Coupled Human And Natural Systems Research Articles

Coupled Human and Natural Systems: A Novel Framework for Complexity Management

Coupled human and natural systems (CHANS) represent dialectic interaction between human and nature subsystems. This dynamic interaction involves a prominent level of complexity stemming from the uncertain interrelation between the systems and the incorporated subsystems. The complexity within CHANS includes reciprocal effects, nonlinearity, uncertainties, and heterogeneity. Although many researchers have highlighted the significance of understanding the nature of the coupling effect, most of the prevailing literature emphasises either human or natural systems separately, while considering the other as exogenous, despite evaluating the reciprocal and complex interrelations. The current review utilises the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA). It focuses on synthesising the prevailing literature on the CHANS framework in several disciplines, focusing on the approach, findings, limitations, and implications. The review comprises 56 relevant articles, found through Endnote and Covidence database searches. The findings identify the dominant complexity character as reciprocal effects and feedback loops, confirming the complex interactions between human and natural systems. Furthermore, the review provides evidence surrounding the significance of developing an analytical framework that can better explain the complex connections between humans and nature, as it provides a comprehensive understanding of CHANS and their potential impacts.

Integrating ecosystem services trade-off, drivers and zoning into watershed water environment management in Nansihu Lake Basin, China

A series of ecosystem services (ESs) have a significant impact on water environment. How these ESs can be integrated into water environment management in the lens of coupled human and natural system (CHANS) is still lack exploration. This study proposes an integrating framework that connects the ESs with water environment management to facilitate the watershed sustainable development. We employ the InVEST model to evaluate typical ESs in the Nansihu Lake Basin (largest freshwater lake in Shandong, China), and analyze the spatiotemporal characteristics and trade-off of multiple ESs indicators. By revealing the interaction mechanism and key drivers of ESs and conducting ecological functional zoning, we investigate how ESs can facilitate water environment management in the Nansihu Lake Basin. The results indicated that: (1) The high-value areas of agricultural supply service are mainly distributed in the western plain area of the basin, while high-value areas of water provision, water purification and soil conservation services are in the mountainous and hilly areas in the eastern part of the basin. (2) There is a significant trade-off between crop supply service and water purification services. Crop and livestock supply services have a greater effect on water purification services (TN) than other services. (3) Crop area sown, total power of agricultural machinery and fertilizer application are the main drivers of water purification services (TN). (4) The basin can be divided into three ecological function zones, the agricultural production zone, the ecological regulation zone and the ecological redline zone. These findings imply that water environment management should be integrated with ESs by strengthening intersectoral collaboration, conducting zoning management in watershed planning and applying differentiated control measures in each zone. This includes optimizing the scale and structure of agriculture, and implementing circular economy and clean production practices. This study explored a comprehensive framework of integrating ESs into water environment management to facilitate the sustainable development of watershed.

A Coupled Human and Natural Systems (CHANS) framework integrated with reinforcement learning for urban flood mitigation

To address the challenge of escalating urban flood risk and the deficiency in effective flood emergency management, this study introduces a novel Coupled Human and Natural Systems (CHANS) modelling framework that employs hierarchical reinforcement learning to optimise mobile pump scheduling and placement for urban flood risk mitigation. The CHANS framework integrates hydrodynamic and agent-based models within a multi-GPU computing environment for high-resolution, real-time flood inundation modelling and risk assessment to enrich Reinforcement Learning (RL) training. In the application to Ninh Kieu District in Can Tho City, Vietnam, the new RL-enabled modelling framework is used to evaluate optimal mobile pumping strategies for concurrent pluvial flooding and post-flooding events against the traditional deployment approaches. Results demonstrate that RL-based strategies can significantly enhance flood risk reduction, outperforming traditional methods by achieving 2× and 4× improvements in the concurrent and post-flooding periods/events, respectively. Incorporating human factors and adapting to local conditions, the RL agent provides valuable insights into mobile pump scheduling and deployment strategies. Sensitivity analysis confirms the robustness of the CHANS modelling framework and underscores the role of RL in optimising mobile pump scheduling and placement where traditional rule-based strategies are challenging.

