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The simultaneous occurrence of extreme weather events such as high temperature, low humidity and strong wind speed can cause devastating impacts on the fragile environment and vulnerable ecosystem in arid Northwest China (NW). However, few studies investigate the multivariate compound hot, dry and windy extremes in NW. In this study, we investigate the temporal and spatial variations of the warm‐season trivariate hot, dry and windy (HDW) and bivariate hot and dry (HD), dry and windy (DW), hot and windy (HW) extremes in NW. From 1960 to 2019, we observed more compound HD, DW, HW and HDW days in the hyper‐arid Xinjiang and west Gansu in NW. Simultaneously, DW days, HW days and HDW days consistently declined at rates of −0.48, −0.88 and −0.42 day·10a−1, except for a discernible increasing rate of 0.56 day·10a−1 in HD days. Notably, trends in four multivariate compound extremes all experienced pronounced reversals from a declining to increasing trend in the 1990s. The higher probability of compound HD, DW and HW extremes contributed to a higher probability of HDW in Xinjiang province. Ultimately driven by the significantly rising temperature (0.21°C·10a−1, p < 0.01), four compound extremes suggested increased probability with the largest increase in compound HW probability from 1960–1989 to 1990–2019. Both the rising trends in the occurrence and the increased probability of four compound extremes highlight intense risks of compound extreme weather over NW in recent decades. [ABSTRACT FROM AUTHOR]

Comprehending the correlation between alterations in human‐flood distance and flood fatalities (as well as displacements) is pivotal for formulating effective human adaptive strategies in response to floods. However, this relationship remains inadequately explored in existing global analyses. To address this gap, we examine 910 flood events occurring from 2000 to 2018, resulting in significant numbers of fatalities and displacements. We find that in 53% of countries, humans tend to distance from floods, particularly in the Middle East. Such distancing greatly mitigates flood fatalities and displacements. Simultaneously, in areas with increased flood protection level (FPL), humans are less likely to move away from floods. Furthermore, FPL and human‐flood distance have decreased in regions affected by ice jam‐ and hurricane‐induced floods from 2000 to 2018. Notably, regions with human‐flood distance slightly below the average for a given flood type experience more severe flood fatalities. Plain Language Summary: People have developed effective ways (i.e., distancing from flood and increasing flood protection level) to adapt and minimize the impact of catastrophic floods on exposed populations. However, the relationship between these behaviors and flood fatalities (as well as displacements) is not well understood on a global scale. To address this knowledge gap, we study 910 flood events that occurred between 2000 and 2018, leading to significant fatalities and displacements. We find that in 53% of countries, people tend to move away from flood‐affected areas, especially in the Middle East. This distancing behavior greatly reduces the number of fatalities and displaced individuals caused by floods. Additionally, in areas with higher flood protection level, people are less likely to relocate away from floods. Over the studied period, both flood protection levels and the distance between humans and flood‐prone areas have decreased in regions affected by ice jam‐ and hurricane‐induced floods. Importantly, regions where the distance between humans and floods is slightly below the average for a given flood type experience more severe flood fatalities. These findings could help improve the efficiency of flood control management and the adoption of adaptive policies. Key Points: 53% of countries witnessed humans distancing themselves from floods between 2000 and 2018, especially those in the Middle EastHumans distancing from the floods leads to a substantial reduction in both flood fatalities and flood displaced populationHumans residing in regions with a high flood protection level tend not to move away from the flood [ABSTRACT FROM AUTHOR]

