Safe and just Earth system boundaries.

The stability and resilience of the Earth system and human well-being are inseparably linked1-3, yet their interdependencies are generally under-recognized; consequently, they are often treated independently4,5. Here, we use modelling and literature assessment to quantify safe and just Earth system boundaries (ESBs) for climate, the biosphere, water and nutrient cycles, and aerosols at global and subglobal scales. We propose ESBs for maintaining the resilience and stability of the Earth system (safe ESBs) and minimizing exposure to significant harm to humans from Earth system change (a necessary but not sufficient condition for justice)4. The stricter of the safe or just boundaries sets the integrated safe and just ESB. Our findings show that justice considerations constrain the integrated ESBs more than safety considerations for climate and atmospheric aerosol loading. Seven of eight globally quantified safe and just ESBs and at least two regional safe and just ESBs in over half of global land area are already exceeded. We propose that our assessment provides a quantitative foundation for safeguarding the global commons for all people now and into the future.

Managing mineral phosphorus application with soil residual phosphorus reuse in Canada.

With limited phosphorus (P) supplies, increasing P demand, and issues with P runoff and pollution, developing an ability to reuse the large amounts of residual P stored in agricultural soils is increasingly important. In this study, we investigated the potential for residual soil P to maintain crop yields while reducing P applications and losses in Canada. Using a P cycling model coupled with a soil P dynamics model, we analyzed soil P dynamics over 110 years across Canada's provinces. We found that using soil residual P may reduce mineral P demand as large as 132 Gg P year-1 (29%) in Canada, with the highest potential for reducing P applications in the Atlantic provinces, Quebec, Ontario, and British Columbia. Using residual soil P would result in a 21% increase in Canada's cropland P use efficiency. We expected that the Atlantic provinces and Quebec would have the greatest runoff P loss reduction with use of residual soil P, with the average P loss rate decreasing from 4.24 and 1.69 kg ha-1 to 3.45 and 1.38 kg ha-1 , respectively. Ontario, Manitoba, and British Columbia would experience relatively lower reductions in P loss through use of residual soil P, with the average runoff P loss rate decreasing from 0.44, 0.36, and 4.33 kg ha-1 to 0.19, 0.26, and 4.14 kg ha-1 , respectively. Our study highlights the importance of considering residual soil P as a valuable resource and its potential for reducing P pollution.

Effects of land use, cover, and protection on stream and riparian ecosystem services and biodiversity.

Protected areas are an important part of broader landscapes that are often used to preserve biodiversity or natural features. Some argue that protected areas may also help ensure provision of ecosystem services. However, the effect of protection on ecosystem services and whether protection affects the provision of ecosystem services is known only for a few services in a few types of landscapes. We sought to fill this gap by investigating the effect of watershed protection status and land use and land cover on biodiversity and the provision of ecosystem services. We compared the ecosystem services provided in and around streams in 4 watershed types: International Union for Conservation of Nature category II protected forests, unprotected forests, unprotected forests with recent timber harvesting, and unprotected areas with agriculture. We surveyed 28 streams distributed across these watershed types in Quebec, Canada, to quantify provisioning of clean water, carbon storage, recreation, wild foods, habitat quality, and terrestrial and aquatic biodiversity richness and abundance. The quantity and quality of ecosystem services and biodiversity were generally higher in sites with intact forest-whether protected or not-relative to those embedded in production landscapes with forestry or agriculture. Clean-water provision, carbon storage, habitat quality, and tree diversity were significantly higher in and around streams surrounded by forest. Recreation, wild foods, and aquatic biodiversity did not vary among watershed types. Although some services can be provided by both protected and unprotected areas, protection status may help secure the continued supply of services sensitive to changes in land use or land cover. Our findings provide needed information about the ecosystem service and biodiversity trade-offs and synergies that result from developing a watershed or from protecting it.

