An Environmental History of theTwentieth-century world-

            Most of the time, we can hear bad or alarming news concerning the environment. The ozone hole is growing, global warming is worse than before, more and more species are threatened with extinction. However, sometimes, some people -like the author, J.R Mc Neill- tries to show us that environmental changes usually are good for some people and bad for others' and that there might be a way out.
             With his work, J.R Mc Neill, made a really surprising job. Indeed, we are not used to study the history of the twentieth century through its environmental history, we most often tell the history of the twentieth century through its wars, its economic and political changes, and trying to explain this history with such a different point of view, could be a very challenging and interesting task. Through his book, the author tells us lots of anecdotes, explanations, show us different kind of documents. This book is really based on an exhaustive research, and it seems to be really difficult to sum up all these things in a paper.
             In first the author argues that to a degree unprecedented in the human history, in the twentieth century, we have been moving Earth: polluting the atmosphere, the water .Indeed, under the pressure of human activity, the biological diversity is impoverishing to an unprecedented rhythm . The natural environments are destructed or damaged, the living resources are overexploited and « pollutions » decimate lots of species. The climatic changes following upon the greenhouse effect modify the present limits of the geographical distribution of species and ecosystems. In this way, the protection of Biodiversity goes in priority through ecosystems' protection. This is the stake in the ecosystemic approach that aims at finding a compromise between the environmental protection and the constraints of the economic development.
             Earth is conventionally divided into a series of spheres : The Lithosphere which is the superficial part of the Earth's globe, The Biosphere is the living covering of Earth, The Hydrosphere which is compounded of the sea and continental waters (superficial and underground), and The Atmosphere which is the gaseous covering of Earth.