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In the EU, including Sweden, organic farming is seen as a promising pathway for sustainable production, protecting human health and animal welfare, and conserving the environment. Despite positive developments in recent decades, expanding organic farming to the Swedish national target of 30% of farmland under organic production remains challenging. In this study, we developed two scenarios to evaluate the role of organic farming in the broader context of Swedish food systems: (i) baseline trend scenario (Base), and (ii) sustainable food system scenario (Sust). Base describes a future where organic farming is implemented alongside the current consumption, production and waste patterns, while Sust describes a future where organic farming is implemented alongside a range of sustainable food system initiatives. These scenarios are coupled with several variants of organic area: (i) current 20% organic area, (ii) the national target of 30% organic area by 2030, and (iii) 50% organic area by 2050 for Sust. We applied the ‘FABLE (Food, Agriculture, Biodiversity, Land-use and Energy) Calculator’ to assess the evolution of the Swedish food system from 2000 to 2050 and evaluate land use, emissions and self-sufficiency impacts under these scenarios. Our findings show that expanding organic farming in the Base scenarios increases the use of cropland and agricultural emissions by 2050 compared to the 2010 reference year. However, cropland use and emissions are reduced in the Sust scenario, due to dietary changes, reduction of food waste and improved agricultural productivity. This implies that there is room for organic farming and the benefits it provides, e.g. the use of fewer inputs and improved animal welfare in a sustainable food system. However, changing towards organic agriculture is only of advantage when combined with transformative strategies to promote environmental sustainability across multiple sections, such as changed consumption, better production and food waste practices.

There is an urgent need for countries to transition their national food and land-use systems toward food and nutritional security, climate stability, and environmental integrity. How can countries satisfy their demands while jointly delivering the required transformative change to achieve global sustainability targets? Here, we present a collaborative approach developed with the FABLE—Food, Agriculture, Biodiversity, Land, and Energy—Consortium to reconcile both global and national elements for developing national food and land-use system pathways. This approach includes three key features: (1) global targets, (2) country-driven multi-objective pathways, and (3) multiple iterations of pathway refinement informed by both national and international impacts. This approach strengthens policy coherence and highlights where greater national and international ambition is needed to achieve global goals (e.g., the SDGs). We discuss how this could be used to support future climate and biodiversity negotiations and what further developments would be needed.

Human actions compromise the many life-supporting functions provided by the freshwater cycle. Yet, scientific understanding of anthropogenic freshwater change and its long-term evolution is limited. Using a multi-model ensemble of global hydrological models, we estimate how, over a 145-year industrial period, streamflow and soil moisture have deviated from pre-industrial baseline conditions (defined by 5th–95th percentiles, at 0.5° grid level and monthly time step). We find increased frequency of local deviations on ~45% of land area, mainly in regions under heavy direct or indirect human pressures. To estimate humanity’s aggregate impact on the freshwater cycle, we present the evolution of deviation occurrence at regional to global scales. Currently, local streamflow and soil moisture deviations occur on 18.2% and 15.8% of global land area, respectively, which is 8.0 and 4.7 percentage points beyond the ~3 percentage point wide pre-industrial variability envelope. Finally, we discuss applying our approach to define a planetary boundary for freshwater change. Our results indicate a substantial shift from stable pre-industrial streamflow and soil moisture conditions to persistently increasing change and a transgression of the freshwater change planetary boundary, calling for urgent actions to reduce human disturbance of the freshwater cycle.

Moisture recycling of local water sources through evaporation allows a region to maintain precipitation in the same region. Many studies have shown that deforestation can reduce evaporation and downwind rainfall, and it has been suggested that reforestation conversely increase evaporation and downwind rainfall. Precipitation has been observed to increase over China’s Loess Plateau over the past two decades, coinciding with the start of the Grain for Green project - the largest active revegetation programme attempted in the world. However, the contribution of revegetation to the increase in precipitation is yet unknown. Here, we aim to quantitatively analyze the relationship between revegetation, evaporation, and locally recycled moisture. Based on the ERA5 reanalysis data, we used the modified Water Accounting model-2 layers (WAM-2layers) to track the recycling moisture over the Loess Plateau. Preliminary results indicate that local recycling moisture (Er) accounted for almost one-tenth of the annual precipitation, and seems to have a decreasing trend, which was more evident after 2000. Meanwhile, the contribution of local evaporation to local precipitation appears to decrease during both 1982-1999 and 2000-2015, while the decreasing trend has been slightly amplified after the revegetation. Spatially, Er over the Loess Plateau showed a decreasing trend from southeast to northwest. Significant increasing trend of Er can be identified in the northern part of the plateau during 1982-1999. However, after the implement of the Green for Grain Project, most area over the Loess Plateau showed a decreasing trend, which is significant in the east. Thus, contrary to popular wisdom, the revegetation appears to have led to a decrease in evaporation and subsequent recycling, and the increase in precipitation seems to have other causes. These results are subject to high data uncertainty, and further research is needed to better understand the hydroclimatic effects of revegetation projects under climate change.