Efectos del Uso, Cobertura y Protección del Suelo sobre los Servicios Ambientales y la Biodiversidad de Arroyos y Ríos Resumen Las áreas protegidas son una parte importante de paisajes más extensos que se usan frecuentemente para preservar la biodiversidad o las características naturales. Hay quienes argumentan que las áreas protegidas también podrían ayudar a asegurar el suministro de servicios ambientales. Sin embargo, el efecto de la protección sobre los servicios ambientales y el hecho de si la protección afecta al suministro de estos sólo se conocen para unos cuantos servicios en muy pocos tipos de paisaje. Buscamos cerrar este vacío investigando el efecto del estado de protección de las cuencas y el uso y cobertura de suelo sobre la biodiversidad y el suministro de servicios ambientales. Comparamos los servicios ambientales proporcionados en y alrededor de los arroyos en cuatro tipos de cuenca: bosques protegidos con categoría II de la Unión Internacional para la Conservación de la Naturaleza, bosques sin protección, bosques sin protección con tala reciente y áreas sin protección con actividad agrícola. Censamos 28 arroyos distribuidos a lo largo de estos tipos de cuenca en Quebec, Canadá, para cuantificar el suministro de agua limpia, secuestro de carbono, actividades recreativas, alimentos silvestres, calidad del hábitat y riqueza y abundancia de biodiversidad acuática y terrestre. La cantidad y la calidad de los servicios ambientales y de la biodiversidad fueron generalmente más altas en los sitios de bosque intacto - protegido o no - en relación con los sitios inmersos en paisajes de producción agrícola o silvícola. El suministro de agua limpia, el secuestro de carbono, la calidad del hábitat y la diversidad de árboles fueron significativamente más altos en y alrededor de los arroyos rodeados por bosque. Las actividades recreativas, los alimentos silvestres y la biodiversidad acuática no varió entre los tipos de cuenca. Aunque algunos servicios pueden ser proporcionados por áreas con o sin protección, el estado de protección puede ayudar a asegurar el suplemento continuo de servicios sensibles a los cambios en el uso en la cobertura del suelo. Nuestros hallazgos brindan información requerida sobre las compensaciones de servicios ambientales y biodiversidad y las sinergias resultantes del desarrollo o protección de una cuenca.

Spatio-temporal dynamics of groundwater storage changes in the Yellow River Basin.

Groundwater is an important source of water supply and ecosystem resilience. However, limited information on spatio-temporal dynamics makes a complete assessment of available groundwater resources difficult, impairing sustainable water management. The Gravity Recovery and Climate Experiment mission (GRACE) has recently made this possible. In this study, we used the Yellow River Basin (YRB) as a model system to explore the use of spatio-temporal dynamics information about groundwater change derived from the GRACE datasets for regional groundwater management. While there was an overall decreasing trend (R2 = 0.57) during the last 14 year, the groundwater storage over the whole basin decreased significantly (p < 0.0001, slope changed from -0.0137 cm/month to -0.0684 cm/month) since 2010 (2010-2016) and showed stronger fluctuations than the time before (2003-2009). The range and the standard deviation of groundwater storage change also increased in recent years especially after 2010. At the basin scale, locations which exhibited higher variabilities (large standard deviation) over time generally showed radical decrease of groundwater storage. The results indicated that groundwater depletion may reduce the aquifers' function for ecosystem resilience, thus posing risks to the ecosystem of the YRB and threatening its people to climate change and extreme events. Despite the overall trend, the changes were heterogeneous if looking at finer scales: spatially, there was a gradual decline of storage from west to east (e.g. the change in December 2016 was -3.6, -9.1 and -25.8 cm for the upper, middle and lower reach, respectively); and temporally, the timeseries among the reaches were significantly different (p = 0.023). Our hotspot analysis also indicated the heterogeneity in groundwater decline across the basin and through the time. Additionally, it showed that human factors (e.g. groundwater consumption) become dominant in determining the groundwater change pattern over climatic variations. We therefore call for more attention to groundwater in developing sustainable water management strategies and suggest a closer cooperation of neighboring provinces in the YRB to have a reciprocal strategic plan for water regulation, protection, and management.