A two-way coupled CHANS model for flood emergency management, with a focus on temporary flood defences

This study presents a novel Coupled Human And Natural Systems (CHANS) modelling framework that integrates a hydrodynamic model with an agent-based model at the memory level within a multi-GPU computing environment. This two-way coupled model captures real-time interactions between human activities and flood dynamics, with a focus on the deployment of temporary flood defences during the 2015 Desmond flood in Carlisle, UK. The findings reveal that temporary defences can significantly reduce flood inundation by 30% with early warnings and 15% through real-time decision-making, leading to financial savings of £30 million and £15 million, respectively. The study further explores the decision-making process for effective emergency flood management, emphasising the importance of early warnings and resources optimisation. The new CHANS model provides a valuable tool for testing and optimising emergency flood management strategies, highlighting the necessity of directly incorporating human activities into flood risk management.

A High‐Performance Coupled Human And Natural Systems (CHANS) Model for Flood Risk Assessment and Reduction

AbstractIn recent years, flood risk in urban areas has been rapidly increasing due to unsustainable urban development, changes of hydrological processes and frequent occurrence of extreme weather events. Flood risk assessment should realistically take into account the complex interactions between human and natural systems to better inform risk management and improve resilience. In this study, we propose a novel Coupled Human And Natural Systems (CHANS) modeling framework to capture the intricate interactive human behaviors and flooding process at a high spatial resolution. The new CHANS modeling framework integrates a high‐performance hydrodynamic model with an agent‐based model to simulate the complex responses of individual households to the evolving flood conditions, leveraging the computing power of graphics processing units (GPUs) to achieve real‐time simulation. The framework is applied to reproduce the 2015 Desmond flood in the 2,500 km2 Eden Catchment in England, demonstrating its ability to predict interactive flood‐human dynamics and assess flood impact at the household‐level. The study also further explores the effectiveness of different flood risk management strategies, including the provision of early warning and distribution of sandbags, in mitigating flood impact. The new CHANS model potentially provides a useful tool for understanding short‐term human behaviors and their impact on flood risk during a flood event, which is important for the development of effective disaster risk management plans.

A meta-model for understanding ‘green-red loop’ social-water interactions at a global scale

Within the coupled human and natural systems (CHANS), social-water interactions exhibit the ‘green-loop’ and ‘red-loop’ patterns, where social development is dependent on the local and external environment for resource provision, respectively. Sustainable management requires coordinating the interactions between water and the other socio-environmental systems, which we term ‘systems water management (SYWM)’. To understand the generic social-water interactions and obtain management implications for green-red loop systems, we develop a SYWM meta-model that conceptualises high-level social-environmental components and formulates their interactions into casual loops. This meta-model is evaluated via structural equation modelling using global datasets. Red- and green-loop scenarios are constructed to investigate the SYWM differences, and mediation analysis is conducted to quantify the reciprocal effects through the loops. Results show a critically weak causal link (0.22) from environmental state to quality of life, implying that the current water management performances have not been successfully incorporated for guiding further social development. Green- and red-loop systems have different direct causal effects in each link, which drives the corresponding behaviour. Red-loop systems have stronger total effects in causal links within the human system, depicting their strengths in socio-economic and water management decision-making. In contrast, green-loop systems have stronger total effects within the natural system, which symbolises receiving more environmental feedback. A sustainable SYWM that enhances both decision-making and feedback is recommended for green-red loop systems. The meta-model provides a platform for interdisciplinary collaborations and practical tools development that implements systems thinking in water management for sustainable development.

Agroecological transitions to sustainability and biosphere reserves

ABSTRACT We examine the potential of local agroecological transitions to sustainability in Spain and their interaction with Biosphere Reserve (BR) designation. The BR program has experienced great success in Spain however questions linger regarding their contribution to agricultural sustainability. Here, we evaluate the performance of two selected local agroecological initiatives through a Coupled Human and Natural Systems (CHANS) approach focusing, specifically, on their potential contribution to community resilience. To do so, we collected survey data from participants in one local agroecological initiative in the non-BR designated “La Vera” area and in the “Mariñas Coruñesas e Terras do Mandeo” BR. We found that participants valued positively the achievements of both initiatives but identified two important obstacles for CHANS community resilience: 1) lack of economic competitiveness of the products and services offered due to the higher prices of agroecological products when compared with conventionally produced market-oriented competitors and, 2) governance obstacles related to subsidy dependence and excessive governmental regulations of local community management practices and decision-making. Though there were no statistically significant differences between BR and non-BR survey data, non-BR respondents did identify more governance issues than BR respondents suggesting that BR designation may empower local communities institutionally providing them with more decision-making leverage in their interactions with the administration.

Challenges and opportunities for modeling coupled human and natural systems.

With the growing recognition of coupled human and natural systems (CHANS), modeling CHANS with two-way feedbacks has become a frontier research area and a critical tool to achieve sustainability. The challenges in CHANS modeling and opportunities to advance its science and application to promote the sustainability of CHANS are discussed in this paper.

Analysis of Sediment Dynamics in Ports: A Case Study from Umm Qasr-Basra for Sustainable Sediment Management

Sedimentation processes are complex and interact with many Coupled Human and Natural Systems (CHANS). In ports, intensive commercial activities result in complicated sediment transport and accumulation processes. Therefore, it is crucial to investigate and analyze the sedimentation factors that may impact shipping activities within commercial ports. A case study has been conducted to investigate these factors in the northern port of Umm Qasr, Basra Governorate in Iraq. The results indicate that several factors increase erosion and sedimentation processes within the study site, including natural factors (climate, river, and tidal processes), and anthropogenic factors (ship movements). These factors have different influences in terms of the intensity of their impact, the amount and composition of sediment within the navigation channel, and the temporal variation in the activity of these factors. Precipitation in the surrounding region causes erosion of soft-fine-sediment that is carried in suspension toward the ports through tributary creeks and temporary rivers. Sediment distribution in the port has been worsened by human activities and tidal processes in the navigation channel. Consequently, the General Company of Ports in Iraq had to implement annual sediment control procedures to maintain the operational standards of the navigation channel. Although these measures are effective, they are greatly lacking efficiency due to high costs and execution difficulties. Therefore, studies are necessary and encouraged to further understand sediment dynamics in the port of Umm Qasr and to create the basis for establishing sustainable sediment management.

Nitrogen budgets and nitrogen use efficiency as agricultural performance indicators in Lake Victoria basin

Too little nitrogen (N) is a threat to crop productivity and soil fertility in sub-Saharan Africa (SSA). Nitrogen budgets (NB) and nitrogen use efficiency (NUE) are critical tools for assessing N dynamics in agriculture and have received little or no attention in the region. Data were collected from smallholder farmers clustered into two categories, farmers applying and farmers not applying N fertilizers. NB were calculated using the Coupled Human and Natural Systems (CHANS) model approach for field and farm spatial scales. The results showed spatial variabilities in NB and NUE at the field level (maize and rice) across all the catchments. At the field level, N balances were negative for the two crops in all the catchments. Similarly, at the farm gate, a deficit of −78.37 kg N ha−1was observed, an indicator of soil N mining. NUE values at the field scale varied across the catchments for both crops, with values for maize grown without N ranging from 25.76 to 140.18%. Even with the application of mineral N at higher levels in rice fields compared to maize fields, NUE values ranged between 81.92 and 224.6%. Our study revealed that the Lake Victoria region suffers from inefficient N cycling due to depleted soil N pools and low synchrony between N input and N removal. Therefore, a challenge lies in exploiting more sustainable N sources for farmers in the region for sustainable farming systems. The NB and NUE provide critical information to agriculture stakeholders to develop environmental, agronomic, and economically viable N management solutions.

Sustainability assessment of coupled human and natural systems from the perspective of the supply and demand of ecosystem services

The sustainability of coupled human and natural systems (CHANS), linked to several of the United Nation’s Sustainable Development Goals, affects both global sustainable development and human wellbeing. However, few studies have explored the relationship between the whole human system and the natural system from the perspective of supply and demand. Based on ecosystem service concept and Maslow’s hierarchy of needs, we constructed an ecosystem services supply index (ESSI) and a human demand index (HMDI) and then analyzed the spatial mismatch of the ESSI and HMDI in 338 prefecture cities in China. We propose a supply-demand balance index inspired by the doughnut theory and demonstrate the conflicts and synergies between ecosystems and human systems. Our results show that the ESSI decreased from 2000 to 2010, but remained almost unchanged from 2010 to 2020. The low ESSI values were mainly distributed over the North China Plain, the Yangtze River Delta, and the Sichuan Basin. The HMDI increased from 2000 to 2020, but the rate of increase has slowed since 2010. The high HMDI values were mainly distributed over the east coast of China, Inner Mongolia, and part of Xinjiang province. From 2000 to 2020, the cities with spatial mismatches of the ESSI and HMDI showed a significant increase and spatial agglomeration. The sustainability of most regions showed a decreasing trend, and the higher the value of the supply-demand balance index, the faster the speed of decrease. Overall, there were more regions in a state of conflict between the natural ecosystem and humans than in a synergistic state, although this number has decreased since 2010. Urban agglomerations and western regions should receive more attention for their ecological health. This study provides a new methodology to assess the sustainability of CHANS that could be applied to other locations. Our findings could support the Chinese government in regional ecosystem governance and territorial space planning.

