Human Population Growth and Global Land-Use/Cover Change

Abstract

Contemporary interdisciplinary research on human-induced global environmental change recognizes two broad and overlapping fields of study (67). That of industrial metabolism investigates the flow of materials and energy through the chain of extraction, production, consumption, and disposal of modem industrial society. That of land-use/land-cover change, our concern here, deals with the alteration of the land surface and its biotic cover. Environmental changes of either kind become global change in one of two ways (106): by affecting a globally fluid system (the atmosphere, world climate, sea level) or by occurring in a localized or patchwork fashion in enough places to sum up to a globally significant total. Land-use change contributes to both kinds of global change: to such systemic changes as trace-gas accumulation and to such cumulative or patchwork impacts as biodiversity loss, soil degradation, and hydrological change. Land-use/land-cover change is a hybrid category. Land use denotes the human employment of the land and is studied largely by social scientists. Land cover denotes the physical and biotic character of the land surface and is studied largely by natural scientists. Connecting the two are proximate sources of change: human activities that directly alter the physical environment. These activities reflect human goals that are shaped by underlying social driving forces. Proximate sources change the land cover, with further environmental consequences that may ultimately feed back to affect land use. Contemporary global environmental change is clearly unique. The human reshaping of the earth has reached a truly global scale, is unprecedented in its magnitude and rate, and increasingly involves significant impacts on the