Rainfall is a key determinant of tropical rainforest resilience in South America and Africa, of which a substantial amount originates from terrestrial and forest evaporation through moisture recycling. Both continents face deforestation that reduces evaporation and thus dampens the water cycle, and climate change that increases the risk of water-stress induced forest loss. Hence, it is important to understand the influence of forest moisture supply for forest rainfall during dry periods. Here, we analyze mean-years and dry-years dry-season anomalies of moisture recycling in the South American (Amazon) and African rainforests (Congo) over the years 1980-2013. Annual average reliance of forest rainfall on their own moisture supply (ρfor) is 26 % in the Amazon and 28% in the Congo forest. In dry seasons, this ratio increases by 7% (or ~2 percentage points) in the Amazon and up to 30 % (or ~8 percentage points) in Congo. Dry years further amplify dry season ρfor in both regions by 4-5 %. In both Amazon and Congo, dry season amplification of ρfor are strongest in regions with a high mean annual ρfor. In the Amazon, forest rainfall self-reliance has declined over time, and in both Amazon and Congo, the fraction of forest evaporation that recycles as forest rainfall has declined over time. At country scale, dry season ρfor can differ drastically from mean annual ρfor (e.g., in Bolivia and Gabon, mean annual ρfor is ~30% while dry season ρfor is ~50 %). Dry period amplification of ρfor illuminates additional risks of deforestation as well as opportunities from forest conservation and restoration, and is essential to consider for understanding upwind forest change impacts on downwind rainfall at both regional and national scales.

Tropical rainforests invest in their root systems to store soil moisture from water-rich periods for use in water-scarce periods. An inadequate root-zone soil moisture storage predisposes or forces these forest ecosystems to transition to a savanna-like state, devoid of their native structure and functions. Yet changes in soil moisture storage and its influence on the rainforest ecosystems under future climate change remain uncertain. Using a mass-balance-based (empirical) understanding of root zone storage capacity, we assess the future state of the rainforests and the forest-savanna transition risk in South America and Africa. For this, we analyse the hydroclimatic estimates of 33 Earth System Models under four different shared socioeconomic pathway scenarios (i.e., SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5). We find that by the end of the 21st century, nearly one-third of the total forest area will be influenced by climate change. Furthermore, beyond 1.5-2⁰C warming, ecosystem recovery reduces gradually, whereas the forest-savanna transition risk increases several folds. For Amazon, this risk can grow by about 1.5-6 times compared to its immediate lower warming scenario, whereas for Congo, this risk growth is not substantial (0.7-1.65 times). The insight from this study underscores the urgent need to limit global surface temperatures below the Paris agreement.

A substantial amount of the tropical forests of South America and Africa is generated through moisture recycling (i.e., forest rainfall self-reliance). Thus, deforestation that reduces evaporation and dampens the water cycle can further increase the risk of water-stress-induced forest loss in downwind areas, particularly during water scarce periods. However, few studies have investigated dry period forest rainfall self-reliance over longer records and consistently compared the rainforest moisture recycling in both continents. Here, we analyze dry-season anomalies of moisture recycling for mean-years and dry-years, in the South American (Amazon) and African (Congo) rainforests over the years 1980-2013. We find that, in the dry seasons, the reliance of forest rainfall on their own moisture supply (ρfor) increases by 7% (from a mean annual value of 26% to 28%) in the Amazon and up to 30% (from 28% to 36%) in the Congo. Dry years further amplify dry season ρfor in both regions by 4-5%. In both the Amazon and Congo, dry season amplification of ρfor is strongest in regions with a high mean annual ρfor. In the Amazon, forest rainfall self-reliance has declined over time. At the country scale, dry season ρfor can differ drastically from mean annual ρfor. In for example Bolivia and Gabon, mean annual ρfor is ~30% while dry season ρfor is ~50%. The dry period amplification of forest rainfall self-reliance further highlights the role of forests for sustaining their own resilience, and for maintaining downwind rainfall at both regional and national scales.

