Food systems are essential for the achievement of the United Nations Sustainable Development Goals in China. Here, using an integrated assessment modelling framework that considers country-specific pathways and covers 18 indicators, we find that most social and environmental targets for the Chinese food system under current trends are not aligned with the United Nations Agenda 2030. We further quantify the impacts of multiple measures, revealing potential trade-offs in pursuing strategies aimed at public health, environmental sustainability and livelihood improvement in isolation. Among the individual packages of measures, a shift towards healthy diets exhibits the lowest level of trade-offs, leading to improvements in nutrition, health, environment and livelihoods. In contrast, focusing efforts on climate change mitigation and ecological conservation, or promoting faster socioeconomic development alone, have trade-offs between social and environmental outcomes. These trade-offs could be minimized by bundling all three aspects of measures. The effectiveness of the different policies and policy bundles for food systems transformation to achieve SDGs in China vary widely. Using an integrated modelling framework covering 18 indicators, this study compares the trade-offs and outcomes of efforts focused on dietary transitions, climate change mitigation and ecological conservation, and faster socioeconomic development, ultimately revealing that dietary shifts offer the most benefits.

Multiple cropping practices, i.e. planting and harvesting crops several times a year at the same plot of land, may increase global food production without further expanding cropland (Wu et al. 2014). Especially the combination of irrigation in the dry season to facilitate multiple harvests a year potentially facilitates more food production on the same amount of land. Global dynamic gridded vegetation models that inform global land-use models usually only model one growing season a year. Neglecting the yield that can be achieved in the second or third season leads to an underestimation of yields and irrigation water requirements and biased projections of the spatial allocation of rainfed and irrigated cropland.With an update of our hydro-economic model (Beier et al. 2023), we are able to estimate multiple cropping potentials and model multiple cropping and irrigation expansion. It is the tandem of these two intensification measures that facilitates production gains without expanding cropland. We estimate multiple cropping potentials considering their interaction with irrigation and water availability limitations to determine how much cropland area can be managed in a multiple cropping system given local crop growth conditions (suitability for multiple cropping), the associated water requirements and locally limited water availability for irrigation. We obtain multiple cropping and irrigation potentials at a 0.5° spatial resolution using biophysical inputs from the global vegetation model LPJmL (Schaphoff et al. 2018, von Bloh et al. 2018). LPJmL provides crop-specific (irrigated and rainfed) crop yields and crop water requirements for the main growing season for 12 crop functional types and gross primary production (GPP) of grass for the entire year at a 0.5° spatial resolution. To derive a metric on the yield increase through multiple cropping, we need an aggregated approach that abstracts from the very high set of potential combinations of crops in multiple cropping. We therefore use the main-season-to-whole-year ratio of grass GPP to obtain the grid-cell-specific potential multiple cropping effect. This ratio is used to scale main season crop yields and crop water requirements. In terms of irrigation water availability, the spatial allocation of irrigation water takes upstream-downstream relationships into account and considers the monetary yield gain through irrigation to determine the location of potentially irrigated areas (Beier et al. 2023).With this, we address the research question: What is the biophysical and economic multiple cropping production potential under consideration of local (spatially explicit) irrigation water availability constraints on current cropland?References Beier, F. et al. (2023a). Technical and Economic Irrigation Potentials within Land and Water Boundaries. Water Resources ResearchBeier, F., et al. (2023b) ‘Mrwater: MadRat Based MAgPIE Water Input Data Library’. 10.5281/zenodo.5801680.Schaphoff, S. et al. (2018). ‘LPJmL4 – a Dynamic Global Vegetation Model with Managed Land – Part 1: Model Description’. Geoscientific Model Development 11 (4)Wu, W., et al. (2018) Global cropping intensity gaps: increasing food production without cropland expansion. Land Use Policy 76 (2018)von Bloh, W. et al. (2018). Implementing the Nitrogen Cycle into the Dynamic Global Vegetation, Hydrology, and Crop Growth Model LPJmL (Version 5.0). Geoscientific Model Development 11 (7)

