Proceedings of a Workshop—in Brief

Convened November 21–22, 2024

CHINA-U.S. SCIENTIFIC ENGAGEMENT: FOOD SYSTEMS AND SUSTAINABILITY
Proceedings of a Workshop—in Brief

Since 2018, the U.S. National Academies of Sciences, Engineering, and Medicine and the Chinese Academy of Sciences (CAS) have convened scientists to discuss cutting-edge sustainability research and practices. The first two workshops, held in 2018 and 2019, focused on urban sustainability. In the current series, a workshop in July 2022 focused on biodiversity and sustainability, and a workshop in June 2023 focused on planetary health and sustainability.¹

The final workshop in the series, summarized below, took place November 21–22, 2024 in Budapest, Hungary and virtually, with a focus on food systems and sustainability. The objectives were: (1) promote scientific coordination, cooperation, and collaboration between China and the United States on food systems and sustainability; (2) examine the state of food systems and sustainability research and practices and identify priority areas for scientific collaboration on specific challenges; and (3) discuss opportunities for advancing policy options in China and the United States, including a solution-focused approach. The final session included a discussion of possible future opportunities and is summarized in the section on Path Forward: Future Needs and Opportunities.

WELCOME AND OVERVIEW

National Academy of Sciences (NAS) President Marcia McNutt and CAS President Jianguo Hou offered remarks to open the workshop. Shortly before the workshop, Dr. McNutt and Dr. Hou launched the U.S.-China Collaborative for Planetary Health. Dr. McNutt noted that the Collaborative will focus on global topics in which scientific cooperation will be critical to safeguard wellbeing in both countries, beginning with human health, food systems, and urbanization. The current workshop, she observed, is aligned with this objective. U.S.–China scientific leadership and collaboration are critical in promoting sustainable food systems from a scientific perspective, she said, and welcomed the workshop to stimulate thinking about research priorities.

Dr. Hou, welcoming participants on behalf of CAS, noted the workshop lies at the intersection of food security, environmental health, and sustainable development. As the world faces increasing challenges of climate change and resource limitations, sustainable food systems are needed, he said. Referring to previous joint efforts, Dr. Hou said the current workshop bridges past efforts and future aspirations to overcome global challenges and ensure a sustainable future.

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Planning committee co-chair Karen Seto (Yale University) recounted the first sustainability engagement between the National Academies and CAS in November 2018, when a U.S. delegation visited Beijing for a symposium on science and technology innovation for the Sustainable Development Goals (SDGs). A December 2019 workshop in Washington, DC, followed on advancing urban sustainability.² In early 2022, the National Academies Science and Technology for Sustainability Program established a committee to convene the current series of workshops. Planning committee co-chair Yongguan Zhu (Research Center for Eco-Environmental Sciences, CAS) underscored the importance of the topic. “Food systems lie at the heart of our global sustainability challenges,” he said. “As we face mounting pressures from environmental changes and growing populations, transitioning to sustainable food systems is no longer an option—it is an imperative.”

FRAMING REMARKS: THE STATE OF FOOD SYSTEMS AND SUSTAINABILITY

Jennifer Chow (Environmental Defense Fund) provided context on climate trends and the impacts of climate on agricultural and food systems. Climate change and natural resource pressures impact food systems; at the same time, food systems exacerbate climate change and degrade natural systems. Worldwide, the agricultural and food system uses 37 percent of ice-free land, 70 percent of fresh water, and contributes 22–34 percent of greenhouse gas (GHG) emissions. Agriculture accounts for 43 percent of global methane, and livestock accounts for two-thirds of these agricultural methane emissions, which will increase with higher meat and dairy consumption. In the United States, accelerating the use of cutting-edge technologies and investing in innovation can reduce livestock methane by 23 percent by 2030. Nitrous oxide (N₂O) accounts for 6 percent of U.S. GHGs but has 300 times the impact of carbon dioxide and remains in the atmosphere for more than 100 years. Agriculture is the main source of N₂O, mostly through fertilizers. Agriculture uses 70 percent of groundwater, mostly for irrigation, and 21 of the world’s 37 largest aquifers are being depleted faster than they can be replenished.³

Crop diversification is an adaption tool, as she summarized in a study of climate-proofing Kansas agriculture.⁴ Barriers include markets, infrastructure, technical assistance, access to land and capital, social norms, finance, and policy. Agriculture also has a role in regional climate adaptation, such as flood mitigation, livestock methane emission reduction, and adaptive management.