Climate change and community fisheries in the arctic: A case study from Pangnirtung, Canada.

Coastal fishery systems in the Arctic are undergoing rapid change. This paper examines the ways in which Inuit fishers experience and respond to such change, using a case study from Pangnirtung, Canada. The work is based on over two years of fieldwork, during which semi-structured interviews (n = 62), focus group discussions (n = 6, 31 participants) and key informant interviews (n = 25) were conducted. The changes that most Inuit fishers experience are: changes in sea-ice conditions, Inuit people themselves, the landscape and the seascape, fish-related changes, and changes in weather conditions, markets and fish selling prices. Inuit fishers respond to change individually as well as collectively. Fishers' responses were examined using the characteristics of a resilience-based conceptual framework focusing on place, human agency, collective action and collaboration, institutions, indigenous and local knowledge systems, and learning. Based on results, this paper identified three community-level adaptive strategies, which are diversification, technology use and fisheries governance that employs a co-management approach. Further, this work recognised four place-specific attributes that can shape community adaptations, which are Inuit worldviews, Inuit-owned institutions, a culture of sharing and collaborating, and indigenous and local knowledge systems. An examination of the ways in which Inuit fishers experience and respond to change is essential to better understand adaptations to climate change. This study delivers new insights to communities, scientists, and policymakers to work together to foster community adaptation.

A novel telecoupling framework to assess social relations across spatial scales for ecosystem services research.

Access to ecosystem services and influence on their management are structured by social relations among actors, which often occur across spatial scales. Such cross-scale social relations can be analysed through a telecoupling framework as decisions taken at local scales are often shaped by actors at larger scales. Analyzing these cross-scale relations is critical to create effective and equitable strategies to manage ecosystem services. Here, we develop an analytical framework -i.e. the 'cross-scale influence-dependence framework'- to facilitate the analysis of power asymmetries and the distribution of ecosystem services among the beneficiaries. We illustrate the suitability of this framework through its retrospective application across four case studies, in which we characterize the level of dependence of multiple actors on a particular set of ecosystem services, and their influence on decision-making regarding these services across three spatial scales. The 'cross-scale influence-dependence framework' can improve our understanding of distributional and procedural equity and thus support the development of policies for sustainable management of ecosystem services.

Historical dynamics in ecosystem service bundles.

Managing multiple ecosystem services (ES), including addressing trade-offs between services and preventing ecological surprises, is among the most pressing areas for sustainability research. These challenges require ES research to go beyond the currently common approach of snapshot studies limited to one or two services at a single point in time. We used a spatiotemporal approach to examine changes in nine ES and their relationships from 1971 to 2006 across 131 municipalities in a mixed-use landscape in Quebec, Canada. We show how an approach that incorporates time and space can improve our understanding of ES dynamics. We found an increase in the provision of most services through time; however, provision of ES was not uniformly enhanced at all locations. Instead, each municipality specialized in providing a bundle (set of positively correlated ES) dominated by just a few services. The trajectory of bundle formation was related to changes in agricultural policy and global trends; local biophysical and socioeconomic characteristics explained the bundles' increasing spatial clustering. Relationships between services varied through time, with some provisioning and cultural services shifting from a trade-off or no relationship in 1971 to an apparent synergistic relationship by 2006. By implementing a spatiotemporal perspective on multiple services, we provide clear evidence of the dynamic nature of ES interactions and contribute to identifying processes and drivers behind these changing relationships. Our study raises questions about using snapshots of ES provision at a single point in time to build our understanding of ES relationships in complex and dynamic social-ecological systems.

Solutions for a cultivated planet.