Climate change has intensified drought severity, duration, frequency, and the spatial extent, promoting considerable concern about the socioeconomic exposure to drought. Some previous studies have suggested the overestimation of drought indices and more drying due to neglecting the impact of vegetation response to CO2. Using models from the Coupled Model Intercomparison Project Phase 6 and the socioeconomic projections, we quantified the impact of vegetation‐CO2 feedback on extreme drought frequency and the corresponding exposure of population and GDP under SSP126, SSP245, SSP370, and SSP585 scenarios. Results show that extreme drought frequency will increase significantly, affecting over 70% of global land by the 2050s. Along with rapid growth of socioeconomic factors, population and GDP exposure will increase by 26.90%–36.12% and 2.51–2.95 folds in the 2030s and 67.78%–78.72% and 3.41–5.94 folds in the 2050s. Underdeveloped countries are projected to face the most significant challenges, with substantial increases in population and GDP exposure to extreme drought. By incorporating the impact of vegetation‐CO2 feedback, we address biases of around 2% in extreme drought frequency, particularly in arid and semi‐arid regions, showing underestimations of more drying across around half of global land in the baseline period and the 2030s. The biases, however, shift to be overestimations globally in the 2050s. As a result, early underestimations of extreme drought frequency will lead to significant underestimations in exposed population and GDP by 5.25% and 6.07% in the baseline period, as well as in the 2030s. In contrast, later overestimations will lead to overestimations of exposed population by 3.16%–8.54% and exposed GDP by 2.82%–6.65% in the 2050s. This study provides a more accurate estimation of socioeconomic exposure to extreme drought and highlights the potential risks associated with global warming. [ABSTRACT FROM AUTHOR]

The most basic features of climatological normals and variability are useful for describing observed or likely future climate fluctuations. Pan evaporation (Epan) is an important indicator of climate change; however, current research on Epan has focused on its change in mean rather than its variability. The variability of monthly Epan from 1961 to 2020 at 969 stations in China was analyzed using a theoretical framework that can distinguish changes in Epan variance between space and time. The Epan variance was decomposed into spatial and temporal components, and the temporal component was further decomposed into interannual and intra-annual components. The results show that the variance in Epan was mainly controlled by the temporal component. The time variance was mainly controlled by intra-annual variance, decreasing continuously in the first 30 years, and slightly increasing after the 1990s. This is mainly due to the fact that the decrease of wind speed and the increase of water vapor pressure deficit with the temperature increase offset each other and inhibit the variability of Epan. The variance decreased more in the northern region, whereas it exhibited a small decrease or slight increase in the southern region. The reduction in seasonality was dominated by spring, followed by summer. The differences in Epan variability in space and season were mainly caused by the differing rates of change in evaporation driving forces, such as a greater reduction in wind speed in the northern region and spring. Significance Statement: The purpose of this study is to better understand how the variability of evaporation changes rather than in mean under climate change. This is important because the variability is useful to describe the observed or likely future fluctuations, and a small fluctuation may have large impacts on water practices, such as agricultural production. Our findings showed that the temporal and spatial variability of evaporation decreased due to its drivers offsetting each other. However, because the drivers are numerous and continuously changing under climate change, it is necessary to pay attention to its mean and variability for serving water resources practice. [ABSTRACT FROM AUTHOR]

Drought changes can profoundly influence vegetation growth while vegetation, in turn, may impact drought by modulating water and energy exchanges between the land and atmosphere. Previous studies have primarily focused on the unidirectional effects of drought on vegetation dynamics. However, the impacts of vegetation on drought and their bidirectional dependencies have remained underexplored. In this study, we employ the Leaf Area Index (LAI) and two drought indices (the Standardized Precipitation Index, SPI, and, the Standardized Precipitation Evapotranspiration Index, SPEI) to investigate the interaction between vegetation greenness and drought globally over the period 2001 to 2020. The results demonstrate a statistically significant and consistent trend between LAI and SPI (SPEI) in 66.9% (54.01%) of global vegetated lands. SPI commonly displays a 2-month delayed response to LAI, whereas SPEI shows no evident lag, implying a more rapid response of SPEI to LAI compared to SPI. A substantial proportion of global vegetated areas, around 66% for LAI-SPI and 52% for LAI-SPEI, exhibit a significant positive relationship. The Granger causality test reveals a bidirectional causal relationship between vegetation greenness and drought across approximately 20% of global vegetated areas. Vegetation greenness is identified as the Granger cause of SPI (SPEI) in >60% (30%) of global vegetated lands, providing statistical observational evidence indicating that vegetation can influence drought in many regions within terrestrial ecosystems. Interestingly, the ratio of areas where LAI serves as the Granger cause of SPI is more extensive than the corresponding ratio where SPI is identified as the Granger cause of LAI, a pattern opposite to that observed with SPEI. Overall, our investigation into the interactions between vegetation greenness and drought holds significance for enhancing our understanding of land-atmosphere interplays in the context of climate change and contributes to advancing sustainable development for ecosystem services. [Display omitted] • A significant coherent trend between LAI and SPI (SPEI) is observed in most areas. • Most areas exhibit an evident positive relationship for both LAI-SPI and LAI-SPEI. • SPI shows a common 2-month delayed response to LAI while SPEI shows no evident lag. • Around 20% of global areas exhibit bidirectional causality between LAI and drought. • Provides observational evidence that vegetation can affect surface water conditions in many regions. [ABSTRACT FROM AUTHOR]

