International food trade reshapes regional water scarcity through virtual water transfers (VWT), influencing water use equality and equity. This study examines eight populous yet impoverished countries in Africa and Asia, representing 30 % of the global poor population and contributing 20 % to agricultural VWT. Despite their significant role, these countries have been understudied due to a lack of data or attention. By integrating multiple datasets and models, we assess how international food trade impacts water scarcity, inequality, and inequity within these countries and identify the driving factors. Our findings reveal varied outcomes: Uganda and Ethiopia benefit from reduced water scarcity (∼40 % and ∼7 %) and improved equality and equity (∼90 % and ∼68 %), while India and Pakistan face exacerbated scarcity (∼4 % and ∼2 %) and widening inequality and inequity (∼4 % and ∼7 %). The effects are largely driven by critical trade flows of staple and cash crops like rice, sugar cane, and cotton among developing countries, propelled by comparative advantages in agricultural production, econo-geography, food demand, and water endowment between importers and exporters. Addressing these water challenges involves diversifying import channels to reduce reliance on detrimental trade flows, such as India's rice exports to Iran, while promoting beneficial flows, like Bangladesh's cotton imports from India, through trade agreements. Additionally, implementing pro-poor water policies (e.g., providing water subsidies) and water-saving techniques (e.g., adopting drip irrigation) is crucial, though caution is needed to avoid unintendedly marginalizing vulnerable groups through large-scale water projects.

Climate change is altering the timing and magnitude of snowmelt, which may either directly, or indirectly via global trade, affect agriculture and livelihoods dependent on snowmelt. Here we integrate sub-annual irrigation and snowmelt dynamics and a model of international trade to assess the global redistribution of snowmelt dependencies and risks under climate change. We estimate that 16% of snowmelt used for irrigation is for agricultural products traded globally, of which over 70% is from five countries. Globally, we observe a prodigious snowmelt dependence and risk diffusion, with particularly evident importing of products at-risk in western Europe. In Germany and U.K, respective local fraction of surface-water-irrigated agriculture supply exposed to snowmelt risks could increase from negligible to 16% and 10% under a 2°C warming. Our results reveal the trade-exposure of agricultural supplies, highlighting regions and crops whose consumption may be vulnerable to changing snowmelt even if their domestic production is not.

International trade separates consumption of goods from related environmental impacts, including greenhouse gas emissions from agriculture and land-use change (together referred to as “land-use emissions”). Through use of new emissions estimates and a multiregional input-output model, we evaluated land-use emissions embodied in global trade from 2004 to 2017. Annually, 27% of land-use emissions and 22% of agricultural land are related to agricultural products ultimately consumed in a different region from where they were produced. Roughly three-quarters of embodied emissions are from land-use change, with the largest transfers from lower-income countries such as Brazil, Indonesia, and Argentina to more industrialized regions such as Europe, the United States, and China. Mitigation of global land-use emissions and sustainable development may thus depend on improving the transparency of supply chains.

The Chinese government accelerated the clean residential heating transition in northern China as part of a successful effort to improve regional air quality. Meanwhile, China has committed to carbon neutrality by 2060, making strategic choices for long-term decarbonization of the residential sector necessary. However, the synergies and trade-offs for health and carbon of alternative heating options and associated costs have not been systematically considered. Here we investigate air-quality– health–carbon interdependencies as well as household costs of using electricity (heat pumps or resistance heaters), gas or clean coal for residential heating for individual provinces across northern China. We find substantial air-quality and health benefits, varied carbon emissions and increased heating costs across clean heating options. With the 2015 power mix, gas heaters offer the largest health–carbon co-benefits, while resistance heaters lead to health–carbon trade-offs. As the power grid decarbonizes, by 2030 heat pumps achieve the largest health–carbon synergies of the options we analysed. Despite high capital costs, heat pumps generally have the lowest operating costs and thus are competitive for long-term use. With increased subsidies on the purchase of heat pumps, the government can facilitate further air-quality improvements and carbon mitigation in the clean heating transition.

Worldwide efforts to switch away from coal have increased the reliance on natural gas imports for countries with inadequate domestic production. In preparing for potential gas import disruptions, there have been limited attempts to quantify the environmental and human health impacts of different options and incorporate them into decision-making. Here, we analyze the air pollution, human health, carbon emissions, and water consumption impacts under a set of planning strategies to prepare for potentially fully disrupted natural gas imports in China. We find that, with China’s current natural gas storage capacity, compensating for natural gas import disruptions using domestic fossil fuels (with the current average combustion technology) could lead up to 23,300 (95% CI: 22,100–24,500) excess premature deaths from air pollution, along with increased carbon emissions and aggravated water stress. Improving energy efficiency, more progressive electrification and decarbonization, cleaner fossil combustion, and expanding natural gas storage capacity can significantly reduce the number of excess premature deaths and may offer opportunities to reduce negative carbon and water impacts simultaneously. Our results highlight the importance for China to increase the domestic storage capacity in the short term, and more importantly, to promote a clean energy transition to avoid potentially substantial environmental consequences under intensifying geopolitical uncertainties in China. Therefore, mitigating potential negative environmental impacts related to insecure natural gas supply provides additional incentives for China to facilitate a clean and efficient energy system transition.

Water competition between the food and energy sector is a critical component of the food-energy-water nexus. However, few studies have systematically characterized the geospatial and, especially, the sub-annual variations in such competition and the associated environmental impacts and targeted mitigation opportunities. This study characterizes competing water uses for crop-specific irrigated agriculture and fuel-specific power generation across global major river basins to reveal their resulting impacts on local water scarcity for global population under both current and a warming climate. Under annual (and most seasonal) accounting, almost all basins currently suffering from extremely high water scarcity are dominated by agricultural water consumption (e.g. accommodating 26%–49% of basin-total population across seasons), which are often simultaneously exposed to potentially decreasing seasonal water availability under a 4 °C warming scenario. Only 13%–20% of population are located in basins dominated by seasonal power sector water uses, which are predominantly with low water scarcity. Agriculture sector provides the most basin-specific water mitigation opportunities across mid-latitude basins in all four seasons. Nevertheless, power sector becomes more important in affecting seasonal water scarcity and provides unique seasonal water mitigation opportunities, particularly in basins among higher northern latitudes in winter. This analysis highlights irrigated agriculture is currently and will likely remain the key in global water management for basins facing the severest water scarcity, yet increasing attention on the seasonal and spatial variations in cross-sector water use competition is needed to better identify region- and season- specific mitigation opportunities.

Snowpack stores cold-season precipitation to meet warm-season water demand. Climate change threatens to disturb this balance by altering the fraction of precipitation falling as snow and the timing of snowmelt, which may have profound effects on food production in basins where irrigated agriculture relies heavily on snowmelt runoff. Here, we analyse global patterns of snowmelt and agricultural water uses to identify regions and crops that are most dependent on snowmelt water resources. We find hotspots primarily in high-mountain Asia (the Tibetan Plateau), Central Asia, western Russia, western US and the southern Andes. Using projections of sub-annual runoff under warming scenarios, we identify the basins most at risk from changing snowmelt patterns, where up to 40% of irrigation demand must be met by new alternative water supplies under a 4 °C warming scenario. Our results highlight basins and crops where adaptation of water management and agricultural systems may be especially critical in a changing climate.