We evaluate the impact of explicitly representing irrigated land and water scarcity in an economy‐wide model with and without a global carbon policy. The analysis develops supply functions of irrigable land from a water resource model for 282 river basins and applies them within a global economy‐wide model. The analysis reveals two key findings. First, explicitly representing irrigated land has a small impact on global food, bioenergy and deforestation outcomes. This is because this modification allows irrigated and rainfed land to expand in different proportions, which counters the effect of rising marginal costs for the expansion of irrigated land. Second, changes in water availability have small impacts on global food prices, bioenergy production, land use change and the overall economy, even with large‐scale (c. 150 exajoules) bioenergy production, due in part to endogenous irrigation and storage responses. However, representing water scarcity and changes in water availability can be important regionally, with relatively arid areas and/or areas with rapidly growing populations fully exhausting our estimated maximum irrigation capacity that allows for improved irrigation efficiency, lining of canals to limit water loss, and expanding storage to fully capture average annual water flows.

During the second half of the 20th century the global food production more than doubled and thus responded to the doubling of world population. But the gains in food production came at a cost, leaving a significant environmental footprint on the ecosystem. Global cropland, plantations and pastures expanded, with large increases in fossil energy, water, and fertilizer inputs, imprinting considerable footprint on the environment. Information from pre eminent publications such as Nature, Science, PNAS and scholarly journals is synthesized to assess the water and energy footprints of global food production. The data show that the footprints are significant, both locally, national and globally and have consequences for global food security and ecosystem health and productivity. The literature nearly agrees that global food production system generates considerable environmental footprints and the situation would likely get worrisome, as global population grows by 50% by 2050. Investments are needed today to buffer the negative impacts of food production on the environment. Investments to boost water productivity and improve energy use efficiency in crop production are two pathways to reduce the environmental footprint.

Food security is a high priority issue on the Chinese political agenda. China's food security is challenged by several anthropogenic, sociopolitical and policy factors, including: population growth; urbanization and industrialization; land use changes and water scarcity; income growth and nutritional transition; and turbulence in global energy and food markets. Sustained growth in agricultural productivity and stable relations with global food suppliers are the twin anchors of food security. Shortfalls in domestic food production can take their toll on international food markets. Turbulence in global energy markets can affect food prices and supply costs, affecting food security and poverty. Policy safeguards are needed to shield food supply against such forces. China must make unremitting policy responses to address the loss of its fertile land for true progress towards the goal of national food security, by investing in infrastructure such as irrigation, drainage, storage, transport, and agricultural research and institutional reforms such as tenure security and land market liberalization. The links between water and other development-related sectors such as population, energy, food, and environment, and the interactions among them require reckoning, as they together will determine future food security and poverty reduction in China. Climate change is creating a new level of uncertainty in water governance, requiring accelerated research to avoid water-related stresses.

The Food-Energy-Water-Waste Nexus (FEWWN) represents the interconnections between food, energy, water, and waste production systems, and it has become a key research area. Enormous quantities of agricultural and organic wastes are produced throughout the FEWWN. Often, these wastes are not treated appropriately because their true costs are rarely quantified, and usually externalized to the environment. This shortcoming is addressed from a systems perspective fused with approaches from ecological economics. A regional bioenergy production model where bioenergy may be produced from ethanol and/or agricultural wastes is constructed. Ecosystem service valuation methods are integrated into the framework, allowing for bioenergy production systems to be designed to minimize ecological damage and/or maximize ecological restoration. These values are captured within a Green Gross Domestic Product (Green GDP) objective that values both energy produced and ecosystem service values lost/gained. System profit is another objective in the multi-objective model. The framework is applied to a bioenergy production system for the U.S. state of New York, which aims to produce 10% more bioenergy compared to its current levels. Net changes in Green GDP ranged from -$16.5 M/y to $90.6 M/y, and corresponding profits ranged from $7.2 M/y to -$74.5 M/y. Corn grain ethanol was the dominant source of bioenergy in solutions with higher profits, while ethanol from corn stover and bioelectricity generated from animal manure biogas contributed more bioenergy in solutions with increasing Green GDP. Results show that there is a trade-off between promoting natural capital/ecological health and financial profit. FEWWN system design should consider these trade-offs moving forward.