Accurate estimation of evapotranspiration (ET) at high spatial resolution is crucial for drought monitoring and water resources management, but currently available remote sensing ET products generally have coarse spatial resolution (≥1000 m). To estimate ET at a high spatial resolution, Landsat images, Global Land Surface Satellite (GLASS), Moderate Resolution Imaging Spectroradiometer (MODIS), and meteorological forcing data were integrated, and the surface energy balance (SEBS) model was employed to calculate the 16-day average ET at 30 m resolution for China's Tarim River Basin, spanning from 2009 to 2018. The results indicated that the average 16-day ET estimates correlated well with ground observations for land and water surfaces (root mean square error (RMSE) for land = 0.92 mm day−1, RMSE for water = 1.63 mm day−1, mean bias for land = 0.3 mm day−1, mean bias for water = 0.52 mm day−1). Cross validation with GLASS, ETMonitor, and Penman-Monteith-Leuning (PML_V2) ET datasets revealed an overall increasing trend for all four products (PML_V2 = 6.277 mm year−1, GLASS = 2.185 mm year−1, ETMonitor = 3.258 mm year−1, SEBS = 1.441 mm year−1), demonstrating good spatial consistency. The consistent increasing pixels were primarily distributed in the northern, southwestern, and southeastern mountainous regions, accounting for 22.8%, while 0.29% of the consistent decreasing pixels were mainly concentrated in the central desert and mountain-front oasis areas. Inconsistent pixels accounted for 76.9%, with 2.34% of the inconsistent decreasing pixels exhibiting a scattered distribution, while 37.28% of the inconsistent increasing pixels were mainly found in the central desert and some oasis areas. Furthermore, SEBS ET trend analysis indicated that the oasis area experienced more pronounced changes than the mountainous and desert areas during the 2009–2018 period. The SEBS ET estimated in this study can provide high-precision data support and a reference for future research on the water resources management. • The evapotranspiration (ET) dataset with 30 m and 16-day resolution was estimated with surface energy balance method (SEBS). • Consistency assessments were conducted on four types of ET data at different time and spaces. • The annual evapotranspiration shows an increasing trend from 2009 to 2018. [ABSTRACT FROM AUTHOR]

Hot and dry extremes have co‐occurred with global warming, causing worse threats than single climate extremes. We analyse the compound hot and dry day (CHDD) and population exposure (Epop) across China based on observations and 11 global climate models (GCMs) from the Coupled Model Intercomparison Project Phase 6. The bias‐corrected GCMs, particularly the two‐stage multivariate quantile mapping‐corrected ones, perform better than the raw ones in catching changes in CHDD but they all overestimate CHDD and Epop. More CHDDs occur in the southeast (SE), north (NC) and northwest (NW) China with increasing trends over regions stretching from the northeast (NE) to southwest (SW) China. Despite the declined CHDD, historical Epop has generally increased by the increased population. Future projections in the SSP5‐8.5 experiment indicate an overall increase of CHDD and Epop at 1.5°C warming and an increasing Epop to dangerous CHDD at 2°C warming. SW, NE and the Tibetan Plateau need effective measures of adaptation to reduce sufferings from CHDD under climate change. [ABSTRACT FROM AUTHOR]

