Feeding the world in a narrowing safe operating space

Abstract

Current world agriculture leads to planetary-boundary transgressions. Although achieving global food security within these environmental bounds is possible through sustainable transformations of the food system, Earth-system feedbacks could increasingly narrow the maneuvering space. Thus, improved understanding of cascading impacts of climate change and other boundary transgressions is imperative. Current world agriculture leads to planetary-boundary transgressions. Although achieving global food security within these environmental bounds is possible through sustainable transformations of the food system, Earth-system feedbacks could increasingly narrow the maneuvering space. Thus, improved understanding of cascading impacts of climate change and other boundary transgressions is imperative. Main textThe future food-security challengeAlthough global food production has been able to surpass the rapid population growth over the past few decades—with more food per capita being produced now than ever—it is based largely on environmentally unsustainable practices. The way we produce and consume food is a prime cause of the present, significant transgressions of planetary boundaries, i.e., limits to nine interacting Earth-system processes that must be respected in order to avoid pushing our planet outside a safe operating space for humanity1Steffen W. Richardson K. Rockström J. Cornell S.E. Fetzer I. Bennett E.M. Biggs R. Carpenter S.R. de Vries W. de Wit C.A. et al.Sustainability. Planetary boundaries: guiding human development on a changing planet.Science. 2015; 347: 1259855Crossref PubMed Scopus (4797) Google Scholar (Figure 1). However, four of these boundaries have already been transgressed, namely those for biosphere integrity, land-system change, biogeochemical flows, and climate change; others such as the boundary for freshwater use have been transgressed in certain regions. A projected world population of ∼10 billion people by 2050 is estimated to require 50%–70% more food to be produced in “business-as-usual” scenarios. Producing enough nutritious food for all, while not only maintaining the Earth’s planetary boundaries but also ideally transforming our food systems so that they strengthen Earth-system resilience, is one of the greatest challenges we face.Here, we argue that agriculture-driven boundary transgressions can be overcome through a combination of different technological and socio-cultural transformations but emphasize that this maneuvering space could become smaller if planetary boundaries are further transgressed due to boundary interactions and feedback loops. Finally, we propose pathways forward to enable next-generation Earth-system research to improve our understanding of these complex dynamics and help to identify solutions for a sustainable food future.Agriculture drives planetary-boundary transgressionsProvisional estimates by Campbell et al2Campbell B.M. Beare D.J. Bennett E.M. Hall-Spencer J.M. Ingram J.S.I. Jaramillo F. Ortiz R. Ramankutty N. Sayer J.A. Shindell D. Agriculture production as a major driver of the Earth system exceeding planetary boundaries.Ecol. Soc. 2017; 22: 8Crossref Scopus (364) Google Scholar suggest that the way the world currently produces food contributes to >80% of transgressions of terrestrial planetary boundaries and ∼25% of transgressions of the climate change boundary (Figure 1; Table 1). Correspondingly, according to a comprehensive, spatially explicit analysis that isolated the effects of agriculture on the status of four planetary and underlying local boundaries,4Gerten D. Heck V. Jägermeyr J. Bodirsky B.L. Fetzer I. Jalava M. Kummu M. Lucht W. Rockström J. Schaphoff S. et al.Feeding ten billion people is possible within four terrestrial planetary boundaries.Nat. Sustain. 