Global Water Research Articles

An investigation of a proposed freezing desalination system integrating sweating effect and a Centrifugal-Based brine rejection technique

Freeze desalination (FD) presents a promising yet underutilized technique for addressing global water scarcity, hindered by challenges such as the necessity for ice crushing and washing. This study introduces an innovative FD system incorporating sweating effects and centrifugal brine rejection, aiming to simplify the process by eliminating these additional steps. We evaluate the impact of key variables including sweating period, centrifugation duration, and rotational velocity on ice quality and process efficiency. Through systematic examination, our findings reveal that the sweating period significantly influences product salinity and salt rejection efficiency, achieving a salinity reduction from 40 ppt to 0.99 ppt with a 95.05 % salt rejection rate. Additionally, the centrifugation method showcased low power consumption, marking a significant advancement towards more sustainable desalination practices. This research not only demonstrates the feasibility of the proposed FD system but also sets the groundwork for future enhancements in the field of desalination technology.

Janus membrane with heterogeneous wettability top surface for fog harvesting

To alleviate the global water scarcity crisis, fog harvesting has seen considerable development as a promising strategy. However, the current main challenge lies in achieving efficient fog deposition, timely transport of water droplets, and storage. Here, inspired by clusters of cactus trichomes and sponges, a Janus membrane with heterogeneous wettability top surface (JM-HWTS) is proposed. The JM-HWTS was obtained by spraying paraffin wax particles (hydrophobic) on the copper mesh top surface (superhydrophilic). The relationship between the loading amount of paraffin particles and the surface morphology, water permeability, and one-way penetration ability of the sample was clarified. Compared to fog collection surfaces with single hydrophilic or hydrophobic properties, the proposed JM-HWTS system significantly increased fog collection efficiency. For JM-HWTS, the fog will first deposit into water droplets on the hydrophobic front side, then grow up, and finally be sucked into the hydrophilic back side. This unique cyclic fog collection method is the key to efficient fog collection. The JM-HWTS exhibits excellent water-collection efficiency, enabling efficient capture of fog and rapid directional delivery of droplets. This work will significantly complement the fog collection and water droplet storage fields.

Characterizing the multisectoral impacts of future global hydrologic variability

There is significant uncertainty in how global water supply will evolve in the future, due to uncertain climate, socioeconomic, and land use change drivers and variability of hydrologic processes. It is critical to characterize the potential impacts of uncertainty in future water supply given its importance for food and energy production. In this work, we introduce a framework that integrates stochastic hydrology and human-environmental systems to characterize uncertainty in future water supply and its multisector impacts. We develop a global stochastic watershed model and demonstrate that this model can generate a large ensemble of realizations of basin-scale runoff with global coverage that preserves the mean, variance, and spatial correlation of a historical benchmark. We couple this model with a well-known human-environmental systems model to explore the impacts of runoff variability on the water and agricultural sectors across spatial scales. We find that the impacts of future hydrologic variability vary across sectors and regions. Impacts are felt most strongly in the water and agricultural sectors for basins that are expected to have unsustainable water use in the future, such as the Indus River basin. For this basin, we find that the variability in future irrigation water withdrawals and irrigated cropland increase over time due to uncertainty in renewable water supply. We also use the Indus basin to show how our stochastic ensemble can be leveraged to explore the global multisector consequences of local extreme runoff conditions. This work introduces a novel technique to explore the propagation of future hydrologic variability across human and natural systems and spatial scales.

Koopman neural operator as a mesh-free solver of non-linear partial differential equations

The lacking of analytic solutions of diverse partial differential equations (PDEs) gives birth to a series of computational techniques for numerical solutions. Although numerous latest advances are accomplished in developing neural operators, a kind of neural-network-based PDE solver, these solvers become less accurate and explainable while learning long-term behaviors of non-linear PDE families. In this paper, we propose the Koopman neural operator (KNO), a new neural operator, to overcome these challenges. With the same objective of learning an infinite-dimensional mapping between Banach spaces that serves as the solution operator of the target PDE family, our approach differs from existing models by formulating a non-linear dynamic system of equation solution. By approximating the Koopman operator, an infinite-dimensional operator governing all possible observations of the dynamic system, to act on the flow mapping of the dynamic system, we can equivalently learn the solution of a non-linear PDE family by solving simple linear prediction problems. We validate the KNO in mesh-independent, long-term, and zero-shot predictions on five representative PDEs (e.g., the Navier-Stokes equation and the Rayleigh-Bénard convection) and three real dynamic systems (e.g., global water vapor patterns and western boundary currents). In these experiments, the KNO exhibits notable advantages compared with previous state-of-the-art models, suggesting the potential of the KNO in supporting diverse science and engineering applications (e.g., PDE solving, turbulence modeling, and precipitation forecasting).