• A new index (SHDWI) was proposed to assess changes in the severity of hot-dry-windy events (HDWEs). • HDWE severity has strengthened particularly in South America, North Africa, western Europe, and southeastern Asia. • HDWE severity is predominated by temperature in the south of 30°N and by humidity in the north of 30°N. Hot-dry-windy events (HDWEs), characterized by concurrent high temperature, low humidity, and strong wind speeds, are associated with reduced crop yields, accelerated spread of wildfire, increased human health risks, and dust storms across various regions. A comprehensive understanding of global HDWE severity is crucial for mitigating these detrimental consequences. However, current assessments of HDWE show notable regional constraints due to the lack of a universal definition for its severity. In this study, we introduce a standardized hot-dry-windy index (SHDWI) using multi-source datasets to assess spatial and temporal changes in the severity of HDWEs across the globe. Influenced by significantly rising temperatures, intensified wind speeds, and declining humidity, a notable decreasing trend (-0.09/decade, p < 0.01) in SHDWI indicates a rise in warm-season HDWE severity on average across the global land areas, particularly in South America, North Africa, western Europe, and southeastern Asia. Geospatially, Europe, Africa, South America, and Asia have experienced substantial increases in HDWE severity and expanded areas affected by strong HDWEs between 1980–1998 and 1999–2017. Notably, HDWE severity is predominated by temperature in the south of 30°N but by humidity in the north of 30°N. The standardized index proposed in this study would be beneficial for a worldwide assessment of future HDWE risks under climate change. [ABSTRACT FROM AUTHOR]

• Hot-dry wind denotes a significant (p < 0.01) weakening trend from 1960 to 2019 in Northern China. • Hot dry wind has become the primary driver of warm-season dryness in recent decades. • Hot dry wind is more influential than precipitation on variations of surface dryness/wetness in Northwest China. The concurrent occurrence of high temperature, low humidity, and specific wind speed, known as hot-dry wind (HDW), is a widespread agro-meteorological hazard in Northern China. HDW can significantly impact surface dryness/wetness by influencing atmospheric water demand. To understand the divergent effect of HDW and precipitation on the spatiotemporal variations of surface dryness/wetness, we collected meteorological data from 673 meteorological stations across Northern China for the warm season (May to September) during 1960–2019. Results reveal a significant (p < 0.05) wetting trend from 1983 to 2019 and a significant (p < 0.01) weakening of HDW across Northern China from 1960 to 2019. Notably, the primary driver of warm-season dryness has transitioned from precipitation before 1982 to HDW in recent decades. Regionally, the wetting trends observed in Northwest (NW) and North China (NC) are primarily attributed to the weakening HDW. Conversely, in Inner Mongolia (IM), a drying trend is noted due to a decline in precipitation that outweighs the reduction in water consumption caused by weakened HDW. During 1960–2019, our analysis affirms that the relative contribution of HDW to variations in warm-season dryness/wetness surpasses that of precipitation in Northern China, particularly in the hyper-arid NW. The persistent HDW is anticipated to exacerbate warm-season dryness and increase water demand for crop growth and animal husbandry in Northern China. [ABSTRACT FROM AUTHOR]