The tropical terrestrial ecosystems naturally exist as alternative stable states, commonly referred to as forest and savanna ecosystems. However, these ecosystems, especially forests, are currently threatened by the risk of drought-induced forest-to-savanna transitions across the tropics and subtropics. Therefore, a better understanding of ecosystem dynamics and characteristics behind these alternative stable states is crucial in predicting their response to future hydroclimatic changes. Previous studies have analyzed these alternative stable states against precipitation predominantly based on space-for-time substitution. However, such a substitution provides a partial picture of ecosystem adaptation dynamics and associated ecosystem structural change over time. Here, we empirically study the transient state of tropical ecosystems and their hydroclimatic adaptations by examining remotely sensed tree cover and root zone storage capacity over the last two decades in South America and Africa. Tree cover represents the above-ground ecosystem structure's density, and is derived directly from MODIS satellite data. Whereas root zone storage capacity is the maximum amount of soil moisture that the vegetation can access for transpiration is derived using daily precipitation and evaporation data. We found that ecosystems at high (>75%) and low (

Tropical rainforests invest in their root systems to store soil moisture from water-rich periods for use in water-scarce periods. An inadequate root-zone soil moisture storage predisposes or forces these forest ecosystems to transition to a savanna-like state, devoid of their native structure and functions. Yet changes in soil moisture storage and its influence on the rainforest ecosystems under future climate change remain uncertain. Using the empirical understanding of root zone storage capacity, we assess the future state of the rainforests and the forest-savanna transition risk in South America and Africa under four different shared socioeconomic pathway scenarios. We find that by the end of the 21st century, nearly one-third of the total forest area will be influenced by climate change. Furthermore, beyond 1.5-2⁰C warming, ecosystem recovery reduces gradually, whereas the forest-savanna transition risk increases several folds. For Amazon, this risk can grow by about 1.5-6 times compared to its immediate lower warming scenario, whereas for Congo, this risk growth is not substantial (0.7-1.65 times). The insight from this study underscores the urgent need to limit global surface temperatures below the Paris agreement.

Heatwaves are extreme weather events that have become more frequent and intense in Europe over the past decades. Heatwaves are often coupled to droughts. The combination of them lead to severe ecological and socio-economic impacts. Heatwaves can self-amplify through internal climatic feedback that reduces local precipitation. Understanding the terrestrial sources of local precipitation during heatwaves might help identify mitigation strategies on land management and change that alleviate impacts. Moisture recycling of local water sources through evaporation allows a region to maintain precipitation in the same region or, by being transported by winds, in adjacent regions. To understand the role of terrestrial moisture sources for sustaining precipitation during heatwaves, we backtrack and analyse the precipitation sources of Northern, Western, and Southern sub-regions across Europe during 20 heatwave periods between 1979 and 2018 using the moisture tracking model Water Accounting Model-2layers (WAM-2layers). In Northern and Western Europe, we find that stabilizing anticyclonic patterns reduce the climatological westerly supply of moisture, mainly from the North Atlantic Ocean, and enhances the moisture flow from the eastern Euro-Asian continent and from within their own regions—suggesting over 10% shift of moisture supply from oceanic to terrestrial sources. In Southern Europe, limited local moisture sources result in a dramatic decrease in the local moisture recycling rate. Forests uniformly supply additional moisture to all regions during heatwaves and thus contribute to buffer local impacts. This study suggests that terrestrial moisture sources, especially forests, may potentially be important to mitigate moisture scarcity during heatwaves in Europe. Supplementary Information The online version contains supplementary material available at 10.1007/s00382-021-05921-7.

Climate tipping points occur when change in a part of the climate system becomes self-perpetuating beyond a forcing threshold, leading to abrupt and/or irreversible impacts. Synthesizing paleoclimate, observational, and model-based studies, we provide a revised shortlist of global ‘core’ tipping elements and regional ‘impact’ tipping elements and their temperature thresholds. Current global warming of ~1.1°C above pre-industrial already lies within the lower end of some tipping point uncertainty ranges. Several more tipping points may be triggered in the Paris Agreement range of 1.5-2°C global warming, with many more likely at the 2-3°C of warming expected on current policy trajectories. In further work we use these estimates to test the potential for and impact of tipping cascades in response to global warming scenarios using a stylised model. This strengthens the evidence base for urgent action to mitigate climate change and to develop improved tipping point risk assessment, early warning capability, and adaptation strategies.Preprint: https://doi.org/10.1002/essoar.10509769.1