Equity in water resource management: A theoretical dynamism

AbstractAs elusive as the concept of equity may be, it has nevertheless been placed at the heart of global water policy. Yet inequities in access to water and participation in water resources management persist all over the world. The global water crisis is one of inequitable access rather than availability. This critical review explores equity and equality in water resources management through multiple lenses, considering its numerous philosophical underpinnings, and offers a definition of ‘water equity’. We suggest that human rights, procedural and distributive equity (social justice), and cultural, socioeconomic, and political elements (context) are the pillars of water equity. The inter‐relatedness between them and causal effects of each of the pillars are exposed, as are cross cutting features. This contribution to the theoretical interpretation of ‘water equity’ suggests that it is a complex dynamism, a complexity of interrelated features that are constantly in flux. Acknowledging the inherent characteristics of water equity will greatly facilitate its actualisation.

Impact of Drip Irrigation with Recycled Wastewater on Aromatic Compound Composition in Capia Pepper (Capsicum annum L.)

In recent years, treating and reusing polluted water for agricultural irrigation has become essential to ensuring water and food sustainability. In addition to the factors affecting human health in vegetables and fruits irrigated with treated wastewater, factors affecting consumer preferences, such as flavor and phenolic compounds, should also be examined. This study investigates the effect of treated wastewater irrigation on the aromatic compounds and phenolic composition of capia pepper, which holds a significant position and is extensively used in various food products in the food industry. Drip irrigation with treated and untreated wastewater from the Kalecik Wastewater Treatment Plant was applied to two pepper varieties in the Kalecik district of Ankara, Türkiye. This research found that wastewater irrigation impacted certain aroma components, including para-dichlorobenzene, alpha-cubebene, hexanoate, alpha-farnesene, limonene, isoamyl butyrate, squalene, and alpha-copaene, which contribute to the distinct aroma and fragrance of capia peppers. Total phenolic content, pH, and soluble solids were found to be high in peppers irrigated with wastewater, and it was observed that these parameters increased as the treatment levels of the wastewater decreased. The highest results were obtained in capia peppers irrigated with wastewater. Results indicate that heavy metal levels in peppers align with permissible limits, confirming the usability of both water sources. In the face of global water scarcity and the challenge of feeding an ever-growing population, studies like this offer valuable insights into sustainable and well-informed agricultural practices.

Evaluating trends in groundwater quality of coastal alluvial aquifers of Eastern India for sustainable groundwater management.

Groundwater is a precious natural element which ensures global water, food, and environmental security in the twenty-first century. Systematic monitoring, sustainable utilization, preservation and remediation are critical aspects of efficient groundwater resource management. This study deals with the analysis of spatial variability and trend in groundwater chemistry as well as identification of possible contamination sources in a coastal alluvial basin of eastern India. Pre-monsoon season data of 14 groundwater-quality variables measured in 'leaky confined' and 'confined' aquifers were analyzed for ten years (2012-2021). Mann-Kendall (M-K) test with the Sen's Slope Estimator, Spearman Rank Order Correlation (SROC) and Innovative Trend Analysis (ITA) tests were employed to assess decadal (2012-2021) trends. The analysis of the results indicated that the 'critical' water-quality parameters exceeding the acceptable limits for drinking are TDS, EC, TH, pH, Mg2+, Na+, K+, Fe2+, HCO3-, Cl- and NO3-. Weak negative correlations between rainfall and groundwater elevation for both the aquifers reveal poor rainfall recharge into the aquifers. Therefore, a reduction in groundwater abstraction and augmentation of groundwater recharge is recommended. Trend analysis results indicated that the concentrations of TH, Mg2+ and Fe2+ exhibit significant increasing trends in the 'leaky confined aquifer'. In contrast, significant rising trends in TH, Mg2+, Na+, Fe2+, HCO3- and NO3- concentrations are identified in the 'confined aquifer'. Further, the SROC test could not detect the trends in groundwater quality in most blocks and for many parameters. On the other hand, the ITA test revealed significant trends in most of the parameters of the two aquifers in almost all the blocks. Trend magnitudes of the groundwater-quality parameters based on the Sen's Slope Estimator and the ITA test vary from -63.7 to 58.65mg/L/year for TDS, -14 to 39.07mg/L/year for TH, -1.49 to 4.83mg/L/year for Mg2+, -7.14 to 22.96mg/L/year for Na+, -0.32 to 0.44mg/L/year for Fe2+, -8.33 to 20.75mg/L/year for HCO3-, -26.52 to 31.01mg/L/year for Cl- and 1.29 to 3.76mg/L/year for NO3- over the study area. The results of M-K and ITA tests were found in agreement in all the blocks for both the aquifers. Groundwater contamination in both the aquifers can be attributed to weathering, geogenic processes, mineral dissolution, seawater intrusion, poor recharge pattern and injudicious anthropogenic activities. It is strongly recommended that concerned authorities urgently formulate efficient strategies for managing groundwater quality in the 'leaky confined' and 'confined' aquifers which serve as vital sources of drinking and irrigationwater suppliesin the study area.