A key challenge for sustainability is protecting water-related ecosystems and the services (WESs) they provide while enhancing food security. Food production usually drives land use change, which results in ecosystem services provision being altered. However, the underlying mechanisms are still unclear and relevant research is scarce. In this study, a spatio-temporal assessment framework was developed to assess the impact of food production-driven land use change on WESs and to analyze tradeoffs between food production and WESs provision, taking Songhua River Basin (SRB) as a case study. The results showed that: 1) food production increased from 0.497×108tons to 0.798×108tons despite area of cultivated land decreasing from 23.61×104km2 to 23.40×104km2 during the study period (2000–2015). 2) Water yield and soil retention both showed a downward trend, while nitrogen and phosphorus exports showed an increasing trend, in 2000–2015.3) Food production showed a trade-off relationship with soil retention and water yield, but a synergistic relationship with nitrogen and phosphorus export. This is important empirical evidence of the impact of food production-driven land use change on WESs. For simultaneous development of food production and WESs, a form of sustainable agricultural production must be established, with intensification of existing land use and establishment of farmland shelterbelts. This critical knowledge can be applied in developing practical ecosystem protection measures and land management strategies for food security in China and beyond.

IntroductionThe objective of this study is to investigate the impact of land use changes on the coupling coordination of the regional water-food-carbon system in Hebei Province. Moreover, the findings aim to offer insights for achieving comprehensive and coordinated development of regional resources.MethodsBy constructing an evaluation index system of the coupled coordinated development of the water-food-carbon system, using the coupled coordination model to study the coupled coordination of the water-food-carbon (WFC) system in Hebei Province from 2010 to 2020, and applying the Pearson correlation coefficient and ArcGIS to analyze the impacts of land-use changes on the degree of coupled coordination.ResultsThe results show that: (1) The most notable characteristics of land type changes include a decrease in cropland and an increase in construction land, primarily driven by the conversion of cropland to construction sites. The total area converted amounts to 8207.20 km2. (2) The degree of coupled coordination of the water-food-carbon system in the study area as a whole shows an upward and then downward trend, and shows a spatial distribution pattern of “high in the north-east and low in the south-west”; (3) In Hebei Province, the degree of coupling coordination within the water-food-carbon system exhibits a stable positive correlation with forest land, grassland, and water area. Additionally, the transfer of forest land and grassland are significant factors influencing the delineation of cold and hot spots within the region.DiscussionTherefore, in addressing the coordinated development of the water-food-carbon system, it is essential to consider the influence of land. Resources should be allocated judiciously based on regional advantages to promote sustainable development effectively.

Bioenergy from cassava is a promising alternative energy source for both energy supply and the mitigation of greenhouse gases. However, major global trends, such as climate change and competing landuse patterns, pose substantial risks to the sustainable development of bioenergy. The main purpose of this study was to assess the sustainable development of bioenergy from cassava, considering landuse change and climate change with a biogeochemical process model within the “water-energy-food” nexus framework. The results showed that the land resources that were suitable for the development of cassava bioenergy have continuously decreased in China since 1990. At the same time, the climate has also undergone significant changes, with temperature showing an increasing trend, and precipitation showing a decreasing trend. With the influences of both landuse change and climate change, the total bioenergy of cassava showed a downward trend. In China, the potential bioenergy production for the year 1990, 2000, and 2010 was 6075 PJ, 5974 PJ, and 4399 PJ, respectively. Compared to 1990, the bioenergy production in 2010 decreased by 1676.40 million GJ, which equals 57 million tons of standard coal. In addition, the water footprint of bioenergy from cassava was discussed. After considering changes to landuse, climate, and water footprint, it was concluded that Guangxi was the most suitable place to develop cassava bioenergy, followed by Fujian, Guangdong, and Yunnan.

