The Drowned World by J.G. Ballard

First published in 1962, J.G. Ballard's mesmerizing and ferociously prescient novel imagines a terrifying future in which solar radiation and global warming have melted the polar ice caps and Triassic-era jungles have overrun a submerged and tropical London. Set during the year 2145, the novel follows biologist Dr. Robert Kerans and his team of scientists as they confront a surreal cityscape populated by giant iguanas, albino alligators, and endless swarms of malarial insects. Nature has swallowed all but a few remnants of human civilization, and, slowly, Kerans and his companions are transformed—both physically and psychologically—by this prehistoric environment. Echoing Joseph Conrad's Heart of Darkness—complete with a mad white hunter and his hordes of native soldiers—this "powerful and beautifully clear" (Brian Aldiss) work becomes a thrilling adventure and a haunting examination of the effects of environmental collapse on the human mind.