Focuses on the transformation of the biosphere. In considering how the ecological history of the planet became so inexorably tied to socioeconomic history, McNeill describes environmental change as the result of social, political, economic, and intellectual patterns. He also presents cases in which people have countered this change through policy. For instance, he explains how the quest to irrigate cotton fields in Russia is transforming the Aral Sea into a salt pan the size of Ireland and how this hydrological change will affect Central Asia in years to come.