The novel's vision of Mars was inspired by astronomical speculations of the time, especially those of Percival Lowell, who saw the planet as a formerly Earth-like world now becoming inhospitable to life because of its advanced age.[25] According to the Barsoomians themselves, Mars was a lush world with global oceans just one million years before the present day. As the oceans evaporated and the atmosphere thinned, the planet devolved into partial barbarism.[26] Living on a dying planet, with dwindling resources, the inhabitants of Barsoom have become hardened and warlike, constantly fighting one another to survive.[27]
Barsoomians distribute scarce water via a worldwide system of canals, controlled by quarreling city-states. The thinning Martian atmosphere is artificially replenished by an "atmosphere plant" on which all life on the planet depends.[28] The days are warm and the nights are cold, and climate varies little across the planet, except at the poles.[29]
