Malin Falkenmark

Future water availability for global food production: The potential of green water for increasing resilience to global change

Future water availability for global food production : the potential of green water for increasing resilience to global change

Global potential to increase crop production through water management in rainfed agriculture

This modeling study explores—spatially explicitly, for current and projected future climate, and for different management intensity levels—the potential for increasing global crop production through on-farm water management strategies: (a) reducing soil evaporation (‘vapor shift’) and (b) collecting runoff on cropland and using it during dry spells (‘runoff harvesting’). A moderate scenario, implying both a 25% reduction in evaporation and a 25% collection of runoff, suggests that global crop production can be increased by 19%, which is comparable with the effect of current irrigation (17%). Climate change alone (three climate models, SRES A2r emissions and population, constant land use) will reduce global crop production by 9% by 2050, which could be buffered by a vapor shift level of 50% or a water harvesting level of 25%. Even if realization of the beneficial effects of rising atmospheric CO2 concentration upon plants was ensured (by fertilizer use) in tandem with the above moderate water management scenario, the water available on current cropland will not meet the requirements of a world population of 9–10 billion.

Global food production in a water-constrained world : exploring ‘green’ and ‘blue’ challenges and solutions

Global food production in a water-constrained world : exploring ‘green’ and ‘blue’ challenges and solutions

Water and human livelihood resilience: a regional-to-global outlook

Abstract This article addresses the need to profoundly expand the way we think about freshwater. Stressing water’s role as the bloodstream of the biosphere, the article highlights water’s functions in sustaining life on the planet (control, state and moisture feedback functions), the role of water partitioning changes in inducing non-linear change at multiple scales, and humanity’s influence on a social-ecological system’s capacity to adapt and continue to function. It reviews water’s roles during its journey through the upper layers of the land mass, different types of water–ecosystem interactions, and water’s roles in landscape-scale resilience building.

Shift in Water Thinking Crucial for Sub-Saharan Africa’s Future

With large development optimism and seen as rich in water resources, Africa is—except for the humid equatorial area—an arid continent, dominated by vast savannas, which require skilful manoeuvring between unreliable rain, very thirsty atmosphere, sharpening droughts and low runoff generation. With a four-folding population and six-folding water demand in just 70 years, the pressure on the water resources is rapidly increasing and already approaching basin closure level in several regions. Since the blue water is concentrated to transnational river corridors, food production is 95% rainfed, i.e. depending on green water in the soil; subsistence farmers’ yields remain low (some 1 ton/ha), and hunger is widespread. An African green revolution is slowly developing as a water harvesting supported agriculture, foreseen to allow even three-folded crop yields. Many countries cannot expect long-term food self-reliance, making national economic planning essential to secure an industrial development for generating necessary foreign currency. Africa’s future is closely linked to its demographic changes, demanding due attention: both towards reducing extreme fertility; and to adaptation to the rapid expansion of middle-age population strata in response to growing life expectancy. Currently, two blindnesses are blocking the road to a sustainable future: city planners’ lack of concern for megacities raw water supply; and the United Nations’ (UN’s) Sustainable Development Goal’s (SDG’s) total unawareness of green water’s crucial role for hunger alleviation. Foreseeable water shortages will demand water-security oriented policies, based on blue water for urban, industrial and energy water supply; green water for food production; and widespread leap-frogging and water decoupling for manoeuvring water supply.