Nothing beside remains.
The lone and level sands stretch far away. Researchers say the overcrowded cities, shortages of water and inadequate energy resources in 21st century California, India and Brazil, for example, are ominous reminders of the fate of the long-lost Roman, Babylonian and Mayan empires. This one-two punch can be lethal, they said, when environmental troubles, such as a prolonged drought or change in the climate, puts too much stress on society. The movement of peoples into big cities, like Rome and Tikal, the Mayan capital, created great wealth and produced rich cultures, but ultimately proved to be unsupportable. The societies themselves appear to have contributed to their own demise, Scarre added.