The threats posed by climate change to food and nutrition security are growing, and the need to develop actions to both mitigate and adapt to climate change is increasingly important. A systems approach to governance that involves stakeholders at the scale of food value chains can address important knowledge gaps between climate change and food and nutrition security outcomes, and facilitate identification and implementation of high-leverage ex ante mitigation actions. Participatory Systems Modeling (PSM) is a methodological approach to identify and assess priority actions that combines facilitated stakeholder discussions with the development of quantitative inter-temporal systems simulation models. PSM has potential benefits deriving from the involvement of stakeholders, the application of well-developed quantitative systems modeling methods, flexibility, low cost and linkages to other systems-oriented frameworks. We propose a roadmap for scaling PSM through multi-context case studies and further development of standardized best practices.

Food systems are a major contributor to exceeding planetary boundaries1-3 and poor quality diets are a key mortality risk globally4. Projected population and income growth could exacerbate these challenges5. In response, there are calls for transformation towards healthy and sustainable food systems6-8. However, the scale and distribution of the impacts of this transformation on agriculture are underexplored. Here we show that, by 2050, the transformation of food systems towards healthy diets (adoption of the EAT-Lancet reference diet), improved productivity and halving of food waste results in a fundamental restructuring of global agriculture, aspects of which break with historical trends. Scenario simulations using a multimodel ensemble of ten global economic models show a 6% median decrease in agricultural land (+1% to -26%) compared with 2020 levels. By 2050, agricultural production would be 17% lower than business-as-usual projections (-2% to -32%) and, economically, the value of this production is US$1.6 trillion (26%) lower (+8% to -58%). Within this, the value of livestock production would be substantially lower than current 2050 projections (-49% to -83%), while vegetable, fruit, nut and legume production value would increase by 23% (-33% to +106%). Results are dependent on the assumed policies to achieve the transformation scenario. We highlight a more active role for food policy to consider the benefits of such a transformation (improved population health and reduced environmental pressures) and navigate the political economy of its impacts.

There is a growing body of literature highlighting the need for increased focus on gender dynamics and inequality within agri-food systems, and in the design of policies that improve food and nutrition security while addressing climate change. Application of analytical tools that both (a) increase understanding of distinct gendered outcomes and constraints in these settings and (b) facilitate the development of policies that are gender-responsive and effective at mitigating climate change impacts is needed. Yet, identification of policies that improve or harm gendered outcomes is limited within many current analytical approaches by significant knowledge gaps about gender-specific realities, and by the lack of a systems perspective. We summarize these challenges in the context of agri-food supply chains under climate change and recommend Participatory Systems Modeling (PSM) as a method to address barriers to capturing “the gender variable” effectively and improving gender-responsive policy design. We discuss the methodology behind PSM and present examples of its usage in understanding agri-food supply chains as an integral component of global agri-food systems and determinant of food and nutrition security outcomes, where gender dynamics and climate change are important overarching system features and drivers. We recommend how PSM can be best utilized to improve the gender sensitivity of policy design for key agri-food system components like agri-food supply chains, and discuss ways that PSM itself can become more gender-responsive as a research and policy design tool.

3 Compatibility of Pastoralism and Conservation? A TEST CASE USING INTEGRATED ASSESSMENT IN THE NGORONGORO CONSERVATION AREA, TANZANIA was published in Conservation and Mobile Indigenous Peoples on page 36.

