Globally, over 2 billion people reside in countries severely affected by water scarcity, with approximately 1.2 billion still lacking basic access to safe drinking water services. Virtual water transfer associated with agricultural trade may help alleviate water scarcity, reshape the distribution pattern of global water resources, and generate differentiated impacts among populations with varying incomes.
Research on the mechanism of redistribution of water risks due to human activities and heterogeneous responses has been relatively scarce, making it difficult to propose targeted adaptation strategies for different regions and populations. Recently, the research findings from the QIN Li research group at the School of Environmental Science and Engineering, Peking University, published in Nature—Water, provide new insights to address this issue.
"In the context of climate change and globalization, this study emphasizes the need to consider the redistribution of water resources and its impact on low-income populations while ensuring global food security through international trade," said corresponding author QIN Li to Chinese Science Bulletin. Accordingly, the study further explores targeted regulatory strategies for different populations, aiming to overcome the bottleneck of homogenization in current water risk assessments and to reverse the relative disadvantage of low-adaptive populations in international agricultural trade. This aims to promote equal, fair, and sustainable global water resource management.
Building on previous work in identifying and assessing the impacts of remote coupling mechanisms of water risks, the research team, in collaboration with partner teams, constructed a comprehensive evaluation model for the mechanism of water risk redistribution and its equity implications. This was achieved through the coupling of crop water demand models, physical flow trade models, and population equity assessment models. Historical data were then systematically evaluated to assess how international agricultural trade reshapes the pattern of scarce water resource use and the differentiated impacts on populations with varying incomes.
The study found that while agricultural trade generally mitigates global water scarcity, there are significant regional heterogeneities that primarily benefit wealthier populations. Agricultural trade reduces the fairness of water resource use in developing countries by approximately 30% (i.e., the average concentration towards the poorest populations in developing countries decreases by about 30%). Conversely, in developed countries, agricultural trade increases the fairness of water resource use by about 65% (i.e., the average concentration towards relatively poorest populations increases by about 65%).
Similarly, in developing countries, 35% of the population simultaneously faces more severe water scarcity and unfair water use, with their income levels only at 84% of the overall per capita income in developing countries. In contrast, in developed countries, a relatively low-income population (13% of the population) typically benefits from the dual alleviation of water scarcity and unfair water use.
The study further identified the relative contributions of different crop types (especially staple food trade such as rice and economic crops trade such as cotton) and different trade patterns (especially extensive trade cooperation among developing countries) to the transmission of water risks, revealing the mechanism of water risk transmission for low-income populations. This provides a research methodology and data basis for further analyzing the cross-population transmission of water risks under climate change.
This research was supported by the National Natural Science Foundation of China, the Ministry of Science and Technology's intergovernmental international cooperation projects, and the "Carbon and Climate" Ph.D. scholarship from Peking University's Boehringer Ingelheim Scholarship Program for Outstanding Graduate Students.
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