Weicai Yang (Yazhouwan National Laboratory, CAS) presented an overview of food systems in China. China’s 127 million hectares (Ha) of arable land constitutes 9 percent of the world’s total. Food security challenges include how to feed 1.41 billion people whose consumption demands are changing. China imported 63.90 million tons of food in 2011, which increased to 161.92 million tons in 2023. Contributors to increased domestic output and food security have included chemical fertilizers and pesticides (the Haber-Bosch process), as well as dwarfing mutations in the First Green Revolution (1950–1960), transgenic technology in the Second Green Revolution (1980–2000), and hybrid rice in the Third Green Revolution (1980s). A Fourth Green Revolution, characterized by synthetic biology, genome design, and de novo domestication, may be forthcoming.

From a sustainability perspective, agriculture impacts soil and water resources. He noted potential areas of discussion around these issues, as well as exploration of marginal land for agriculture, new germplasm creation and breeding technologies, and new food resources such as fungi, algae, see grass, and synthetic proteins.

PANEL I: FOOD SYSTEMS, CLIMATE CHANGE, AND BIODIVERISTY

Planning committee members Jianguo “Jack” Liu (Michigan State University) and Yi Yang (Chongqing University, CAS) moderated the first panel on agricultural sensitivity, ecological genomics and adaptation of insects, soil-plant responses, and education related to food systems, climate change, and biodiversity.

Multiple Components and Challenges to Sustainability in Agriculture

Roger Beachy (Emeritus, Washington University in St. Louis; NAS) offered a broad context on agriculture and food systems. While the aim of sustainable or regenerative agriculture and food systems is to produce and

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consume food and feed with little or low environmental impact, food must be available at accessible prices. Components of a successful system will ensure soil health; use high-quality seeds adapted to local conditions; use distribution channels that lengthen product life and avoid waste, nutrition and food safety, and supportive policies. Scaling sustainable agriculture per se requires the use of cropping technologies that maintain soil health, stimulate microbial diversity, reduce water and wind erosion, and increase resilience to weather and climate changes. Another essential component is availability of a trained workforce.

Historical knowledge and advanced technologies must work together to find solutions, Dr. Beachy said. While advanced DNA tools can improve seeds/propagules of locally adapted and familiar foods, directed genetic mutations and gene transfers will be needed in certain cases to achieve resilience to changing climates and the crop pests and pathogens that can dramatically reduce crop yields. As a way forward, Dr. Beachy urged replacing the use of objectionable agrichemicals with biologicals, resilient seeds, and new generations of agrichemicals that have lower risks to human and environmental health. Synthetic biology and artificial intelligence (AI) can help in the design of chemicals and biologicals in a manner similar way that is being applied to producing new human pharmaceuticals and vaccines. He also urged expanded research in identification of beneficial microbes and microbial products and development of next generation of more sensitive devices, or biological sensors that detect the presence of potentially damaging pests and pathogens, or with capacity to predict damaging weather changes. Having these and related technologies available at accessible costs to small holder farmers as well as larger, more wealthy farmers is essential to scaling sustainable agriculture.

Dr. Beachy called for strong collaborations between researchers, farmers, and the private sector providers. However, it is clear that adoption of certain technologies in biotechnologies will require leadership at the highest levels. Without such leadership, regulatory hurdles and widespread adoption will slow progress to sustainable agriculture. While there is public support to reduce the footprint of agriculture and for better nutrition in foods, reluctance to certain technologies and systems that deliver food and nutrition remain in high percentages of consumers with sufficient means. He urged empowering local scientists and entrepreneurs, as well as expanding local control of appropriate regulations that oversee food systems to ensure that such regulations do not restrict access to foods while still ensuring food safety. Finally, Dr. Beachy called for international collaboration in pre-competitive research to bring solutions that can be applied to sustainable food systems that are relevant to the wide diversity of agriculture and those that it serves.

The Role of Insects in Food Security

Le Kang (Institute of Zoology, CAS) addressed the role of insects in food security. Climate change impacts insects’ growth, survival, reproduction, distribution, phenology, generation number, and community structure. It is imperative to comprehend these impacts to manage them and ensure sufficient food production. Insects play a central role in ecosystems by recycling nutrients and nourishing other organisms in the food chain, including humans. Insects as pests pose an important threat to crops and plants and cause economic losses in agricultural ecosystem. Climate change can affect the interactions of insect-plant and insect-natural enemies, providing new challenge for pest management. Food supply largely depends on insect pollinators, and conservation of pollinators is an important issue when pesticide application. Healthy ecosystems keep population numbers in check, but climate change may make some insects more pervasive to the detriment of human health and agriculture. In addition, global warming is expected to expand the geographical range of some disease vectors, such as aphids, planthoppers, and mosquitoes.⁵ Further pest management strategies are needed to control outbreaks.