2020; 3: 200-208Crossref Scopus (156) Google Scholar almost half of current global food production depends on the violation of one or more boundaries. Specifically, 19% of food production is at the expense of transgressing the boundaries for biosphere integrity and land-system change; another 4% violates the freshwater boundary by tapping into the environmental flow requirements of rivers; and yet another 25% relies on application of nitrogen fertilizer in excess of the tolerable (local) boundary.Table 1Role of agriculture in planetary boundary transgressionsPlanetary boundary∗Only boundaries directly linked to agriculture; see all nine boundaries in Figure 1.Contribution of agriculture to overall boundary transgressionShare of global food production depending on respective boundary transgressionBiosphere integrity (functional and genetic biodiversity)80%12.4%Land-system change (forest-cover loss)80%6.9%Freshwater use (environmental-flow violation)84%4.1%Biogeochemical flows (nitrogen and phosphorus leaching)85% (N), >99% (P)25.2% (only N)Climate change (atmospheric CO2 concentration)25%N/AAverage/Sum>80%48.6% (w/o climate change)Estimated percentage contribution of food production to the current transgressions of planetary boundaries (recent decade, Campbell et al2Campbell B.M. Beare D.J. Bennett E.M. Hall-Spencer J.M. Ingram J.S.I. Jaramillo F. Ortiz R. Ramankutty N. Sayer J.A. Shindell D. Agriculture production as a major driver of the Earth system exceeding planetary boundaries.Ecol. Soc. 2017; 22: 8Crossref Scopus (364) Google Scholar), as well as percentage share of how much of the global food production currently depends on these transgressions (Gerten et al.,4Gerten D. Heck V. Jägermeyr J. Bodirsky B.L. Fetzer I. Jalava M. Kummu M. Lucht W. Rockström J. Schaphoff S. et al.Feeding ten billion people is possible within four terrestrial planetary boundaries.Nat. Sustain. 2020; 3: 200-208Crossref Scopus (156) Google Scholar reference year 2005).∗ Only boundaries directly linked to agriculture; see all nine boundaries in Figure 1. Open table in a new tab These transgressions exhibit a distinct geographical pattern: freshwater withdrawals for irrigation of crops, fodder, or cotton critically reduce streamflow levels mainly in subtropical regions, endangering the integrity of riverine ecosystems.5Huang Z. Yuan X. Liu X. The key drivers for the changes in global water scarcity: Water withdrawal versus water availability.J. Hydrol. (Amst.). 2021; 601: 126658Crossref Scopus (24) Google Scholar Although a thorough, region-specific attribution of irrigation (and other) water withdrawals to aquatic ecosystem degradation is still due, they add to the rapid and dramatic decline in freshwater biodiversity observed in the past decades in response to multiple stressors.6Reid A.J. Carlson A.K. Creed I.F. Eliason E.J. Gell P.A. Johnson P.T.J. Kidd K.A. MacCormack T.J. Olden J.D. Ormerod S.J. et al.Emerging threats and persistent conservation challenges for freshwater biodiversity.Biol. Rev. Camb. Philos. Soc. 2019; 94: 849-873Crossref PubMed Scopus (964) Google Scholar Nitrogen overuse prevails in parts of Europe, China, and the United States, where fertilizer application ultimately leads to an excess of critical nitrogen concentrations in waterbodies, often resulting in eutrophication.1Steffen W. Richardson K. Rockström J. Cornell S.E. Fetzer I. Bennett E.M. Biggs R. Carpenter S.R. de Vries W. de Wit C.A. et al.Sustainability. Planetary boundaries: guiding human development on a changing planet.Science. 2015; 347: 1259855Crossref PubMed Scopus (4797) Google Scholar Forest-cover loss as well as biodiversity loss induced by changes in land cover for the purpose of food production are both widespread across continents, and deforestation of tropical rainforest in South America, southeast Asia, and Africa is a particular concern. The Near East and southern Asia are among the worst-affected regions, with multiple boundaries being transgressed synchronously.4Gerten D. Heck V. Jägermeyr J. Bodirsky B.L. Fetzer I. Jalava M. Kummu M. Lucht W. Rockström J. Schaphoff S. et al.Feeding ten billion people is possible within four terrestrial planetary boundaries.Nat. Sustain. 