Can Neo-Rural Initiatives Bolster Community Resilience in Depopulated Coupled Human and Natural System?: Insights From Stakeholder Perceptions in Central Spain

Preindustrial era agro-sylvopastoral land uses have influenced structure, function and disturbance in Mediterranean type mountainous landscapes for millennia. In this study we analyze through semi-structured interviews, stakeholder perceptions of coupled human and natural system (CHANS) community resilience in one such landscape; the municipality of Puebla de la Sierra, Madrid. The municipality is part of the Biosphere Reserve of the Sierra del Rincon and the Natura 2000 network and as such is subject to various conservationist regulations emanating from multiple levels of governance. In the preindustrial past most municipal lands formed an oak “dehesa” or open forest CHANS that made biomass extraction through pollarding compatible with pastoralism and shifting agriculture. After a period of rapid land-use change in the early 20th century—marked by the state led plantation of coniferous forests, the final decades of the last century were characterized by rural abandonment and the collapse of traditional forms of land use as well as the gradual transformation of the municipality into an eco-touristic, exurban destination for Madrid residents. More recently, the municipality has experienced an influx of neo-rural settlers in the area wishing to connect traditional knowledge and management with modern agro-environmental practices. In our study, we identify two limiting factors to community resilience in Puebla de la Sierra; governance and financing. The current governance model is perceived by respondents to be contrary to their reality and needs, which translates into environmental, urban and health regulations that, in their views, penalizes agroecological and small-scale economic activities. In addition, respondents believe there is a dearth of material and financial resources to initiate these transformative local actions which further weakens community resilience. Stakeholders however also identified other factors that reinforce community resilience such as a collective willingness to revive key traditional ecosystem management practices such as pollarding, the networks of trust existing between the people participating in these new initiatives and the capacity for deliberating between different visions of future development pathways amongst local stakeholders.

Coupling human and natural systems for sustainability: experience from China's Loess Plateau

Abstract. Addressing the sustainability challenges that humanity is facing in the Anthropocene requires the coupling of human and natural systems, rather than their separate treatment. To help understand the dynamics of a coupled human and natural system (CHANS) and support the design of policies and measures that promote sustainability, we propose a conceptual cascade framework of “pattern–process–service–sustainability”, which is characterized by coupling landscape patterns and ecological processes, linking ecological processes to ecosystem services, and promoting social–ecological sustainability. The use of this framework is illustrated by a review of CHANS research experience in China's Loess Plateau (LP), a well-known region for its historically severe soil erosion and successful ecological restoration achieved in recent decades. Ecological restoration in the LP has greatly increased its vegetation coverage and controlled its soil erosion. However, some accompanied issues, like soil drying in some areas due to the introduction of exotic plant species and the mismanagement of planted vegetation and water use conflicts between vegetation and humans caused by the trade-off between carbon sequestration and water supply, have started to threaten the long-term sustainability of the LP. Based on a comprehensive understanding of CHANS dynamics, the social–ecological sustainability of the LP can be improved through enhancing water and food security, implementing basin-wide governance, maintaining ecological restoration achievements, and promoting rural livelihood transition. The research experience accumulated on the LP offers examples of the application of the pattern–process–service–sustainability framework. Future research using this framework should especially focus on the integrated research of multiple processes; the cascades of ecosystem structure, function, services, and human well-being; the feedback mechanisms of human and natural systems; and the data and models for sustainability.

A CHANS Approach to Investigating Post-Disaster Recovery Potential in Rural Japan

Natural disaster recovery is a critical issue in rural Japan, yet repairing infrastructure, stabilising landscapes, and aiding those displaced is exceedingly expensive. Restoration of disaster affected landscapes mainly focuses on infrastructure repair, with less attention to socio-ecological activities pre- and post-disaster. The absence of integrated socio-ecological perspectives to disaster restoration creates missed opportunities for approaches more sensitive to local needs and resources. Coupled human and natural systems (CHANS) frameworks attempt to bridge social and natural sciences with the effect that interactions between human and natural systems can emerge that might not be apparent by studying them separately. However, application of CHANS frameworks in the context of natural disaster recovery in rural Japan is limited, and more consideration of the challenges is needed. The aim of this paper is to describe the design of a CHANS project and summarize lessons learned in applying this complex framework. The CHANS project comprised four graduate student projects investigating different topics related to landslide recovery and future disaster vulnerability after the Northern Kyushu Heavy Rainfall in July 2012 event in rural Japan. For lessons learned, we suggest CHANS projects to be designed as a nested hierarchy of research questions, aims, objectives, and hypotheses to enable deeper synthesis at a higher level. Despite limitations in the design of our CHANS project, triangulation of data enabled us to conclude meaningful findings. When faced with limited resources, it is impossible to design a complex study accounting for all relevant factors, but a CHANS approach can enable integrated socio-ecological insights and foster innovative solutions for improving resource management and cost-effectiveness of disaster recovery plans.

CHANS-Law: preventing the next pandemic through the integration of social and environmental law

Zoonotic viruses have sacrificed hundreds of millions of people throughout human history. There are currently 1.7 million unidentified viruses estimated to be circulating in mammal and bird populations. It is foreseeable that in the near future, another of these will transmit to people, heralding the start of the next pandemic—one potentially more deadly than COVID-19. At the core of this article is a call for pre-emptive protection of the natural environment and its regenerative systems as the first fundamental step in the prevention of future epidemics and pandemics. While zoonoses originate in nature, the predominant legal discipline, managing these crises, is international health law which is invoked reactively once an outbreak has been reported. In this paper, we identify the need for a legal shift in epidemic and pandemic responses. In particular, we call for the incorporation of international environmental agreements to prevent the initial viral spillover from animal to human populations. We propose a strategy of strengthening existing agreements and a coupling of legal disciplines, such as health and environmental law, emphasizing the need for synergies across legal disciplines to enhance the emergence and management of future pandemics and epidemics. We introduce Coupled Human and Natural Systems (CHANS) Law to frame the required integration across legal instruments to regulate inextricably human-nature connections and advocate for the development of a Convention on Epidemics and Pandemics.

Climate Gentrification: Methods, Gaps, and Framework for Future Research

The topic of climate gentrification has been receiving increasing attention in both peer-reviewed literature and in popular discourse. Climate gentrification refers to the ways that climate impacts and adaptations may contribute to changes in community characteristics and potential displacement of vulnerable residents through changes in property values. Here, we conduct a review of the current literature on climate gentrification in order to understand methods and key themes, identify research gaps, and guide future research. Our search yielded a total of 12 relevant articles, beginning in 2018. After reviewing these articles, we identified several key methodological gaps including the lack of participatory methods, limited availability of longitudinal data, difficulty defining and measuring displacement, and challenges surrounding causality. We suggest that future work on climate gentrification should draw from Coupled Human and Natural Systems (CHANS) theory to further understand the complex feedbacks that exist in climate gentrification dynamics. To guide future research, we propose a framework as a CHAN that highlights the multi-spatial, multi-temporal, and multi-faceted dimensions of climate gentrification.

Complex Effects of Telecouplings on Forest Dynamics: An Agent-Based Modeling Approach

Abstract Rural areas are increasingly subject to the effects of telecouplings (socioeconomic and environmental interactions over distances) whereby their human and natural dynamics are linked to socioeconomic and environmental drivers operating far away, such as the growing demand for labor and ecosystem services in cities. Although there have been many studies evaluating the effects of telecouplings, telecouplings in those studies were often investigated separately, and how telecouplings may interact and affect dynamics of rural coupled human and natural systems (CHANS) jointly was rarely evaluated. In this study, we developed an agent-based model and simulated the impacts of two globally common telecouplings, nature-based tourism and labor migration, on forest dynamics of a rural CHANS, China’s Wolong Nature Reserve (Wolong). Nature-based tourism and labor migration can facilitate forest recovery, and the predicted forest areas in Wolong in 2030 would be reduced by 26.2 km2 (6.8%) and 23.9 km2 (6.2%), respectively, without their effects. However, tourism development can significantly reduce the probability of local households to have member(s) outmigrate to work in cities and decrease the positive impact of labor migration on forest recovery. Our simulations show that the interaction between tourism and labor migration can reduce the potential forest recovery by 3.5 km2 (5.0%) in 2030. Our study highlights that interactions among different telecouplings can generate significant impacts on socioeconomic and environmental outcomes and should be jointly considered in the design, management, and evaluation of telecouplings for achieving sustainable development goals. Significance Statement Rural areas are increasingly connected with other places through telecouplings, such as tourism and labor migration. However, telecouplings’ effects were often evaluated separately, and their interaction remains poorly understood. In this study, we evaluated how two globally common telecouplings, tourism and labor migration, jointly affect forest dynamics in a demonstration site using an agent-based modeling approach. Although both tourism and labor migration can benefit forest conservation, we found that their interaction generates an antagonistic effect: households’ involvement in tourism activities reduces their probability to have members outmigrate to work in cities and significantly diminishes the beneficial impact of labor migration on forest recovery. Our study highlights the importance of considering interaction among telecouplings in the management of telecouplings for sustainability.