Introducing MapSWAT: An open source QGIS plugin integrated with google earth engine for efficiently generating ready-to-use SWAT+ input maps.

Hydrological modeling plays a significant role in addressing global water challenges. Streamlining the implementation of hydrological models enables more people to participate in designing solutions to water issues. This study presents the development and workflow of a QGIS-based tool called MapSWAT, designed to facilitate the application of the Soil and Water Assessment Tool (SWAT+). MapSWAT is an open-source plugin written in Python for collecting and producing ready-to-use SWAT + input maps. It can generate SWAT + input maps for any location globally, including limited data regions, by connecting to the Google Earth Engine. The potential for and feasibility of MapSWAT have been demonstrated through its application in a case study in southeast Spain. The results indicate that MapSWAT is a useful tool for efficiently generating SWAT + input maps that optimizes the hydrological modeling process with SWAT+. The MapSWAT software is freely and publicly available at https://github.com/AdrLBallesteros/MapSWAT.

Integration of coagulation–flocculation and photolysis processes for treating reverse osmosis concentrate (ROC) of pharmaceutical wastewater management

ABSTRACT This study provides novel insights into optimizing the integral treatment process, contributing to ROC treatment strategies. A comprehensive treatment approach for reverse osmosis concentrate (ROC) from pharmaceutical wastewater was investigated using an integral system consisting of a coagulation-flocculation and photolysis process. Ferric chloride (FC) and poly-aluminum chloride (PAC) are examined as coagulants within the range (0.1–1) gL−1, focusing on turbidity, chemical oxygen demand (COD), and total organic carbon (TOC) removal. The findings show that the optimal FeCl3 dosage is 0.4 gL−1, achieving significant turbidity reduction to 1 NTU. PAC at 0.2 gL−1 is optimal, reducing turbidity to 1 NTU and exhibiting non-linear behavior in COD and TOC removal, introducing them as a starting point to the post-treatment. Photolysis of treated samples at pH 7 yields COD reductions of 60.5% for PAC and 79.5% for FC, with respective TOC reductions of 79.5% and 75.23% over 360 min. At (pH 3.5) showed a significant reduction in the COD and TOC of treated ROC. The FC coagulant could decrease the COD from 261 to 5 mgL−1 (98% COD removal) and the TOC from 143.9 to 5 mgL−1 (74.8% TOC removal). The FAC coagulant could decrease the COD from 675 to 39 mgL−1 (93% COD removal) and the TOC from 186 to 13.1 mgL−1 (69.7% TOC removal). The conventional oxidant (H2O2) at optimal dosages enhanced COD and TOC removal at pH 7, with treated PAC and FeCl3 achieving 81.8% and 97.2% COD reduction and 89% and 98% TOC reduction at 360 minutes. These results were supported by the cost analysis in which this system was cost effective manner. This system can offer a solution for the efficient treatment of other types of industrial wastewater and open the door to new applications for water reuse on a broad scale, contributing to global water sustainability.