The increasing demand of ScenarioMIP is calling for GDP projections of high resolution for the future Shared Socioeconomic Pathways (SSPs) in both socioeconomic development and in climate change of adaption and mitigation research. While to date the global GDP projections for five SSPs are mainly provided at national scales, and the gridded data set are very limited. Meanwhile, the historical GDP can be disaggregated using nighttime light (NTL) images but the results are not open accessed, making it cumbersome in climate change impact and socioeconomic risk assessments across research disciplines. To this end, we produce a set of spatially explicit global Gross Domestic Product (GDP) that presents substantial long-term changes of economic activities for both historical period (2005 as representative) and for future projections under all five SSPs with a spatial resolution of 30 arc-seconds. Chinese population in SSP database were first replaced by the projections under the two-children policy implemented since 2016 and then used to spatialize global GDP using NTL images and gridded population together as fixed base map, which outperformed at subnational scales. The GDP data are consistent with projections from the SSPs and are freely available at http://doi.org/10.5281/zenodo.4350027 (Wang and Sun, 2020). We also provide another set of spatially explicit GDP using the global LandScan population as fixed base map, which is recommended at county or even smaller scales where NTL images are limited. Our results highlight the necessity and availability of using gridded GDP projections with high resolution for scenario-based climate change research and socioeconomic development that are consistent with all five SSPs. [ABSTRACT FROM AUTHOR]

Stationarity is an assumption that permeates training and practice in water-resource engineering. However, with global change, the validity of stationarity as well as uncertainty of nonstationarity in water-resource planning are being questioned; thus, it is critical to evaluate the stationarity of climate variables, especially precipitation. Based on the continuous observation data of precipitation from 1427 stations across China, 593 efficient grid cells (1° × 1°) are constructed, and the annual precipitation stationarities from 1959 to 2018 are analyzed. The evaluated autocorrelation stationarity indicates that 92.24%–96.12% of the grid cells for an autocorrelation coefficient of lag 1–8 years of precipitation are indistinguishable from 0 [90% confidence level (CL)]. The mean stationarity indicates that 97.47% of the grid cells have a stable mean for 30 years (90% CL); beyond the confidence limits, they are mainly located in the northwest of China, where annual precipitation is less, and the average exceeding range is ±3.78 mm. The long-term observation of annual precipitation in Beijing (1819–2018) and Shanghai (1879–2018) also yields autocorrelation and mean stationarities. There is no significant difference in the annual precipitations between the past 20 years (1999–2018) and the past 60 years (1959–2018) over China. Therefore, the annual precipitation in China exhibits a weak stationary behavior that is indistinguishable from the stationary stochastic process. The average variation in precipitation is ±9.55% between 30 successive years and 16.53% between 10 successive years. Therefore, it is valuable and feasible to utilize the historical data of annual precipitation as the basis of water-resources application. [ABSTRACT FROM AUTHOR]

China has begun a rapid move towards Sponge City implementation, which will include widespread installation of various Low Impact Development (LID) stormwater infrastructure. Ambitious goals have been set for all Sponge Cities, including a target capture rate of 80–85% of annual precipitation in Beijing. However, there has so far been limited investigation into whether these goals are obtainable at the catchment scale given the physical restrictions of the existing urban landscape. This paper demonstrates the use of long-term continuous hydrologic modelling to evaluate the potential of meeting rainfall capture goals over a long time period for a case study area in Beijing. Detailed land cover classification derived from satellite imagery aided in the parameterization of a SWMM (Stormwater Management Model) model representing a 133 km2 urban study area. The calibrated and validated model demonstrated satisfactory agreement between computed and observed runoff for a variety of precipitation events ranging from 10 to 207 mm. A synthetic high resolution rainfall time series was generated from historic daily observations then used as input to run the model continuously for a 35 year period. Feasible LID model scenarios based on varying degrees of implementation of rain gardens, permeable pavements and green roofs were compared in terms of their potential volume capture of annual rainfall. Modelling results demonstrated that the conversion of 30% of roof area to green roof, 10% of green areas to rain gardens and 35% of paved areas to permeable pavement could increase the baseline volume capture ratio from 59.9% to 82.2%, indicating that Sponge City goals can be met within the case study area with realistic levels of LID implementation. This study provides a decision-making basis for future planning in the study area. • Satellite imagery based hydrologic model shows good agreement with observed flows. • Continuous modelling approach suggested for evaluation of Volume Capture Ratio. • >80% of annual rainfall captured with moderate catchment wide implementation of LID. [ABSTRACT FROM AUTHOR]

