The Time Before This — Nicholas Monsarrat

On the icy slopes of the great ice-mountain of Bylot Island, set against the metallic blue of the Canadian Arctic sky, Shepherd has a vision of the world as it used to be, before the human race was weakened by stupidity and greed. Peter Benton, the young journalist to whom Shepherd tells his story, is dramatically snapped out of his cozy cynicism and indolent denial of responsibility, to face a dreadful reality. He discovers that he can no longer take a back-seat in the rapid self-destruction of the world, and is forced to make a momentous decision.