Twenty years after The Population Bomb comes the Explosion. And an apt word that is: For all that Paul Ehrlich warned about in that volume has come about--and more. Indeed, reading the first nine chapters of this current work is an exercise in depression. Population out of control in major parts of the world, deforestation, pollution, loss of species, loss of ground water, holes in the ozone, global warming--the all-too-familiar litany made even more chilling by such graphic details as the fact that Mexico City, the most polluted city in the world, occasionally suffers from fecal rain--the airborne dried excrement of human street life. The solution has to be a curbing of population; but even were that to begin now on a global basis, it would take 50 to 60 years before populations achieve zero growth rates. And the solution also means husbanding of resources, conservation, more aid from the haves to have-nots, and all the other hard choices. The hope is that more people than ever have awakened to the problems. The population explosion will end, the Ehrlichs foresee, but whether that occurs because of voluntary measures or coercion is not clear. In any case, they offer strategies to promote changes--including model letters, political actions, and the like. Of fundamental importance is the need to counteract the myth of economic ""growthness"" that fuels the runaway consumption of resources, creates a costly affluence, and adds the burden of expensive technology. This is worked out in the formula I = PAT, P for population, A for affluence, and T for technology. A sobering study needed to balance get-it-while-you-can greed and the false optimism that somehow Earth will survive because it always has.