Dr. Kang’s research has found biological characteristics that can be used to control insects. For example, his group has revealed the molecular mechanism of locust phase change and its connection with population density. His group found the aggregation pheromone of locusts. If chemicals can be designed as antagonists of aggregation pheromones so locusts cannot aggregate, locust plague can be reduced. Pathogenic fungi have also been devel-

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oped as a biological approach to control pests in farmland, forest, and grassland.

Climate change will affect plants and insects associated with them, he concluded. These effects are complicated, but pest pressures will increase. Monitoring, forecasting, and modeling can help develop adaptation strategies. Countries should share information, with historical data and modeling He also called for greater exploration of modern biological tools to devise effective pest management strategies to improve crop production and food security.

Climate Change, Rice, and Human Health

Chunwu Zhu (Institute of Soil Science, CAS) drew from his research on climate change and ecosystems in China, Japan, and the United States. As noted, climate change impacts the agricultural system, including productivity, nutrition, heavy metal risk, soil quality, and GHGs.

Dr. Zhu described studies of the impact of climate change on heavy metal risk. In experiments that stimulated elevated CO₂, higher CO₂ increased global “hidden hunger” as nutritional quality in several important crops declined, but several pathways can benefit nutritional integrity. In a three-year experiment on how elevated CO₂ affects cadmium (Cd) accumulation in soils, it was found that Cd availability decreased in soils, Cd retention increased in the iron plaque of roots, and Cd transfer decreased from the root to the grain.

Dr. Zhu next turned to bioaccumulation. A 10-year study showed that climate change may influence arsenic uptake in many rice cultivars. A health risk assessment looked at rice consumption in seven Asian countries. The mean inorganic arsenic exposure due to rice ingestion increased by 44 percent, with both non-cancer and cancer disease risks. Looking ahead to 2050, the situation is most dangerous in China and India.

As take-home messages, Dr. Zhu said zinc, iron, protein and vitamin intake are decreasing globally, but increased plant transpiration, enlarged root systems, and enhanced nitrate absorption can mitigate nutrient decline. Climate change increases inorganic arsenic accumulation in rice grain, with increased disease risks in the countries studied. Dr. Zhu called for a climate-change resilient agricultural ecosystem with high-quality food, low GHG, high yields, and healthy soils.

Shifting Systems: Role of Education

Heidi Gibson (Smithsonian Science Education Center) praised the science presented at the workshop. Education also needs to be part of the conversation because while science uncovers knowledge about sustainable paths, knowledge alone does not ensure people will change behaviors. People under age 20 are one-third of the global population and have the most to lose or gain from the choices today about the future. The Smithsonian Science Education Center has a mission to transform K-12 education through science in collaboration with communities across the globe.

As a snapshot of global sustainability education, the Smithsonian and Gallup partnered on a study about educating for sustainable development in the United States, France, Canada, India, and Brazil.⁶ More than 80 percent of teachers surveyed think sustainability should be taught. However, there was a huge drop-off when asked if they have the knowledge and time to teach it. As a case study in shifting knowledge and attitudes, Ms. Gibson described the Smithsonian Science for Global Goals project. Free downloadable guides help young people think about SDG topics, such as biodiversity, climate resilience, and food, in their local environments. In addition to the science, young people develop sustainable mindsets. The guides honor local knowledge through a Discover/Understand/Act framework. Ms. Gibson drew from a recent guide on ecosystem resilience to show how the integration between human and natural systems is addressed. Almost 7 million students and 50,000 educators have been involved. Upcoming guides are on climate innovation, sustainable agriculture, and water, and she welcomed input from workshop participants.

Discussion

Dr. Liu opened the discussion by observing that Dr. Beachy provided the big picture on production, environmental impacts, and the workforce, and the following presenters delved into issues within that context. A participant emphasized that discussions about sustainability in the Global South and Global North diverge. Concern

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about climate problems and local solutions cannot take place in situations without food security. He also noted that long supply chains to feed people in cities are the norm and a necessity, as cost of foods and feeds are generally lower when produced at distance and shipped to local markets. Another participant commented on the impact of climate changes on microbiomes and noted a need for studying the intersection of agriculture-relevant microbes with human health. When asked about materials for undergraduates, Ms. Gibson said the Smithsonian guides have been used successfully by first- and second-year undergraduates and pre-service teachers. Regarding areas of collaboration in the next five years, Dr. Beachy suggested identifying the pre-competitive knowledge needed now to have outcomes in coming years. Leadership is needed to say, “if you invent it, we will use it.”

PANEL II: FOOD SYSTEMS, WATER, AND HUMAN HEALTH

Judith Wasserheit (University of Washington) and Yue Qin (Peking University) served as moderators to discuss the connections among food systems, water, health, and sustainability.