The majority of signatories to The United Nations Climate Change Conference in 2021 (COP26) made a declaration to end deforestation by 2030. Here, we quantify future changes in land use and associated CO _2 emissions to examine the impact of ending deforestation by 2030 on global land dynamics and emissions using an open-source land-use model. We show that if the COP26 declaration to end deforestation is fully implemented globally, about 167 Mha of deforestation could be avoided until 2050, compared to a baseline scenario which does not have extended forest protection. However, avoided deforestation and associated emissions come at the cost of strongly increased conversion of unprotected non-forested land to agricultural land, while land-use intensification in most regions is similar compared to a baseline scenario. Global initiatives are needed to facilitate a common dialogue on addressing the possible carbon emissions and non-forest leakage effects due to the expedited loss of non-forested land under a policy aimed at halting deforestation by 2030.

The future of food and land systems is crucial for achieving multiple UN Sustainable Development Goals, given their essential role in providing adequate nutrition and their significant impact on Earth system processes. Despite widespread consensus on the need for transformation, discussed strategies vary widely, from technology-driven to sufficiency-focused approaches, emphasizing different agents of change and policy mixes. This study assesses the implications of a new generation of target-seeking scenarios incorporating such diverse sustainability perspectives. We apply two integrated assessment models to explore food and land futures under three whole-economy sustainable development pathways (SDPs): Economy-driven Innovation, Resilient Communities, and Managing the Global Commons. Our assessment shows that the SDPs align sufficient food supply with progress towards planetary integrity, halting biodiversity loss, mitigating adverse impacts from irrigation, and significantly reducing nitrogen pollution. While all SDPs comply with the Paris climate target, they diverge in the timing of climate mitigation efforts and focus on different greenhouse gases and emission sources. The Economy-driven Innovation pathway rapidly achieves net-negative CO _2 emissions from the land system, whereas the pathways Resilient Communities and Managing the Global Commons significantly decrease agricultural non-CO _2 emissions. Moreover, sustainability interventions attenuate trade-offs associated with narrowly focused mitigation scenarios and reduce reliance on carbon dioxide removal strategies like bioenergy with carbon capture and storage.

Water security is at stake today. While climate changes influence water availability, urbanization and agricultural activities have led to increasing water demand as well as pollution, limiting safe water use. We conducted a global assessment of future clean-water scarcity for 2050s by adding the water pollution aspect to the classical water quantity-induced scarcity assessments. This was done for >10,000 sub-basins focusing on nitrogen pollution in rivers by integrating land-system, hydrological and water quality models. We found that water pollution aggravates water scarcity in >2000 sub-basins worldwide. The number of sub-basins with water scarcity triples due to future nitrogen pollution worldwide. In 2010, 984 sub-basins are classified as water scarce when considering only quantity-induced scarcity, while 2517 sub-basins are affected by quantity & quality-induced scarcity. This number even increases to 3061 sub-basins in the worst case scenario in 2050. This aggravation means an extra 40 million km 2 of basin area and 3 billion more people that may potentially face water scarcity in 2050. Our results stress the urgent need to address water quality in future water management policies for the Sustainable Development Goals.

In India, the production of rice and wheat account for more than 80% of its total agricultural water use. As farming is highly dependent on water availability, rapidly receding water levels require urgent measures to manage withdrawals. We assess policy instruments that can reduce pressures on water resources, while at the same time limiting adverse impacts on water-intensive cereal production systems, land-use changes and economic welfare. To this end, we use a dynamic and integrated partial equilibrium model of agricultural production and its impact on the environment to reflect two options: an increase in energy costs for irrigation water (price-related effects), and alternatively, physical quotas on water withdrawals (quantity-related effects). We conclude that it is possible to increase energy prices for agriculture with minimal impacts on agricultural production, agricultural prices, and trade in cereal crops, and moderately reduce water withdrawals by 2050. We find that the intermediate effects of pricing policies are negative for all indicators as compared to quota policies. However, by 2050, both policies yield similar outcomes for all indicators. Our results offer insights into ways in which these policies drive different mechanisms and trade-offs on important agro-economic indicators, and they offer the choice for water conservation policy decision-making based on other critical factors such as implementation costs.

