This is neither a superficial man-and-weather number, such as Bova's duo (1973 and 1974) or Boersen's Doing Something About the Weather (1975), nor a trendy digest of the dramatic predictions featured in recent adult books, but a careful review by a Columbia U. climatologist of the basics which should be absorbed before entertaining any such speculation. The first half of the book carefully explains how global, regional, and local climate is determined by the sun's radiation; the earth's shape, distance from the sun, tilt, and orbit; the composition of the atmosphere; and the positions of continents, oceans, and mountains. That established, Hays turns to climatic fluctuations beginning with the ice ages, with a note on the influence of continental drift and--after reviewing different theories--a cautious projection for the future. The long term trend is certainly toward cooler conditions, with greater variability likely in the near future. Hays considers what likely changes mean in terms of crop production and how man's accidental modification might complicate the picture, and he cautions that far too little is known for artificial tampering (say, by adding carbon dioxide to the atmosphere to slow the natural cooling trend) to be advisable. Solid.