The tropical terrestrial ecosystems naturally exist as alternative stable states, commonly referred to as forest and savanna ecosystems. However, these ecosystems, especially forests, are currently threatened by the risk of drought-induced forest-to-savanna transitions across the tropics and subtropics. Therefore, a better understanding of ecosystem dynamics and characteristics behind these alternative stable states is crucial in predicting their response to future hydroclimatic changes. Previous studies have analyzed these alternative stable states against precipitation predominantly based on space-for-time substitution. However, such a substitution provides a partial picture of ecosystem adaptation dynamics and associated ecosystem structural change over time. Here, we empirically study the transient state of tropical ecosystems and their hydroclimatic adaptations by examining remotely sensed tree cover and root zone storage capacity over the last two decades in South America and Africa. Tree cover represents the above-ground ecosystem structure's density, and is derived directly from MODIS satellite data. Whereas root zone storage capacity is the maximum amount of soil moisture that the vegetation can access for transpiration is derived using daily precipitation and evaporation data. We found that ecosystems at high (>75%) and low (

We develop a framework within which to conceptualize World-Earth System resilience. Our notion of World-Earth System resilience emphasizes the need to move beyond the basin of attraction notion of resilience as we are not in a basin we can stay in. We are on a trajectory to a new basin and we have to avoid falling into undesirable basins. We thus focus on `pathway resilience', i.e. the relative number of paths that allow us to move from the transitional operating space we occupy now as we leave the Holocene basin to a safe and just operating space in the Anthropocene. We develop a mathematical model to formalize this conceptualization and demonstrate how interactions between earth system resilience (biophysical processes) and world system resilience (social processes) impact pathway resilience. Our findings show that building earth system resilience is probably our only chance to reach a safe and just operating space. We also illustrate the importance of world system dynamics by showing how the notion of fairness coupled with regional inequality affects pathway resilience.

Forest and savanna ecosystems naturally exist as alternative stable states. The maximum capacity of these ecosystems to absorb perturbations without transitioning to the other alternative stable state is referred to as ‘resilience’. Previous studies have determined the resilience of terrestrial ecosystems to hydroclimatic changes predominantly based on space-for-time substitution. This substitution assumes that the contemporary spatial frequency distribution of ecosystems’ tree cover structure holds across time. However, this assumption is problematic since ecosystem adaptation over time is ignored. Here we empirically study tropical forests’ stability and hydroclimatic adaptation dynamics by examining remotely sensed tree cover change (ΔTC; aboveground ecosystem structural change) and root zone storage capacity (Sr; buffer capacity towards water-stress) over the last two decades. We find that ecosystems at high (>75%) and low (

Forests worldwide supply moisture to downwind precipitation through moisture recycling. Agricultural areas located downwind of forests are, hence, susceptible to changes in precipitation caused by upwind forest changes. In fact, human activities have driven extensive forest cover changes in different parts of the world, in different directions, and at different rates. Nevertheless, the forest-agriculture relationship has yet to be systematically quantified and mapped globally. Previous regional studies in South America show that upwind deforestation of the Amazon forest can reduce downwind precipitation and thus decrease agricultural production. A global coverage analysis of forest-agriculture relationship is therefore necessary to identify other hotspot regions where downwind agriculture relies heavily on upwind forests. In this study, we establish the global source-to-sink relationship between forests and their downwind agriculture by analysing 10 years of high resolution (0.25°x0.25°) ERA5-based moisture flows processed by the UTrack moisture tracking model. We assess the seasonality of the reliance on forests considering the growing season of crops cultivated in the downwind regions. Our study provides a global overview of the cross-sectoral and remote dependence of agriculture on forests globally through moisture recycling.

Rainforests have been a major controller of local and global climate by maintaining carbon stocks and regulating global water cycle. However, the water cycle is increasingly impacted by climate change and ongoing deforestation, which forces rainforest ecosystems to adapt differently to increasing water-stress. To understand future rainforest dynamics towards changing hydroclimate, their resilience capacity to future changes and estimating potential tipping points, it is detrimental that we quantify moisture available to vegetation. However, due to the physical limitations in quantifying subsurface moisture availability of terrestrial ecosystems at continental scales, only rainfall is considered a primary control variable to represent the forest's ecohydrological status. In the present study, using remote-sensing derived rootzone storage capacity (Sr), we analyze the water-stress and drought coping strategies along rainforest-savanna transects in South America and Africa at different tree cover densities. We further classified the ecosystem's adaptability to water-stress into four classes: lowly, moderately, highly water-stressed forest, and savanna-grassland regime using empirical and statistical analysis. Based on these analyses, we can show that forests subsequently invest in their rooting strategy and modify their above-ground forest cover in response to the water-stress experienced by it. We observed that remote sensing-based rootzone storage capacity reveals important subsoil forest dynamics and can act as an important hydroclimatic stress indicator for vegetation. Monitoring of rootzone storage capacity helps open new paths to understanding the eco-hydrological state, ecosystem resilience, and adaptation dynamics in a rapidly changing climate. Source: Singh, C. et al. (2020). Rootzone storage capacity reveals drought coping strategies along rainforest-savanna transitions. Environmental Research Letters, 15(12), 124021. doi: 10.1088/1748-9326/abc377