To satisfy the increasing global demand for agricultural products, the expansion of irrigation is an important intensification measure. At the same time, unsustainable water abstractions and cropland expansion pose a threat to biodiversity and ecosystem functioning. Irrigation potentials are influenced by local biophysical irrigation water availability and competition of different water users. Using a novel hydro‐economic data processing routine that considers economic criteria of water allocation via a productivity ranking of grid cells and both land and water sustainability criteria, we estimate global irrigation potentials at a 0.5° spatial resolution. We show that there is considerable technical potential to expand irrigation within local water and land boundaries. In terms of potentially irrigated areas on all global land suitable for crop production, 2,144 Mha could be irrigated within land and water environmental boundaries when only considering biophysical criteria. However, not all of these areas would actually be irrigated under consideration of irrigation costs. Of these, only 698 Mha (330 Mha) have a yield gain of more than 300 (600) USD ha −1 under the current crop mix valued at their current commodity price (economic irrigation potential).

The current global food system has detrimental outcomes for global health, environmental conditions and social inclusion. A coherent vision of a desirable food system can guide a sustainable food system transformation and help to structure political processes and private decisions by quantifying potential benefits, facilitating debates about co-benefits and trade-offs, and identifying key measures for desirable change. Such a transformation requires integrating measures targeting human diets, livelihoods, biosphere integrity, and agricultural management. Here, we apply a global food and land system modeling framework to quantify the impacts of 23 food system measures by 2050. Our multi-criteria assessment shows that a food system transformation can improve outcomes for health, the environment, social inclusion, and the economy. All individual measures come with trade-offs, particularly those targeting agricultural management, while few trade-offs and multiple co-benefits are linked to dietary change measures. By combining measures in packages, trade-offs can be reduced and co-benefits enhanced. We show that a sustainable food system also requires a transformation of the overall economy to stop global warming, reduce absolute poverty, and create alternative employment options. Within the context of a cross-sectoral sustainable development pathway, the food system transformation improves 14 of our 15 outcome indicators.

Degrowth proponents advocate reducing ecologically destructive forms of production and resource throughput in wealthy economies to achieve environmental goals, while transforming production to focus on human well-being. Here we present a quantitative model to test degrowth principles in the food and land system. Our results confirm that reducing and redistributing income alone, within current development paradigms, leads to limited greenhouse gas (GHG) emission mitigation from agriculture and land-use change, as the nutrition transition towards unsustainable diets already occurs at relatively low income levels. Instead, we show that a structural, qualitative food system transformation can achieve a steady-state food system economy that is net GHG-neutral by 2100 while improving nutritional outcomes. This sustainable transformation reduces material throughput via a convergence towards a needs-based food system, is enabled by a more equitable income distribution and includes efficient resource allocation through the pricing of GHG emissions as a complementary strategy. It thereby integrates degrowth and efficiency perspectives. Income reduction in high-income regions is insufficient for mitigating food systems greenhouse gas emissions. A deeper transformation is required that changes consumption patterns and prices emissions.

