The United States is an extremely wealthy country, both economically and in natural resources. With a population of over 310 million people, it is the third most highly-populated country in the world, and the only western nation expected to experience large population growth in the future. All of those people need to live somewhere, and at the beginning of the 21st century, many of those people were choosing to live in the deserts of the American southwest.
Flash-forward into the future, and take a stroll around one of these desert cities, like Las Vegas, Phoenix, Tucson or Palm Springs. You will see similar adaptive strategies in all of them.
First, they will be smaller. Continuing changes in precipitation across the continental divide will mean less snowfall across the Rockies, which means less run-off into the Colorado River. As the Colorado River is the main source of water across much of the southwest, its decline will limit the number of people the desert can support, despite water conservation measures. While conservation certainly helps, it won’t be enough.
Las Vegas is by far the most precarious of these cities, partly because of its size, with over 1.9 million (2006) in its metro area, but also its reliance on the Colorado River and the reservoir at Lake Mead for nearly 95% of its drinking water.
The future Las Vegas will be a much smaller city. The tourist trade, while important, will be much smaller due to the high cost of air-travel in a post-peak-oil world. Much of the tourist industry will therefore be aimed at the more hard-core gamblers, and the wealthy. The more family-focused attractions, with their high water usages, will likely be gone. No more water parks, aquariums or massive outdoor fountain shows.
The eastern portions of Los Angeles, where the city sprawls onto the high desert, are also in a precarious position. This area is heavily reliant on water from the Colorado River, and becomes untenable if that supply should fail. Increased demands from cities further upstream, like Las Vegas, coupled with the declining rainfalls, will see this resource largely unavailable by the time water reaches Los Angeles. The city will be likely forced to turn to expensive desalination plants, which require large amounts of power. The advantage here will be the eventual lessening of demand upon the depleted Colorado River.
Most of the desert cities will see large population reductions to more sustainable levels. As water becomes more scarce, and water-preservation means becomes more strict, these cities will become far less attractive spots for migrants. The harsher conditions and work shortages will lead many people to leave. Many of these cities will return largely to the desert, their populations reduced to manageable levels or core workers and support workers for the smaller, but still significant, retirement communities.
Housing in these cities will be an odd mix of extreme-high density buildings for efficiency, often combining living and working areas, and very low density, sustainable housing in the outlying areas. Both types of housing will make use of geothermal systems for cooling and heating when required, and will feature extensive water-savings measures. High thermal-mass materials like concrete will be common, as will thick, fortress-like walls to retain interior temperatures. Solar power, in the form of thin-film systems covering entire buildings will be very common.
Life in the future desert will be a combination of the old and the new, ultra-high density housing, side-by-side with proven sustainable designs, all sprouting solar arrays and satellite communication dishes. It will be adapted to desert conditions, rather than trying to force the desert to adapt to man, to force upon it a simulation of life in a land with much more water than the desert can provide. Future life in the desert will be, and must be, sustainable.