Increasing population and consumption are placing unprecedented demands on agriculture and natural resources. Today, approximately a billion people are chronically malnourished while our agricultural systems are concurrently degrading land, water, biodiversity and climate on a global scale. To meet the world's future food security and sustainability needs, food production must grow substantially while, at the same time, agriculture's environmental footprint must shrink dramatically. Here we analyse solutions to this dilemma, showing that tremendous progress could be made by halting agricultural expansion, closing 'yield gaps' on underperforming lands, increasing cropping efficiency, shifting diets and reducing waste. Together, these strategies could double food production while greatly reducing the environmental impacts of agriculture.

Effect of woody-plant encroachment on livestock production in North and South America.

A large fraction of the world grasslands and savannas are undergoing a rapid shift from herbaceous to woody-plant dominance. This land-cover change is expected to lead to a loss in livestock production (LP), but the impacts of woody-plant encroachment on this crucial ecosystem service have not been assessed. We evaluate how tree cover (TC) has affected LP at large spatial scales in rangelands of contrasting social-economic characteristics in the United States and Argentina. Our models indicate that in areas of high productivity, a 1% increase in TC results in a reduction in LP ranging from 0.6 to 1.6 reproductive cows (Rc) per km(2). Mean LP in the United States is 27 Rc per km(2), so a 1% increase in TC results in a 2.5% decrease in mean LP. This effect is large considering that woody-plant cover has been described as increasing at 0.5% to 2% per y. On the contrary, in areas of low productivity, increased TC had a positive effect on LP. Our results also show that ecological factors account for a larger fraction of LP variability in Argentinean than in US rangelands. Differences in the relative importance of ecological versus nonecological drivers of LP in Argentina and the United States suggest that the valuation of ecosystem services between these two rangelands might be different. Current management strategies in Argentina are likely designed to maximize LP for various reasons we are unable to explore in this effort, whereas land managers in the United States may be optimizing multiple ecosystem services, including conservation or recreation, alongside LP.

Temperate forest fragments maintain aboveground carbon stocks out to the forest edge despite changes in community composition.

Edge effects are among the primary mechanisms by which forest fragmentation can influence the link between biodiversity and ecosystem processes, but relatively few studies have quantified these mechanisms in temperate regions. Carbon storage is an important ecosystem function altered by edge effects, with implications for climate change mitigation. Two opposing hypotheses suggest that aboveground carbon (AGC) stocks at the forest edge will (a) decrease due to increased tree mortality and compositional shifts towards smaller, lower wood density species (e.g., as seen in tropical systems) or, less often, (b) increase due to light/temperature-induced increases in diversity and productivity. We used field-based measurements, allometry, and mixed models to investigate the effects of proximity to the forest edge on AGC stocks, species richness, and community composition in 24 forest fragments in southern Quebec. We also asked whether fragment size or connectivity with surrounding forests altered these edge effects. AGC stocks remained constant across a 100 m edge-to-interior gradient in all fragment types, despite changes in tree community composition and stem density consistent with expectations of forest edge effects. We attribute this constancy primarily to compensatory effects of small trees at the forest edge; however, it is due in some cases to the retention of large trees at forest edges, likely a result of forest management. Our results suggest important differences between temperate and tropical fragments with respect to mechanisms linking biodiversity and AGC dynamics. Small temperate forest fragments may be valuable in conservation efforts based on maintaining biodiversity and multiple ecosystem services.

Agronomic phosphorus imbalances across the world's croplands.

Increased phosphorus (P) fertilizer use and livestock production has fundamentally altered the global P cycle. We calculated spatially explicit P balances for cropland soils at 0.5° resolution based on the principal agronomic P inputs and outputs associated with production of 123 crops globally for the year 2000. Although agronomic inputs of P fertilizer (14.2 Tg of P·y(-1)) and manure (9.6 Tg of P·y(-1)) collectively exceeded P removal by harvested crops (12.3 Tg of P·y(-1)) at the global scale, P deficits covered almost 30% of the global cropland area. There was massive variation in the magnitudes of these P imbalances across most regions, particularly Europe and South America. High P fertilizer application relative to crop P use resulted in a greater proportion of the intense P surpluses (>13 kg of P·ha(-1)·y(-1)) globally than manure P application. High P fertilizer application was also typically associated with areas of relatively low P-use efficiency. Although manure was an important driver of P surpluses in some locations with high livestock densities, P deficits were common in areas producing forage crops used as livestock feed. Resolving agronomic P imbalances may be possible with more efficient use of P fertilizers and more effective recycling of manure P. Such reforms are needed to increase global agricultural productivity while maintaining or improving freshwater quality.