2020; 3: 200-208Crossref Scopus (156) Google ScholarOpportunities for more sustainable food supplyMany options and opportunities exist to produce and consume food in a more sustainable way. These include yield-gap closure, i.e., improved water, soil, and nutrient-management practices that can be applied (ideally in combination) by farmers. These methods mainly comprise water conservation and water-use efficiency increases through rainwater harvesting, upgraded irrigation systems and soil-conservation techniques, restoration of degraded soils, and increased nitrogen-use efficiency. The yield-gap closure together with reductions in food waste “from field to fork” and adoption of diets with less animal-based products and proteins by individual consumers could double the food supply without using more land and water.7Kummu M. Fader M. Gerten D. Guillaume J.H.A. Jalava M. Jägermeyr J. Pfister S. Porkka M. Siebert S. Varis O. Bringing it all together: linking measures to secure nations’ food supply.Curr. Opin. Environ. Sustain. 2017; 29: 98-117Crossref Scopus (37) Google Scholar The most promising opportunity varies depending on the region; e.g., in Africa and South Asia yield-gap closure is the most optimal solution, whereas in most parts of Europe and North America dietary change has the largest potential. However, all these measures need to be implemented together to meet to the immense challenge ahead.4Gerten D. Heck V. Jägermeyr J. Bodirsky B.L. Fetzer I. Jalava M. Kummu M. Lucht W. Rockström J. Schaphoff S. et al.Feeding ten billion people is possible within four terrestrial planetary boundaries.Nat. Sustain. 2020; 3: 200-208Crossref Scopus (156) Google ScholarRecent scenario-based assessments indicate that the ambitious, synergistic combination of these practices could even provide enough healthy food for 10 billion people while reversing the transgression of planetary boundaries for freshwater use, biosphere integrity, land-system change, and nitrogen flows.4Gerten D. Heck V. Jägermeyr J. Bodirsky B.L. Fetzer I. Jalava M. Kummu M. Lucht W. Rockström J. Schaphoff S. et al.Feeding ten billion people is possible within four terrestrial planetary boundaries.Nat. Sustain. 2020; 3: 200-208Crossref Scopus (156) Google Scholar,8Springmann M. Clark M. Mason-D’Croz D. Wiebe K. Bodirsky B.L. Lassaletta L. de Vries W. Vermeulen S.J. Herrero M. Carlson K.M. et al.Options for keeping the food system within environmental limits.Nature. 2018; 562: 519-525Crossref PubMed Scopus (1049) Google Scholar New inventions such as vertical indoor farming or cell cultures in which food is grown under laboratory conditions could further reduce the pressure on these boundaries, but their high energy use could increase pressure on the climate change boundary.Risk of boundary interactionsAlthough global scenarios suggest that a safe operating space in which the Earth system and the food system are harmonized could indeed exist, careful consideration of the role of complex feedbacks and trade-offs is largely lacking in current studies. For instance, as pointed out in a recent semi-quantitative study,3Lade S.J. Steffen W. de Vries W. Carpenter S.R. Donges J.F. Gerten D. Hoff H. Newbold T. Richardson K. Rockström J. Human impacts on planetary boundaries amplified by Earth system interactions.Nat. Sustain. 2020; 3: 119-128Crossref Scopus (108) Google Scholar the safe operating space could be notably smaller than was previously assumed, because interactions between planetary boundaries (i.e., the underlying biophysical processes) could exert strong pressure on each other. For example, transgressing the planetary boundary for climate change is likely to alter the seasonality and magnitude of the hydrological cycle and is already in some regions diminishing the environmental flows of rivers that define the boundary for freshwater use.9Virkki V. Alanärä E. Porkka M. Ahopelto L. Gleeson T. Mohan C. Wang-Erlandsson L. Flörke M. Gerten D. Gosling S.N. et al.Environmental flow envelopes: quantifying global, ecosystem–threatening streamflow alterations.Hydrol. Earth Syst. Sci. Discuss. 2021; 2021: 1-31Google Scholar The effects of climate change (and human activities) can also reduce the forest cover that defines the boundary for land-system change, which can lead to further feedbacks that can compromise biosphere integrity, affect freshwater, and amplify climate change (Figure 1).The self-amplifying effects of land-use change on the climate as observed in the Amazon region are a prime example. Here, anthropogenic deforestation reduces precipitation, and the ensuing droughts can in turn accelerate forest dieback,10Staal A. Flores B.M. Aguiar A.P.D. Bosmans J.H.C. Fetzer I. Tuinenburg O.A. Feedback between drought and deforestation in the Amazon.Environ. Res. Lett. 2020; 15: 044024Crossref Scopus (58) Google Scholar reducing the size of a vital carbon sink. A recent study11Gatti L.V. Basso L.S. Miller J.B. Gloor M. Gatti Domingues L. Cassol H.L.G. Tejada G. Aragão L.E.O.C. Nobre C. Peters W. et al.Amazonia as a carbon source linked to deforestation and climate change.Nature. 