Connection between Climate, Food, and Nutrition Outcomes

Jessica Fanzo (Columbia University) described food systems as the lifeline between climate resilience, environmental sustainability, and food security, nutrition, and health outcomes. How food systems are managed—encompassing production, storage, distribution, processing, packaging, markets, consumption, and waste—influence these outcomes. Food is both a victim and transgressor of climate change (Figure 1).

Layered on top of climate change, nutrition outcomes are not optimal universally, Dr. Fanzo continued. Almost 10 percent of the world’s population are undernourished, and many more are affected by stunting, wasting, overweight, and obesity. Diets contribute to morbidity and mortality. The social determinants of health have implications on exposure, sensitivity, and adaptive capacity to deal with climate drivers.

Measuring food systems is critical to understand interactions with climate, she said. Dr. Fanzo is co-chair of the Food Systems Countdown Initiative, which is monitoring food system change and performance to align policy, action, and accountability.⁷ Five groups have organized, and 50 indicators are mapped to the groups’ themes. Without monitoring, she said, countries’ attempts to transform food systems can lose their bearings. Critical data gaps prevent effective monitoring. While there has been work on impacts of climate on food security, there is less on nutrition outcomes. Many types of empirical methods, data, and models are used in the climate, weather, and nutrition fields, and bringing data together is complex.

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She expressed hope that research gaps in such areas as causality, methods to understand temporal and spatial relationships, disaggregated data, and other issues can be addressed. Many communities must be involved to deal with these multisectoral and multifactorial issues, not only climate and nutrition communities, but also health, water, humanitarian response, social protection, and education.

Climate/Environmental Change, Food Systems, Diet, Nutrition, and Health

In our efforts to address the increasingly complex intersection between climate/environmental change, food systems, diet, nutrition and health, Daniel Raiten (National Institutes of Health) underscored as a core principle that food is not the same as nutrition. Nutrition is a biological variable achieved by a series of processes that start with the ingestion of food but does not stop there. The biology of nutrition is essential to all aspects of human health and is both an input and an outcome of health and disease. In a global health context, it is not just about too much or too little food. Disease and safety are affected by the biology of nutrition as well as by the global food environment and the choices available to consumers across their life course. He summarized these relationships as a “nutrition ecology” reflecting an interaction amongst internal (genetics, life stage, health status) and external (social determinants of health, food security, physical) environments. Raiten suggested that nutrition is the glue that ties the impacts of climate, food systems, diet and health together.

Typically, public health approaches focus on programs and policy but ignore the ecological realities of health and disease, he said. An exploding population exists alongside limited resources, climate change, new infections, and political crises. The Food and Agriculture Organization of the United Nations (FAO) has highlighted the growing impact of climate on diet and nutrition; and he posed how to interpret the trends. Although strides have been made, many settings see a collision of communicable and non-communicable diseases, food insecurity, and over- and undernutrition, often within the same population and even individuals. All of these trends are being negatively impacted by a changing environment including climate change. This complexity is beginning to be meaningfully addressed, he said. He called for an approach to ensure dietary patterns that support sustainable food systems and meet the nutritional needs of a growing population.

A focus on sustainable nutrition might add value to the conversation, he suggested. He defined sustainable nutrition as the ability to maintain a nutritional status that will support growth, development, and health throughout the life course and is achievable through recognition of synergy between the needs of the target population, their unique health context (i.e., their ecology), and factors affecting the capacity of food systems to meet those needs. NIH established the ADVANTAGE Project (Agriculture and Diet: Value Added for Nutrition, Translation, and Adaptation in a Global Ecology) to develop an approach to support efforts to develop evidence-informed interventions and guidance to address diet and health in a changing environment.⁸ He highlighted the project’s core premise and questions, and how it is structured.

Carbon-Neutral Staple Food Production in China

Xiaoyuan Yan (Institute of Soil Science, CAS) has worked to answer whether carbon neutrality can be achieved in China’s production of more than 600 million tons of maize, rice, and wheat. Estimates are these crops have an annual net emission of 667 teragrams of CO₂ equivalent, or about 5 percent of total GHGs: 60 percent from rice, 22 percent from maize, and 18 percent from wheat. Four years ago, China announced that emissions would peak before 2030 and carbon neutrality achieved before 2060. He showed the impact of three agricultural options to achieve the carbon neutrality goal.⁹

First are conventional options such as reducing CH₄ from rice paddies through water and residue management, reducing N₂O from optimized fertilizer use, and soil carbon sequestration from crop residue return and biomass. Taken together, these options reduce GHGs but cannot achieve carbon neutrality. The second option adds biochar production to stabilize carbon. Conventional options plus biochar results in greater GHG reduction, but still not carbon neutrality. A third option adds energy substi-

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tution, which includes biochar byproducts such as bio-oil for clean energy production. Conventional, plus biochar, plus energy substitution can result in a reduction in GHG of 95 to 118 percent, which would mean achieving carbon neutrality.

