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Anthropogenic climate change has increased the frequency of drought, wildfire, and invasions of non-native species. Although high-severity fires linked to drought can inhibit recovery of native vegetation in forested ecosystems, it remains unclear how drought impacts the recovery of other plant communities following wildfire. We leveraged an existing rainfall manipulation experiment to test the hypothesis that reduced precipitation, fuel load, and fire severity convert plant community composition from native shrubs to invasive grasses in a Southern California coastal sage scrub system. We measured community composition before and after the 2020 Silverado wildfire in plots with three rainfall treatments. Drought reduced fuel load and vegetation cover, which reduced fire severity. Native shrubs had greater prefire cover in added water plots compared to reduced water plots. Native cover was lower and invasive cover was higher in postfire reduced water plots compared to postfire added and ambient water plots. Our results demonstrate the importance of fuel load on fire severity and plant community composition on an ecosystem scale. Management should focus on reducing fire frequency and removing invasive species to maintain the resilience of coastal sage scrub communities facing drought. In these communities, controlled burns are not recommended as they promote invasive plants.

Abstract: The influence of climate feedbacks on regional hydrological changes under warming is poorly understood. Here, a moist energy balance model (MEBM) with a Hadley Cell parameterization is used to isolate the influence of climate feedbacks on changes in zonal‐mean precipitation‐minus‐evaporation (P − E) under greenhouse‐gas forcing. It is shown that cloud feedbacks act to narrow bands of tropical P − E and increase P − E in the deep tropics. The surface‐albedo feedback shifts the location of maximum tropical P − E and increases P − E in the polar regions. The intermodel spread in the P − E changes associated with feedbacks arises mainly from cloud feedbacks, with the lapse‐rate and surface‐albedo feedbacks playing important roles in the polar regions. The P − E change associated with cloud feedback locking in the MEBM is similar to that of a climate model with inactive cloud feedbacks. This work highlights the unique role that climate feedbacks play in causing deviations from the “wet‐gets‐wetter, dry‐gets‐drier” paradigm.

Understanding population dynamics across environmental contexts is essential to predict ecosystem stability. Functional traits influence population growth, which can in turn influence the traits and thus create feedbacks between population and trait dynamics. Here, by augmenting models of population and trait change with trait and population information, respectively, we demonstrate that such a feedback occurred in an autotrophic but not in a heterotrophic microbial system. Furthermore, exposure to a pollutant disrupted this feedback: trait change and population growth ceased to interact in either system. Finally, when the models augmented with trait/population information were superior, the improvement was substantial, showing that density–trait feedbacks are potentially large, even though they are system‐ and environment‐specific. [ABSTRACT FROM AUTHOR]

Globally, land subsidence (LS) often adversely impacts infrastructure, humans, and the environment. As climate change intensifies the terrestrial hydrologic cycle and severity of climate extremes, the interplay among extremes (e.g., floods, droughts, wildfires, etc.), LS, and their effects must be better understood since LS can alter the impacts of extreme events, and extreme events can drive LS. Furthermore, several processes causing subsidence (e.g., ice‐rich permafrost degradation, oxidation of organic matter) have been shown to also release greenhouse gases, accelerating climate change. Our review aims to synthesize these complex relationships, including human activities contributing to LS, and to identify the causes and rates of subsidence across diverse landscapes. We primarily focus on the era of synthetic aperture radar (SAR), which has significantly contributed to advancements in our understanding of ground deformations around the world. Ultimately, we identify gaps and opportunities to aid LS monitoring, mitigation, and adaptation strategies and guide interdisciplinary efforts to further our process‐based understanding of subsidence and associated climate feedbacks. We highlight the need to incorporate the interplay of extreme events, LS, and human activities into models, risk and vulnerability assessments, and management practices to develop improved mitigation and adaptation strategies as the global climate warms. Without consideration of such interplay and/or feedback loops, we may underestimate the enhancement of climate change and acceleration of LS across many regions, leaving communities unprepared for their ramifications. Proactive and interdisciplinary efforts should be leveraged to develop strategies and policies that mitigate or reverse anthropogenic LS and climate change impacts. Plain Language Summary: Our article reviews existing research on the global issue of land subsidence (LS), or the relative sinking of the land surface. At the global scale, a variety of LS drivers and physical processes are present and interact with one another. The combination of climatic extremes (e.g., droughts, floods, wildfires, etc.) and LS can lead to devastating impacts on natural and built systems as well as feedbacks within our Earth system that enhance climate change. Yet, a review of the combined effects of extreme events, climate, subsidence, and their impacts, does not currently exist. In this article, we identify and characterize LS drivers, rates, and impacts throughout many different climates (e.g., arid and humid regions) and landscapes (coastal and inland locales, urban and agricultural areas). We also bring together the interplay among extreme events and LS and their connections to climate, human activities, and infrastructure. Integrating such relationships into LS analysis and monitoring frameworks is necessary to better understand cascading hazards and identify vulnerable populations, assess at‐risk infrastructure, and develop mitigation and adaptation strategies for LS. Key Points: Human activities led to the largest land subsidence (LS) rates and greater human exposure to anthropogenic LS is expected in the futureModeling the interplay of extreme events and LS is vital as feedbacks can amplify impacts on infrastructure, the environment, and societyProcesses such as permafrost thaw and soil organic matter oxidation drive LS and release greenhouse gases, enhancing climate change [ABSTRACT FROM AUTHOR]

Climate models predict at least another 1.5°C warming in the next 75 years. This warming drives increased atmospheric drying and a global increase in the severity and duration of ecological drought. Vegetation has the capacity to reduce microclimate temperatures and atmospheric aridity.All species of plants create shade, move water, evapotranspire, humidify the air around them, and affect the temperature and vapour pressure deficit of the environment. Vegetation can thus act as a nature‐based solution to warming and atmospheric drying.These microclimate modifications likely depend on the traits, functional groups and diversity of the plant community. Vegetative feedbacks on microclimate are strong enough to buffer some plants against the negative impacts of warming and drying (e.g. facilitation).Synthesis: Here we present, for the first time, a trait‐based framework that can be applied across study systems for assessing microclimate temperature and humidity under vegetation. This framework includes multiple new hypotheses for future work in this area. We emphasize that a systematic examination of trait–microclimate relationships will enable us to use vegetation as a nature‐based solution to warming and atmospheric drying in a changing climate. [ABSTRACT FROM AUTHOR]

The Clarence River (New South Wales, Australia) was the main transport corridor for the timber and sugar cane industries operating in the catchment from the 1860s to the 1970s. Using archaeological, documentary, and oral historical resources we explore some of the anthropogenic impacts of these industries upon the fluvial geomorphology of the lower Clarence River. In particular, the deliberate abandonment of obsolete vessels on the river system is a focus. These discarded former cane and timber barges have been used as erosion control devices in several areas around the Harwood Island sugar mill, resulting in the accumulation of sediments and the establishment of mangrove environments in what were degraded areas. [ABSTRACT FROM AUTHOR]

