Understanding the mechanisms underlying nutrient (nitrogen and phosphorus) and carbon cycling in reefs is critical for effective management. Research on reef nutrient and carbon cycling needs to account for (i) the contributions of multiple organisms, (ii) abiotic and biotic drivers, and (iii) a social-ecological perspective. In this paper, we review the mechanisms underlying nutrient and carbon cycling in reef social-ecological systems and analyse them using causal loop analysis. We identify direct and indirect pathways and feedback loops through nutrient and carbon cycles that shape the dominant benthic state of reefs: coral, algal, and sponge-dominated states. We find that two of three anthropogenic impact scenarios (size-selective fishing and land use change) have primarily negative consequences for coral and macroalgae via the nutrient and carbon cycles. A third scenario (runoff) has fewer negative impacts on sponges compared to other benthos. In all scenarios, frequent positive feedback loops (size-selective fishing: 7 of 12 loops; runoff: 6 of 9 loops; land use change: 8 of 11 loops) lead to system destabilization; however, the presence of multiple loops introduces avenues whereby reefs may retain coral dominance despite anthropogenic pressures. Context-specific information on the relative strength of loops will be necessary to predict future reef state.

The Paris Agreement has seen the adoption of a 1.5° to 2 °C climate target, based on the belief that climate change becomes ‘dangerous’ above this level. Since then, the scientific community and the countries most affected by global warming have reiterated that the maximum limit to be reached should be 1.5 °C. This paper goes one step further by questioning the reasoning behind the adoption of these targets, arguing that the fossil fuel-dependent political context in which they were adopted has undermined justice concerns. We highlight the political influence of the fossil fuels industry within target-setting negotiations, analyzing the evolution of climate targets and fossil fuel lobbying. We then harness published scientific evidence and the Earth System Justice framework to analyze the impacts of the 1.5 °C target, and the injustices that have so far been implicitly deemed acceptable. We argue that 1 °C would have been a far more just target and was undermined by vested interests and status quo maintenance. Finally, we propose just supply-side policies to ensure an adequate placement of responsibility on the fossil fuel industry. This way we (a) identify political influences and scientific blind spots that have and could continue to hinder climate action, (b) reveal how these influences delayed more ambitious climate objectives, contributing to the adoption of an unjust climate target, and (c) promote a focus on supply-side measures and polluting industries in order to break free from the impasse in the energy transition and foster more just outcomes.

Safe and just Earth system boundaries (ESBs) for surface water and groundwater (blue water) have been defined for sustainable water management in the Anthropocene. Here we assessed whether minimum human needs could be met with surface water from within individual river basins alone and, where this is not possible, quantified how much groundwater would be required. Approximately 2.6 billion people live in river basins where groundwater is needed because they are already outside the surface water ESB or have insufficient surface water to meet human needs and the ESB. Approximately 1.4 billion people live in river basins where demand-side transformations would be required as they either exceed the surface water ESB or face a decline in groundwater recharge and cannot meet minimum needs within the ESB. A further 1.5 billion people live in river basins outside the ESB, with insufficient surface water to meet minimum needs, requiring both supply- and demand-side transformations. These results highlight the challenges and opportunities of meeting even basic human access needs to water and protecting aquatic ecosystems.

Understanding and building resilience is critical to responding to the deepening polycrisis. Pathway diversity is a promising approach to resilience that combines individual and systems perspectives, but so far has only been applied to idealized cases. Here, we use a rich case study from the mosaic landscape of Västra Harg, Sweden, to test and advance pathway diversity. Mosaic landscapes can simultaneously produce food, support biodiversity, and provide space for recreation, but these benefits require multiple actors to collectively and individually respond to changing circumstances. Our results indicate that, although the mosaic landscape provides many options for actors, forestry strategies are generally more resilient than agricultural strategies due to higher risks of abandonment in agriculture. We also found that supporting a specific strategy may create lock-in and undermine livelihood resilience overall. The study contributes toward developing a practical method for assessing resilience that can inform governance of complex social-ecological systems.

Open system analysis is prone to the oversimplification of dynamics due to tightly coupled variables and their nonlinear, complex, and often unpredictable behavior. By assessing the combination of different ecosystem variables (structural, chemical, and biological) and their dynamic states in time and space, individual complexity measurements can capture phase changes of ecosystem stability and enhance efficiency, disease detection, and ecosystem understanding. This article summarizes the latest developments in complexity research and investigates the potential of metrics to assess and predict the sustainability and resilience of ecosystems, with a particular focus on farming systems. It provides an outlook on improving machine learning approaches by considering the system’s complexity and the necessary data requirements. A GitHub repository [1] is presented that enables practitioners to use complexity applications (e.g. entropy metrics and reconstructed phase spaces). This research provides a deeper understanding of the connections between data complexity, machine learning algorithms, and environmental modeling.

Operating within safe and just Earth system boundaries requires mobilizing key actors across scale to set targets and take actions accordingly. Robust, transparent and fair cross-scale translation methods are essential to help navigate through the multiple steps of scientific and normative judgements in translation, with clear awareness of associated assumptions, bias and uncertainties. Here, through literature review and expert elicitation, we identify commonly used sharing approaches, illustrate ten principles of translation and present a protocol involving key building blocks and control steps in translation. We pay particular attention to businesses and cities, two understudied but critical actors to bring on board.

Living within planetary limits requires attention to justice as biophysical boundaries are not inherently just. Through collaboration between natural and social scientists, the Earth Commission defines and operationalizes Earth system justice to ensure that boundaries reduce harm, increase well-being, and reflect substantive and procedural justice. Such stringent boundaries may also affect ‘just access’ to food, water, energy and infrastructure. We show how boundaries may need to be adjusted to reduce harm and increase access, and challenge inequality to ensure a safe and just future for people, other species and the planet. Earth system justice may enable living justly within boundaries. 

The Anthropocene is characterized by accelerating change and global challenges of increasing complexity. Inspired by what some have called a polycrisis, we explore whether the human trajectory of increasing complexity and influence on the Earth system could become a form of trap for humanity. Based on an adaptation of the evolutionary traps concept to a global human context, we present results from a participatory mapping. We identify 14 traps and categorize them as either global, technology or structural traps. An assessment reveals that 12 traps (86%) could be in an advanced phase of trapping with high risk of hard-to-reverse lock-ins and growing risks of negative impacts on human well-being. Ten traps (71%) currently see growing trends in their indicators. Revealing the systemic nature of the polycrisis, we assess that Anthropocene traps often interact reinforcingly (45% of pairwise interactions), and rarely in a dampening fashion (3%). We end by discussing capacities that will be important for navigating these systemic challenges in pursuit of global sustainability. Doing so, we introduce evolvability as a unifying concept for such research between the sustainability and evolutionary sciences.