The human-earth system is confronted with the challenge of providing a range of resources for a growing and more prosperous world population while simultaneously reducing environmental degradation. The sustainable development goals and the planetary boundaries define targets to manage this challenge. Many of these are linked to the land system, such as biodiversity, water, food, nutrients and climate, and are strongly interconnected. A key question is how measures can be designed in the context of multi-dimensional sustainability targets to exploit synergies. To address this, a nexus approach is adopted that acknowledges the interconnectedness between the important sub-systems water, land, food, and climate. This study quantifies synergies and trade-offs from ambitious interventions in different components of this water-land-fod-climate nexus at the global scale. For this purpose, a set of six harmonized scenarios is simulated with the MAgPIE and IMAGE models. The multi-model approach improves robustness of the results while shedding light on variations coming from different modelling approaches. Our results show that measures in the food component towards healthy diets with low meat consumption have synergies with all other nexus dimensions: Increased natural land improving terrestrial biodiversity (+4% to +8%), lower greenhouse gas emissions from land (−45% to −58%), reduced irrigation water withdrawals to protect or restore hydrological environmental flows (−3% to −24%), and reductions in nitrogen surpluses (−23% to −35%). Climate mitigation measures in line with the Paris Agreement have trade-offs with the water and food components of the nexus, as they adversely affect irrigation water withdrawals (+5% to +30% in 2050 compared to reference scenario) and food prices (+1% to +20%). The analysis of a scenario combining all measures reveals how certain measures are in conflict while others reinforce each other. This study provides an example of a nexus approach to scenario analysis providing input to the next generation of pathways aiming to achieve multiple dimensions of sustainable development.

To satisfy increasing global agricultural demand, the expansion of irrigation is an important intensification measure. At the same time, unsustainable water abstractions and cropland expansion pose a threat to biodiversity and ecosystem functioning. Irrigation potentials are influenced by local biophysical irrigation water availability and competition of different water users. Because water abstractions for various human uses along the river divert the river flow, it is also important to consider competing water uses when estimating irrigation potentials. Using a novel river routing routine that considers economic criteria of water allocation via a productivity ranking of grid cells and both land and water sustainability criteria, we estimate global irrigation potentials at a halfdegree spatial resolution. We show that there are considerable potentials to expand irrigation without harming the environment, but not necessarily at the places where irrigation is taking place today. In terms of potentially irrigated areas on current cropland, 711 Mha could be sustainably irrigated when only considering biophysical criteria. Of these, only 254 Mha have a yield value gain of more than 500 USD/ha and would be economically viable to be irrigated. The open-source data processing routine is a valuable aggregation and disaggregation tool for the use of hydrological inputs within land-system models that do not have a highly resolved representation of land use. The potentials can be aggregated to different simulation level units (e.g. basin level or country level) while maintaining biophysical and economic consistency.

Data and model source code for the publication: Land use change and carbon emissions of a transformation to timber cities(Nature Communications, 2022)DOI: 10.1038/s41467-022-32244-w Abhijeet Mishra1,2,*, Florian Humpenöder1, Galina Churkina1, Christopher P.O. Reyer1, Felicitas Beier1,2, Benjamin Leon Bodirsky1, Hans Joachim Schellnhuber1, Hermann Lotze-Campen1,2, and Alexander Popp1 1 Potsdam Institute for Climate Impact Research (PIK), Member of Leibniz Association, P.O.Box 60 12 03, 14412,6Potsdam, Germany2 Humboldt University of Berlin, Department of Agricultural Economics, Unter den Linden 6, 10099 Berlin,8Germany Abhijeet Mishra*mishra@pik-potsdam.deMay 2022 See README.txt for further details.

Using engineered wood for construction has been discussed for climate change mitigation. It remains unclear where and in which way the additional demand for wooden construction material shall be fulfilled. Here we assess the global and regional impacts of increased demand for engineered wood on land use and associated CO 2 emissions until 2100 using an open-source land system model. We show that if 90% of the new urban population would be housed in newly built urban mid-rise buildings with wooden constructions, 106 Gt of additional CO 2 could be saved by 2100. Forest plantations would need to expand by up to 149 Mha by 2100 and harvests from unprotected natural forests would increase. Our results indicate that expansion of timber plantations for wooden buildings is possible without major repercussions on agricultural production. Strong governance and careful planning are required to ensure a sustainable transition to timber cities even if frontier forests and biodiversity hotspots are protected.

