Agroecosystems are essential to human well-being. Many, however, are already threatened by damage to soil and water resources, and climatic and atmospheric changes will further affect these stressed and rapidly changing systems. The ability to capitalize on the potential benefits of global change while avoiding or reducing the adverse effects requires a strong predictive capability. Focus 3 undertakes strategic, interdisciplinary research to improve management of food and fibre production in a rapidly changing world. It is organised around four themes, or Activities: