Human-earth System Research Articles

Uncertainty-informed selection of CMIP6 Earth system model subsets for use in multisectoral and impact models

Abstract. Earth system models (ESMs) and general circulation models (GCMs) are heavily used to provide inputs to sectoral impact and multisector dynamic models, which include representations of energy, water, land, economics, and their interactions. Therefore, representing the full range of model uncertainty, scenario uncertainty, and interannual variability that ensembles of these models capture is critical to the exploration of the future co-evolution of the integrated human–Earth system. The pre-eminent source of these ensembles has been the Coupled Model Intercomparison Project (CMIP). With more modeling centers participating in each new CMIP phase, the size of the model archive is rapidly increasing, which can be intractable for impact modelers to effectively utilize due to computational constraints and the challenges of analyzing large datasets. In this work, we present a method to select a subset of the latest phase, CMIP6, featuring models for use as inputs to a sectoral impact or multisector dynamics models, while prioritizing preservation of the range of model uncertainty, scenario uncertainty, and interannual variability in the full CMIP6 ensemble results. This method is intended to help impact modelers select climate information from the CMIP archive efficiently for use in downstream models that require global coverage of climate information. This is particularly critical for large-ensemble experiments of multisector dynamic models that may be varying additional features beyond climate inputs in a factorial design, thus putting constraints on the number of climate simulations that can be used. We focus on temperature and precipitation outputs of CMIP6 models, as these are two of the most used variables among impact models, and many other key input variables for impacts are at least correlated with one or both of temperature and precipitation (e.g., relative humidity). Besides preserving the multi-model ensemble variance characteristics, we prioritize selecting CMIP6 models in the subset that preserve the very likely distribution of equilibrium climate sensitivity values as assessed by the latest Intergovernmental Panel on Climate Change (IPCC) report. This approach could be applied to other output variables of climate models and, possibly when combined with emulators, offers a flexible framework for designing more efficient experiments on human-relevant climate impacts. It can also provide greater insight into the properties of existing CMIP6 models.

GCAM–GLORY v1.0: representing global reservoir water storage in a multi-sector human–Earth system model

Abstract. Reservoirs play a significant role in modifying the spatiotemporal availability of surface water to meet multi-sector human demands, despite representing a relatively small fraction of the global water budget. Yet the integrated modeling frameworks that explore the interactions among climate, land, energy, water, and socioeconomic systems at a global scale often contain limited representations of water storage dynamics that incorporate feedbacks from other systems. In this study, we implement a representation of water storage in the Global Change Analysis Model (GCAM) to enable the exploration of the future role (e.g., expansion) of reservoir water storage globally in meeting demands for, and evolving in response to interactions with, the climate, land, and energy systems. GCAM represents 235 global water basins, operates at 5-year time steps, and uses supply curves to capture economic competition among renewable water (now including reservoirs), non-renewable groundwater, and desalination. Our approach consists of developing the GLObal Reservoir Yield (GLORY) model, which uses a linear programming (LP)-based optimization algorithm and dynamically linking GLORY with GCAM. The new coupled GCAM–GLORY approach improves the representation of reservoir water storage in GCAM in several ways. First, the GLORY model identifies the cost of supplying increasing levels of water supply from reservoir storage by considering regional physical and economic factors, such as evolving monthly reservoir inflows and demands, and the leveled cost of constructing additional reservoir storage capacity. Second, by passing those costs to GCAM, GLORY enables the exploration of future regional reservoir expansion pathways and their response to climate and socioeconomic drivers. To guide the model toward reasonable reservoir expansion pathways, GLORY applies a diverse array of feasibility constraints related to protected land, population, water sources, and cropland. Finally, the GLORY–GCAM feedback loop allows evolving water demands from GCAM to inform GLORY, resulting in an updated supply curve at each time step, thus enabling GCAM to establish a more meaningful economic value of water. This study improves our understanding of the sensitivity of reservoir water supply to multiple physical and economic dimensions, such as sub-annual variations in climate conditions and human water demands, especially for basins experiencing socioeconomic droughts.

FeliX 2.0: An integrated model of climate, economy, environment, and society interactions

The Full of Economic-Environment Linkages and Integration dX/dt (FeliX) model is a System Dynamics-based Integrated Assessment Model (IAM), explicitly incorporating human behaviors and their dynamic interactions among global systems. This paper presents FeliX 2.0, describing the detailed framework and key interactions among nine integrated modules. FeliX 2.0 refined its original version in population dynamics, food and land use systems, and socioeconomic settings for poverty analysis. Robust calibration is applied to key variables against their historical data since 1950. Future projections of multiple variables up to 2100 demonstrate coherences between FeliX 2.0 and the IAMs used in IPCC assessments. Both outputs (the robust calibration results and future projections) underscore the efficacy of FeliX 2.0 in capturing complex interdependencies within global systems. FeliX 2.0 stands as an informative tool and offers insights into interactions within the human-Earth system and the analysis of complex economic-environmental-social challenges in short- and long-term future.

A consistent dataset for the net income distribution for 190 countries and aggregated to 32 geographical regions from 1958 to 2015

Abstract. Data on income distributions within and across countries are becoming increasingly important for informing analysis of income inequality and understanding the distributional consequences of climate change. While datasets on income distribution collected from household surveys are available for multiple countries, these datasets often do not represent the same concept of inequality (or income concept) and therefore make comparisons across countries, over time and across datasets difficult. Here, we present a consistent dataset of income distributions across 190 countries from 1958 to 2015 measured in terms of net income. We complement the observed values in this dataset with values imputed from a summary measure of the income distribution, specifically the Gini coefficient. For the imputation, we use a recently developed nonparametric principal-component-based approach that shows an excellent fit to data on income distributions compared to other approaches. We also present another version of this dataset aggregated from the country level to 32 geographical regions. Our dataset is developed for the purpose of calibrating models such as integrated human–Earth system models with detailed data on income distributions. This dataset will enable more robust analysis of income distribution at multiple scales. The latest version of our data are available on Zenodo: https://doi.org/10.5281/zenodo.7093997 (Narayan et al., 2022b).

Evolution Characteristics and Influencing Factors of the Human-Earth System in Minority Areas of Yunnan, China

Evolution Characteristics and Influencing Factors of the Human-Earth System in Minority Areas of Yunnan, China

Limited increases in Arctic offshore oil and gas production with climate change and the implications for energy markets

Climate change impacts on sea ice thickness is opening access to offshore Arctic resources. The degree to which these resources are exploited will depend on sea-ice conditions, technology costs, international energy markets, and the regulatory environment. We use an integrated human-Earth system model, GCAM, to explore the effects of spatial–temporal patterns of sea-ice loss under climate change on future Arctic offshore oil and gas extraction, considering interactions with global energy markets and emission reduction scenarios. We find that under SSP5, a “fossil-fueled development” scenario, the effects of sea-ice loss are larger for Arctic offshore oil production than gas. Under SSP5, future extraction of Arctic offshore oil and gas through 2100 adds roughly 0.8–2.6 EJ/year to oil and gas markets but does not have large impacts on global oil and gas markets. Surprisingly, a low-carbon scenario results in greater Arctic offshore oil production to offset the more emissions-intensive unconventional oil production.

Dynamic urban land extensification is projected to lead to imbalances in the global land-carbon equilibrium

Human-Earth System Models and Integrated Assessment Models used to explore the land-atmosphere implications of future land-use transitions generally lack dynamic representation of urban lands. Here, we conduct an experiment incorporating dynamic urbanization in a multisector model framework. We integrate projected dynamic non-urban lands from a multisector model with projected dynamic urban lands from 2015 to 2100 at 1-km resolution to examine 1st-order implications to the land system, crop production, and net primary production that can arise from the competition over land resources. By 2100, future urban extensification could displace 0.1 to 1.4 million km2 of agriculture lands, leading to 22 to 310 Mt of compromised corn, rice, soybean, and wheat production. When considering increased corn production required to meet demands by 2100, urban extensification could cut increases in yields by half. Losses in net primary production from displaced forest, grassland, and croplands ranged from 0.24 to 2.24 Gt C yr−1, potentially increasing land emissions by 1.19 to 6.59 Gt CO2 yr−1. Although these estimates do not consider adaptive responses, 1st-order experiments can elucidate the individual role of sub-sectors that would otherwise be masked by model complexity.

Advocating Feedback Control for Human-Earth System Applications

Advocating Feedback Control for Human-Earth System Applications

Interactive relationship and zoning management between county urbanization and ecosystem services in the Loess Plateau

The interaction between urbanization and ecosystem services (ESs) is a hot topic in the modern human-earth system science. Currently, most studies only focus on the effects of urbanization on ESs supply, few studies have accurately quantified the ESs demand and explored the spatial–temporal coupling interactions between urbanization and ESs supply–demand balance. To address these gaps, this study used process-based modeling to estimate the absolute number of ESs demand. Ecosystem supply–demand ratio (ESDR) is employed to measure the ESs balance. Finally, pearson correlation analysis, coupling coordination degree model, and bivariate local Moran’s I method were used to explore the interactive relationship between urbanization and ESs balance in the Loess Plateau (LP). Results indicated that the LP experienced rapid urbanization with characteristics of faster economic urbanization than land and population urbanization from 2000 to 2018. Negative correlations between construction land proportion and ESDR enhanced over time. Although the coupling coordination degree between urbanization and ESDR increased, most counties were mild incoordination and basic coordination. The spatial interaction of urbanization and ESDR was divided into four types: co-promotion type, ecological lag type, urbanization lag type, and co-loss type. This study can contribute to providing a scientific reference and practical guidance for coordinating ecological protection and high-quality development in underdeveloped areas.

Enhancing the representation of water management in global hydrological models

Abstract. This study enhances an existing global hydrological model (GHM), Xanthos, by adding a new water management module that distinguishes between the operational characteristics of irrigation, hydropower, and flood control reservoirs. We remapped reservoirs in the Global Reservoir and Dam (GRanD) database to the 0.5∘ spatial resolution in Xanthos so that a single lumped reservoir exists per grid cell, which yielded 3790 large reservoirs. We implemented unique operation rules for each reservoir type, based on their primary purposes. In particular, hydropower reservoirs have been treated as flood control reservoirs in previous GHM studies, while here, we determined the operation rules for hydropower reservoirs via optimization that maximizes long-term hydropower production. We conducted global simulations using the enhanced Xanthos and validated monthly streamflow for 91 large river basins, where high-quality observed streamflow data were available. A total of 1878 (296 hydropower, 486 irrigation, and 1096 flood control and others) out of the 3790 reservoirs are located in the 91 basins and are part of our reported results. The Kling–Gupta efficiency (KGE) value (after adding the new water management) is ≥ 0.5 and ≥ 0.0 in 39 and 81 basins, respectively. After adding the new water management module, model performance improved for 75 out of 91 basins and worsened for only 7. To measure the relative difference between explicitly representing hydropower reservoirs and representing hydropower reservoirs as flood control reservoirs (as is commonly done in other GHMs), we use the normalized root mean square error (NRMSE) and the coefficient of determination (R2). Out of the 296 hydropower reservoirs, the NRMSE is > 0.25 (i.e., considering 0.25 to represent a moderate difference) for over 44 % of the 296 reservoirs when comparing both the simulated reservoir releases and storage time series between the two simulations. We suggest that correctly representing hydropower reservoirs in GHMs could have important implications for our understanding and management of freshwater resource challenges at regional-to-global scales. This enhanced global water management modeling framework will allow the analysis of future global reservoir development and management from a coupled human–earth system perspective.

Anthropogenic activities mediate stratification and stability of microbial communities in freshwater sediments

BackgroundFreshwater sediment microbes are crucial decomposers that play a key role in regulating biogeochemical cycles and greenhouse gas emissions. They often exhibit a highly ordered structure along depth profiles. This stratification not only reflects redox effects but also provides valuable insights into historical transitions, as sediments serve as important archives for tracing environmental history. The Anthropocene, a candidate geological epoch, has recently garnered significant attention. However, the human impact on sediment zonation under the cover of natural redox niches remains poorly understood. Dam construction stands as one of the most far-reaching anthropogenic modifications of aquatic ecosystems. Here we attempted to identify the ecological imprint of damming on freshwater sediment microbiome.ResultsWe conducted a year-round survey on the sediment profiles of Lake Chaohu, a large shallow lake in China. Through depth-discrete shotgun metagenomics, metataxonomics, and geophysiochemical analyses, we unveiled a unique prokaryotic hierarchy shaped by the interplay of redox regime and historical damming (labeled by the 137Cs peak in AD 1963). Dam-induced initial differentiation was further amplified by nitrogen and methane metabolism, forming an abrupt transition governing nitrate–methane metabolic interaction and gaseous methane sequestration depth. Using a random forest algorithm, we identified damming-sensitive taxa that possess distinctive metabolic strategies, including energy-saving mechanisms, unique motility behavior, and deep-environment preferences. Moreover, null model analysis showed that damming altered microbial community assembly, from a selection-oriented deterministic process above to a more stochastic, dispersal-limited one below. Temporal investigation unveiled the rapid transition zone as an ecotone, characterized by high species richness, low community stability, and emergent stochasticity. Path analysis revealed the observed emergent stochasticity primarily came from the high metabolic flexibility, which potentially contributed to both ecological and statistical neutralities.ConclusionsWe delineate a picture in which dam-induced modifications in nutrient availability and sedimentation rates impact microbial metabolic activities and generate great changes in the community structure, assembly, and stability of the freshwater sediment microbiome. These findings reflect profound ecological and biogeochemical ramifications of human–Earth system interactions and help re-examine the mainstream views on the formation of sediment microbial stratification.CKW67QzkRJsDF17fMBne_jVideo

Study on the efficiency evolution trend of coordinated development of the human–earth system in minority areas of Yunnan, China

IntroductionImproving the development efficiency of human–earth systems is a practical requirement for achieving high-quality regional development.MethodsThe article designs a data envelopment analysis (DEA) model under the constraints of coordinated development degree from the perspective of the interaction of natural, economic and social systems to evaluate the development efficiency of human–earth systems and uses GA-BP neural network model for the prediction of the development efficiency of the human–earth system of each geographical unit from 2018 to 2025 based on the panel data of the 8 ethnic autonomous prefectures in Yunnan Province form 1995 to 2017.ResultsThe study found that from 1995 to 2017, the coordination degree and the coordinated development degree of the human–earth system in Yunnan minority areas were on the rise, but mainly manifested in the coordination of low development degree, and the average comprehensive efficiency value of input and output showed a downward trend. The prediction results for 2018–2025 showed that the human–earth system in Yunnan minority areas will be at a low efficient coordinated development level, and the coordinated development degree will show a downward trend. The development degree of natural subsystems in many ethnic minority areas showed negative growth and was negatively correlated with the development degree of economic and social subsystems. In 2025, except Honghe and Banna, the other six regions will be inefficient regions. Among these six inefficient regions, only Wenshan has input redundancy in the natural subsystem, but the phenomenon of input redundancy in the economic subsystem and insufficient output in the natural subsystem is common, indicating that industrial pollution has been controlled to a certain extent in most regions, but the economic investment mode and resource recycling efficiency need to be optimized and improved.DiscussionOur results could enrich the content of human–earth system characteristics in typical regions, and also provide theoretical support for regional coordinated development in China.

Scientific cognition and detection methods of modern human-earth system

Scientific cognition and detection methods of modern human-earth system

Flood hazard potential reveals global floodplain settlement patterns

Flooding is one of the most common natural hazards, causing disastrous impacts worldwide. Stress-testing the global human-Earth system to understand the sensitivity of floodplains and population exposure to a range of plausible conditions is one strategy to identify where future changes to flooding or exposure might be most critical. This study presents a global analysis of the sensitivity of inundated areas and population exposure to varying flood event magnitudes globally for 1.2 million river reaches. Here we show that topography and drainage areas correlate with flood sensitivities as well as with societal behaviour. We find clear settlement patterns in which floodplains most sensitive to frequent, low magnitude events, reveal evenly distributed exposure across hazard zones, suggesting that people have adapted to this risk. In contrast, floodplains most sensitive to extreme magnitude events have a tendency for populations to be most densely settled in these rarely flooded zones, being in significant danger from potentially increasing hazard magnitudes given climate change.

Understanding integrated human-Earth system models as boundary objects: Enhancing credibility and interdisciplinary collaboration

Integrated human-Earth system models could be a useful tool for interdisciplinary collaboration on sustainability issues. However, it is challenging to integrate all disciplines equally. Considering modeling frameworks as boundary objects could help. In this perspective, a modeling framework, while clearly defined in its basic function, could be adapted and reinterpreted by researchers from different disciplines according to their specific contexts and questions, yet the framework still remains a common reference point behind these different adaptations. This flexibility and plasticity could contribute to the evolution of the modeling framework itself. The authors discuss how this might look, using the copan:CORE framework as an example.

A brief review of the coupled human-Earth system modeling: Current state and challenges

Human activities have profound impacts on climate and ecosystems via fossil fuel use and land-use changes, and environmental changes in turn affect human society. Due to strong bidirectional links between the human society and the environment, there is a need to understand the complex dynamics of coupled human-Earth systems (CHES) for mitigation and adaptation purposes. In this paper, four main feedback links between human and Earth systems are identified, and the simulated impacts of some of these feedbacks on natural and social variables based on CHES models are examined. To better understand the current state of CHES modeling, the model development history is briefly described including the implementation of several different coupling forms and approaches. The CHES models are still in a quickly developing stage facing several gaps and challenges in theoretical understanding and modeling techniques. To meet these gaps and challenges, more studies across different research communities with truly interdisciplinary collaboration are required.