Green water - soil moisture, evaporation, and precipitation over land - is fundamental to safeguard Earth system functioning. Nonlinear green-water driven changes in climate, ecosystems, biogeochemistry, and hydrology are becoming increasingly evident and widespread. Yet, considerations of continental to planetary scale green-water dynamics are yet to be assessed and incorporated in management and governance. Here, we propose a green water planetary boundary (PB) - as part of the planetary boundary framework that demarcates a global “safe-operating space” for humanity - for assessing green-water related changes that can affect the capacity of the Earth system to remain in Holocene-like conditions. We consider green-water related processes associated with all scales: spatially distributed units, regions or biomes, and the Earth system as a whole. The proposed green water PB variable is selected through expert elicitation based on a set of transparent evaluation criteria that consider both scientific and governability aspects. Finally, we clarify the appropriate use of a green water PB, outline remaining challenges, and propose a research agenda for future navigation and quantitative assessments of the biophysical Earth system scale boundaries of green water changes.

The global hydrological cycle is characterized by complex interdependencies and self-regulating feedbacks that keep water in an ever-evolving state of flux at local, regional, and global levels. Increasingly, the scale of human impacts in the Anthropocene is altering the dynamics of this cycle, which presents additional challenges for water governance. “Earth system law” provides an important approach for addressing gaps in governance that arise from the mismatch between the global hydrological cycle and dispersed regulatory architecture across institutions and geographic regions. In this article, we articulate the potential for Earth system law to account for core hydrological problems that complicate water governance, including delay, redistribution, intertwinements, permanence, and scale. Through merging concepts from Earth system law with existing policy and legal principles, we frame an approach for addressing hydrological problems in the Anthropocene and strengthening institutional fit between established governance systems and the global hydrological cycle. We discuss how such an approach can be applied, and the challenges and implications for governing water as a cycle and complex social-hydrological system, both in research and practice.

The planetary boundaries framework defines nine Earth system processes that together demarcate a safe operating space for humanity at the planetary scale. Freshwater - the bloodstream of the biosphere - is an obvious member of the planetary boundary framework. Water fluxes and stores play a key role for the stability of the Earth’s climate and the world’s aquatic and terrestrial ecosystems. Recent work has proposed to represent the water planetary boundary through six sub-boundaries based on the five primary water stores, i.e., atmospheric water, soil moisture, surface water, groundwater, and frozen water. In order to make it usable on all spatial scales we examine bottom-up and top-down approaches for quantification of the water planetary boundary. For the bottom-up approaches, we explore possible spatially distributed variables defining each of the proposed sub-boundaries, as well as possible weighting factors and keystone regions that can be used for aggregation of the distributed water sub-boundaries to the global scale. For the top-down approaches, we re-examine the stability of key biomes and tipping elements in the Earth System that may be crucially influenced by water cycle modifications. To identify the most appropriate variables for representing the water planetary boundary, we evaluate the range of explored variables with regard to scientific evidence and scientific representation using a hierarchy-based evaluation framework. Finally, we compare the highest ranked top-down and bottom-up approaches in terms of the scientific outcome and implications for governance. In sum, this comprehensive and systematic identification and evaluation of variables, weighting factors, and baseline conditions provides a detailed basis for the future operational quantification of the water planetary boundary.