Navigating social‐ecological systems toward sustainable trajectories is an important challenge of the Anthropocene. Models of social‐ecological systems can increase our understanding of how social and ecological subsystems interact, their response to environmental changes, and how their dynamics may be altered by management interventions. However, the level of representational detail required for models to describe a particular social‐ecological system with high fidelity (i.e., accurately quantifying system dynamics) may hamper both the interpretability of model results and our ability to identify key processes and feedbacks within the system. In contrast, stylized models describe simplified interactions between a small subset of social‐ecological system elements. Stylized models are a useful tool to identify potential consequences of specific key processes and feedbacks on system functioning. However, the relatively low level of representational detail in these models limits their ability to deliver concrete management options for a particular social‐ecological system. Here, we describe how an exploratory modeling approach can utilize the strengths of stylized models before the construction of social‐ecological system models with high fidelity and representational detail. This exploratory modeling approach is an iterative strategy, with the initial steps comprising the development of stylized models informed by empirical observations. We illustrate this with two examples of stylized modeling of isolated and connected social‐ecological systems. Through repeated confrontation of alternative models with empirical data, exploratory modeling provides useful stepping stones toward the development of models that describe social‐ecological systems in increasingly specific settings with increasing levels of representational detail. When these latter types of models reach a high level of fidelity, they could be used for scenario‐based analyses and participatory decision‐making processes. At this stage, the conceptual insights previously obtained during the exploratory modeling phase may aid in the interpretation and communication of the outcomes of scenario‐based analyses. Hence, exploratory modeling aims to create a synergy between the insights obtained from stylized models and system‐specific, high‐fidelity models in order to generate a deep understanding of the drivers of social‐ecological system dynamics, and how to leverage these drivers to initiate desired changes. [ABSTRACT FROM AUTHOR]

A Perturbed Parameter Ensemble (PPE) with the Community Atmosphere Model version 6 (CAM6) is used to better understand the sensitivity of aerosol forcing and cloud feedbacks to changes in model processes. Aerosol forcing through aerosol‐cloud interactions is mostly negative (a cooling) due to shortwave radiation, while feedbacks are positive or negative in different regions due to contrasting longwave and shortwave effects. Both forcing and feedbacks are related to the mean climate state. Higher magnitude cloud radiative effects generally mean larger magnitude net negative forcing and larger magnitude net positive feedback. Aerosol forcing is broadly related to the susceptibility of clouds to drop number. Feedbacks also related to susceptibility, but to a lesser extent and in different regions to aerosol forcing. Aerosol forcing and cloud feedbacks are anti‐correlated in the CAM6 PPE such that stronger negative forcing is associated with stronger positive feedbacks. Even the processes governing forcing and feedback sensitivity in the PPE are similar. These include the warm rain formation process, ice loss processes and deep convective intensity. Plain Language Summary: A climate model is run many times with modified parameters to see how the parameters affect key aspects of climate change. The paper focuses on two aspects of climate change. First, the cloud response to aerosol particles tends to create a cooling, which partially offsets greenhouse gas warming, but the magnitude of the cooling is not well known. It varies a lot in the model when parameters are changed. Second, the paper examines the cloud response to surface temperature increases, called cloud feedbacks, which are the largest uncertainty in estimating the level of future climate change. Cloud feedbacks are also sensitive to parameters. The results show that the cloud feedbacks and aerosol forcing changes are similar but opposite in the model: the cooling and warming generally increase together. This occurs because they are linked to similar parameters, which indicate sensitivity to critical processes, including how rain forms, and how much ice is in the atmosphere. Key Points: Parametric uncertainty of Aerosol Forcing and Cloud Feedbacks are largeAerosol Forcing and Cloud Feedbacks are related through cloud processes and depend on the mean state of cloudsWarm rain formation and ice processes are critical sensitivities that couple forcing and feedback [ABSTRACT FROM AUTHOR]

Termite mounds are keystone structures in African savannas, affecting multiple ecosystem processes. Despite the large size of termite mounds having the potential to modify conditions around them, patterns of mound‐induced ecosystem effects have been assumed to be isotropic, with little attention given to how effects might vary around mounds. We measured soil nitrogen content, grass species composition, and mammalian grazing on and off termite mounds in the four cardinal directions, and across wet and dry seasons at three savanna sites varying in mean annual rainfall in South Africa's Kruger National Park. Evidence of directional effects (anisotropy) on ecosystem properties around termite mounds varied with site. Grass species composition differed between north‐ and south‐facing slopes at the two drier sites where mounds were taller. However, differences in grazing extent and soil nitrogen content around mounds were only present at the intermediate rainfall site where mammalian herbivore biomass was highest, and mounds were of medium height. Our results suggest that termite mound effects display significant variation with direction, but that the emergence of directional effects is context dependent. Our results further suggest that such context‐dependent directional effects can lead to positive feedback loops between termites, abiotic conditions, and mammalian herbivores. [ABSTRACT FROM AUTHOR]

Within communities, species are wrapped in a set of feedbacks with each other and with their environment. When such feedbacks are strong enough they can generate alternative stable states. So far, research on alternative stable states has mostly focused on systems with a small number of species and a limited diversity of interaction types. Here, we analyze a spatial model of plant community dynamics in stressed ecosystems such as drylands, where each species is characterized by a strategy, and the different species interact through facilitation and competition for space and resources, such as water. We identify three different types of multistability emerging from the interplay of competition and facilitation. Under low‐stress levels, plant communities organize in small groups of coexisting species, maintained by space, competition and facilitation ("cliques"). Under higher stress levels, positive feedback from facilitation lead to the dominance of a single facilitating species ("mutual exclusion states"). At the highest stress levels, the single facilitating species left in the system coexists with the desert state. By linking community ecology and alternative stable states theory using a spatial plant community model for stressed ecosystems, our study contributes to highlight the importance of positive feedback loops for the stability of ecological communities. [ABSTRACT FROM AUTHOR]

To bridge the knowledge gap between (a) our (instantaneous‐to‐seasonal‐scale) process understanding of plants and water and (b) our projections of long‐term coupled feedbacks between the terrestrial water and carbon cycles, we must uncover what the dominant dynamics are linking fluxes of water and carbon. This study uses the simplest empirical dynamical systems models—two‐dimensional linear models—and observation‐based data from satellites, eddy covariance towers, weather stations, and machine‐learning‐derived products to determine the dominant sub‐annual timescales coupling carbon uptake and (normalized) evaporation fluxes. We find two dominant modes across the Contiguous United States: (1) a negative correlation timescale on the order of a few days during which landscapes dry after precipitation and plants increase their carbon uptake through photosynthetic upregulation. (2) A slow, seasonal‐scale positive covariation through which landscape drying leads to decreased growth and carbon uptake. The slow (positively correlated) process dominates the joint distribution of local water and carbon variables, leading to similar behaviors across space, biomes, and climate regions. We propose that vegetation cover/leaf area variables link this behavior across space, leading to strong emergent spatial patterns of water/carbon coupling in the mean. The spatial pattern of local temporal dynamics—positively sloped tangent lines to a convex long‐term mean‐state curve—is surprisingly strong, and can serve as a benchmark for coupled Earth System Models. We show that many such models do not represent this emergent mean‐state pattern, and hypothesize that this may be due to lack of water‐carbon feedbacks at daily scales. [ABSTRACT FROM AUTHOR]

Abstract Navigating social‐ecological systems toward sustainable trajectories is an important challenge of the Anthropocene. Models of social‐ecological systems can increase our understanding of how social and ecological subsystems interact, their response to environmental changes, and how their dynamics may be altered by management interventions. However, the level of representational detail required for models to describe a particular social‐ecological system with high fidelity (i.e., accurately quantifying system dynamics) may hamper both the interpretability of model results and our ability to identify key processes and feedbacks within the system. In contrast, stylized models describe simplified interactions between a small subset of social‐ecological system elements. Stylized models are a useful tool to identify potential consequences of specific key processes and feedbacks on system functioning. However, the relatively low level of representational detail in these models limits their ability to deliver concrete management options for a particular social‐ecological system. Here, we describe how an exploratory modeling approach can utilize the strengths of stylized models before the construction of social‐ecological system models with high fidelity and representational detail. This exploratory modeling approach is an iterative strategy, with the initial steps comprising the development of stylized models informed by empirical observations. We illustrate this with two examples of stylized modeling of isolated and connected social‐ecological systems. Through repeated confrontation of alternative models with empirical data, exploratory modeling provides useful stepping stones toward the development of models that describe social‐ecological systems in increasingly specific settings with increasing levels of representational detail. When these latter types of models reach a high level of fidelity, they could be used for scenario‐based analyses and participatory decision‐making processes. At this stage, the conceptual insights previously obtained during the exploratory modeling phase may aid in the interpretation and communication of the outcomes of scenario‐based analyses. Hence, exploratory modeling aims to create a synergy between the insights obtained from stylized models and system‐specific, high‐fidelity models in order to generate a deep understanding of the drivers of social‐ecological system dynamics, and how to leverage these drivers to initiate desired changes.

There are many uncertainties in future climate, including how the Earth may react to different types of radiative forcing, such as CO2, aerosols, and even geoengineered changes in the amount of sunlight absorbed by Earth's surface. Here, we analyze model simulations where the climate system is subjected to an abrupt change of the solar constant by ±4%, and where the atmospheric CO2 concentration is abruptly changed to quadruple and half its preindustrial value. Using these experiments, we examine how clouds respond to changes in solar forcing, compared to CO2, and feedback on global surface temperature. The total cloud response can be decomposed into those responses driven by changes in global surface temperature, called the temperature mediated cloud feedbacks, and responses driven directly by the forcing that are independent of the global surface temperature. In this paper, we study the temperature mediated cloud changes to answer two primary questions: (a) How do temperature mediated cloud feedbacks differ in response to abrupt changes in CO2 and solar forcing? And (b) Are there symmetrical (equal and opposite) temperature mediated cloud feedbacks during global warming and global cooling? We find that temperature mediated cloud feedbacks are similar in response to increasing solar and increasing CO2 forcing, and we provide a short review of recent literature regarding the physical mechanisms responsible for these feedbacks. We also find that cloud responses to warming and cooling are not symmetric, due largely to non‐linearity introduced by phase changes in mid‐to‐high latitude low clouds and sea ice loss/formation. Plain Language Summary: As the global mean temperature changes, there are changes in cloud amount, location, and thickness, which can all impact the radiative balance of the Earth. Cloud changes driven directly by global temperature change are called temperature mediated cloud feedbacks. In this paper, we study the temperature mediated cloud feedbacks that occur in model simulations where the amount of sunlight incident upon the Earth is increased or decreased abruptly, and then held constant for 150 years. We compare the cloud changes in these experiments with experiments where the CO2 concentration is similarly increased or decreased abruptly and held constant for 150 years. In doing so we find that the temperature mediated cloud feedbacks following abrupt changes in solar radiation are characteristically similar to those occurring following CO2 increase. There are however substantial differences in the temperature mediated cloud feedbacks that occur while the climate is warming versus cooling. Key Points: The temperature mediated cloud changes and feedbacks incurred by changes in solar and CO2 forcing are similarOptical depth changes at high latitudes produce substantial differences in cloud feedbacks in cooling and warming experimentsLikewise, tropical circulations respond differently in models to cooling and warming, with a stronger change in the Walker circulation in warming experiments [ABSTRACT FROM AUTHOR]

Eco‐evolutionary experiments are typically conducted in semi‐unnatural controlled settings, such as mesocosms; yet inferences about how evolution and ecology interact in the real world would surely benefit from experiments in natural uncontrolled settings. Opportunities for such experiments are rare but do arise in the context of restoration ecology—where different "types" of a given species can be introduced into different "replicate" locations. Designing such experiments requires wrestling with consequential questions. (Q1) Which specific "types" of a focal species should be introduced to the restoration location? (Q2) How many sources of each type should be used—and should they be mixed together? (Q3) Which specific source populations should be used? (Q4) Which type(s) or population(s) should be introduced into which restoration sites? We recently grappled with these questions when designing an eco‐evolutionary experiment with threespine stickleback (Gasterosteus aculeatus) introduced into nine small lakes and ponds on the Kenai Peninsula in Alaska that required restoration. After considering the options at length, we decided to use benthic versus limnetic ecotypes (Q1) to create a mixed group of colonists from four source populations of each ecotype (Q2), where ecotypes were identified based on trophic morphology (Q3), and were then introduced into nine restoration lakes scaled by lake size (Q4). We hope that outlining the alternatives and resulting choices will make the rationales clear for future studies leveraging our experiment, while also proving useful for investigators considering similar experiments in the future. [ABSTRACT FROM AUTHOR]

The global movement for ecosystem restoration has gained momentum in response to the Bonn Challenge (2010) and the UN Decade on Ecosystem Restoration (UNDER, 2021–2030). While several science‐based guidelines exist to aid in achieving successful restoration outcomes, significant variation remains in the outcomes of restoration projects. Some of this disparity can be attributed to unexpected responses of ecosystem components to planned interventions.Given the complex nature of ecosystems, we propose that concepts from Complex Systems Science (CSS) that are linked to non‐linearity, such as regime shifts, ecological resilience and ecological feedbacks, should be employed to help explain this variation in restoration outcomes from an ecological perspective.Our framework, Explore Before You Restore, illustrates how these concepts impact restoration outcomes by influencing degradation and recovery trajectories. Additionally, we propose incorporating CSS concepts into the typical restoration project cycle through a CSS assessment phase and suggest that the need for such assessment is explicitly included in the guidelines to improve restoration outcomes.To facilitate this inclusion and make it workable by practitioners, we describe indicators and methods available for restoration teams to answer key questions that should make up such CSS assessment. In doing so, we identify key outstanding science and policy tasks that are needed to further operationalize CSS assessment in restoration.Synthesis and applications. By illustrating how key Complex Systems Science (CSS) concepts linked to non‐linear threshold behaviour can impact restoration outcomes through influencing recovery trajectories, our framework Explore Before You Restore demonstrates the need to incorporate Complex Systems thinking in ecosystem restoration. We argue that inclusion of CSS assessment into restoration project cycles, and more broadly, into international restoration guidelines, may significantly improve restoration outcomes. [ABSTRACT FROM AUTHOR]

The response of tropical high clouds to surface warming and their radiative feedbacks are uncertain. For example, it is uncertain whether their coverage will contract or expand in response to surface warming and whether such changes entail a stabilizing radiative feedback (iris feedback) or a neutral feedback. Global satellite observations with passive and active remote sensing capabilities over the last two decades can now be used to address such effects that were previously observationally limited. Using these observations, we show that the vertically averaged coverage exhibits no significant contraction or expansion. However, we find a reduction in coverage at the altitude where high clouds peak and are particularly radiatively‐relevant. This results in a negative longwave (LW) feedback and a positive shortwave (SW) feedback which cancel to yield a near‐zero high‐cloud amount feedback, providing observational evidence against an iris feedback. Next, we find that tropical high clouds have risen but have also warmed, leading to a positive, but small, high‐cloud altitude feedback dominated by the LW feedback. Finally, we find that high clouds have been thinning, leading to a near‐zero high‐cloud optical depth feedback from a cancellation between negative LW and positive SW feedbacks. Overall, high clouds lead the total tropical cloud feedback to be small due to the negative LW‐positive SW feedback cancellations. Plain Language Summary: Tropical high clouds can have both cooling and heating effects: by reflecting sunlight, they cool the planet and by preventing terrestrial radiation from escaping to space, they also heat the planet. Despite their influence on how much heat gets stored in the Earth system, there is a surprisingly poor understanding of how these clouds will respond to global warming. This uncertainty is largely due to the paucity of observational data. Now, however, instruments aboard satellites orbiting Earth have provided unprecedented data on the changes in the vertical structure of clouds as well as their heat impacts. Our work shows that the dominant signal in the satellite cloud record is the rise of high clouds in response to warming, not any net contraction of coverage. The high clouds are also found to be warming and thinning. Overall, these high cloud changes induce less reflection of sunlight and allow more terrestrial radiation to escape to space. However, these radiative effects cancel and altogether cause no significant heating impact in the tropics. Key Points: Tropical high clouds are rising, warming, thinning, and when vertically averaged, are not contractingTropical high clouds show a positive altitude radiative feedback and near‐zero optical depth and amount radiative feedbacks [ABSTRACT FROM AUTHOR]

Abstract Termite mounds are keystone structures in African savannas, affecting multiple ecosystem processes. Despite the large size of termite mounds having the potential to modify conditions around them, patterns of mound‐induced ecosystem effects have been assumed to be isotropic, with little attention given to how effects might vary around mounds. We measured soil nitrogen content, grass species composition, and mammalian grazing on and off termite mounds in the four cardinal directions, and across wet and dry seasons at three savanna sites varying in mean annual rainfall in South Africa's Kruger National Park. Evidence of directional effects (anisotropy) on ecosystem properties around termite mounds varied with site. Grass species composition differed between north‐ and south‐facing slopes at the two drier sites where mounds were taller. However, differences in grazing extent and soil nitrogen content around mounds were only present at the intermediate rainfall site where mammalian herbivore biomass was highest, and mounds were of medium height. Our results suggest that termite mound effects display significant variation with direction, but that the emergence of directional effects is context dependent. Our results further suggest that such context‐dependent directional effects can lead to positive feedback loops between termites, abiotic conditions, and mammalian herbivores.

Astronomical cycles are strongly expressed in marine geological records, providing important insights into Earth system dynamics and an invaluable means of constructing age models. However, how various astronomical periods are filtered by the Earth system and the mechanisms by which carbon reservoirs and climate components respond, particularly in absence of dynamic ice sheets, is unclear. Using an Earth system model that includes feedbacks between climate, ocean circulation, and inorganic (carbonate) carbon cycling relevant to geological timescales, we systematically explore the impact of astronomically‐modulated insolation forcing and its expression in model variables most comparable to key paleoceanographic proxies (temperature, the δ13C of inorganic carbon, and sedimentary carbonate content). Temperature predominately responds to obliquity and is little influenced by the modeled carbon cycle feedbacks. In contrast, the cycling of nutrients and carbon in the ocean generates significant precession power in atmospheric CO2, benthic ocean δ13C, and sedimentary wt% CaCO3, while inclusion of marine sedimentary and weathering processes shifts power to the long eccentricity period. Our simulations produce reduced pCO2 and dissolved inorganic carbon δ13C at long eccentricity maxima and, contrary to early Cenozoic marine records, CaCO3 preservation in the model is enhanced during eccentricity modulated warmth. Additionally, the magnitude of δ13C variability simulated in our model underestimates marine proxy records. These model‐data discrepancies hint at the possibility that the Paleogene silicate weathering feedback was weaker than modeled here and that additional organic carbon cycle feedbacks are necessary to explain the full response of the Earth system to astronomical forcing. Plain Language Summary: The Earth's tilt and orbit around the Sun change periodically, influencing the amount and distribution of solar energy that reaches the surface over time. We use a numerical model to simulate how changes in solar radiation impact the surface climate, ocean circulation, and the carbon cycle. Our model output shows that global mean surface temperatures are mainly controlled by obliquity (a measure for how tilted the Earth is), changing every 40,000 years. Changes in the carbon cycle are mainly controlled by precession (a measure for the direction in which the Earth is tilted relative to the Sun), changing approximately every 20,000 years. However, precession cycles are not well preserved in geological records because, (a) the large total mass of carbon in the atmosphere and ocean means that small fluxes over 20,000 years are insufficient to cause drastic changes, and (b) mixing of marine sediments distorts the signal. We also find that modeled variations in the climate‐carbon cycle are smaller than those observed in geological records. This suggests that other processes not modeled here, such as burial and release of organic carbon, are important to explain the full astronomical climate‐carbon cycle variability. Key Points: Time‐varying astronomical forcing simulated on a multi‐million‐year timescale using an Earth system model of intermediate complexityStrong 100 kyr power present in temperature and wt% CaCO3 is absent from δ13C cycles in the inorganic carbon reservoirAdditional organic carbon feedbacks and a reduced weathering feedback likely played a role in early Cenozoic climate‐carbon cycle dynamics [ABSTRACT FROM AUTHOR]

Feedbacks are an essential feature of resilient socio-economic systems, yet the feedbacks between biodiversity, ecosystem services and human wellbeing are not fully accounted for in global policy efforts that consider future scenarios for human activities and their consequences for nature. Failure to integrate feedbacks in our knowledge frameworks exacerbates uncertainty in future projections and potentially prevents us from realizing the full benefits of actions we can take to enhance sustainability. We identify six scientific research challenges that, if addressed, could allow future policy, conservation and monitoring efforts to quantitatively account for ecosystem and societal consequences of biodiversity change. Placing feedbacks prominently in our frameworks would lead to (i) coordinated observation of biodiversity change, ecosystem functions and human actions, (ii) joint experiment and observation programmes, (iii) more effective use of emerging technologies in biodiversity science and policy, and (iv) a more inclusive and integrated global community of biodiversity observers. To meet these challenges, we outline a five-point action plan for collaboration and connection among scientists and policymakers that emphasizes diversity, inclusion and open access. Efforts to protect biodiversity require the best possible scientific understanding of human activities, biodiversity trends, ecosystem functions and-critically-the feedbacks among them.

Astronomical cycles are strongly expressed in marine geological records, providing important insights into Earth system dynamics and an invaluable means of constructing age models. However, how various astronomical periods are filtered by the Earth system and the mechanisms by which carbon reservoirs and climate components respond, particularly in absence of dynamic ice sheets, is unclear. Using an Earth system model that includes feedbacks between climate, ocean circulation, and inorganic (carbonate) carbon cycling relevant to geological timescales, we systematically explore the impact of astronomically modulated insolation forcing and its expression in model variables most comparable to key paleoceanographic proxies (temperature, the δ13C of inorganic carbon, and sedimentary carbonate content). Temperature predominately responds to short and long eccentricity and is little influenced by the modeled carbon cycle feedbacks. In contrast, the cycling of nutrients and carbon in the ocean generates significant precession power in atmospheric CO2, benthic ocean δ13C, and sedimentary wt% CaCO3, while inclusion of marine sedimentary and weathering processes shifts power to the long eccentricity period. Our simulations produce reduced pCO2 and dissolved inorganic carbon (DIC) δ13C at long eccentricity maxima and, contrary to early Cenozoic marine records, CaCO3 preservation in the model is enhanced during eccentricity-modulated warmth. Additionally, the magnitude of δ13C variability simulated in our model underestimates marine proxy records. These model-data discrepancies hint at the possibility that the Paleogene silicate weathering feedback was weaker than modeled here and that additional organic carbon cycle feedbacks are necessary to explain the full response of the Earth system to astronomical forcing.

Abstract Multiple global crises – including the pandemic, climate change, and Russia's war on Ukraine – have recently linked together in ways that are significant in scope, devastating in effect, but poorly understood. A growing number of scholars and policymakers characterize the situation as a ‘polycrisis’. Yet this neologism remains poorly defined. We provide the concept with a substantive definition, highlight its value-added in comparison to related concepts, and develop a theoretical framework to explain the causal mechanisms currently entangling many of the world's crises. In this framework, a global crisis arises when one or more fast-moving trigger events combine with slow-moving stresses to push a global system out of its established equilibrium and into a volatile and harmful state of disequilibrium. We then identify three causal pathways – common stresses, domino effects, and inter-systemic feedbacks – that can connect multiple global systems to produce synchronized crises. Drawing on current examples, we show that the polycrisis concept is a valuable tool for understanding ongoing crises, generating actionable insights, and opening avenues for future research. Non-technical summary The term ‘polycrisis’ appears with growing frequently to capture the interconnections between global crises, but the word lacks substantive content. In this article, we convert it from an empty buzzword into a conceptual framework and research program that enables us to better understand the causal linkages between contemporary crises. We draw upon the intersection of climate change, the covid-19 pandemic, and Russia's war in Ukraine to illustrate these causal interconnections and explore key features of the world's present polycrisis. Technical summary Multiple global crises – including the pandemic, climate change, and Russia's war on Ukraine – have recently linked together in ways that are significant in scope, devastating in effect, but poorly understood. A growing number of scholars and policymakers characterize the situation as a ‘polycrisis’. Yet this neologism remains poorly defined. We provide the concept with a substantive definition, highlight its value-added in comparison to related concepts, and develop a theoretical framework to explain the causal mechanisms currently entangling many of the world's crises. In this framework, a global crisis arises when one or more fast-moving trigger events combines with slow-moving stresses to push a global system out of its established equilibrium and into a volatile and harmful state of disequilibrium. We then identify three causal pathways – common stresses, domino effects, and inter-systemic feedbacks – that can connect multiple global systems to produce synchronized crises. Drawing on current examples, we show that the polycrisis concept is a valuable tool for understanding ongoing crises, generating actionable insights, and opening avenues for future research. Social media summary No longer a mere buzzword, the ‘polycrisis’ concept highlights causal interactions among crises to help navigate a tumultuous future.

Abstract The popularity of the term polycrisis suggests a growing demand for new thinking about the world's intersecting crises, but loose and haphazard uses of the concept impede knowledge generation. The special issue, ‘Polycrisis in the Anthropocene’, aims to close the gap. This introductory comment first elaborates upon three key contributions of the lead article ‘Global Polycrisis: The Causal mechanisms of Crisis Entanglement’: a conceptualization of crisis as systemic disequilibrium; the distinction between the slow-moving stresses and the fast-moving trigger events that interact to generate a crisis; and a grammar with which to map the causality of crisis interactions. The commentary then explores three key debates around the polycrisis concept: Are we in a polycrisis, at risk of a polycrisis, or neither? Is the present polycrisis truly unique and unprecedented? And where are power and agency in a systemic approach to polycrisis? These ongoing debates suggest promising directions for polycrisis research that could feature in this special issue and advance the field of polycrisis analysis. Non-technical summary This commentary introduces the special issue ‘Polycrisis in the Anthropocene’ by elaborating upon three major contributions of its lead article, ‘Global Polycrisis: The Causal Mechanisms of Crisis Entanglement’, and exploring three key debates surrounding the polycrisis concept. It invites others to contribute to the special issue in order to advance polycrisis analysis, build a community of knowledge and practice, and generate new insights and strategies with which to address the world's worsening crises. Technical summary The popularity of the term polycrisis suggests a growing demand for new thinking about the world's intersecting crises, but loose and haphazard uses of the concept impede knowledge generation. The special issue, ‘Polycrisis in the Anthropocene’, aims to close the gap. This introductory comment first elaborates upon three key contributions of the lead article ‘Global Polycrisis: The Causal mechanisms of Crisis Entanglement’: a conceptualization of crisis as systemic disequilibrium; the distinction between the slow-moving stresses and the fast-moving trigger events that interact to generate a crisis; and a grammar with which to map the causality of crisis interactions. The commentary then explores three key debates around the polycrisis concept: Are we in a polycrisis, at risk of a polycrisis, or neither? Is the present polycrisis truly unique and unprecedented? And where are power and agency in a systemic approach to polycrisis? These ongoing debates suggest promising directions for polycrisis research that could feature in this special issue and advance the field of polycrisis analysis. Social media summary Inviting contributions and debates to Global Sustainability journal's special issue ‘Polycrisis in the Anthropocene’.

On the basis of Earth remote sensing data for 2000–2020, quantitative estimates of the influence of vegetation cover degradation on the summer warming in Belarus have been obtained. The average leaf area index of Belarus for this period increased by 3.3%, mainly due to forest areas, the leaf index of which increased by about 8%. The growth of the leaf area index slowed down the summer warming of forest lands in the north (above 54° N) by about half and by more than a quarter in the south of Belarus. At the same time, the leaf area index of croplands decreased by about 5%, which caused their additional warming and amplified their land surface temperature daily cycle for the summer period. Statistically significant signs of bioclimatic land degradation have been found on the territory of Belarus with a total area of about 400 000 ha, which are enhanced by high values of positive feedback between temperature, vegetation cover, and soil moisture. About of 58% of the degrading lands are agricultural lands located mainly in the southern part of the country. On these lands, the summer temperature grows twice as fast as the average for Belarus, and the leaf index decreases at a rate of about 2% per year, which indicates the insufficiency of agriculture climate mitigation in certain regions of Belarus. [ABSTRACT FROM AUTHOR]

The many components of the Earth System are linked through complex feedbacks that can be revealed in large compilations of diverse geochemical proxy data for paleoclimate and ocean conditions. In those archives, for example, temporal and spatial trends can be visualized as topologies ('landscapes') defined by areas of high-density data, corresponding to steady states (= stability basins) maintained by negative feedbacks. The boundaries between those stability basins, representing low-density data areas (potential tipping points), are crossed when external drivers are involved, moving the system to a new steady state. These external drivers are often associated with positive feedbacks. As a proof of concept, we produced a stability 'landscape' using an extensive set of published carbon (δ13C) and oxygen (δ18O) isotope data from sedimentary carbonates spanning the last 2.5 billion years. The superimposed C-O isotopic pathways show a preference for particular regions of the 'landscape' at different times in Earth history. Major excursions reflect positive loops often set into motion by external inputs (drivers) that can overwhelm the system, such as major volcanic and tectonic events and human-induced climate effects. Our approach can be applied to other proxy datasets, and multivariate statistical treatments, including machine-learning approaches, can potentially yield a robust, high-resolution 'landscape' of the Earth System through time. [ABSTRACT FROM AUTHOR]

A fundamental challenge is to understand and navigate trade-offs between ecosystem services (ES) in dynamic landscapes and to account for interactions between local people and broad-scale drivers, such as agricultural intensification. Many analyses of ES trade-offs rely on static mapping and biophysical indicators while disregarding the multiple uses, values, and desires for ES (UVD-ES) that local people associate with their changing landscapes. Here, a participatory UVD-ES framework was applied to assess differences in the use, values, and desire of ES between three zones with different land-use intensities (with pre-frontier, frontier, and post-frontier landscapes) in West Kalimantan (Indonesia). The analysis revealed that (1) almost the full suite of ES uses has become destabilized as a result of agricultural intensification; (2) ES more closely associated with agricultural intensification were largely desired by local people yet they still valued a diversity of traditional ES, such as those derived from the provision of non-timber forest products, fish, and other ES associated with non-material aspects including those tied to traditional culture; (3) the mismatch in used ES versus valued ES increased with agricultural intensification due to a decrease in the flow of non-timber forest products, aquatic, regulating, and non-material (cultural) ES. Together, exploring UVD-ES patterns in a participatory way helped to reveal locally relevant social-ecological drivers of ES and a multidimensional perspective of ES trade-offs. Our UVD-ES framework offers an opportunity to foster participation as a way to reconnect global environmental research agendas with local and regional landscape contexts. [ABSTRACT FROM AUTHOR]

Complexity theory predicts that self‐organized, regularly patterned ecosystems store more biomass and are more resilient than spatially uniform systems. Self‐organized ecosystems are well‐known from the terrestrial realm, with "tiger bushes" being the archetypical example and mussel beds and tropical coral reefs the marine examples. We here identify regular spatial patterns in cold‐water coral reefs (nicknamed "tiger reefs") from video transects and argue that these are likely the result of self‐organization. We used variograms and Lomb–Scargle analysis of seven annotated video transects to analyze spatial patterns in live coral and dead coral (i.e., skeletal remains) cover at the Logachev coral mound province (NE Atlantic Ocean) and found regular spatial patterns with length scales between 62 and 523 m in live and dead coral distribution along these transects that point to self‐organization of cold‐water coral reefs. Self‐organization theory shows that self‐organized ecosystems can withstand large environmental changes by adjusting their spatial configuration. We found indications that cold‐water corals can similarly adjust their spatial configuration, possibly providing resilience in the face of climate change. Dead coral framework remains in the environment for extended periods of time, providing a template for spatial patterns that facilitates live coral recovery. The notion of regular spatial patterns in cold‐water coral reefs is interesting for cold‐water coral restoration, as transplantation will be more successful when it follows the patterns that are naturally present. This finding also underlines that anthropogenic effects such as ocean acidification and bottom trawling that destroy the dead coral template undermine cold‐water coral resilience. Differences in the pattern periodicities of live and dead coral cover further present an interesting new angle to investigate past and present environmental conditions in cold‐water coral reefs. [ABSTRACT FROM AUTHOR]

BACKGROUND: Today, doodle videos are employed as a teaching tool in contemporary education, and they are known to aid in the development of attention and likelihood of increase in the memory. Feedback is a systematic ongoing review process to evaluate and improvise the teaching methodology to ensure its effectiveness. AIMS AND OBJECTIVE: The aim of this study was to evaluate the impact of newer teaching method compared to traditional method and assess the student's perception on the same. METHODOLOGY: This is a nonrandomized experimental study, wherein a doodle video on the topic of “Parkinson's disease” was designed and displayed to the students through the link generated. The knowledge acquisition was evaluated using a comprehensive multiple-choice question test for both groups, and another structured questionnaire on the perceptions of newer teaching method was assessed. RESULTS/OBSERVATION: There was a statistically significant difference (P < 0.03) for the mean assessment scores between the groups. A total of 80 responses were obtained for feedback assessment on perception of newer method for five closed-ended questions, and 54 responses were obtained for one open-ended question. Thematic analysis was performed for open-ended questions. CONCLUSION: Student's performance was better with doodle video teaching. Doodle video was considered an innovative method of teaching by students; it helped them understand better. The feedback taken offered an opportunity to understand the student's perspective and their teaching needs.

Vegetation browning has progressively increased globally under a background of climate change. Under climate change, increases in the intensity and duration of disturbances (i.e., drought, wildfire, insect and pathogen outbreaks, and wind and ice storms) are the major driving factors behind vegetation browning. The weakening of ecosystem services and functions and alterations to vegetation structure and species composition will be accompanied by vegetation browning. Potential positive browning feedbacks may exacerbate climate change. As global climate conditions continue to change, disturbance regimes and environmental drivers will continue to shift, impacting global vegetation dynamics. Following a period of vegetation greening, there has been a progressive increase in remotely sensed vegetation browning globally. Given the many societal benefits that forests provide, it is critical that we understand vegetation dynamic alterations. Here, we review associative drivers, impacts, and feedbacks, revealing the complexity of browning. Concomitant increases in browning include the weakening of ecosystem services and functions and alterations to vegetation structure and species composition, as well as the development of potential positive climate change feedbacks. Also discussed are the current challenges in browning detection and understanding associated impacts and feedbacks. Finally, we outline recommended strategies. [ABSTRACT FROM AUTHOR]

Purpose: The study focuses on tourism, and how online consumer ratings are handled. Online reviews and properly managing them are critical components of running a successful tourism business. Research Methodology: A descriptive research design is used to collect data utilizing the survey method and a structured questionnaire is used and the survey is carried out online. Findings: According to the respondents, more than 80 percent of travelers have booked travel services online, and most of them had read internet reviews before making travel purchases. Before making a vacation reservation, many clients read internet reviews. Originality: The research can be leveraged as a foundation for further research on Tourism and Hospitality. The uniqueness is in how internet reviews affect the tourist industry and the many segments of the tourism sector, and how these reviews play a vital role in the growth of the firms. In this study piece, we tested how internet reviews affect MakeMyTrip, Yatra.com, and Cleartrip's user behavior. [ABSTRACT FROM AUTHOR]

Abstract Complexity theory predicts that self‐organized, regularly patterned ecosystems store more biomass and are more resilient than spatially uniform systems. Self‐organized ecosystems are well‐known from the terrestrial realm, with “tiger bushes” being the archetypical example and mussel beds and tropical coral reefs the marine examples. We here identify regular spatial patterns in cold‐water coral reefs (nicknamed “tiger reefs”) from video transects and argue that these are likely the result of self‐organization. We used variograms and Lomb–Scargle analysis of seven annotated video transects to analyze spatial patterns in live coral and dead coral (i.e., skeletal remains) cover at the Logachev coral mound province (NE Atlantic Ocean) and found regular spatial patterns with length scales between 62 and 523 m in live and dead coral distribution along these transects that point to self‐organization of cold‐water coral reefs. Self‐organization theory shows that self‐organized ecosystems can withstand large environmental changes by adjusting their spatial configuration. We found indications that cold‐water corals can similarly adjust their spatial configuration, possibly providing resilience in the face of climate change. Dead coral framework remains in the environment for extended periods of time, providing a template for spatial patterns that facilitates live coral recovery. The notion of regular spatial patterns in cold‐water coral reefs is interesting for cold‐water coral restoration, as transplantation will be more successful when it follows the patterns that are naturally present. This finding also underlines that anthropogenic effects such as ocean acidification and bottom trawling that destroy the dead coral template undermine cold‐water coral resilience. Differences in the pattern periodicities of live and dead coral cover further present an interesting new angle to investigate past and present environmental conditions in cold‐water coral reefs.

We integrated a mechanistic wildfire simulation system with an agent-based landscape change model to investigate the feedbacks among climate change, population growth, development, landowner decision-making, vegetative succession, and wildfire. Our goal was to develop an adaptable simulation platform for anticipating risk-mitigation tradeoffs in a fire-prone wildland–urban interface (WUI) facing conditions outside the bounds of experience. We describe how five social and ecological system (SES) submodels interact over time and space to generate highly variable alternative futures even within the same scenario as stochastic elements in simulated wildfire, succession, and landowner decisions create large sets of unique, path-dependent futures for analysis. We applied the modeling system to an 815 km2 study area in western Oregon at a sub-taxlot parcel grain and annual timestep, generating hundreds of alternative futures for 2007–2056 (50 years) to explore how WUI communities facing compound risks from increasing wildfire and expanding periurban development can situate and assess alternative risk management approaches in their localized SES context. The ability to link trends and uncertainties across many futures to processes and events that unfold in individual futures is central to the modeling system. By contrasting selected alternative futures, we illustrate how assessing simulated feedbacks between wildfire and other SES processes can identify tradeoffs and leverage points in fire-prone WUI landscapes. Assessments include a detailed "post-mortem" of a rare, extreme wildfire event, and uncovered, unexpected stabilizing feedbacks from treatment costs that reduced the effectiveness of agent responses to signs of increasing risk. [ABSTRACT FROM AUTHOR]

Humans play an interconnecting role in social-ecological systems (SES), they are part of these systems and act as agents of their destruction and regulation. This study aims to provide an analytical framework, which combines the concept of SES with the concept of tipping dynamics. As a result, we propose an analytical framework describing relevant dynamics and feedbacks within SES based on two matrixes: the “tipping matrix” and the “cross-impact matrix.” We take the Southwestern Amazon as an example for tropical regions at large and apply the proposed analytical framework to identify key underlying sub-systems within the study region: the soil ecosystem, the household livelihood system, the regional social system, and the regional climate system, which are interconnected through a network of feedbacks. We consider these sub-systems as tipping elements (TE), which when put under stress, can cross a tipping point (TP), resulting in a qualitative and potentially irreversible change of the respective TE. By systematically assessing linkages and feedbacks within and between TEs, our proposed analytical framework can provide an entry point for empirically assessing tipping point dynamics such as “tipping cascades,” which means that the crossing of a TP in one TE may force the tipping of another TE. Policy implications: The proposed joint description of the structure and dynamics within and across SES in respect to characteristics of tipping point dynamics promotes a better understanding of human-nature interactions and critical linkages within regional SES that may be used for effectively informing and directing empirical tipping point assessments, monitoring or intervention purposes. Thereby, the framework can inform policy-making for enhancing the resilience of regional SES.

Janus is the Roman god of transitions. In many environments, state transitions are an important part of our understanding of ecological change. These transitions are controlled by the interactions between exogenous forcing factors and stabilizing endogenous feedbacks. Forcing factors and feedbacks are typically considered to consist of different processes. We argue that during extreme events, a process that usually forms part of a stabilizing feedback can behave as a forcing factor. And thus, like Janus, a single process can have two faces. The case explored here pertains to state change in drylands where interactions between wind erosion and vegetation form an important feedback that encourages grass‐to‐shrub state transitions. Wind concentrates soil resources in shrub‐centered fertile islands, removes resources through loss of fines to favor deep‐rooted shrubs, and abrades grasses' photosynthetic tissue, thus further favoring the shrub state that, in turn, experiences greater aeolian transport. This feedback is well documented but the potential of wind to act also as a forcing has yet to be examined. Extreme wind events have the potential to act like other drivers of state change, such as drought and grazing, to directly reduce grass cover. This study examines the responses of a grass‐shrub community after two extreme wind events in 2019 caused severe deflation. We measured grass cover and root exposure due to deflation, in addition to shrub height, grass patch size, and grass greenness along 50‐m transects across a wide range of grass cover. Root exposure was concentrated in the direction of erosive winds during the storms and sites with low grass cover were associated with increased root exposure and reduced greenness. We argue that differences between extreme, rare wind events and frequent, small wind events are significant enough to be differences in kind rather than differences in degree allowing extreme winds to behave as endogenous forcings and common winds to participate in an endogenous stabilizing feedback. Several types of state change in other ecological systems in are contextualized within this framework. [ABSTRACT FROM AUTHOR]

In contrast to surface greenhouse warming, surface greenhouse cooling has been less explored, especially on multi-century timescales. Here, we assess the processes controlling the pacing and magnitude of the multi-century surface temperature response to instantaneously doubling and halving atmospheric carbon dioxide concentrations in a modern global coupled climate model. Over the first decades, surface greenhouse warming is larger and faster than surface greenhouse cooling both globally and at high northern latitudes (45–90° N). Yet, this initial multi-decadal response difference does not persist. After year 150, additional surface warming is negligible, but surface cooling and sea ice expansion continues. Notably, the equilibration timescale for high northern latitude surface cooling (∼437 years) is more than double the equivalent timescale for warming. The high northern latitude responses differ most at the sea ice edge. Under greenhouse cooling, the sea ice edge slowly creeps southward into the mid-latitude oceans amplified by positive lapse rate and surface albedo feedbacks. While greenhouse warming and sea ice loss at high northern latitudes occurs on multi-decadal timescales, greenhouse cooling and sea ice expansion occurs on multi-century timescales. Overall, this work shows the importance of multi-century timescales and sea ice processes for understanding high northern latitude climate responses.

Tropical forest and savanna frequently coexist under the same climatic conditions, which has led to the hypothesis that they could represent alternative ecosystem states, stabilized by internal feedbacks. An implication of this hypothesis is that forest and savanna may be bistable and exhibit tipping behavior in response to changing conditions. However, we pose that the local presence of forest and savanna within coexistence landscapes is not sufficient evidence that these are alternative stable states at larger ecosystem scales. Therefore, we explore forest-savanna coexistence and bistability at landscape scale in Central Africa. Using remote sensing data on tree cover, we classify 0.1° × 0.1° (approx. 10 × 10 km) landscapes as homogeneous forest, homogeneous savanna, or coexistence, and analyze the roles of climate, topography and soil sand content in driving their distributions. We find that local coexistence of forest and savanna within landscapes is common and occurs for the whole range of mean annual precipitation in our study area. At low precipitation, however, coexistence increases with topographic roughness and is therefore likely driven by local redistribution of resources rather than internal feedbacks. Coexistence within intermediate and high precipitation landscapes remains unexplained by the studied variables, and may be caused either by heterogeneity in unmeasured drivers or by feedback-driven bistability. At landscape scale, the precipitation ranges for which homogeneous forest and savanna occur have only limited overlap, and this overlap can be largely explained by other external drivers, such as seasonality, soil sand content, and topography. This lack of evidence that homogeneous forest and savanna in Central Africa are alternative ecosystem states at this landscape scale means that transitions between them may be mostly local, resulting in coexistence states. Therefore, we conclude that the likelihood of large-scale tipping between homogeneous forest and savanna ecosystems may be lower than previously thought.

Despite recurrent emphasis on their ecological and economic roles, the importance of high trophic levels (HTLs) on ocean carbon dynamics, through passive (fecal pellet production, carcasses) and active (vertical migration) processes, is still largely unexplored, notably under climate change scenarios. In addition, HTLs impact the ecosystem dynamics through top‐down effects on lower trophic levels, which might change under anthropogenic influence. Here we compare two simulations of a global biogeochemical–ecosystem model with and without feedbacks from large marine animals. We show that these large marine animals affect the evolution of low trophic level biomasses, hence net primary production and most certainly ecosystem equilibrium, but seem to have little influence on the 21st‐century anthropogenic carbon uptake under the RCP8.5 scenario. These results provide new insights regarding the expectations for trophic amplification of climate change through the marine trophic chain and regarding the necessity to explicitly represent marine animals in Earth System Models. [ABSTRACT FROM AUTHOR]

Fire-plant feedbacks engineer recurrent fires in pyrophilic ecosystems like savannas. The mechanisms sustaining these feedbacks may be related to plant adaptations that trigger rapid responses to fire's effects on soil. Plants adapted for high fire frequencies should quickly regrow, flower, and produce seeds that mature rapidly and disperse postfire. We hypothesized that the offspring of such plants would germinate and grow rapidly, responding to fire-generated changes in soil nutrients and biota. We conducted an experiment using longleaf pine savanna plants that were paired on the basis of differences in reproduction and survival under annual ("more" pyrophilic) versus less frequent ("less" pyrophilic) fire regimes. Seeds were planted in different soil inoculations from experimental fires of varying severity. The more pyrophilic species displayed high germination rates followed by species-specific rapid growth responses to soil location and fire severity effects on soils. In contrast, the less pyrophilic species had lower germination rates that were not responsive to soil treatments. This suggests that rapid germination and growth constitute adaptations to frequent fires and that plants respond differently to fire severity effects on soil abiotic factors and microbes. Furthermore, variable plant responses to postfire soils may influence plant community diversity and fire-fuel feedbacks in pyrophilic ecosystems. [ABSTRACT FROM AUTHOR]

