Few now can tell for certain what calamity caused the Greylands before the Regression. Most believe it was a combination of pollution, climate change, and devastating wars which killed off most of the vegetation and mutated the rest into pitiful remnants of trees and bushes together with an anemic species of grass. These live haphazardly in the vast grey desert where things only grow when intensely cultivated and irrigated. A ruptured ozone-layer makes the sun into a threat to be avoided, and among the Greylanders melanoma is ten times as common as in the cities. Also, the constant shortage of clean freshwater causes far more sickness and deformities in the Greyland dwellers than in the urbanites.