Machine learning and CORDEX-Africa regional model for assessing the impact of climate change on the Gilgel Gibe Watershed, Ethiopia

Climate change is one of the most pressing challenges of our time, profoundly impacting global water resources and sustainability. This study aimed to predict the long-term effects of climate change on the Gilgel Gibe watershed by integrating machine learning (ML) methods and climate model scenarios. Utilizing an ensemble mean of four regional climate models (RCMs) from the Coordinated Regional Climate Downscaling Experiment (CORDEX) Africa project, we forecast future climatic conditions. Although global and regional climate simulations offer valuable insights, their limitations necessitate alternative approaches, such as ML, for improved accuracy. Employing an ensemble ML model with Random Forest (RF), Extra Tree (ET), and CatBoost (CB) algorithms, we assessed various bias-correction methods using historical data from 1993 to 2009. Our results highlight the effectiveness of distribution mapping (DM) in capturing temperature variability and precipitation patterns, using the power transpiration (PT) method to represent precipitation variability. Projections indicate a decline in future precipitation under the RCP 8.5 (−32.2%) and SSP 4.5 (−88.8%) for 2024–2049, with further decreases expected for 2050–2099. Conversely, temperatures will rise under RCP 4.5 (TMAX 0.67 °C) and RCP 8.5 (TMAX 0.25 °C and TMIN 1.11 °C) in the near term, exacerbated by higher emissions under SSP 4.5 and 8.5. By leveraging an ensemble mean of four observed RCMs in an ML framework, our study successfully reproduced future Coupled Model Intercomparison Project (CMIP5) and (CMIP6) climatic datasets, with the CB model demonstrating superior performance in predicting future precipitation and temperature trends. These findings offer valuable insights for shaping future climate scenarios and informing policy decisions for the Gilgel Gibe Watershed, thereby enhancing water resource management in the basin and its environs.

ANSYS Fluent-CFD analysis of a continuous single-slope single-basin type solar still

The present study endeavours to substantially contribute towards alleviating the global water scarcity problem. The task entailed designing a computational model of a renewable energy-based evaporator. Using ANSYS Fluent, the CFD simulations of a three-dimensional conventional continuous single slope, single basin solar still were carried out in summer at 23.79°N, 86.43°E coordinates. With the optimized inclination condensation angle of 29° and water depth at 1 cm, the solar still recorded the highest hourly drinking water, about 1.5 kg m−2, at 11:00 h. The continuous production resulted in a water collection rate of 8.6 kg m−2 day −1, encompassing the production of all previous models. Additionally, compared with the literature correlation for solar still simulated mass, the Power model calculation was the closest, with a 12.4% variation. Furthermore, the study showcases that CFD is an economical, efficient, and easily diagnosable technique for designing solar stills.

A harmonized global gridded transpiration product based on collocation analysis

Transpiration (T) is pivotal in the global water cycle, responding to soil moisture, atmospheric stress, climate changes, and human impacts. Therefore, establishing a reliable global transpiration dataset is essential. Collocation analysis methods have been proven effective for assessing the errors in these products, which can subsequently be used for multisource fusion. However, previous results did not consider error cross-correlation, rendering the results less reliable. In this study, we employ collocation analysis, taking error cross-correlation into account, to effectively analyze the errors in multiple transpiration products and merge them to obtain a more reliable dataset. The results demonstrate its superior reliability. The outcome is a long-term daily global transpiration dataset at 0.1°from 2000 to 2020. Using the transpiration after partitioning at FLUXNET sites as a reference, we compare the performance of the merged product with inputs. The merged dataset performs well across various vegetation types and is validated against in-situ observations. Incorporating non-zero ECC considerations represents a significant theoretical and proven enhancement over previous methodologies that neglected such conditions, highlighting its reliability in enhancing our understanding of transpiration dynamics in a changing world.

Analysis of the temporal and spatial evolution of turbidity in Tonle Sap Lake and its influencing factors

Turbidity is a crucial indicator of water quality. The European Commission's Copernicus Land Monitoring Service Platform provides free turbidity data for large lakes to monitor the global water quality of lakes. However, the data were missing from April 2012 to April 2016, severely limiting long-term analysis. Based on MODIS and turbidity data, Random Forest and XGBoost models are used to invert Tonle Sap Lake's turbidity. Random Forest outperformed the XGBoost model. Based on Random Forest model, missing data were filled in to construct long-term series data of Tonle Sap Lake turbidity (2004–2021). Trend, persistence and correlation analyses were conducted to reveal spatiotemporal characteristics and driving mechanism of turbidity. The results showed that: (1) spatially, the average annual, monthly, and seasonal turbidity was higher in the north but lower in the south, with regions of higher turbidity exhibiting more significant changes; (2) temporally, the annual turbidity mean was 53.99 NTU and showed an increasing trend. Monthly, turbidity values were higher from March to August and lower from September to February, with the highest and lowest recorded in June and November at 110.06 and 5.82 NTU, respectively. Seasonally, turbidity was higher in spring and summer compared to autumn and winter, with mean turbidity values of 84.16, 93.47, 15.33 and 23.21 NTU, respectively; (3) In terms of sustainability, the Hurst exponent for annual turbidity was 0.23, indicating a reverse trend in the near future; (4) Dam construction's impact on turbidity was not significant. Compared with natural factors (permanent wetlands, grasslands, lake surface water temperature, and remote sensing ecological index), human activities (barren, urban and built-up lands, croplands and population density) had a more significant impact on turbidity. Turbidity was highly correlated with croplands (r = 0.76), followed by population density (r = 0.71), and urban and built-up lands (r = 0.69).

Sustainability of global small-scale constructed wetlands for multiple pollutant control

The global wastewater surge demands constructed wetlands (CWs) to achieve the UN’s Sustainable Development Goals (SDG); yet the pollutant removal interactions and global sustainability of small CWs are unclear. This study synthesizes small CW data from 364 sites worldwide. The removal efficiency of organic matter and nutrient pollutants of small CWs had a 75th percentile of 68.8–84.0%. Bivariate analysis found consistent synergies between pollutant removals, lasting 3–12 years. The optimal thresholds for maintaining the synergistic effects were as follows: area size—17587 m2, hydraulic loading rate—0.45 m/d, hydraulic retention time—8.2 days, and temperature—20.2 °C. When considering the co-benefits and sustainability of small CWs for multi-pollutants control, promoting small-scale CWs could be an effective and sustainable solution for managing diverse wastewater pollutants while simultaneously minimizing land requirements. This solution holds the potential to address the challenges posed by global water scarcity resulting from wastewater discharge and water pollution.

Multifunctional MoS2 membrane for integrated solar-driven water evaporation and water purification

Solar-driven interfacial water evaporation shows great potential to address the global water crisis, but its efficient implementation in the presence of organic wastewater remains challenging. Here, we achieved integrated water evaporation and organic compound degradation by designing a multifunctional MoS2 membrane. Under 1.0 sun irradiation, the membrane exhibits an evaporation rate of 2.07 kg m−2 h−1 and 82% degradation efficiency of organic pollutants, with negligible organic pollutant residues in the condensate. The high performance is attributed to the thermal energy generated by the evaporation process of MoS2 membrane. This promotes an increase in the rate constant of interfacial electron transfer during the photocatalytic reaction, accelerating the generation of free radicals and facilitating the removal of organic pollutants. The study demonstrated that fresh water can be collected from high-salinity wastewater at a rate of 1.56 kg m−2 h−1. The MoS2 membrane provides a sustainable approach to addressing the water crisis.

Review of the Mechanism and Methodology of Water Demand Forecasting in the Socio-Economic System

As global water scarcity becomes increasingly acute, water demand forecasting has emerged as a critical component in water resource management and planning. This review aims to comprehensively survey and analyze the current state of research, existing issues, and development trends in the field of water demand forecasting. Presently, there are numerous studies on water demand forecasting; however, most of the forecasting results tend to be overestimated. On the mechanistic level, research has gradually shifted from considering single factors to accounting for the complex influences of multiple factors. This paper summarizes the mechanism of water demand from the three levels of agriculture, industry, and residential life. In terms of forecasting methods, various techniques have been explored and applied, particularly new methods based on artificial intelligence and machine learning, which have demonstrated significant advantages in improving forecasting accuracy and handling nonlinear relationships. Despite the notable progress and practical achievements in water demand forecasting, several challenges and issues remain. Future research should focus on diversifying methodologies, comprehensively considering multiple influencing factors, further refining forecasting models and technical systems, strengthening uncertainty and risk management, and emphasizing practical applications and policy guidance.

Stomatal CO2 responses at sub- and above-ambient CO2 levels employ different pathways in Arabidopsis.

Stomatal pores that control plant CO2 uptake and water loss affect global carbon and water cycles. In the era of increasing atmospheric CO2 levels and vapor pressure deficit (VPD), it is essential to understand how these stimuli affect stomatal behavior. Whether stomatal responses to sub-ambient and above-ambient CO2 levels are governed by the same regulators and depend on VPD remains unknown. We studied stomatal conductance responses in Arabidopsis (Arabidopsis thaliana) stomatal signaling mutants under conditions where CO2 levels were either increased from sub-ambient to ambient (400 ppm) or from ambient to above-ambient levels under normal or elevated VPD. We found that guard cell signaling components involved in CO2-induced stomatal closure have different roles in the sub-ambient and above-ambient CO2 levels. The CO2-specific regulators prominently affected sub-ambient CO2 responses, whereas the lack of guard cell slow-type anion channel SLOW ANION CHANNEL-ASSOCIATED 1 (SLAC1) more strongly affected the speed of above-ambient CO2-induced stomatal closure. Elevated VPD caused lower stomatal conductance in all studied genotypes and CO2 transitions, as well as faster CO2-responsiveness in some studied genotypes and CO2 transitions. Our results highlight the importance of experimental setups in interpreting stomatal CO2-responsiveness, as stomatal movements under different CO2 concentration ranges are controlled by distinct mechanisms. Elevated CO2 and VPD responses may also interact. Hence, multi-factor treatments are needed to understand how plants integrate different environmental signals and translate them into stomatal responses.