BACKGROUND:Current food systems leave one in ten individuals at risk of hunger while driving unsustainable environmental impacts. Inaction risks further exacerbating negative impacts on both human and planetary health. These challenges emerge from complex system interactions, requiring approaches that engage with this complexity and consider how transformation measures interact across food systems. We aimed to quantify the magnitude and uncertainty of the impacts of key food systems transformation measures both individually and in a bundle using an ensemble of global economic models. METHODS:In this global multimodel assessment, we applied an ensemble of ten state-of-the-art global economic models to evaluate the potential of four key measures in transforming food systems: increasing agricultural productivity, halving food loss and waste, shifting towards healthier diets, and economy-wide climate mitigation policies aligned with limiting warming to 1·5°C. The scenarios used a middle-of-the-road shared socioeconomic pathway for population and gross domestic product growth, climate impact data from Jägermeyr and colleagues, Thornton and colleagues, and Nelson and colleagues, and dietary targets based on the EAT-Lancet healthy reference diet, with model simulations conducted from 2020 to 2050. We then assessed the effect of these measures in isolation and in combination in a bundled scenario. To further understand the interactions between these measures, we conducted a decomposition analysis that distinguishes between the individual effects of a measure (effect when implemented alone), total effects (its contribution within the bundle), and interaction effects (the difference between total and individual effects). This approach aimed to show complementarities and trade-offs that emerge when multiple measures are implemented simultaneously. FINDINGS:Our analysis showed that individual measures in isolation are insufficient to achieve high-level environmental objectives and might generate unintended consequences. In contrast, bundling measures produces co-benefits: avoiding 50% of projected agricultural greenhouse gas emissions by 2050 and almost 20% of anticipated land conversion, while moderating food price increases associated with ambitious climate change mitigation policies. Our decomposition analysis further shows that measures can have varying effects across different dimensions. Although dietary shifts and climate mitigation policies are the largest drivers of environmental benefits (each contributing to a median decline of >10 percentage points in non-CO2 emissions and 5 percentage points in agricultural land use globally), productivity improvements and reducing food loss and waste play essential roles in moderating price increases (each contributing to a median decline of >5 percentage points in average prices). INTERPRETATION:This study highlights the importance of implementing coordinated approaches to food system transformation and climate change mitigation rather than relying on isolated interventions. Comprehensive transformation requires understanding how supply-side and demand-side changes can interact with climate mitigation policies, enabling policy makers to design intervention packages that maximise benefits while minimising trade-offs across environmental, economic, and social dimensions. FUNDING:Bill & Melinda Gates Foundation; Cornell Atkinson Center for Sustainability; Environment Research and Technology Development Fund; the Asahi Glass Foundation; CGIAR Initiative on Foresight; the CGIAR Science Program on Policy Innovations; US Department of Agriculture, Economic Research Service; and the ClimateWorks Foundation, European Union.

Multilateralism, as epitomized by Western liberal hegemony and the concomitant intergovernmental agreements and institutions set up after World War II, is in crisis. Reductions in development funding coupled with inadequate climate action and limited progress toward the Sustainable Development Goals do not bode well for the challenges that food systems are increasingly facing. In crisis lies opportunity, however. Here, the outputs of a process lasting several months are described, involving stakeholders and experts from organizations ranging from funders, NGOs, government, the private sector, and research institutes, whose objective was to consider what is needed to facilitate the move toward more sustainable and equitable food systems. Along with a scan of recent writings on alternative narrative framings of food systems as drivers of behavioral change, one output of this process was the identification of five potential elements of a modified global architecture for accelerating climate action in food systems. These five were embracing multiplicity, expanding localism, addressing justice, being positive and inclusive in messaging, and out-competing legacy systems. These are neither new nor original ideas, but if actioned together their implications could be far-reaching for those working at the intersection of agricultural development and climate. Some planned, concrete actions for each element are briefly described-the early stages of an organizational experiment to gauge their effectiveness in contributing to food system reconfiguration at different scales.

Food system transformation will require the expansion of new ideas and solutions while phasing out old and obsolete ones, potentially leading to unintended and undesirable consequences. This Perspective argues that anticipatory governance approaches can shape technological visions while informing and prioritizing actions to support sustainable transformation. We present a framework to engage systematically with uncertainty and complexity, and to identify potential positive and negative outcomes. We argue for the adoption of mission-oriented innovation systems to better align innovation efforts with environmental, social and health objectives while mitigating negative consequences-and create a culture of more inclusive and responsible innovation.

Food systems exert significant stress on planetary boundaries1–3 while healthy diets are currently unaffordable for billions worldwide4. These challenges are expected to continue under global population trends, projected to reach 9.6 billion by mid-century5. Food systems must therefore transform in pursuit of health and sustainability goals6–8. However, the scale and distribution of this transformation on agriculture is underexplored. Here we show that, by 2050, an EAT-Lancet style food systems transformation results in a fundamental restructuring of global agriculture, aspects of which break with historical trends. Scenario simulations using a multi-model ensemble of 10 global economic models show a 6% median decrease in agricultural land of 274Mha (+1 to -26%, +48 to -1257Mha) compared to 2020 levels. By 2050, agricultural production would be 2 to 32% (-0.2x109 to -3.7x109 tonnes) lower than business-as-usual projections, and economically, the value of this production shows a 26% median relative decline of $1.6tn in USD2020 (+8% to -58%, +$0.5tn to -$2.9tn USD2020) Within this, the value of livestock production would fall substantially (-$1tn to -$2.2tn, -49% to -83%). These results reinforce the need for a more active role for food policy and stakeholder dialogue to catalyse such a transformation and navigate the political economic consequences of its impacts.