Abiotic environmental conditions can significantly influence the way species interact. In particular, plant–herbivore interactions can be substantially dependent on temperature and nutrients. The overall product of these relationships is critical for the fate and stability of vegetated ecosystems like marine forests. The last few decades have seen a rapid spread of barrens on temperate rocky reefs mainly as a result of overgrazing. The ecological feedbacks that characterize the barren state involve a different set of interactions than those occurring in vegetated habitats. Reversing these trends requires a proper understanding of the novel feedbacks and the conditions under which they operate. Here, we explored the role of a secondary herbivore in reinforcing the stability of barrens formed by sea urchin overgrazing under different nutrient conditions. Combining comparative and experimental studies in two Mediterranean regions characterized by contrasting nutrient conditions, we assessed: (i) if the creation of barren areas enhances limpet abundance, (ii) the size‐specific grazing impact by limpets, and (iii) the ability of limpets alone to maintain barrens. Our results show that urchin overgrazing enhanced limpet abundance. The effects of limpet grazing varied with nutrient conditions, being up to five times more intense under oligotrophic conditions. Limpets were able to maintain barrens in the absence of sea urchins only under low‐nutrient conditions, enhancing the stability of the depauperate state. Overall, our study suggests a greater vulnerability of subtidal forests in oligotrophic regions of the Mediterranean and demonstrates the importance of environment conditions in regulating feedbacks mediated by plant–herbivore interactions. [ABSTRACT FROM AUTHOR]

Since the mid-1990s, there has been a marked decrease in the sea ice extent (SIE) in the Arctic Ocean. After reaching an absolute minimum in September 2012, the seasonal variations in the SIE have settled at a new level, which is almost one-quarter lower than the average climatic norm of 1979–2022. Increased melting and accelerated ice export from marginal seas ensure an increase in the open water area, which affects the lower atmosphere and the surface layer of the ocean. Scientists are cautiously predicting a transition to a seasonally ice-free Arctic Ocean as early as the middle of this century, which is about 50 years earlier than was predicted just a few years ago. Such predictions are based on the fact that the decrease in sea ice extent and ice thinning that occurred at the beginning of this century, initially caused by an increase in air temperature, triggered an increase in the thermal and dynamic contribution of the ocean to the further reduction in the ice cover. This paper reviews published evidence of such changes and discusses possible mechanisms behind the observed regional anomalies of the Arctic Sea ice cover parameters in the last decade. [ABSTRACT FROM AUTHOR]

How hosts respond to and cope with infectious agents can change the environment and in so doing, alter selective pressures and evolutionary trajectories. To date, such eco-evolutionary feedbacks are best known from simplified mathematical models and laboratory experiments with a limited number of genetically homogenous model systems. However, the extent to which ecology and (co)-evolution interact to shape disease over space and time in natural communities remains poorly understood. Studies in this theme issue break new ground by integrating empirical and field studies stemming from a diverse array of taxa and ecosystems to understand how ecological and evolutionary feedbacks shape host-parasite interactions. Contributing papers synthesize emerging research and diverse perspectives on pathogen life history, virulence, resistance, leveraging novel methodological advances and integrating infection processes across multiple scales of biological organization. Two key take-aways emerge from this theme issue. First, more research tackling the eco-evolutionary dynamics of infectious disease in truly multi-species contexts is needed. Second, while we are far from understanding eco-evolutionary dynamics in the 'natural theater' where hosts encounter their parasites, exciting advances and foundational studies provide a well-defined road map. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the global practical uniform h-stability analysis problem for a certain class of nonlinear non-autonomous systems where the associated nominal system is linear that depends on the time t and the perturbation term satisfies some conditions. Moreover, with the help of the new notion of practical h-stable functions, we study the separation principle in the practical sense for two classes of nonlinear non-autonomous systems having a nominal linear part. We propose some classes of memoryless state linear and nonlinear feedback controllers. Furthermore, an illustrative example is given to demonstrate the applicability of main result. [ABSTRACT FROM AUTHOR]

Drought is a persistent hazard that impacts the environment, people's livelihoods, access to education and food security. Adaptation choices made by people can influence the propagation of this drought hazard. However, few drought models incorporate adaptive behavior and feedbacks between adaptations and drought. In this research, we present a dynamic drought adaptation modeling framework, ADOPT-AP, which combines socio-hydrological and agent-based modeling approaches. This approach is applied to agropastoral communities in dryland regions in Kenya. We couple the spatially explicit hydrological Dryland Water Partitioning (DRYP) model with a behavioral model capable of simulating different bounded rational behavioral theories (ADOPT). The results demonstrate that agropastoralists respond differently to drought due to differences in (perceptions of) their hydrological environment. Downstream communities are impacted more heavily and implement more short-term adaptation measures than upstream communities in the same catchment. Additional drivers of drought adaptation concern socio-economic factors such as wealth and distance to wells. We show that the uptake of drought adaptation influences soil moisture (positively through irrigation) and groundwater (negatively through abstraction) and, thus, the drought propagation through the hydrological cycle.

This chapter deals with the linguistic manifestations of conversation. For a long time, linguists have been interested in the levels of oral language (phonology, lexicon, syntax, discourse) separately, particularly based on prepared and non-interactive speech corpora. Research on conversational speech highlights what modern linguistic theories seek to integrate: the interdependence of these dimensions. Moreover, beyond the description of variants, this work allows us to study in a specific way the processes of language production and comprehension, including by considering them jointly, by relying on the most recent theories of interaction.In this chapter, we propose to first discuss the particularities of conversational language and their impact on the units and phenomena generally studied by linguists: phonemes, morphemes, syntagms, prosodic units, propositions, discourse units. These particularities stem from common parameters to most conversational communication situations: temporal pressure, co-presence of participants, fleeting nature of these conversational productions whose form is forgotten as soon as the message has been transmitted. Temporal pressure provides strong characteristics to conversational language linked to time management (lexical and phonetic reductions, disfluencies, etc.). The transience of productions allows the use of particular strategies (repetitions, redundancies, reformulations) which are generally avoided in other language uses. Finally, co-presence allows the use of all the modalities involved in an interaction, and on which the multiple mechanisms of alignment between participants are based. Moreover, the study of these particularities is profoundly impacted by the notions of context and shared knowledge that underlie an interaction. All these particularities due to conversational language suggest adjustments at all levels of production, but in a specific way for each of them. These adjustments are not always described at each level, but even more so, they are rarely analysed together. An important point is to put into perspective the different types of linguistic modifications linked to conversation.Moreover, understanding these general issues requires a precise description of conversation phenomena (cf. conversational analysis and interactional linguistics). These phenomena include turns of speech, listening signals and conversational feedback, or co-produced utterances.These specific phenomena of conversation must be put into perspective with the question of the interaction existing between units. We know, for example, that phonetic reductions more specifically affect sequences with a low semantic and informational load. It is therefore necessary to describe the conditions under which these interactions are possible. In particular, it is necessary to explain them by putting them in perspective with the question of comprehension.The participants in a conversation seek to achieve goals that are external to the communicative activity, but which involve the achievement of these participants’ communicative goals. In order to achieve these goals, the participants must articulate informative elements through the traditionally studied structures of language which allow the construction and articulation of representations. Conversation is a privileged place to observe these phenomena. Interactions between participants are generally built on an exchange of information. This is not a fixed mechanism as linguistics has long explained. It can be based on very superficial processing during which each participant produces and perceives bits of information. The way in which these are aggregated during a conversation is probably not always based on a compositional process, but rather consists in allowing all participants to construct a shared body of knowledge. In this chapter, we will describe the observable evidence of this mechanism, addressing in particular the question of the alignment of linguistic units that we observe during a conversation. This approach to interaction provides a theoretical framework for explaining the conversational phenomena mentioned above.This chapter will be structured as follows: 1/ conversation will be discussed as the articulation between representation and communication through language as a social action; 2/ a second part will aim at drawing up an inventory of the “traces” of the activity of conversation (communicative goal, temporal pressure, co-presence, cognitive load, social pressure) on the different linguistic units (phonemes, lexicon, syntax, prosody); 3/ we will then address the phenomena specific to conversation which are not identifiable in other types of speech (speech turns, disfluencies, conversational feedback, co-produced utterances, non-phrastic utterances, non-lexical utterances, etc.)); 4/ we will finally develop some perspectives related to all these works.