Impacts of climatic zones on urban heat island: Spatiotemporal variations, trends, and drivers in China from 2001–2020

Urban heat island (UHI) adversely impacts the human-earth system. However, the impact of climatic zones on UHI remains unclear. This study, therefore, aimed at investigating how climatic zones affect spatiotemporal variations, trends and potential drivers of surface UHI intensity (SUHII) based upon 253 Chinese cities in five climatic zones: middle temperate zone (MTZ), south temperate zone (STZ), north subtropical zone (NSZ), middle subtropical zone (MSZ), and south subtropical zone (SSZ) during 2001–2020. The results showed that the SUHII ranged from -2.59 to 6.20 °C, average daytime SUHII showed higher seasonal fluctuations and larger variation than nighttime and summer daytime had the highest seasonal and annual SUHII variation (SUHIISAV). Cities in NSZ, MSZ, and SSZ had high average daytime SUHIISAV and a large proportion had significant increasing trends (TrendSI) (P<0.05) from 2001–2020, while the nighttime showed opposite rule in general. Random forest (RF) model explained 68% of day/night SUHIISAV on average. Except for city area, which greatly impacted day/night SUHIISAV in all periods and climatic zones, other drivers more significantly influenced SUHII in certain periods and climatic zones, e.g. aerosol optical depth (AOD) in winter nighttime in MTZ and STZ. Compared with single or serval drivers’ determination of UHI effect, we highlighted the multi-factor driven of day/night SUHIISAV. Specific suggestions, e.g. controlling haze pollution can bring co-benefits on urban air quality and UHI mitigation were proposed. These findings could help to provide valuable reference for future climatic adaptive strategy.

Identifying ecosystem service supply-demand imbalance for sustainable land management in China’s Loess Plateau

Supply-demand relationships of ecosystem services (ESs) are the core of human-earth system coupling. This study explored the spatiotemporal characteristic of ESs supply-demand relationships and revealed the influencing factors of ESs balance based on the redundancy analysis in China’s Loess Plateau (LP). Results indicated that the total food and soil conservation were surplus from 2000 to 2018, while water and carbon existed deficits in some years. The ESs supply pairs generally showed a tendency of weakening synergies and strengthening trade-offs, while the ESs demand pairs were mainly synergistic. The dominant supply-demand match type of water yield changed from Low supply-Low demand (L-L) pattern to High supply-Low demand (H-L) pattern, while the food supply and soil conservation mainly presented L-L pattern. Slope, contagion index and construction land area ratio were the dominant influencing factors of ESs balance. Our findings suggested that ESs should be considered into land use policies making and spatial planning for alleviating ESs deficits and coordinating regional human-earth relationship.

Sustainable Revitalization and Green Development Practices in China’s Northwest Arid Areas: A Case Study of Yanchi County, Ningxia

Consolidating and expanding the achievements of poverty alleviation, and effectively connecting it with rural revitalization, are part of an important path to achieving sustainable poverty alleviation and common prosperity in China, especially in its northwest arid areas. In this paper, the human–earth system was employed to analyze the elemental composition, structural organization, and functional state of China’s northwest arid areas. The results revealed the following: (1) poverty in northwest arid areas stems from the lack of a coupling and coordinating mechanism among humans, the economy, resources, and environmental elements; this is not conducive to transforming ecological advantages into regional development. (2) In the antipoverty stage, China’s northwest arid areas innovate human–earth coupling and a coordinating mechanism through a series of targeted measures. (3) We found that three paths, namely “promoting the integration of featured advantageous industries and tourism culture, innovating the realization path according to local conditions, and paying attention to the subjectivity of farmers” broaden the means of sustainable livelihood, consolidate the achievements of poverty alleviation, and achieve rural revitalization. (4) In particular, it is necessary to practice the concept of green development and pursue ecological industrialization by establishing a policy system of green land-people-industry-right, thus building an endogenous growth mechanism of sustainable poverty alleviation and green development in China’s northwest arid areas. The results provide theoretical support and model reference for the effective connection between consolidating and expanding the key achievements of poverty alleviation and rural revitalization in China’s northwest arid areas.

China's Rural Areas toward 2035: Vision, Challenges and Strategies

Rural revitalization and development are mainly based on the urban-rural integration, which can be regarded as a key factor for China's rural land-use policy reform. This paper focuses on the research of the theory, technology, and management of rural revitalization from the perspective of the human-earth areal system. Firstly, this paper constructs the regional digital economy development evaluation index system according to the three-step selection process of indicators. Secondly, this research uses land engineering for land capacity building as the technical support to solve rural issues and constructs a framework of rural land management policy reform in China. Finally, the research results show that the consolidation of hollowed villages as well as gullied, degraded, and sandy land for highstandard farmland has been implemented, providing an important approach in improving land productivity. Collaboration among policymakers, multilateral organizations, and the private sector is crucial in filling gaps in solving the current problems.