The spatiotemporal change of cultivated land can exert significant effects on food production and the associated water consumption. The quantification of these effects is meaningful for guiding relevant policies. However, few studies have explored systematic methods assessing changes of food production and water consumption and the relations between them, caused by cultivated land change. This study developed new spatially explicit datasets for constant food crop yield and constant food crop water consumption, combining agricultural statistical data, the China-AEZ model, and the GIS spatial analysis method, and estimated the impact of cultivated land change on food crop production, food crop water consumption and food-water relations characterized by two major indicators, i.e., crop water productivity (CWP) and green water proportion (GWP), in China during 1990–2015. The results showed that the increase of approximately 0.80% in cultivated land area in China resulted in a decrease of approximately 0.37% in average food crop yield per unit area, an increase of approximately 1.97% in blue water consumption per unit area (ETbₗᵤₑ), and continuous decreases in both total water consumption per unit area (ETₐ) and green water consumption per unit area (ETgᵣₑₑₙ), with overall rates of 2.41% and 3.11%, respectively, at the national scale from 1990 to 2015. Concurrently, the average CWP continuously increased with an overall rate of 2.06%, while the average GWP continuously decreased with an overall rate of 0.86% at the national scale. A low-level coupling trend of food-water relations was concluded, together with a negative environmental effect. The food-water relations were getting even worse in major cultivated land expansion areas and during the later period of 2000–2015. The findings of this study can be useful for providing a deep understanding of food-water relations corresponding to cultivated land change and giving suggestions for the sustainable development of cultivated land and the integrated management of water resources.

The roles of both landscape alteration and in-lake processes need to be considered in conservation strategies for shallow lakes in the prairie regions of North America. Here we focus on shallow lakes in west-central Minnesota, USA, highlighting the long-term ecological history and response to known landscape changes of a clear-water, macrophyte-dominated, shallow lake. Contemporary limnological data suggest the aquatic ecosystem has been very stable and fishless for the last ~15 years. Sediment proxies for primary production and ecological change confirm that a stable ecosystem likely prevailed for the last ~200 years. However, sedimentary indicators of catchment erosion detail a distinct response to land-use change during the conversion of native grassland to agricultural land, and following establishment of a protected waterfowl production area (WPA) around the lake. Post-WPA, the rate of sediment accrual decreased dramatically within 5–10 years and sources of organic matter were similar to those of the pre-settlement period. The aquatic ecosystem has been able to withstand nutrient enrichment and allochthonous inputs because stable trophic interactions have likely been in place for more than 200 years. We conclude that lack of hydrologic connectivity and isolated, small catchments are important factors in the promotion of clear-water shallow lake ecosystems, mainly because they prevent colonization by fish and associated ecological consequences. This study highlights the importance of managing both the landscape and in-lake processes to maintain stable, clear-water, shallow lakes.

The goals of ensuring energy, water, food, and climate security can often conflict. Microalgae (algae) are being pursued as a feedstock for both food and fuels—primarily due to algae's high areal yield and ability to grow on non-arable land, thus avoiding common bioenergy-food tradeoffs. However, algal cultivation requires significant energy inputs that may limit potential emission reductions. We examine the tradeoffs associated with producing fuel and food from algae at the energy–food–water–climate nexus. We use the GCAM integrated assessment model to demonstrate that algal food production can promote reductions in land-use change emissions through the offset of conventional agriculture. However, fuel production, either via co-production of algal food and fuel or complete biomass conversion to fuel, is necessary to ensure long-term emission reductions, due to the high energy costs of cultivation. Cultivation of salt–water algae for food products may lead to substantial freshwater savings; but, nutrients for algae cultivation will need to be sourced from waste streams to ensure sustainability. By reducing the land demand of food production, while simultaneously enhancing food and energy security, algae can further enable the development of terrestrial bioenergy technologies including those utilizing carbon capture and storage. Our results demonstrate that large-scale algae research and commercialization efforts should focus on developing both food and energy products to achieve environmental goals.