"For 40 years, the best basic book for learning environmental modeling skills has been John Harte’s classic text, Consider a Spherical Cow. It is now even better. This updated and expanded new edition belongs on the bookshelf of everyone who cares about the fate of our civilization." --Paul R. Ehrlich, Stanford University "For young scientists, Harte’s book is an invaluable set of calisthenics to get the brain working across a wide range of problems. But non-scientists will enjoy this too—it will give you insights into how people think quantitatively." --Bill McKibben, author The End of Nature "Spherical Cow has been, for more than 30 years, much more than a book. It is a lantern that shows the way to a powerful and transferable problem-solving strategy: capture any problem’s key concepts in a highly simplified, quantified approximation to reality, and then perform straightforward calculations that lead you to good-enough conclusions. Cow applies this strategy to environmental problem-solving, producing accessible insights into a suite of urgent issues, ranging from rain’s acidity to population dynamics to nuclear power and toxic chemicals – the last two only in this much awaited, updated edition." --Rob Socolow, Princeton University