2021; 595: 388-393Crossref PubMed Scopus (128) Google Scholar found that southeastern parts of the Amazon are already transitioning into a carbon source due to high rates of deforestation and climate change. Many other feedbacks and tipping points are known from Earth’s history,12Brovkin V. Brook E. Williams J.W. Bathiany S. Lenton T.M. Barton M. DeConto R.M. Donges J.F. Ganopolski A. McManus J. et al.Past abrupt changes, tipping points and cascading impacts in the Earth system.Nat. Geosci. 2021; 14: 550-558Crossref Scopus (20) Google Scholar and human perturbations enhance the likelihood of their occurrence. Such interactions and cascading effects clearly have implications for the land and freshwater demands of agriculture and could undermine the optimistic projections of a sustainable food system. One such feedback cascade contributed to the emergence of the Syrian civil war, when climate-change-driven droughts hit the food production in the region and in some of world’s large grain exporters, leading to increased commodity prices, displacement, and unrest.13Kelley C. Mohtadi S. Cane M. Seager R. Kushnir Y. Commentary on the Syria case: Climate as a contributing factor.Polit. Geogr. 2017; 60: 245-247Crossref Scopus (22) Google ScholarRisks of leaving a safe climatic spaceIn addition to such indirect effects and feedbacks, anthropogenic climate change is anticipated to directly diminish crop production in many regions, particularly through heatwaves (damaging plant tissues at temperatures >30°C) and droughts (increasing plant water stress through reduced soil moisture). A recent study14Kummu M. Heino M. Taka M. Varis O. Viviroli D. Climate change risks pushing one-third of global food production outside the safe climatic space.One Earth. 2021; 4: 720-729Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar found that climate change will push a significant portion of present food production areas outside the global climatic envelope—the “safe climatic space” defined by temperature, precipitation, and aridity conditions—under which crops are currently being grown. In the study’s worst case climate change scenario (mean global warming of ∼5°C by 2100), as much as one-third of global food production is found to be at risk of moving beyond the safe climatic space. In all scenarios, Africa’s Sudano-Sahelian zone and south and southeast Asia suffer the most. The study reinforces the importance of keeping global warming well below 2°C, because then such a risk would be considerably diminished.It remains to be studied, however, to what extent this finding holds for specific crops, which could still keep their niches and benefit from growth-stimulating direct CO2 effects through improved plant water-use efficiency. Also, the aforementioned measures to sustainably increase food production through improved water and soil management could provide effective opportunities to adapt to climate change.15Jägermeyr J. Gerten D. Schaphoff S. Heinke J. Lucht W. Rockström J. Integrated crop water management might sustainably halve the global food gap.Environ. Res. Lett. 2016; 11: 025002Crossref Scopus (146) Google Scholar However, whether a solution package of improved resource management, reduced food losses, and dietary changes would enable us to feed a growing population in a much warmer world needs to be comprehensively re-investigated in the light of the findings by Kummu et al.,14Kummu M. Heino M. Taka M. Varis O. Viviroli D. Climate change risks pushing one-third of global food production outside the safe climatic space.One Earth. 2021; 4: 720-729Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar as Gerten et al.4Gerten D. Heck V. Jägermeyr J. Bodirsky B.L. Fetzer I. Jalava M. Kummu M. Lucht W. Rockström J. Schaphoff S. et al.Feeding ten billion people is possible within four terrestrial planetary boundaries.Nat. Sustain. 