In summary, staple crop production causes GHG emissions, with CH₄ from rice paddies the dominant source. Conventional mitigation can reduce GHG emissions but is insufficient to achieve carbon neutrality. These practices, combined with biochar application and energy capture, have potential. Constraints are mechanisms to incorporate these practices into the marketplace and to develop methodologies and technologies to store energy in seasonal conditions.

Managing the Water-Energy-Food Nexus

Junguo Liu (North China University of Water Resources and Electric Power) reviewed global data about water, food, energy, and carbon security. His team has found significant alterations (21 percent of 10,120 measuring stations) in river flow seasonality globally, and Anthropogenic climate change is a key reason for the changes in northern high latitudes. Many regions of Africa will have new areas of water scarcity after 2050, although scarcity will disappear in many parts of Asia, including China. Emerging water scarcity will influence food production.

Climate change and other anthropogenic activities have also transformed groundwater dynamics, which will influence agricultural systems, he continued. By 2050, 10 billion people will require 60 percent more food, 55 percent more water, and 80 percent more energy than today.¹⁰ Water is closely linked to achievement of SDGs. The water-food nexus must take changing consumption patterns into account. When compared with other countries, per capita water usage is smaller in China but will increase if China follows U.S. and European trends.

Dr. Liu stressed the tradeoff in energy choices. Biofuels have a larger water footprint compared to coal and natural gas. Bioenergy crops impact food prices via demand for land and water. Reducing the carbon footprint may increase the water footprint, which shows the complexity of policy choices. Dr. Liu is principal investigator on a project to understand the water-food-energy nexus and impacts of climate change in the Lancang-Mekong River Basin. In the future, it is important to think about water with other resources in an interdisciplinary model, he stated. Multiple stakeholders could go beyond water quantity to address both quality and the entire ecosystem. He closed with an introduction of an international science initiative, Earth Water Futures, to advance next-generation solutions.

Discussion

When asked about the link between climate change and obesity, Dr. Fanzo suggested two hypotheses, although stressed the lack of literature in this area: People may consume less fresh food and more ultra-processed food, and/or they may exercise less in excessive heat or disruptive infrastructure. When asked about priorities for research and capacity-building, she suggested the need to understand heat impacts on nutritional outcomes. She also suggested providing usable information about climate to rural clinics to assist in their daily practices.

A participant asked about the barriers to biochar. Dr. Yan said the process requires a lot of energy and is expensive. However, capturing the biogas and bio-oil, and other co-benefits can make the economic picture more attractive. As another aspect of a holistic perspective, there is a need to consider land use, a participant commented. Land is needed for nature, people, and food production. Dr. Raiten said the ADVANTAGE Project will address this nexus and the holistic food environment. A participant raised another issue of tradeoffs. Changing diets have decreased iodine consumption in the United States, which might apply to other countries and nutrients. Dr. Raiten said the problem is solvable but not easy. Measurement systems across systems are key and an important area of collaboration, which ADVANTAGE will address.

Day One Wrap-Up

Dr. Seto commented on the complexity of the issues raised. There are trade-offs between resources and different challenges in the Global North and Global South. The scalability of sustainable agriculture and nutrition must be considered. Capacity and research are needed for the future, but there is also an immediacy. Entry points are needed to move forward beyond just recognition that human health and the environment are interconnected.

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PANEL III: FOOD SYSTEMS, URBAN TRANSFORMATION, AND FOOD LOSS AND WASTE

Dr. Seto and Weiqiang Chen (Institute of Urban Environment, CAS) moderated a panel to discuss challenges and opportunities for local food systems, changing dietary patterns, and potential approaches to address food loss and waste (FLW).

Managing FLW

Prabhu Pingali (Cornell University) said that transformations in food systems impact FLW. Reducing FLW contributes both to affordability and environmental sustainability and must be tackled globally. While SDG 12.3 addresses FLW, meeting it will contribute to other SDG goals and targets. Dr. Pingali discussed FLW-related issues of measurement, data sources, and changing consumer expectations. The commonly used figure of 30 percent FLW comes from a 2011 FAO report, Dr. Pingali said. Adjustments in 2020 showed 13.8 percent of food produced on farms, and at transport, storage, processing, and wholesale stages is lost. Nineteen percent that reaches the consumption stage is wasted. However, FAO, United Nations Environment Programme (UNEP), and U.S. Department of Agriculture (USDA) have different FLW definitions, which leads to different measurements and difficulty in tracking progress.¹¹

Another problem is 75 percent of FLW data comes from four databases: African Post-Harvest Loss, FAO, USDA, and the Indian government. There is a need for more diverse sources, Dr. Pingali said. Also, almost all data are for cereals and pulses, with little about other products. Along the value chain, there are differences in where FLW occurs for staples in the Global North and Global South. Fruit and vegetable post-harvest losses occur globally.

