Toward Integrated Land-Change Science: Advances in 1.5 Decades of Sustained International Research on Land-Use and Land-Cover Change

Abstract

Land change is likely the most ancient of all human-induced environmental impacts on the biosphere and the first to obtain a magnitude to warrant the title “global”. Evidence mounts that Homo sapiens was instrumental in the worldwide destruction of megafauna before the last glacial maximum, and by the seventeenth century, humankind had restructured global biota by the transcontinental movement of domesticates and ornamental flora, complete with the unintentional transport of vermin, pests, weeds, and diseases that affected ecosystems globally. Today, virtually no land surface remains untouched in some way by humankind, and ~50% of the ice-free surface of Earth is considered significantly modified by human action. Land use commands as much as 40% of the net primary productivity of the Earth (Vitousek 40% of the net primary productivity of the Earth (Vitousek et al. 1997), although the uncertainties are large (Rojstaczer et al 2001). About 35300 dams have been constructed basins worldwide. Water diversion for irrigation consuming about 70% of all water withdrawals is sufficiently significant to stop the flow of such large rivers as the Colorado, Huang Ho, and Amu Darya from reaching the sea during the dry season (Johnson et al. 2001).