People and Pixels 20 years later: the current data landscape and research trends blending population and environmental data.

In 1998 the National Research Council published . The volume focused on emerging research linking changes in human populations and land use/land cover to shed light on issues of sustainability, human livelihoods, and conservation, and led to practical innovations in agricultural planning, hazard impact analysis, and drought monitoring. Since then, new research opportunities have emerged thanks to the growing variety of remotely sensed data sources, an increasing array of georeferenced social science data, including data from mobile devices, and access to powerful computation cyberinfrastructure. In this article we outline the key extensions of the foundation since 1998 and highlight several breakthroughs in research on human-environment interactions. We also identify pressing research problems - disaster, famine, drought, war, poverty, climate change - and explore how interdisciplinary approaches integrating people and pixels are being used to address them.