Relational place-based solutions for environmental policy misalignments.

Current reductionist approaches to environmental governance cannot resolve social-ecological crises. Siloed institutions fail to address linked social and ecological processes, thereby neglecting issues of equity, justice, and cumulative effects. Global insights can be gained from Indigenous-led initiatives that support the resilience of relationships within and among places.

Un-yielding: Evidence for the agriculture transformation we need.

There has been a seismic shift in the center of gravity of scientific writing and thinking about agriculture over the past decades, from a prevailing focus on maximizing yields toward a goal of balancing trade-offs and ensuring the delivery of multiple ecosystem services. Maximizing crop yields often results in a system where most benefits accrue to very few (in the form of profits), alongside irreparable environmental harm to agricultural ecosystems, landscapes, and people. Here, we present evidence that an un-yielding, which we define as de-emphasizing the importance of yields alone, is necessary to achieve the goal of a more Food secure, Agrobiodiverse, Regenerative, Equitable and just (FARE) agriculture. Focusing on yields places the emphasis on one particular outcome of agriculture, which is only an intermediate means to the true endpoint of human well-being. Using yields as a placeholder for this outcome ignores the many other benefits of agriculture that people also care about, like health, livelihoods, and a sense of place. Shifting the emphasis to these multiple benefits rather than merely yields, and to their equitable delivery to all people, we find clear scientific evidence of win-wins for people and nature through four strategies that foster FARE agriculture: reduced disturbance, systems reintegration, diversity, and justice (in the form of securing rights to land and other resources). Through a broad review of the current state of agriculture, desired futures, and the possible pathways to reach them, we argue that while trade-offs between some ecosystem services in agriculture are unavoidable, the same need not be true of the end benefits we desire from them.

Earth stewardship: Shaping a sustainable future through interacting policy and norm shifts.

Transformation toward a sustainable future requires an earth stewardship approach to shift society from its current goal of increasing material wealth to a vision of sustaining built, natural, human, and social capital-equitably distributed across society, within and among nations. Widespread concern about earth's current trajectory and support for actions that would foster more sustainable pathways suggests potential social tipping points in public demand for an earth stewardship vision. Here, we draw on empirical studies and theory to show that movement toward a stewardship vision can be facilitated by changes in either policy incentives or social norms. Our novel contribution is to point out that both norms and incentives must change and can do so interactively. This can be facilitated through leverage points and complementarities across policy areas, based on values, system design, and agency. Potential catalysts include novel democratic institutions and engagement of non-governmental actors, such as businesses, civic leaders, and social movements as agents for redistribution of power. Because no single intervention will transform the world, a key challenge is to align actions to be synergistic, persistent, and scalable.

Governance in the Face of Extreme Events: Lessons from Evolutionary Processes for Structuring Interventions, and the Need to Go Beyond.

The increasing frequency of extreme events, exogenous and endogenous, poses challenges for our societies. The current pandemic is a case in point; but "once-in-a-century" weather events are also becoming more common, leading to erosion, wildfire and even volcanic events that change ecosystems and disturbance regimes, threaten the sustainability of our life-support systems, and challenge the robustness and resilience of societies. Dealing with extremes will require new approaches and large-scale collective action. Preemptive measures can increase general resilience, a first line of protection, while more specific reactive responses are developed. Preemptive measures also can minimize the negative effects of events that cannot be avoided. In this paper, we first explore approaches to prevention, mitigation and adaptation, drawing inspiration from how evolutionary challenges have made biological systems robust and resilient, and from the general theory of complex adaptive systems. We argue further that proactive steps that go beyond will be necessary to reduce unacceptable consequences.