2020; 3: 200-208Crossref Scopus (156) Google Scholar assumed that the planetary boundary for climate change would be maintained.Boundaries and opportunities: One integrated wholeIt should also be emphasized that although climate change and its impacts can be largely avoided through radical greenhouse gas (GHG) emissions cuts, delayed action gives rise to another complication: many mitigation scenarios assume rather high amounts of “negative emissions” to balance delayed or ineffective GHG reductions, provided via large-scale biomass plantations. Such carbon-dioxide-removal strategies have potentially substantial biophysical side effects, such that it is highly questionable whether they are compatible with the aspirational target of maintaining all planetary boundaries even if the food system was to be made more sustainable as suggested above.16Heck V. Gerten D. Lucht W. Popp A. Biomass-based negative emissions difficult to reconcile with planetary boundaries.Nat. Clim. Chang. 2018; 8: 151-155Crossref Scopus (153) Google Scholar This dilemma underlines that combating climate change through cutting GHG emissions must remain the top priority, not only to avoid many of its biophysical and societal impacts, including those on agriculture, but also to minimize additional pressure of mitigation methods on the Earth system. Similarly, measures to maintain planetary boundaries other than the one for climate change must not be implemented at the cost of violating the status of other boundaries; rather, synergistic solutions must be sought. In other words, no planetary boundary can be treated in isolation; they are to be assessed and maintained in a fully integrated manner.The need to integrate complex feedbacks and trade-offsIn view of these complex interactions, which pose significant challenges to the goal of achieving food security within planetary boundaries, we propose that Earth-system feedbacks require deeper integration into food scenarios. This could be done based on the following cornerstones of model development and coupling.First, an internally consistent, geographically explicit representation of planetary boundaries relevant for food production is required, going beyond former approaches that focused on terrestrial processes4Gerten D. Heck V. Jägermeyr J. Bodirsky B.L. Fetzer I. Jalava M. Kummu M. Lucht W. Rockström J. Schaphoff S. et al.Feeding ten billion people is possible within four terrestrial planetary boundaries.Nat. Sustain. 2020; 3: 200-208Crossref Scopus (156) Google Scholar by also including climate change as a dynamic process. This could be achieved through coupling global biosphere/vegetation models (which represent natural and agricultural ecosystems as well as the linked carbon and water cycle) to climate models. Such Earth-system models can then be used to assess the historic, current, and potential status of each planetary boundary to get a better understanding of how their (single or simultaneous) transgressions affect each other’s status and to verify the hypothesis that their interactions reduce the safe operating space. This will at best be done in an intercomparative manner by using multiple models and input datasets, in order to account for uncertainties, as also called for by the Earth Commission.17Rockström J. Gupta J. Lenton T.M. Qin D. Lade S.J. Abrams J.F. Jacobson L. Rocha J.C. Zimm C. Bai X. et al.Identifying a Safe and Just Corridor for People and the Planet.Earth’s Future. 2021; 9 (e2020EF001866)Crossref Scopus (30) Google ScholarSecond, an advanced, temporally dynamic representation of the diverse opportunities to increase food production within the—possibly shrinking—safe operating space is required, as part of, or coupled to, the models that represent the interactive boundaries. A particular need for this integration is to account for the social dynamics that determine the scale, effectiveness, and outcome of the required transformations, which are not well represented in integrated assessment models.18Donges J.F. Heitzig J. Barfuss W. Wiedermann M. Kassel J.A. Kittel T. Kolb J.J. Kolster T. Müller-Hansen F. Otto I.M. et al.Earth system modeling with endogenous and dynamic human societies: the copan:CORE open World–Earth modeling framework.Earth System Dynamics. 