Food production is at the heart of global sustainability challenges, with unsustainable practices being a major driver of biodiversity loss, emissions and land degradation. The concept of foodscapes, defined as the characteristics of food production along biophysical and socio-economic gradients, could be a way addressing those challenges. By identifying homologues foodscapes classes possible interventions and leverage points for more sustainable agriculture could be identified. Here we provide a globally consistent approximation of the world's foodscape classes. We integrate global data on biophysical and socio-economic factors to identify a minimum set of emergent clusters and evaluate their characteristics, vulnerabilities and risks with regards to global change factors. Overall, we find food production globally to be highly concentrated in a few areas. Worryingly, we find particularly intensively cultivated or irrigated foodscape classes to be under considerable climatic and degradation risks. Our work can serve as baseline for global-scale zoning and gap analyses, while also revealing homologous areas for possible agricultural interventions.

Pastoral-agropastoral transition zones across the African continent are projected to face crop production difficulties due to climate change. A greater emphasis on livestock production may be an appropriate response in some places. Here we explore how heat stress may impact livestock productivity and human work capacity. While adaptations can alleviate some of the challenges related to heat stress, data-driven, systemic changes and multi-stakeholder participation are needed to accommodate the complex socio-economic factors involved in shaping a vision for pastoral and agropastoral food systems and to enact local-and effective-change.

Demand for animal source foods and livestock feed are forecast to increase across sub-Saharan Africa. In this context, there is a need to estimate the availability of livestock feed to support decision making at local, sub-national and national levels. In this study we assess feed balances for ruminant livestock in Ethiopia and Burkina Faso. Feed availability was estimated using remotely sensed products and detailed feed composition data. Feed requirements were estimated for maintenance, growth, lactation, gestation and locomotion using a data intensive model. Biomass available as animal feed was estimated to be 8.6 tonnes dry matter (DM) per hectare in the Ethiopian highlands and midlands, 3.2 tonnes DM per hectare in the Ethiopian lowlands, 2.9 tonnes DM per hectare in Burkina Faso’s Sudanian agro-ecological zone and 1.0 tonne DM per hectare in the Sahel. The energy requirements of lactating cows were estimated to be 62.1 Megajoules (MJ) per animal per day in the Ethiopian highlands and midlands, 62.7 MJ in the Ethiopian lowlands, 88.5 MJ in Burkina Faso’s Sudanian agro-ecological zone and 53.1 MJ per animal per day in the Sahel. Feed scarcity hotspots are most prominently located in the Ethiopian highlands and the Sahelian agro-ecological zone of Burkina Faso. Demand side policy and investment initiatives can address hotspots by influencing herd sizes, nutritional requirements and herd mobility. Supply side policy and investment initiatives can secure existing feed resources, develop new sources of feed and incentivise trade in feed resources. Improving feed balances will be of value to decision makers with the aims of optimising livestock productivity, minimising exposure to climatic shocks and minimising greenhouse gas emission intensity.

There is a clear and urgent call to transform our food systems as a critical nexus to tackle ongoing global climate, biodiversity, equity, and nutrition crises. Many food and agricultural innovations are being developed and scaled but these innovations often target sector-specific problems and remain disconnected from the more complex demand for transformative change at scale. To bridge this demand for systemic change within the innovation ecosystem, initiatives are applying various approaches such as visioning, holistic assessments, innovation portfolio management and multistakeholder co-creation. Here we report on insights from applying a food systems tailored backcasting approach in a diversity of settings since 2021, including a national food system dialogue, a youth business innovation challenge, a landscape multi-stakeholder platform, a public-private sector co-learning session, an agroecological transitions program, and a hybrid food systems university course for graduate students and global professionals. We thereby build on existing literature and case studies of how change happens (or does not happen) and aim to use those insights to support food systems change makers. Across these settings, the backcasting approach asks participants to connect innovations with broader systems-change visions, to anticipate tradeoffs for multiple food system outcomes and population groups, and to cross sectoral boundaries. The use cases demonstrate that the backcasting process contributes to changes in views, practices and structures that participants work with. Specifically, it supports moving beyond “silver bullet” innovation approaches, the bundling of social and technical innovations, and building action-oriented cross-sectoral bridges. Food systems change is complex and innovations alone are insufficient to address its complexity. But innovations can play a positive role if connected to more holistic systems-change processes and goals. Considering strengths and limitations of the backcasting approach, the diversity of practical applications supports its potential to connect innovations to holistic food systems visions, to strengthen cross-sectoral collaboration and to bundle social and technical innovations for desirable food systems change.