Another issue is food quality. As incomes rise, consumer demands increase for food safety and nutritive value. Most food safety concerns come from middle-income countries transitioning to more modern food systems. Investments in better technology are crucial to conserve nutrient value. He also commented about “ugly” food with nutritive value, such as misshaped vegetables. If the market has no price differential, they are not harvested or thrown away. Packaging is another challenge. It maintains quality and safety but uses plastics and other non-degradable materials. The food industry has struggled with sustainable packaging, as it costs more. Dr. Pingali concluded that FLW issues to address include coherence of definitions, investments in better data, and behavior change.

Implications of Rapidly Transforming Food Systems

Thomas Reardon (Michigan State University) concurred with the need to address the implications of system transformation. Imports receive most attention, but 85 to 95 percent of food in Africa and Asia come from domestic supply chains, which receive little attention in policy debates. Cities consume 60 to 70 percent of food in Africa and Asia, while rural areas consume 30 to 40 percent. Eighty to 85 percent of food is purchased. Urban agriculture can feed only about 0.5 percent of the population.

Massive amounts of food move through supply chains. Although people say food systems are broken, he countered they have grown 800 percent in two decades in Africa. Diets have changed radically. Around half of food purchases are processed. Non-grain supply chains in Africa and Asia are growing longer and restructuring, as occurred in Europe and the United States. Wholesalers, processors, and third-party logistics providers form what he calls the “hidden middle.”

The supply chain will grow longer for decades to come, and their vulnerability to climate is a central issue. Cities require food from intensive high-yield farming and long supply chains. Global South consumers will not back away from animal products, produce, and processed food. It is important to find sustainability within this reality. He pointed to a paradox. Energy intensity increases, but deceases over time. In a transitional point, things are worse before processes become efficient. For example, larger trucks reduce transit costs and reduce the overall footprint of shorter chains. Agrifood value chains are crucial to farmers being climate-smart, he concluded.

Challenges and Opportunities in Sustainable Urban Food Systems

Shenghui Cui (Institute of Urban Environment, CAS) presented a conceptual framework for sustainable food systems. Urbanization and urban transformation have created a growing middle class and increased economic development, but also resource and environmental constraints and climate change. Opportunities can result from effective responses to drivers that include urbanization and urban transformation (Figure 2).

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Dr. Cui shared a definition of urban transformation as fundamental irreversible changes in infrastructure, ecosystems, lifestyles, service provision, innovation, institutions, and governance. China has experienced many of these transformations, including in transportation, food, and broadcasting platforms. In this context, challenges of sustainable food systems include broken biogeochemical cycles; climate change; industrialization and globalization; spatial heterogeneity; free market behaviors; and synergy and tradeoffs to achieve the SDGs.

Innovative examples of sustainable food systems are occurring. For example, more than 100 cities have food waste utilization projects. Organic fertilizers from food waste, analogous to livestock manure, are accepted by Chinese farmers. Experiments also show potential in changing the flow of nitrogen and addressing GHG. Dr. Cui called for more attention to consumption behaviors, as well as within-border and cross-border strategies.

Shifts in Food Production and Consumption

Baojing Gu (Zhejiang University) broadened the transformation discussion to regional scales beyond urban locations. About 80 percent of the population will be urbanized by 2050. Urbanization saves land, he stated. It will lead to large-scale farming and release 5–8 million hectares of rural land. Larger farms are more efficient, do not use cropland ridges, and reduce overfertilization. Smallholders use fertilizer as a substitute for machinery and knowledge inputs. They also apply fertilizer by hand, leading to more ammonia emission and leakage in the environment. Appropriate farm sizes optimize fertilization and re-use livestock manure, reducing pollution while maintaining yield and increasing income. Farmers in China are aging, but opportunities are needed to attract younger people to rural areas.

Income levels affect dietary structures in both rural and urban areas. However, according to Dr. Gu, education and change in social structures in urban areas result in decreased overall food consumption, which can benefit food systems. Dr. Gu also called for incentives for farmers to do sustainable agriculture. For example, a Nitrogen Credit System could resolve the mismatch in which farmers pay abatement costs while the whole society benefits. Urbanization can lead to land consolidation and large-scale farming, which will benefit the food supply and the environment.