Over the past 15 years climate tipping points have emerged as both an important research topic and source of public concern. Some articles have suggested that some tipping points could begin within the 1.5-2oC Paris climate target range, with many more potentially starting by the ~3-4oC of warming that current policy is projected to be committed to. Recent work has also proposed that these tipping points could interact and potentially ‘cascade’ – with the impacts of passing one tipping point being sufficient to trigger the next and so on – resulting in an emergent global tipping point for a long-term commitment to a ‘Hothouse Earth’ trajectory of 4+oC (Steffen et al., 2018). However, much of the recent discussion relies largely on a decade-old characterisation of climate tipping points, based on a literature review and expert elicitation exercise. An updated characterisation would fully utilise more recent results from coupled and offline models, model inter-comparisons, and palaeoclimate studies. The ‘tipping cascade’ hypothesis has also not yet been tested, with the suggestion of 2oC as the global tipping point remaining speculative. Furthermore, the definition of what counts as a climate tipping point is often inconsistent, with some purported tipping points represented more accurately as threshold-free positive feedbacks. Here we perform an updated systematic review of climate tipping points, cataloguing the current evidence for each suggested element with reference to rigorously-applied tipping point definitions. Based on this we test the potential for a global tipping cascade using a stylised model, from which we will present preliminary results.ReferencesSteffen, W., et al.: Trajectories of the Earth System in the Anthropocene, Proc. Natl. Acad. Sci., 115(33), 8252–8259, doi:10.1073/pnas.1810141115, 2018.

Change in rainfall patterns and extended drought events can cause water stress in the rainforest which can also lead to a permanent shift of the biome into a savanna state. Rainforest in response may adapt to such environmental stress conditions to sustain ecosystem functioning or reduce functioning altogether. Previous studies related to forest resilience have mostly relied on precipitation or climatological drought as a control variable, but neither is a direct measure of forest resilience. As such, forest adaptability dynamics of the forest is poorly understood. Our research defines this adaptation capacity of vegetation as a dynamic reserve which rainforest can utilize before a potential shift to an alternate stable state, as the resilience of the rainforest. Here, we introduce the Rootzone Storage Potential (RZSP) as a direct water stress metric to understand adaptive forest resilience behaviour, using the cumulative difference between precipitation and potential evaporation (radiation-based). Since the potential evaporation used for RZSP calculation is purely radiation-based, it minimizes the effect of moisture recycling (and transport) on the system. RZSP is the potential of vegetation to optimize their resources enduring the greatest dry period. In this study, we have investigated the spatio-temporal resilience loss of the South American and African rainforest. An increasing trend of resilience loss was observed in the past few decades. Using RZSP is a useful indicator for estimating resilience dynamics and water stress characteristics of the rainforest.

The planetary boundaries framework has proven useful for many global sustainability contexts, but is challenging to apply to freshwater, which is spatially heterogeneous, part of complex socio-ecological systems and often dominated by local dynamics. To date, the planetary boundary for water has been simplistically defined by as the global rate of blue water consumption, functioning as a proxy for water partitioning in the global hydrological cycle, and considering impacts on rivers’ environmental flow requirements. We suggest the current planetary boundary should be replaced since it does not adequately represent the influence of water in critical Earth System functions such as regional climate and biodiversity. We review the core functions of water in the Earth System and set out a roadmap towards a more robust, holistic, and locally applicable water planetary boundary. We propose defining the boundary using four core functions of water (hydroclimatic regulation, hydroecological regulation, storage, and transport) in conjunction with five water stores (surface water, atmospheric water, soil moisture, groundwater and frozen water). Through the functions, the stores are inextricably interconnected with the atmosphere, land, ocean and biosphere. The roadmap outlined here suggests how to move towards setting six new water planetary sub-boundaries. This ambitious scientific and policy Grand Challenge that could substantially improve our understanding and management of water cycle modifications in the Earth System and provide a complementary approach to existing water management tools.

Climate change is expected to increase the incidences of extremes in environmental conditions. To investigate how repeated disturbances affect microbial ecosystem resistance, natural lake bacterioplankton communities were subjected to repeated temperature disturbances of two intensities (25 °C and 35 °C), and subsequently to an acidification event. We measured functional parameters (bacterial production, abundance, extracellular enzyme activities) and community composition parameters (richness, evenness, niche width) and found that, compared to undisturbed control communities, the 35 °C treatment was strongly affected in all parameters, while the 25 °C treatment did not significantly differ from the control. Interestingly, exposure to multiple temperature disturbances caused gradually increasing stability in the 35 °C treatment in some parameters, while others parameters showed the opposite, indicating that the choice of parameters can strongly affect the outcome of a study. The acidification event did not lead to stronger changes in community structure, but functional resistance of bacterial production towards acidification in the 35 °C treatments increased. This indicates that functional resistance in response to a novel disturbance can be increased by previous exposure to another disturbance, suggesting similarity in stress tolerance mechanisms for both disturbances. These results highlight the need for understanding function- and disturbance-specific responses, since general responses are likely to be unpredictable. De två första författarna delar förstaförfattarskapet

