Water cycle and people: water for feeding humanity

The distinction of ‘blue’ (liquid) and ‘green’ (vapour) water flow is introduced to make possible an assessment of water flows to be appropriated for future food production. The author offers a ‘backcasting approach’ in assessing the consumptive water requirements for feeding humanity by 2050 and from where the needed water may be provided (irrigation, crop-per-drop improvements and horizontal expansion into grasslands and forests). She concludes that food security will demand a major shift in thinking.Resource /Energy Economics and Policy,

Water Governance Challenges: Managing Competition and Scarcity for Hunger and Poverty Reduction and Environmental Sustainability

human development, water, sanitation

Understanding of water resilience in the Anthropocene

Water is indispensable for Earth resilience and sustainable development. The capacity of social-ecological systems to deal with shocks, adapting to changing conditions and transforming in situations of crisis are fundamentally dependent on the functions of water to e.g., regulate the Earth's climate, support biomass production, and supply water resources for human societies. However, massive, inter-connected, human interference involving climate forcing, water withdrawal, dam constructions, and land-use change have significantly disturbed these water functions and induced regime shifts in social-ecological systems. In many cases, changes in core water functions have pushed systems beyond tipping points and led to fundamental shifts in system feedback. Examples of such transgressions, where water has played a critical role, are collapse of aquatic systems beyond water quality and quantity thresholds, desertification due to soil and ecosystem degradation, and tropical forest dieback associated with self-amplifying moisture and carbon feedbacks. Here, we aggregate the volumes and flows of water involved in water functions globally, and review the evidence of freshwater related linear collapse and non-linear tipping points in ecological and social systems through the lens of resilience theory. Based on the literature review, we synthesize the role of water in mediating different types of ecosystem regime shifts, and generalize the process by which life support systems are at risk of collapsing due to loss of water functions. We conclude that water plays a fundamental role in providing social-ecological resilience, and suggest that further research is needed to understand how the erosion of water resilience at local and regional scale may potentially interact, cascade, or amplify through the complex, globally hyper-connected networks of the Anthropocene. © 2018 The Author

Water cycle and people: water for feeding humanity

The distinction of ‘blue’ (liquid) and ‘green’ (vapour) water flow is introduced to make possible an assessment of water flows to be appropriated for future food production. The author offers a ‘backcasting approach’ in assessing the consumptive water requirements for feeding humanity by 2050 and from where the needed water may be provided (irrigation, crop-per-drop improvements and horizontal expansion into grasslands and forests). She concludes that food security will demand a major shift in thinking

Consumptive water use to feed humanity : curing a blind spot

Since in large parts of the world it is getting difficult to meet growing water demands by mobilising more water, the discourse has turned its focus to demand management, governance and the necessary concern for aquatic ecosystems by reserving an "environmental flow" in the river. The latter calls for attention to river depletion which may be expected in response to changes in consumptive water use by both natural and anthropogenic systems. Basically, consumptive use has three faces: runoff generation influenced by land cover changes; consumptive use of water withdrawn; and evaporation from water systems (reservoirs, canals, river based cooling). After demonstrating the vulnerability to changes in consumptive use under savanna region conditions - representative of many poverty and hunger prone developing countries subject to attention in the Millennium Development Goal activities - the paper exemplifies; 1) changes in runoff generation in response to regional scale land cover changes; 2) consumptive use in large scale irrigation systems. It goes on to analyse the implications of seeing food as a human right by estimating the additional consumptive use requirements to produce food for the next two generations. Attention is paid to remaining degrees of freedom in terms of uncommitted water beyond an environmental flow reserve and to potential food trade consequences (so-called virtual water). The paper concludes that a human-right-to-food principle will have major consequences in terms of altered consumptive water use. It will therefore be essential for humanity to address river depletion to avoid loss of resilience of the life support system. This will demand a deep-going cooperation between hydrology, ecology and water governance.Since in large parts of the world it is getting difficult to meet growing water demands by mobilising more water, the discourse has turned its focus to demand management, governance and the necessary concern for aquatic ecosystems by reserving an "environmental flow" in the river. The latter calls for attention to river depletion which may be expected in response to changes in consumptive water use by both natural and anthropogenic systems. Basically, consumptive use has three faces: runoff generation influenced by land cover changes; consumptive use of water withdrawn; and evaporation from water systems (reservoirs, canals, river based cooling). After demonstrating the vulnerability to changes in consumptive use under savanna region conditions - representative of many poverty and hunger prone developing countries subject to attention in the Millennium Development Goal activities - the paper exemplifies; 1) changes in runoff generation in response to regional scale land cover changes; 2) consumptive use in large scale irrigation systems. It goes on to analyse the implications of seeing food as a human right by estimating the additional consumptive use requirements to produce food for the next two generations. Attention is paid to remaining degrees of freedom in terms of uncommitted water beyond an environmental flow reserve and to potential food trade consequences (so-called virtual water). The paper concludes that a human-right-to-food principle will have major consequences in terms of altered consumptive water use. It will therefore be essential for humanity to address river depletion to avoid loss of resilience of the life support system. This will demand a deep-going cooperation between hydrology, ecology and water governance.Original Publication:Malin Falkenmark and Mats Lannerstad, Consumptive water use to feed humanity: curing a blind spot, 2005, Hydrology and Earth System Sciences, (9), 15-28.http://www.hydrol-earth-syst-sci.net/9/15/2005/Licensed by: European Geophysical Societyhttp://www.egu.eu