Discussion

Dr. Pingali said examples of successful behavior change FLW interventions are few. As one example, U.S. supermarkets distribute almost-expired fresh food, but some worry about their liability. International platforms may reach young people to change behaviors, such as portion size or use of ugly food, a participant suggested. Dr. Reardon noted similarities across regions, albeit at different time scales. Going back to the “ugly” food example, price can have an impact, Dr. Pingali added. With increasing demand for perishable foods, FLW will increase, but more data is needed.

A participant asked about population redistribution to smaller cities and towns. Dr. Gu said China is encouraging this. People still prefer the largest cities, and middle-sized cities are following a global trend of getting smaller. Another benefit of urbanization, a participant noted, is the ability to reach younger people with conservation messages.

PANEL IV: FOOD SYSTEMS, BEHAVIORAL SCIENCE, AND TECHNOLOGICAL INNOVATION

Nebojsa Nakicenovic (International Institute for Applied Systems Analysis) and Beibei Liu (Nanjing University) moderated the final session. Panelists discussed behavioral science and emerging technologies across the supply chain and the new science and research needed to transform food systems.

Perspectives on Innovation and Technology

David Zilberman (University of California, Berkeley) defined innovation as a new way of doing things, whether mechanical, chemical, biological or agronomical, or in managerial, institutional, and political systems. Innovations are affected by economics and policy, and they require capital and labor. Conditions can induce innovation. For example, a lack of water leads to improved irrigation, labor scarcity to mechanization, new knowledge to development, or consumer demand to other changes. Thinking of innovation only in terms of market is narrow, Dr. Zilberman continued. He and colleagues developed a concept around the feedback between the symbiotic innovation and product supply chains. Supply chains evolve and expand over time and are designed to pursue profit, adjusted for risk, credit, and policy. He agreed with the mistake in emphasizing small farmers.

A key element in innovation is adoption by individuals and diffusion in the aggregate. Individuals become aware of an innovation. They assess, decide, and then reevaluate their choices. Adoption follows an S-Shaped diffusion curve: early adopters and takeoff, followed by saturation. The term climate-smart agriculture recognizes that farmers only implement more sustainable practices if they solve other problems. The bioeconomy must help farmers. Policy challenges include support for research, education, mechanisms to support new industries, science-based regulation, rewards for pollution reduction and carbon sequestration, and thinking globally and acting locally.

Microbiome Support

Haiyan Chu (Institute of Soil Science, CAS) reminded the group that the microbiome is a collection of microorganisms in a particular environment or ecosystem, and they link the health of humans, animals, plants, and environments. Microbiomes regulate climate, degrades pollution, resists disease, promotes plant growth, and cycles nutrients.

Dr. Chu has focused on development of synthetic microbial communities (SynComs), which are “artificial combinations of two or more distinct cultured microorganisms with well-defined taxonomic status and specific functional characteristics.”¹² SynComs can work more efficiently compared with single species. They can improve soil fertility, bioremediate, suppress disease, and improve soil resilience. His lab is working on SynComs to degrade herbicides and microplastics, address salt stress, fight plant disease, and promote growth. Dr. Chu stated that SynComs have great potential to improve soil health, crop productivity, and sustainability of agriculture and the environment.

AI-Driven Food Systems

Ranveer Chandra (Microsoft Corporation) brings technology to agriculture to give back to the people he grew up with in India. More broadly, the world needs to increase food production and decrease environmental impact, which a data-driven agriculture food system can help do. New efficiencies and business models will result if every entity in the supply chain uses and shares data and AI. Microsoft Research has worked toward this vision of democratizing data- and AI-driven agriculture through its own research, support for academia, and product development. Technologies include FarmBeats for farmers, FoodVibes for the supply chain, and AI to accelerate R&D food production.

Precision agriculture improves yields, reduces costs, and has less impact on the environment. It was proposed in the 1980s but adoption has been low because costs are high. The goal is to bring down the cost of AI for farmers. Innovations developed by the team include improved connectivity on farms, multi-modal AI to merge data from multiple sources, and improved upload of data by farmers so experts can improve services. Farmers have documented the savings across the crop lifecycle. Another goal is to bridge the skills gap and educate farmers to use technology. With the average age of farmers increasing, a personal passion is “to make agriculture cool” by introducing technology to young people. Another effort is to use smartphones for low-cost soil moisture and electrical connectivity sensing. Generative AI can be used to provide answers to farmers on a daily basis although the system needs finetuning. A lot of waste occurs in

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the “first mile” after harvest, so efforts are underway to focus on these practices.