The inputdata.zip folder contains data created by the fullWATER.R function of the mrwater library v1.2.5 (https://doi.org/10.5281/zenodo.5801680, https://github.com/pik-piam/mrwater/) for the resubmission of the article "Technical and Economic Irrigation Potentials within land and water boundaries". It is used to create the graphs and tables in outputs_22-07-2022.zip created by the mrwater_CurrentIrrigationPotentials_v2.0.0.Rmd in the public github repository (https://github.com/FelicitasBeier/IrrigationPotentials)

Ambitious climate policies, as well as economic development, education, technological progress and less resource-intensive lifestyles, are crucial elements for progress towards the UN Sustainable Development Goals (SDGs). However, using an integrated modelling framework covering 56 indicators or proxies across all 17 SDGs, we show that they are insufficient to reach the targets. An additional sustainable development package, including international climate finance, progressive redistribution of carbon pricing revenues, sufficient and healthy nutrition and improved access to modern energy, enables a more comprehensive sustainable development pathway. We quantify climate and SDG outcomes, showing that these interventions substantially boost progress towards many aspects of the UN Agenda 2030 and simultaneously facilitate reaching ambitious climate targets. Nonetheless, several important gaps remain; for example, with respect to the eradication of extreme poverty (180 million people remaining in 2030). These gaps can be closed by 2050 for many SDGs while also respecting the 1.5 °C target and several other planetary boundaries. Current action is insufficient to meet both the Paris Agreement and the Sustainable Development Goals. Integrated model-based analysis shows that strong interventions across many dimensions, together with ambitious lifestyle change, are needed to enable real progress towards the UN Agenda 2030.

Data repository: Integrating Degrowth and Efficiency Perspectives to Enable an Emission-neutral Food SystemBenjamin Leon Bodirsky, David Meng-Chuen Chen, Isabelle Weindl, Bjoern Soergel, FelicitasBeier, Edna J. Molina Bacca, Franziska Gaupp, Alexander Popp, Hermann Lotze-Campen. In review. Folder structure: 1. Figures: Contains .Rmd notebook for figure production, as well as source data (from model inputs and outputs) 2. Magpie_start_script: Contains start script degrowth.R for replication of model runs. See readme.txt for precise instructions. 3. Scenario_outputs. Entire output folders of model scenario runs.

Agricultural nitrogen (N) emissions represent the most substantial N source in Germany. Even though multiple policies have been introduced at the EU and German national level to reduce agriculturally sourced reactive Nitrogen (N), Germany is exceeding the target of the government’s national sustainability strategy to limit N surpluses. To form a better view of the current N policy challenges, this paper seeks to identify what constrains family-managed pig farmers in Germany from adopting N-reduced farming practices. Our study applies a practice-based approach and reconstructs farmers’ practice and individual perception of the possible capability to change practices ( perceived agency ) through problem-centred interviews. The study identifies different ideal types of farmers based on their reported farming practices and perceived agency : The first type feeling overburdened and weary of the current requirements, the second type acting based on routine and incremental improvement efforts, and the third type adapting early and inventing. However, regarding the perceived agency to adopt N-reduced farming practices our results show that all three farmer types report only low to little agency. Based on the findings, the study identifies type-specific and type-spanning constraining factors. To resolve farmers’ perceived contradictions and inconsistencies which result in the unwillingness to accept further N reduction measures, we argue that policies need to address these factors. To enhance long-term paths for sustainable N-reduced farming practices, this study concludes that N policies need to shift towards outcome-oriented policies to create a collective and holistic understanding of the desired outcome while considering their embeddedness into regional and individual contexts.

Hydro-economic models (HEMs) constitute useful instruments to assess water-resource management and inform water policy. In the last decade, HEMs have achieved significant advances regarding the assessment of the impacts of water-policy instruments at a river basin or catchment level in the context of climate change (CC). This paper offers an overview of the alternative approaches used in river-basin hydro-economic modelling to address water-resource management issues and CC during the past decade. Additionally, it analyses how uncertainty and risk factors of global CC have been treated in recent HEMs, offering a discussion on these last advances. As the main conclusion, current challenges in the realm of hydro-economic modelling include the representation of the food-energy-water nexus, the successful representation of micro-macro linkages and feedback loops between the socio-economic model components and the physical side, and the treatment of CC uncertainties and risks in the analysis.