Take a globe-circling tour of our endangered planet with conservation biologist Stuart Pimmwho is taking stock and keeping score. We use 50 percent of the world's freshwater supply. We consume 42 percent of the world's plant growth. We are liquidating animals and plants 100 times faster than the natural rate of extinction. Such numbers should make it clear that the human impact on our planet has been, and continues to be, extreme and detrimental. Yet even after decades of awareness of our environmental peril, there remains passionate disagreement over what the problems are and how they should be remedied. Much of the impasse stems from the fact that the problems are difficult to quantify. How do we assess the impact of habitat loss on various species, when we haven't even counted them all? And just what factors go into that 42 percent of biomass we are hungrily consuming? It is only through an understanding of the numbers that we will be able to break that impasse and come to agreement. Working on the front lines of conservation biology, Stuart Pimm is one of the pioneers whose work has put the "science" in environmental science. In this book, he appoints himself "investment banker of the global, biological accounts," checking the numbers gathered by tireless scientists in work that is always painstaking and often heartbreaking. Pimm explains the numerical results in lucid prose. With wit, passion, and candor, he reveals the importance of understanding where those numbers come from and what they mean. To do so, he takes the reader on a globe-circling tour of our beautiful, but weary, planet. With Pimm as our indomitable guide, we travel from the volcanic mountains and rainforests of Hawaii to the boreal forests of Siberia. We see a blue whale off the Pacific coast of Mexico, where the blue oceans are slowly turning to barren deserts. We go birdwatching high up in the leafy canopy of the Amazon, from which we can see the hundreds of smoke plumes busily working at deforestation. At times, the view looks rather grim. But Pimm is no Cassandra; he never preaches or scolds. Ever optimistic, this book presents a world filled with mysterious beauty, the infinite variety of nature, and an urgent hope that through an understanding of our planet's environmental past and present, we will be inspired to save it from future extinction. "[T]his book is unashamedly optimistic. It is a celebration of our spectacular and fascinating world. I have made no attempt to restrain my joy as I encounter its natural history and its peoples. By the time you read the Epilogue you will know that our world is not doomed, it is not fatally wounded, but neither is it healthy. It needs attention. . . ." Stuart Pimm, from the Prologue