Natural microbial communities in soils are highly diverse, allowing for rich networks of microbial interactions to unfold. Identifying key players in these networks is difficult as the distribution of microbial diversity at the local scale is typically non-uniform, and is the outcome of both abiotic environmental factors and microbial interactions. Here, using spatially resolved microbial presence-absence data along an aquifer transect contaminated with hydrocarbons, we combined co-occurrence analysis with association rule mining to identify potential keystone species along the hydrocarbon degradation process. Derived co-occurrence networks were found to be of a modular structure, with modules being associated with specific spatial locations and metabolic activity along the contamination plume. Association rules identify species that never occur without another, hence identifying potential one-sided cross-feeding relationships. We find that hub nodes in the rule network appearing in many rules as targets qualify as potential keystone species that catalyze critical transformation steps and are able to interact with varying partners. By contrasting analysis based on data derived from bulk samples and individual soil particles, we highlight the importance of spatial sample resolution. While individual inferred interactions are hypothetical in nature, requiring experimental verification, the observed global network patterns provide a unique first glimpse at the complex interaction networks at work in the microbial world.

Human activities are disrupting the Earth system's biophysical processes, which underlie human wellbeing. The planetary boundary framework sets 'safe' global limits on these pressures, but a sub-gl ...

In this study, we investigated the effect of land use intensity, soil parameters and vegetation on protistan communities in grassland soils. We performed qualitative (T-RFLP) and quantitative (qPCR) analyses using primers specifically targeting the 18S rRNA gene for all Eukarya and for two common flagellate groups, i.e. the Chrysophyceae and the Kinetoplastea. Both approaches were applied to extracted soil DNA and RNA, in order to distinguish between the potentially active protists (i.e. RNA pool) and the total protistan communities, including potentially inactive and encysted cells (i.e. DNA pool). Several environmental determinants such as site, soil parameters and vegetation had an impact on the T-RFLP community profiles and the abundance of the quantified 18S rRNA genes. Correlating factors often differed between quantitative (qPCR) and qualitative (T-RFLP) approaches. For instance the Chrysophyceae/Eukarya 18S rDNA ratio as determined by qPCR correlated with the C/N ratio, whereas the community composition based on T-RLFP analysis was not affected indicating that both methods taken together provide a more complete picture of the parameters driving protist diversity. Moreover, distinct T-RFs were obtained, which could serve as potential indicators for either active organisms or environmental conditions like water content. While site was the main determinant across all investigated exploratories, land use seemed to be of minor importance for structuring protist communities. The impact of other parameters differed between the target groups, e.g. Kinetoplastea reacted on changes to water content on all sites, whereas Chrysophyceae were only affected in the Schorfheide. Finally, in most cases different responses were observed on RNA- and DNA-level, respectively. Vegetation for instance influenced the two flagellate groups only at the DNA-level across all sites. Future studies should thus include different protistan groups and also distinguish between active and inactive cells, in order to reveal causal shifts in community composition and abundance in agriculturally used systems.

Highlights • Water security can depend on terrestrial evaporation that sustains precipitation. • Water resilience of landscapes varies depending on human use of ecosystems. • Moisture recycling governance may require entirely new approaches., Water security is key to planetary resilience for human society to flourish in the face of global change. Atmospheric moisture recycling – the process of water evaporating from land, flowing through the atmosphere, and falling out again as precipitation over land – is the invisible mechanism by which water influences resilience, that is the capacity to persist, adapt, and transform. Through land-use change, mainly by agricultural expansion, humans are destabilizing and modifying moisture recycling and precipitation patterns across the world. Here, we provide an overview of how moisture recycling changes may threaten tropical forests, dryland ecosystems, agriculture production, river flows, and water supplies in megacities, and review the budding literature that explores possibilities to more consciously manage and govern moisture recycling. Novel concepts such as the precipitationshed allows for the source region of precipitation to be understood, addressed and incorporated in existing water resources tools and sustainability frameworks. We conclude that achieving water security and resilience requires that we understand the implications of human influence on moisture recycling, and that new research is paving the way for future possibilities to manage and mitigate potentially catastrophic effects of land use and water system change.

Assessing the ecological impacts of environmental change requires knowledge of the relationship between biodiversity and ecosystem functioning. The exact nature of this relationship can differ considerably between ecosystems, with consequences for the efficacy of species diversity as a buffer against environmental change. Using a microbial model system, we show that the relationship can vary depending on environmental conditions. Shapes suggesting functional redundancy in one environment can change, suggesting functional differences in another environment. We find that this change is due to shifting species roles and interactions. Species that are functionally redundant in one environment may become pivotal in another. Thus, caution is advised in drawing conclusions about functional redundancy based on a single environmental situation. It also implies that species richness is important because it provides a pool of species with potentially relevant traits. These species may turn out to be essential performers or partners in new interspecific interactions after environmental change. Therefore, our results challenge the generality of functional redundancy.

