Human interactions with the Earth system: people and pixels revisited

The human use of the land is one of the critical links between people and the Earth system, with changes in land use contributing to the significant modification of hydrology, ecology, geomorphology, climate and biogeochemical cycles. Over the past decade there have been several major research efforts (e.g. IGBP-IHDP LUCC, ESSP) to link the social and natural sciences through the study of land-use and land-cover change, with particular attention being paid to the potential of linking remote sensing with socioeconomic data, local case studies with larger scale modelling efforts, and scientific research with the needs of stakeholders. This paper evaluates the extent to which such land-use-change studies can provide reliable data, explanation and projections of future land use. It assesses how such studies might address major theoretical questions in social and natural science such as those concerning the role of population or of institutions in land-use dynamics, or the detailed attribution of hazards to physical or social processes. In general, and using examples of research conducted in Mexico, the paper concludes that progress has been limited, because of factors that include the difficulties in gathering socio-economic information at global and regional scales, linking social data to satellite imagery, and forecasting human activities and policies. For interactions between the social and earth sciences to succeed, a certain level of tolerance and mutual understanding will be needed so that social scientists understand the earth science aspiration for quantitative socio-economic scenarios and predictions, and earth scientists understand the variations in how social scientists explain human behaviour and institutions and accept the clear limits to predicting human activities and decisions. Copyright © 2008 John Wiley & Sons, Ltd.