Are there limits to our ability to adapt food systems to climate change? This overview paper for the special issue highlights results of research on potential limits and responses by food system actors. Responses are shaped by the critical interactions among the physical, chemical, biological, and social impacts in food systems arising from climate change. Food grains, temperate perennials, livestock, and oceanic capture fisheries and farming are covered. Climate change impacts on the biology of plants, animals, and humans, as well as the options for societal responses are explored. The results show where and how possible adaptations will be limited.

There has been growing interest in the Conference of Parties (COPs) meetings of the United Nations Framework Convention on Climate Change (UNFCCC) in food systems, which account for a third of global emissions and are heavily impacted by climate change. While there has been much rhetoric about the need for transformation at recent COPs, we examine whether this solely remains at the level of rhetoric and ambition or is likely to deliver the climate action that is needed. Based on literature, documentation of UNFCCC meetings, and our own participation, we observe that progress in the past on agriculture has been extremely slow and has led to limited action, while the recent verbiage on food systems has not been matched by significant progress in the negotiations. The urgent action needed is not realised through the UNFCCC processes. New and radically different ways to catalyse action are needed, and the UNFCCC process urgently needs reform as part of wider multilateral reforms. We propose that the scale of the COPs is reduced and that the focus shifts to the results delivered through rigorous evaluation, accountability and transparency, and a shift towards less consensus-based approaches to drive action and ambition.

It is widely accepted that current food systems are not on a trajectory for achieving the Sustainable Development Goals by the end of the decade. Technological innovation will have a considerable role to play in different parts of the food system; many promising options exist or are in the pipeline, some of which may be highly disruptive to existing value chains. Scaling up the innovations required, at the same time as protecting those who may lose out in the short term, will require a strong enabling environment. Here we apply an existing framework of eight change accelerators to six case studies of historical agricultural innovation. We estimated the degree to which each accelerator had been addressed at some stage in the innovation process, as a measure of the gap between what was needed and what was achieved. For the innovations that are being taken to scale and widely utilized, these accelerator gaps are small. Uptake of other innovations is stalled, and for these we found large gaps for one or more of the eight accelerators. Impactful innovation processes address all eight change accelerators at some point, with different phasing of the accelerators depending on the nature of the technology and on the impact pathway being pursued. This simple framework, when used in combination with narratives of uptake based on theories of change and impact pathways, may provide an effective means of screening future innovation processes to help prioritize and guide investment that can lead to more resilient, sustainable and equitable food systems.

Food production data — such as crop, livestock, aquaculture and fisheries statistics — are critical to achieving multiple sustainable development goals. However, the lack of reliable, regularly collected, accessible, usable and spatially disaggregated statistics limits an accurate picture of the state of food production in many countries and prevents the implementation of effective food system interventions. In this Review, we take stock of national and international food production data to understand its availability and limitations. Across databases, there is substantial global variation in data timeliness, granularity (both spatially and by food category) and transparency. Data scarcity challenges are most pronounced for livestock and aquatic food production. These challenges are largely concentrated in Central America, the Middle East and Africa owing to a combination of inconsistent census implementation and a global reliance on self-reporting. Because data scarcity is the result of technical, institutional and political obstacles, solutions must include technological and policy innovations. Fusing traditional and emerging data-gathering techniques with coordinated governance and dedicated long-term financing will be key to overcoming current obstacles to sustained, up-to-date and accurate food production data collection, foundational in promoting and monitoring progress towards healthier and more sustainable food systems worldwide.

To meet climate targets, a shift to low-emission diets that also support health and sustainability is necessary. A high-impact target is to reduce red meat consumption by 50 percent by 2030 in high- and middle-income countries based on the 2019 EAT-Lancet diet. Actions to lessen animal-based meat consumption could cut dietary emissions by 3–8 billion tonnes of carbon dioxide equivalent per year (Table 9.1). Scaling up plant-based meat will require viable products, low costs, effective public policy to catalyse change, and strong markets. The priority actions are to facilitate consumer behavioural change for large segments of populations, promote policy targets and actions for reduced-meat diets in high- and middle-income countries, use public-private finance to improve alternative meat product nutrition and sustainability, and enhance affordable technology and business options.

Alternative protein sources for human food, as well as for terrestrial and aquatic animal feed, are increasingly commercially available. These products have considerable potential for sustainably delivering protein for food and feed and could lead to significant reductions in climate and land use impacts. Alternative protein sources include meat analogs, insects, certain woody plants, and algae including seaweed. We briefly review recent work on their nutritional, environmental, technological, and socioeconomic impacts. We outline possible trade-offs at scale and consider the ways in which the alternative protein sector may develop in the next decades.