Water is a major factor limiting crop production in many regions around the world. Irrigation can greatly enhance crop yields, but the local availability and timing of freshwater resources constrains the ability of humanity to increase food production. Innovations in irrigation infrastructure have allowed humanity to utilize previously inaccessible water resources, enhancing water withdrawals for agriculture while increasing pressure on environmental flows and other human uses. While substantial additional water will be required to support future food production, it is not clear whether and where freshwater availability is sufficient to sustainably close the yield gap in cultivated lands. The extent to which irrigation can be expanded within presently rainfed cropland without depleting environmental flows remains poorly understood. Here we perform a spatially explicit biophysical assessment of global consumptive water use for crop production under current and maximum attainable yield scenarios assuming current cropping practices. We then compare these present and anticipated water consumptions to local water availability to examine potential changes in water scarcity. We find that global water consumption for irrigation could sustainably increase by 48% (408 km 3 H 2 O yr −1 )expanding irrigation to 26% of currently rainfed cultivated lands (2.67×10 6 km 2 ) and producing 37% (3.38×10 15 kcal yr −1 ) more calories, enough to feed an additional 2.8 billion people. If current unsustainable blue water consumption (336 km 3 yr −1 ) and production (1.19×10 15 kcal yr −1 ) practices were eliminated, a sustainable irrigation expansion and intensification would still enable a 24% increase in calorie (2.19×10 15 kcal yr −1 ) production. Collectively, these results show that the sustainable expansion and intensification of irrigation in selected croplands could contribute substantially to achieving food security and environmental goals in tandem in the coming decades.
accurately assessing green and blue water requirements from croplands is fundamental to promote sustainable water management. In the last decade, global hydrological models have provided important insights into global patterns of water requirements for crop production. as important as these models are, they do not provide monthly crop-specific and year-specific data of green and blue water requirements. Gridded crop-specific products are therefore needed to better understand the spatial and temporal evolution of water demand. Here, we present a global gridded database of monthly crop-specific green (rain-fed) and blue (irrigated) water requirements for 23 main crops and 3 crop groups obtained using our WATNEEDS model. For the time periods in which our dataset matched, these estimates are validated against existing global products and satellite based datasets of evapotranspiration. the data are publicly available and can be used by practitioners in the waterenergy-food nexus to assess the water sustainability of our food and energy systems at multiple spatial (local to global) and temporal (seasonal to multi-year) scales.
Global palm oil production has greatly increased in recent years with the adoption of renewable energy policies by the E.U. and U.S.A. and growing demand for its use in food, biodiesel, and other commodities. Indonesia, the world's largest oil palm producer, has leased large tracts of forested and tribal lands as new concessions, thereby expanding oil palm plantations. While previous studies have focused on some of the important social and environmental consequences of this process, the full suite of potential environmental impacts from land conversion and cultivation remains poorly understood. Here we quantify these impacts in terms of forest loss and fragmentation, CO 2 emissions from land use change, and freshwater pollution from fertilizer application. Within all concession types, forest cover decreased by 20% and forest fragmentation increased by 44%, both of which are significantly higher than in comparable non-concession areas. We also assess to what extent CO 2 emissions and freshwater pollution are attributable to increasing palm oil demand abroad. We find that four-fifths of Indonesia's palm oil production is for export markets and that 66% of this is destined for just eight countries -
Since the turn of the century, rubber plantations have been expanding their footprint across Southeast Asia in response to an increasing global demand for rubber products. Between 2000 and 2014, the area cultivated with rubber more than doubled. It is not clear how this major change in the agricultural landscape of Southeast Asia, the main area of rubber production in the world, is affecting land‐use patterns and water resources in the region. Here we use maps of rubber plantations and other croplands in conjunction with a hydrological model and remote sensing analyses to assess land‐use patterns and water resources affected by natural rubber plantations. Results show water requirements of rubber trees are comparable to those of forests but by far exceed those of the other predominant crops and shrubland vegetation with the effect of potentially increasing water scarcity when rubber plantations replace these crops. The expansion of rubber plantations accounts for a 38 km3/yr increase in green water consumption, thereby exacerbating the monthly water scarcity, with an additional 2.4 million people and more than 0.6 Mha facing water scarcity in the driest months as a result of the increase in rubber production. Monthly runoff substantially decreases (by up to 25%) in 14% of the basins where rubber was planted. These results highlight the existence of major land use and hydrological impacts of agricultural development in Southeast Asia that affect the local environment and rural communities, calling for a more sustainable management of the limited land and water resources.
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