Pollution controls in Lake Tai with the reduction of the watershed nitrogen footprint

To feed an increasingly affluent population, the nitrogen input into global food production systems is currently two times the safe planetary boundary leading to adverse impacts on the local and global environments. The nitrogen footprint is an important index to understand the impact of human activities on the environment, however, it is rarely applied at a watershed scale. By using the Coupled Human And Natural System (CHANS) model, it was found that the total nitrogen input to the Lake Tai watershed has increased from 141.1 Gg N yr−1 in 1995 to 244.3 Gg N yr−1 in 2010, and then decreased again to 201.2 Gg N yr−1 in 2015. The study findings are consistent with the change in the total nitrogen concentration observed in Lake Tai. While the per capita nitrogen footprint remained stable at around 30 kg N yr−1 before 2010, a substantial decrease to approximately 25 and 20 kg N yr−1 in 2010 and 2015, respectively, has occurred. Dominant sources of nitrogen emissions contributing to the nitrogen footprint gradually have changed from agricultural production to wastewater and nitrogen oxides emissions from fossil fuel combustion. A reduction of the nitrogen footprint is beneficial for effective nitrogen pollution control strategies and better wastewater treatment techniques should be prioritized for future policymaking.

Resilience as a Moving Target: An Evaluation of Last Century Management Strategies in a Dry-Edge Maritime Pine Ecosystem

Forests are intrinsically coupled to human dynamics, both temporally and spatially. This evolution is conditioned by global changes in climatic conditions (teleconnections) and distant socio-economical processes (telecoupling). The main goal of this study is to describe the teleconnections and telecoupling dynamics that have shaped structure and processes in a dry-edge—highly vulnerable to desertification—Mediterranean pine forest during the last century and to evaluate the contribution of historical management strategies to this coupled human and natural system’s (CHANS) overall resilience. For this study, we collected relevant human and natural system data from a dry edge Pinus pinaster Ait. located forest in Central Spain using a CHANS analytical framework operationalizing telecoupling and teleconnection. A key extractive economic activity in the studied forest was resin tapping, which was the main form of land use from the 1920s to the 1950s. Since the 1950s changes in the Spanish economy linked to the emergence of new resin-producing countries, such as China, led to a sharp decline in resin production. Despite additional human system transformations affecting forest governance (e.g., the Spanish Civil War, the transition to democracy, European integration, etc.) and changes in biophysical conditions linked to climate change (e.g., aridification, CO2 fertilization), the standing stocks of P. pinaster increased during the monitoring period due to sound technical and management planning bolstering overall resilience. These historical management decisions, we argue, successfully reconciled overall resilience goals (defined as the maintenance of forest function beyond and desertification avoidance) with three successive historical forest use challenges: intensive firewood collection by local communities in fragile sandy soils, extensive pastoralism in the forest understory and tradeoffs between resin tapping damaged trees, timber production and tree cover as well as the emerging risks of wildfire and climate change.

Uncertainty of nitrogen budget in China

The accuracy of the nitrogen (N) budget is of great importance for evidence-based decision-making to address both food security and environmental protection challenges. This study attempts to advance understanding of uncertainties in China's N budget using the Coupled Human And Natural Systems (CHANS) model and Monte Carlo simulation from 1980 to 2018. Results show that the spatial and temporal variations in agricultural and industrial activities and insufficient knowledge on N cycling parameterization are the two dominant causes of uncertainties in the N budget in China. Uncertainties of N inputs generally are <10%, while they are <30% for N outputs and >30% for N accumulations. Uncertainty of nitrogen oxides emission is more sensitive to energy consumption due to the large contributions from industry and transportation. While the uncertainty of ammonia emission is predominantly affected by agricultural activity. Combining surface measurements, satellite observations, and atmospheric simulation models enables cross-check of N fluxes in multiple systems and reduces uncertainties of N budget.