The beauty of environmental complexity is lucidly displayed in this Cook's Tour of grand earthly processes. Schneider (Biological Sciences/Stanford; Global Warming, 1989, etc.) thinks globally and suggests that we do, too, for if we don't look at the big picture when fashioning development decisions, if we don't 'fess up to our ignorance when it comes to the global consequences of our environmental behavior, if we continue to allow public-policy polemicists to exploit ""that uncertainty as an excuse to delay action that could lower risks,"" then what we are taking is a planetary gamble with the biological riches of the earth--a risk that terrifies Schneider. To give his readers a hint at the interrelatedness of our environmental system, he uses climatic flux as a running example, poring over some of the theories and conjectures that have been proposed to explain the changes, refreshing memories that have forgotten the hydrologic and element cycles, laying bare the likes of the Milankovitch mechanism (variations in Earth orbit equals axial shifts equals Ice Age), and explaining how climate impinges on keystone species, population thresholds, biodiversity in general. The beauty of this book lies in its simple, fluid explication of nature's crazy-wild fandango. But Schneider also has a modest proposal to make: Why don't we, as a species, pause for a moment, take stock of potential consequences, become collectively less destructive, and ""rethink a global-scale value system that puts human numerical and economic growth ahead of all other competing values""? That would require an ""informed public with the scientific knowledge and political will to make a difference,"" Schneider admits, but he's not only a talented writer with a supple ranging imagination, he's also an incurable optimist. Earth could use more nimble old souls like Schneider, with his commonsensical voice.