The fantasy-drenched concept of a race of humans living below ground is actually an old one. Indigenous tribes have long recognized the climatological and security benefits afforded by living underground. Modern versions of these dwellings are already underway in some quarters. Homes are being constructed below ground, as are other facilities, like the underground Marin County Jail, designed by legendary architect Frank Lloyd Wright. In creating these subterranean dwellings, measures are being taken to ensure a future sketch of humanity doesn't depict sheet-white, blind creatures that suffer from rickets and crippling depression and subsist on a diet of worms plucked from dirt walls. Even when living below ground, we must find ways to harness the essentials that we need to survive.
Water's not a problem; 30 percent of the freshwater on Earth can be found underground at any given time in the form of aquifers. This source is constantly replenished by precipitation trickling through the soil, which acts as a purifier [source: USGS]. Air doesn't operate the same way as water below ground. The density of soil makes it difficult to breathe, and less air is found below ground, which explains why you suffocate shortly after being buried alive.
This little problem and the need for sunlight are addressed through the atrium or courtyard design of earth-sheltered homes. These homes are built below ground on all sides, save for an entrance that usually looks like a door planted in the side of the hill. The only exposed area of the structure is a central atrium or courtyard, which allows air and sunlight into the home. In subterranean homes without any exposed areas, ventilation systems and shaft skylights serve the same purposes as an atrium.
Sunlight will stream into a much more massive underground structure in Japan through a pair of covered domes, the only feature that will divulge the subterranean city beneath. Due to their immense population sharing a proportionately small land mass, the Japanese are unsurprisingly at the cutting edge of underground construction. Their biggest project is the double-domed Alice City, based around two central shafts plunged 500 feet (152 m) below ground. The shafts allow light to enter and serves as the nucleus for an ant farm of office space, entire shopping malls and residences. Necessities like ventilation, power generation and waste are all handled on-site below ground [source: Time].
Alice City is not yet constructed, though slightly less ambitious projects are operating around Japan. Through ventures like underground offices and shopping malls, the Japanese are hammering out the problems with subterranean living. A television studio 66 feet (about 20 m) beneath Tokyo's street level addressed the problem of a sense of isolation among workers by simulating the weather aboveground. A fire in the subterranean mall that took the lives of 15 people in 1980 taught designers to keep the air thinner to reduce smoke and invest more heavily in fire sensors and sprinkler systems in underground structures than they do in aboveground ones [source: Time].
The Japanese are also hammering out the intricacies of growing food below ground through the Pasona O2 project. The Pasona staffing agency created a working underground farm in an unused bank vault located beneath the company's offices, five stories below ground. Using hydroponics and artificial lighting systems, the company is successfully growing crops like tomatoes, strawberries and rice [source: Trends in Japan].
Population trends suggest the globe will experience as many as nine billion people packed across its surface by 2050 [source: U.S. Census Bureau]. With space aboveground at a premium, subterranean living could become more than just viable, it may become a necessity.