His last nonfiction book, Our Angry Earth (1991, co-written with his long-time friend, science fiction author Frederik Pohl), deals with elements of the environmental crisis such as overpopulation, oil dependence, war, global warming, and the destruction of the ozone layer.
O suyo zaguer libro de no ficción, A ira d'a Tierra, escrito de conchunta con unatro autor de sciencia ficción, Frederik Pohl, tracta d'aspectos medioambientals como o calentamiento global y a destrucción d'a capa d'ozono.WikiMatrix WikiMatrix