2020; 11: 395-413Crossref Scopus (16) Google Scholar That is, novel approaches including, for example, agent-based models that account for networked dynamics of individual people, actors, social groups, or nations, which underlie e.g. dietary shifts or management changes, are needed.Third, through using enhanced models, it would be possible to quantify the extent to which climate change would compromise options to stay below other planetary boundaries (e.g., whether water-saving techniques would be less efficient). Such analyses could be done systematically for any boundary interactions. Eventually, the much-needed full account of the extent to which transgression of the climate change boundary (atmospheric CO2 concentration) would compromise ecologically sustainable world food production—both through direct climate impacts and through worsening the status of other boundaries (e.g., via impact cascades highlighted in Figure 1)—might be possible.Such efforts could culminate in analyses of how interactive boundary transgressions complicate or even undermine the achievement of other sustainable development goals, the Paris Agreement, or the suggested target to protect ≥30% of the planet’s land and oceans envisaged in the zero draft of the post-2020 Global Biodiversity Framework as proposed by the UN Convention on Biological Diversity.The growing risk of multiple planetary-boundary transgressions and interactions could seriously compromise strategies to sustainably achieve food security. Because the compound effects of such interactions are as of yet largely under-researched, a major interdisciplinary effort is needed for their systematic and transparent quantification and communication, based on the newest scientific insights, diverse and state-of-the-art model approaches, and the latest datasets. In the meantime, in the absence of this knowledge, radical transformation toward a more sustainable food system as well as decarbonization of all sectors, including those related to the world’s food system, are essential: for its own sake, humanity needs to secure a safe climatic and biospheric space alike. Main textThe future food-security challengeAlthough global food production has been able to surpass the rapid population growth over the past few decades—with more food per capita being produced now than ever—it is based largely on environmentally unsustainable practices. The way we produce and consume food is a prime cause of the present, significant transgressions of planetary boundaries, i.e., limits to nine interacting Earth-system processes that must be respected in order to avoid pushing our planet outside a safe operating space for humanity1Steffen W. Richardson K. Rockström J. Cornell S.E. Fetzer I. Bennett E.M. Biggs R. Carpenter S.R. de Vries W. de Wit C.A. et al.Sustainability. Planetary boundaries: guiding human development on a changing planet.Science. 2015; 347: 1259855Crossref PubMed Scopus (4797) Google Scholar (Figure 1). However, four of these boundaries have already been transgressed, namely those for biosphere integrity, land-system change, biogeochemical flows, and climate change; others such as the boundary for freshwater use have been transgressed in certain regions. A projected world population of ∼10 billion people by 2050 is estimated to require 50%–70% more food to be produced in “business-as-usual” scenarios. Producing enough nutritious food for all, while not only maintaining the Earth’s planetary boundaries but also ideally transforming our food systems so that they strengthen Earth-system resilience, is one of the greatest challenges we face.Here, we argue that agriculture-driven boundary transgressions can be overcome through a combination of different technological and socio-cultural transformations but emphasize that this maneuvering space could become smaller if planetary boundaries are further transgressed due to boundary interactions and feedback loops. Finally, we propose pathways forward to enable next-generation Earth-system research to improve our understanding of these complex dynamics and help to identify solutions for a sustainable food future.Agriculture drives planetary-boundary transgressionsProvisional estimates by Campbell et al2Campbell B.M. Beare