The complex array of processes that govern the evolution of the Earth's surface affects nearly all aspects of today's society. Topical examples include weather-related issues such as forecasting, severe storms, floods, and extreme events; global change issues such as climate change, loss of biodiversity, and ozone depletion; land-use issues for both managed and unmanaged ecosystems; and other natural hazards. Addressing such problems requires comprehensive programs of systematic observation, advanced data analysis, and numerical modeling, often using state-of-the-art computational facilities.