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Agricultural production is the main consumer of water. Future population growth, income growth, and dietary shifts are expected to increase demand for water. The paper presents a brief review of the water footprint of crop production and the sustainability of the blue water footprint. The estimated global consumptive (green plus blue) water footprint ranges from 5938 to 8508 km3/year. The water footprint is projected to increase by as much as 22% due to climate change and land use change by 2090. Approximately 57% of the global blue water footprint is shown to violate the environmental flow requirements. This calls for action to improve the sustainability of water and protect ecosystems that depend on it. Some of the measures include increasing water productivity, setting benchmarks, setting caps on the water footprint per river basin, shifting the diets to food items with low water requirements, and reducing food waste.

Agriculture is by far the largest user of water. Agricultural production needs to increase by almost 50% by 2050 compared to 2012 to meet the rising demand for food, fiber, and biofuels. This is probably going to require more water. Most of the increase in agricultural production is expected to occur in Sub-Saharan Africa and South Asia, where the agricultural output will need to more than double by 2050 [1]. The expected increase in the rest of the world is around 30%. Agricultural production has increased by 260% between 1961 and 2018 [2]. During the same period, the harvested crop area increased by 47%, suggesting that 113% of the increase in production is linked to an increase in crop yield. The increase in crop yield between 1961 and 1990 was 72%, but between 1991 and 2018, the increase was 43%, indicating that yields are now rising at a slower rate than in previous decades [2]. The increase in crop yields was largely due to increased irrigation, improved crop varieties, agrochemical inputs, and improved soil and water management. However, the increase in crop productivity is not expected to continue indefinitely. In most parts of the world, yields for major crops have begun to stagnate [3,4]. Climate change, soil degradation, and salinization of irrigated areas will potentially limit future increases in production. Ray et al. [5] have shown that with the current rate of yield increase, it is not possible to meet the expected food demand by 2050. They have argued that some level of cropland expansion is needed to meet the food production deficits but at a higher environmental cost to biodiversity.

The amount of food available for human consumption is affected by the allocation of crops to other nonfood uses such as animal feed, bioenergy, and industrial uses. Globally, only 67% of the crop produced (by mass) or 55% of the calories produced is available for direct human consumption [6]. The remaining crop was allocated to animal feed (24% by mass) and other industrial use, including bioenergy (9% by weight). Animal production is less efficient than crop production in converting feed to human edible food [7,8,9,10]. As a result, only 12% of the 36% of the global calories used for animal feed will ultimately contribute to human diets [6].

In 2011, the global water footprint (WF) of agricultural production was 8362 km3/year (80% green, 11% blue, and 9% grey) [11]. World water demand is expected to increase by 20%–30% between 2010 and 2050 [12]. Demand for land and water resources has increased significantly, and these resources are expected to be scarcer in the future. Efficient water management in agriculture is needed to meet the growing demand for food and reduce poverty and hunger in a sustainable manner. The question is how the world will feed the global population without further impacting the freshwater and ecosystems. Several researchers have advocated for sustainable intensification [10,13,14,15,16], dietary changes, and reduction of food waste and loss [17,18,19] to feed the world. A number of studies have shown the value of virtual water trade in global water saving, reducing water scarcity, and it will help to reduce the risk of water scarcity [20,21,22,23]. This paper provides a brief review of the WF of food production, the water demand for different food products and diets, and the WF of food loss and waste. Finally, the paper presents the unsustainability of the current crop production showing the contribution of the main crops and countries toward the unsustainable blue WF.

Szerző: Nagy testvéra
Megjelenési dátum: 2022-07-12