Paper contact with cynthia festin: festin@iiasa.ac.at Agraïments: The research leading to these results has received funding from the Stordalen Foundation via the Planetary Boundary Research Network (PB.net), the Earth League's EarthDoc programme, the Leibniz Association (project DOMINOES), Project Grant 2014-589 from the Swedish Research Council Formas, and a core grant to the Stockholm Resilience Centre by Mistra. We thank Malin Ödalen for her comments on the manuscript. Changes to climate-carbon cycle feedbacks may significantly affect the Earth System's response to greenhouse gas emissions. These feedbacks are usually analysed from numerical output of complex and arguably opaque Earth System Models (ESMs). Here, we construct a stylized global climate-carbon cycle model, test its output against complex ESMs, and investigate the strengths of its climate-carbon cycle feedbacks analytically. The analytical expressions we obtain aid understanding of carbon-cycle feedbacks and the operation of the carbon cycle. We use our results to analytically study the relative strengths of different climate-carbon cycle feedbacks and how they may change in the future, as well as to compare different feedback formalisms. Simple models such as that developed here also provide 'workbenches' for simple but mechanistically based explorations of Earth system processes, such as interactions and feedbacks between the Planetary Boundaries, that are currently too uncertain to be included in complex ESMs.

Highlights • An individual-based model was developed and coupled to a pore-network model. • The bacterial distribution patterns were geostatistically analyzed. • The effects from bacterial chemotactic properties on bacterial distribution patterns were examined. • The additional influences from structural heterogeneities were examined. Abstract Spatial distribution of soil microorganisms is relevant for the functioning and performance of many ecosystem processes such as nutrient cycling or biodegradation of organic matters and contaminants. Beside the multitude of abiotic environmental factors controlling the distribution of microorganisms in soil systems, many microbial species exhibit chemotactic behavior by directing their movement along concentration gradients of nutrients or of chemoattractants produced by cells of their own kind. This chemotactic ability has been shown to promote the formation of complex distribution patterns even in the absence of environmental heterogeneities. Microbial population patterns in heterogeneous soil systems might be, hence, the result of the interplay between the heterogeneous environmental conditions and the microorganisms' intrinsic pattern formation capabilities. In this modeling study, we combined an individual-based modeling approach with a reactive pore-network model to investigate the formation of bacterial patterns in homogeneous and heterogeneous porous media. We investigated the influence of different bacterial chemotactic sensitivities (toward both substrate and bacteria) on bacterial distribution patterns. The emerging population patterns were classified with the support of a geostatistical approach, and the required conditions for the formation of any specific pattern were analyzed. Results showed that the chemotactic behavior of the bacteria leads to non-trivial population patterns even in the absence of environmental heterogeneities. The presence of structural pore scale heterogeneities had also an impact on bacterial distributions. For a range of chemotactic sensitivities, microorganisms tend to migrate preferably from larger pores toward smaller pores and the resulting distribution patterns thus resembled the heterogeneity of the pore space. The results clearly indicated that in a porous medium like soil the distribution of bacteria may not only be related to the external constraints but also to the chemotactic behavior of the bacterial cells.

Bottom-fermenting Saccharomyces pastorianus strains driving brewing fermentation processes are usually reused several times. It is still unclear, whether the number of successions may have an impact on cell physiology prompting consequences for brewing quality. In this study, fermentation performance of up to twenty consecutive runs in a brewery was investigated. For each run mRNA expression levels of cellular marker molecules, which are known to correlate with metabolism, hexose transport, aging processes, stress response mechanisms and flocculation capability was estimated to obtain information on changes in cell physiology over the successive runs. Low-density microarrays were used for this purpose and the resulting gene expression profiles were finally correlated with changes in the abiotic micro-environments. A surprising stability of the marker molecule expression profiles within each specific serial repitching was stated. Loss of flocculation or an advanced aging could not be detected during serial repitching in the analyzed brewery. However, certain runs of the serial repitchings showed high variation in stress response which was found to be caused by perturbations of the abiotic conditions. Regardless, the study showed that S. pastorianus can be used repeatedly in serial repitching processes without loss of prominent physiological characteristics.