two enormous reservoirs created by the Hoover and Glen Canyon dams, respectively. They haven’t been full since 1999. A bitter combination of high demand, high evaporation, and falling river flows has thrown the Colorado River system into a massive net deficit of nearly one million acre-feet per year, enough water for eight million people. By 2005, Lake Powell was two-thirds empty and almost to “dead pool” (the elevation of its lowest outlet, below which no water can be released by the dam and it ceases to function).271 This desiccation stranded marinas and boat docks on dry land and left a white bathtub ring some ten stories high on Lake Powell’s newly exposed canyon walls. “It was as though in four years . . . Lake Powell had simply vanished,” wrote James Lawrence Powell of his namesake in Dead Pool.
I’m glad humanity has a decent track record with things