Set in A.D. 2038 on a strange planet (ours) that is reeling from pollution and overpopulation but muddling through with the help of technological and political Band-Aids, David Brin's sci-fi epic Earth is a zap-by-zap chronicle of the eco-catastrophe to end them all. An artificial black hole has been ''dropped'' into the planet's core, where it begins to gobble magma with the infinite gluttony peculiar to black holes. The earth has become an apple with a burning stick of dynamite in it.
Brin is a physicist of note who has been a NASA consultant, and he knows how to turn the abstractions of particle physics into high adventure without resorting to the time-saving but unconvincing tricks of Star Trek-style space operas. He excels at the essential craft of the page-turner, which is to devise an elegantly knotted plot that yields a richly variegated succession of high-impact adventures undergone by an array of believably heroic characters. Overall, Earth resembles Herman Wouk's The Winds of War, except that the history Brin is dramatizing, though also on a similar global scale, is of his own imagining. Among the more memorable set pieces are a young black zookeeper's set-to with a tribe of angry baboons inside a latter-day ark; a female astronaut coping with disaster in high orbit; and her escape from a pitch-black cave by way of an underground river.
Brin's hugger-mugger is first-rate, but the prime attraction of Earth is the author's unfailing resourcefulness in extrapolating a post-greenhouse effect future that is plausible, dismaying, and amazing in equal parts. Since John Brunner's classic Stand on Zanzibar of 1968 (the best panorama before Earth of overpopulation in action), sci-fi writers have been reluctant to come to terms with the darker side of the foreseeable future. Technophile writers of the School of Heinlein have preferred to rocket about among the farther galaxies. When they did touch down on Earth it was in a gingerly and often Pollyannaish way, as if admitting that this planet's problems had top priority would be a form of treason to their prime loyalty, the space program.
Brin, though he has a gut feeling for hardware, doesn't come on as a ''stars or bust'' booster for SDI technology. His basic take on the future combines a liberal sensitivity to human needs with a libertarian hardheadedness about the price of omelets. Earth won't warm the hearts of the more extreme ''deep ecologists,'' but even they will have to admit that their concerns have never been more vividly rendered into fiction.
Similarly, Earth doesn't recommend itself to the finicky taste of those who demand highbrow art from genre fiction. Brin's prose ranges from regular to high octane; he excels at both action and argumentation of a discursive, Shavian sort; his characters have vivid intellectual lives. But there is too much happening, at too fast a pace, for the kind of nuances and psychological renderings that ''literary'' readers demand. Those readers aren't wrong, but they are missing something wonderful. A