Promise and Challenges of Precision Molecular Breeding

Yuhong Cao (National Center for Nanoscience and Technology) discussed nanotechnology to accelerate plant breeding for a sustainable future. Traditional and transgenic breeding takes 8 to 12 years. In contrast, genome editing can take 4 to 6 years. The resulting plants could also occur spontaneously in nature or be achieved or developed with traditional breeding. Over the past decade, achievements relating to the development of precision molecular breeding (PMB) technologies include enabling high-throughput gene screening in some plant species, integrating PMB with bioinformatics to enhance efficiency, and incorporating automation.

While advances have been made, PMB is in its infancy because of incomplete understanding of complex genomes, lack of effective delivery of gene-editing tools to target cells, regulatory and ethical hurdles, intellectual property and accessibility, as well as environmental and ecological risks. Intracellular delivery is currently the bottleneck. Conventional delivery methods have limitations. Developing novel delivery systems remains uncharted territory. Dr. Cao suggested that nanotechnology can be a solution for enhancing plant breeding technologies based on its efficient delivery, broad applicability, minimum physical damage to plant tissues, and controlled release of gene editing components.

Discussion

Dr. Seto commented on the different types of innovations offered by the presenters. Given the range, she asked which innovation can solve the most pressing problem and have the most scalable impact. Dr. Zilberman offered as a first principle that the innovation must be ready to be commercialized. The benefits must outweigh costs and barriers cannot be too complex to overcome, with the smartphone as an example. In his view, the top barrier in agriculture is regulation. He also noted the need for incentives if farmers are to practice more sustainable farming.

PATH FORWARD: FUTURE NEEDS AND OPPORTUNITIES

Dr. Seto placed the workshop in the broader context of National Academies-CAS activities around sustainability. She underscored that the new U.S.-China Collaborative will focus on interlinkages under the banner of planetary health. She asked about the mechanisms needed in the next 1 to 5 years to move the collaborative forward. Acknowledging political changes, she urged leading with science. Suggested actions by participants to advance engagement between CAS and the National Academies are outlined below.

DISCLAIMER This Proceedings of a Workshop—in Brief was prepared by Franklin Carrero-Martínez, Paula Whitacre, and Emi Kameyama as a factual summary of what occurred at the workshop. The planning committee’s role was limited to planning the workshop. The statements made are those of the rapporteurs or individual workshop participants and do not necessarily represent the views of all workshop participants; the planning committee; or the National Academies of Sciences, Engineering, and Medicine.

REVIEWERS To ensure that it meets institutional standards for quality and objectivity, this Proceedings of a Workshop—in Brief was reviewed in draft form by Beibei Liu, Nanjing University, and G. David Tilman (NAS), University of Minnesota. The review comments and draft manuscript remain confidential to protect the integrity of the process.

U.S. PLANNING COMMITTEE Karen Seto (NAS) (Chair), Yale University; Ashok Gadgil (NAE), University of California, Berkeley and Lawrence Berkeley National Laboratory; Jianguo “Jack” Liu, Michigan State University; Steward Pickett (NAS), Cary Institute of Ecosystem Studies; and Judith N. Wasserheit (NAM), University of Washington.

CHINA PLANNING COMMITTEE Yongguan Zhu (CAS) (Chair), Chinese Academy of Sciences; Xingwang Deng (NAS), Peking University; Le Kang (CAS/NAS), Chinese Academy of Sciences; Keping Ma, University of Chinese Academy of Sciences; Weicai Yang (CAS), Yazhouwan National Laboratory.

U.S. STAFF Franklin Carrero-Martínez, Senior Director, Science and Technology for Sustainability (STS) Program; Emi Kameyama, Program Officer, STS Program; and Danielle Etheridge, Administrative Assistant.

CHINESE ACADEMY OF SCIENCES STAFF Ting Tong, Director, Division of American and Oceanian Affairs, Bureau of International Cooperation; Xiaonan Duan, Director, Division of Earth and Resources Department, Bureau of Sustainable Development Research; and Sumeng Wang, Program Officer, Division of American and Oceanian Affairs, Bureau of International Cooperation.

SPONSORS This workshop was supported by the National Academies George and Cynthia Mitchell Endowment for Sustainability Science, the Chinese Academy of Sciences, Carnegie Corporation of New York, and the Gordon and Betty Moore Foundation.

For additional information regarding the workshop, visit: www.nas.edu/sustainability.

SUGGESTED CITATION National Academies of Sciences, Engineering, and Medicine. 2025. China-U.S. Scientific Engagement: Food Systems and Sustainability: Proceedings of a Workshop—in Brief. Washington, DC: National Academies Press. https://doi.org/10.17726/29079.

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