Johan Rockstrom, Stockholm Environment Institute, Elena M. Bennett, McGill University, Garry D. Peterson, McGill University, and Line Gordon, Stockholm University and Stockholm Environment Institute.
Agricultural development has largely focused on incremental productivity, centered on improving soil, crop, and water management within the production system. Over the past 50 years this has, in many regions of world, proven an apparent success, resulting in more than a doubling of yield levels for key staple food crops. Evidence points at the limitations of a sector approach to agricultural development. Declining productivity in farming systems are increasingly a result of ecosystem feedbacks from outside the production system. Water related ecological functions are critical for agricultural productivity and sustainability. At the same time agriculture is a dominant driver degrading ecological functions. Water is a key determining factor of productivity and sustainability of agricultural systems. No human economic activity has so large impacts on water systems. Future scenarios points at dramatically growing pressures on freshwater resources for food production, with a need to double global water consumption for food production by 2050 in order to eradicate malnourishment and keep pace with population growth. For sub-Saharan Africa the increased demand for food corresponds to no less than a new Green Revolution. This dramatic increase in water needs for agriculture has raised the calls for further investments in agricultural water supply. Very limited focus is given to the role of ecosystem services in agricultural landscapes in determining the water available for agriculture. Furthermore, agrarian crises, from desertification in the Sahel region, to salinisation of irrigation systems in different parts of the world, points at the risk that deterioration of water systems may push farming systems across tipping points towards undesirable states of low productivity. Water balance indicators of system-wide agricultural resilience against tipping points are presented, and avenues to build resilience against flips discussed. Agricultural transformations, through agrarian revolutions are discussed in the context of land and water induced agrarian crises.