Multi-criteria analysis for sustainable and cost-effective development of desalination plants in Chile

In Chile, there is an increasing demand for freshwater supply for human consumption, agriculture, and industrial activities. In this sense, the country is highly threatened by climate change, which is drastically affecting the availability of water resources in the north-central region due to desertification processes. Therefore, seawater reverse osmosis (SWRO) desalination is becoming one of the most feasible alternatives to address current and future challenges regarding water scarcity in the country. This investigation aims to evaluate potential locations for a sustainable and cost-effective installation of desalination projects; the latter, under a multi-criteria and geographic information system (GIS)-model. The model was tested in the highly water scarcity-threatened Valparaiso Region, Chile, as a case study. The model was developed integrating economic and socio-environmental criteria involved in the development and/or construction of desalination projects. The results of the multi-criteria analysis show that the Valparaıso Region presents optimal areas for developing SWRO projects. Both the northern and central areas of the Region show appropriate locations for installing SWRO plants and their freshwater distribution lines, ensuring short- and long-term water supply, especially for agriculture and population consumption. The results obtained in this study could be extrapolated as a tool to assess the desalination projects development in other world regions to make future desalination projects more viable and sustainable for addressing global water demands.

Preparation of ternary composite film TiO2/Fe2O3/Ti3C2 for photoelectrocatalytic degradation of organic pollutants and bacterial inactivation in water

Global water pollution is a serious problem, and photoelectrocatalytic technology is expected to be a new path to solve it. In this study, a ternary composite TiO2/Fe2O3/Ti3C2 photoanode was synthesized by hydrothermal, water bath, and spin-coating methods for the photoelectrocatalytic degradation of pollutants and disinfection in water. The results showed that the composite film was capable of degrading 96.74 % of MB solution within 120 min and killing 99.43 % of E. coli and 100.00 % of S. aureus within 30 min. Furthermore, the MB degradation efficiency remained nearly constant throughout the 35th cyclic photoelectrocatalytic reaction, demonstrating the adequate stability of the photoanode. The outstanding performance of the film is attributed to (1) the large specific surface area due to the unique structure of composite, (2) low surface-interface resistance and improvement of photogenerated carrier separation and migration because of heterojunction structure and co-catalyst Ti3C2 with high conductivity. It is also proved that the four radicals ·O2-, ·OH, ∙Cl, ∙ClO play a role in the system. This study provides a practical direction for designing future photocatalytic materials and advancing the treatment of pollutants in water.

Dissecting the Characteristics and Driver Factors on Global Water Use Efficiency Using GLASS Data Sets

AbstractEcosystem water use efficiency (WUE) is a crucial parameter for understanding the interaction between carbon and water cycles. However, the spatio–temporal evolution and drivers of WUE remain unclear. This study utilized global annual scale global land surface satellite gross primary productivity and evapotranspiration data from 1982 to 2018 to estimate WUE and analyze its spatio–temporal characteristics. Additionally, the study investigated the response of WUE changes to five environmental factors (precipitation [PRE], soil moisture, temperature [TEM], palmer drought severity index, and vapor pressure deficit [VPD]) on WUE changes using partial correlation and structural equation modeling. The results suggested that the global annual WUE increased markedly over the study period, at an average rate of 0.0016 gC m−2 mm−1 H2O year−1. In contrast to the existing knowledge on the drivers of WUE change, climate change was found to have a larger contribution to WUE changes at the global and regional scales, especially in terms of TEM and VPD. A positive correlation between TEM and WUE was observed, but extreme TEM could lead to a decrease in WUE. VPD had the most significant direct effect on WUE, and its negative effect offset the positive influence of TEM especially in hyper‐arid, semi‐arid, and arid regions. These findings offer new insights into the impact of VPD and global warming on WUE.