Social networks influence farming practices and agrarian sustainability.

The social-ecological effects of agricultural intensification are complex. We explore farmers' perceptions about the impacts of their land management and the impact of social information flows on their management through a case study in a farming community in Navarra, Spain, that is undergoing agricultural intensification due to adoption of large scale irrigation. We found that modern technology adopters are aware that their management practices often have negative social-ecological implications; by contrast, more traditional farmers tend to recognize their positive impacts on non-material benefits such as those linked with traditions and traditional knowledge, and climate regulation. We found that farmers' awareness about nature contributions to people co-production and their land management decisions determine, in part, the structure of the social networks among the farming community. Since modern farmers are at the core of the social network, they are better able to control the information flow within the community. This has important implications, such as the fact that the traditional farmers, who are more aware of their impacts on the environment, rely on information controlled by more intensive modern farmers, potentially jeopardizing sustainable practices in this region. We suggest that this might be counteracted by helping traditional farmers obtain information tailored to their practices from outside the social network.

Socio-ecological determinants on spatio-temporal changes of groundwater in the Yellow River Basin, China.

The spatio-temporal complexity of groundwater storage change is a result of interconnected impact of socio-ecological factors. Previous research indicates several socio-ecological factors (e.g. human extraction, land cover change, and climate change) that may result in groundwater depletion. However, we seldom have empirical studies that provide spatio-temporally explicit information on the main drivers among these factors that determine regional groundwater change. This research explored a spatio-temporally explicit understanding on the socio-ecological determinants on the changes of groundwater storage in the Yellow River Basin (YRB) of north China. We selected this basin because the spatial heterogeneity of this basin complicates the relationship between socio-ecological factors and groundwater resources, whose changes would in turn fundamentally affect the socio-ecological system in the YRB. We collected annual (time resolution) data between 2003 and 2016 (time scope) with 1° × 1° grid (space resolution) about 18 social-ecological factors that might affect groundwater storage change in the YRB (space scope). Using this data and groundwater storage information from Gravity Recovery and Climate Experiment database, we determined best predictors, highly-performed predictive models, and dominant drivers for temporal and spatial changes of groundwater storage. Temporal changes of groundwater in the YRB between 2003 and 2016 were mainly contributed by anthropogenic factors, including population density, plantation, and irrigation water consumption over time. The spatial groundwater change across the YRB was determined by both the geographical location (e.g. indicated by longitude) and urbanization level (e.g. indicated by the domestic and industrial water consumption). The knowledge about socio-ecological determinants on groundwater dynamics in space and time in the YRB can help determine main levers to control regional change of groundwater storage and assist in a sustainable use of groundwater resource.

Benthic-based contributions to climate change mitigation and adaptation.

Innovative solutions to improve the condition and resilience of ecosystems are needed to address societal challenges and pave the way towards a climate-resilient future. Nature-based solutions offer the potential to protect, sustainably manage and restore natural or modified ecosystems while providing multiple other benefits for health, the economy, society and the environment. However, the implementation of nature-based solutions stems from a discourse that is almost exclusively derived from a terrestrial and urban context and assumes that risk reduction is resolved locally. We argue that this position ignores the importance of complex ecological interactions across a range of temporal and spatial scales and misses the substantive contribution from marine ecosystems, which are notably absent from most climate mitigation and adaptation strategies that extend beyond coastal disaster management. Here, we consider the potential of sediment-dwelling fauna and flora to inform and support nature-based solutions, and how the ecology of benthic environments can enhance adaptation plans. We illustrate our thesis with examples of practice that are generating, or have the potential to deliver, transformative change and discuss where further innovation might be applied. Finally, we take a reflective look at the realized and potential capacity of benthic-based solutions to contribute to adaptation plans and offer our perspectives on the suitability and shortcomings of past achievements and the prospective rewards from sensible prioritization of future research. This article is part of the theme issue 'Climate change and ecosystems: threats, opportunities and solutions'.