D.J. Bennett E.M. Hall-Spencer J.M. Ingram J.S.I. Jaramillo F. Ortiz R. Ramankutty N. Sayer J.A. Shindell D. Agriculture production as a major driver of the Earth system exceeding planetary boundaries.Ecol. Soc. 2017; 22: 8Crossref Scopus (364) Google Scholar suggest that the way the world currently produces food contributes to >80% of transgressions of terrestrial planetary boundaries and ∼25% of transgressions of the climate change boundary (Figure 1; Table 1). Correspondingly, according to a comprehensive, spatially explicit analysis that isolated the effects of agriculture on the status of four planetary and underlying local boundaries,4Gerten D. Heck V. Jägermeyr J. Bodirsky B.L. Fetzer I. Jalava M. Kummu M. Lucht W. Rockström J. Schaphoff S. et al.Feeding ten billion people is possible within four terrestrial planetary boundaries.Nat. Sustain. 2020; 3: 200-208Crossref Scopus (156) Google Scholar almost half of current global food production depends on the violation of one or more boundaries. Specifically, 19% of food production is at the expense of transgressing the boundaries for biosphere integrity and land-system change; another 4% violates the freshwater boundary by tapping into the environmental flow requirements of rivers; and yet another 25% relies on application of nitrogen fertilizer in excess of the tolerable (local) boundary.Table 1Role of agriculture in planetary boundary transgressionsPlanetary boundary∗Only boundaries directly linked to agriculture; see all nine boundaries in Figure 1.Contribution of agriculture to overall boundary transgressionShare of global food production depending on respective boundary transgressionBiosphere integrity (functional and genetic biodiversity)80%12.4%Land-system change (forest-cover loss)80%6.9%Freshwater use (environmental-flow violation)84%4.1%Biogeochemical flows (nitrogen and phosphorus leaching)85% (N), >99% (P)25.2% (only N)Climate change (atmospheric CO2 concentration)25%N/AAverage/Sum>80%48.6% (w/o climate change)Estimated percentage contribution of food production to the current transgressions of planetary boundaries (recent decade, Campbell et al2Campbell B.M. Beare D.J. Bennett E.M. Hall-Spencer J.M. Ingram J.S.I. Jaramillo F. Ortiz R. Ramankutty N. Sayer J.A. Shindell D. Agriculture production as a major driver of the Earth system exceeding planetary boundaries.Ecol. Soc. 2017; 22: 8Crossref Scopus (364) Google Scholar), as well as percentage share of how much of the global food production currently depends on these transgressions (Gerten et al.,4Gerten D. Heck V. Jägermeyr J. Bodirsky B.L. Fetzer I. Jalava M. Kummu M. Lucht W. Rockström J. Schaphoff S. et al.Feeding ten billion people is possible within four terrestrial planetary boundaries.Nat. Sustain. 2020; 3: 200-208Crossref Scopus (156) Google Scholar reference year 2005).∗ Only boundaries directly linked to agriculture; see all nine boundaries in Figure 1. Open table in a new tab These transgressions exhibit a distinct geographical pattern: freshwater withdrawals for irrigation of crops, fodder, or cotton critically reduce streamflow levels mainly in subtropical regions, endangering the integrity of riverine ecosystems.5Huang Z. Yuan X. Liu X. The key drivers for the changes in global water scarcity: Water withdrawal versus water availability.J. Hydrol. (Amst.). 2021; 601: 126658Crossref Scopus (24) Google Scholar Although a thorough, region-specific attribution of irrigation (and other) water withdrawals to aquatic ecosystem degradation is still due, they add to the rapid and dramatic decline in freshwater biodiversity observed in the past decades in response to multiple stressors.6Reid A.J. Carlson A.K. Creed I.F. Eliason E.J. Gell P.A. Johnson P.T.J. Kidd K.A. MacCormack T.J. Olden J.D. Ormerod S.J. et al.Emerging threats and persistent conservation challenges for freshwater biodiversity.Biol. Rev. Camb. Philos. Soc. 2019; 94: 849-873Crossref PubMed Scopus (964) Google Scholar Nitrogen overuse prevails in parts of Europe, China, and the United States, where fertilizer application ultimately leads to an excess of critical nitrogen concentrations in waterbodies, often resulting in eutrophication.1Steffen W. Richardson K. Rockström J. Cornell S.E. Fetzer I. Bennett E.M. Biggs R. Ca