Comprehensive knowledge about wind energy potential is critical for decision-making to achieve carbon neutrality and shape future energy pathways. Wind turbine technology advances (e.g., higher hub-heights, larger rotor diameters and rated power) can better support wind energy harvesting and alter wind energy potential. This study established an integrated model to evaluate the impact of wind turbine technology advances on onshore wind energy potentials under different wind resource conditions by using China as a case study. We found that technological advances of wind turbine can significantly impact wind energy potential. Compared with land-based 1.5-MW turbines, the onshore wind energy potential using newer generation turbines (land-based 2.5-MW turbines) would increase by 43% to 14.8 PWh (i.e., 2.0 times the electricity consumption of China in 2020). Importantly, advances in wind turbine technology can significantly increase capacity factor in poor wind resource regions, and thus enable economically viable generation in more areas. This can significantly increase wind energy potential in poor wind resource regions with large electrical load (e.g., Central, South and East China). Moreover, in contrast to the wind production of 0.46 PWh in 2020, China's wind energy potential is projected to hit 20.1 PWh by 2030 under the assumption of developed turbine technology in line with the trends of the past decade. The corresponding potential CO 2 emission reduction would range from 12.6 Gt in 2020 to 21.7 Gt in 2030. These values are 1.3 and 2.2 times higher than China's CO 2 emissions in 2020, respectively. To enhance wind energy contribution toward China's carbon neutrality goal, we recommend that the conversion of wind turbines to be accelerated, especially in poor wind resource regions with large electrical load. • Onshore wind potential for China is 2.0 times national electricity demand of 2020 • Wind turbine technology has more influence on wind potential in low wind regions • China's wind potential reach 20.1 PWh (equivalent to 21.7 Gt CO 2 emission) by 2030 [ABSTRACT FROM AUTHOR]

Measurements of evaporation from pans have traditionally been used to represent the evaporative demand of the atmosphere when estimating the crop water requirements. In China, Pan evaporation (E pan) has been observed routinely at meteorological stations since the 1950 s with D20 pans, but since 2002, the pans have been replaced by E-601B. To explore the effective reconstruction of missing daily D20 E pan over China from 1951 to 2020, this study employed three types of E pan models: the widely used physical model PenPan, two popular machine learning (ML) models (multivariate adaptive regression splines (MARS) and random forest (RF)), and multiple linear regression (MLR). Daily E pan data were predicted based on the daily wind speed (U), atmospheric pressure (AP), relative humidity (Rh), air temperature (Ta), and sunshine hours (n) of 2410 meteorological stations. The results showed that the MARS and RF predictions were superior to those of PenPan, and the results of MLR were the worst. The average determination coefficient for RF, MARS, PenPan, and MLR values were 0.95, 0.91, 0.88, and 0.86, respectively, and the average root-mean-square difference were 0.62, 0.91, 1.17, and 1.15 mm day−1, respectively. Thus, the missing daily E pan were predicted using RF and the reconstructed E pan had the same probability density function as the observed E pan. The annual E pan first showed a downward trend (at a rate of 6.17 mm yr−1) from 1961 to 1993 and then a reverse upward trend (at a rate of 1.84 mm yr−1) from 1994 to 2020. E pan predictions by PenPan are limited by regional characteristics, making it difficult to transfer between regions. However, ML methods are less affected by regional characteristics and can be used across regions. Furthermore, ML methods can effectively reconstruct missing E pan providing support for verification of PenPan, which is beneficial for the study of driving factors of E pan. • Three types methods for accurate prediction of daily pan evaporation were explored. • The D20 pan evaporation were reconstructed effectively with machine learning method. • The annual evaporation shows downward and reverse upward trends from 1951 to 2020. [ABSTRACT FROM AUTHOR]

Understanding to what extent can terrestrial ecosystems maintain their structure and functions and recover after being hit by drought is critical for sustainable ecosystem management and drought mitigation practices. This study assesses multi-scale (i.e., at grid, climate type, land use, basin, province scales) eco-hydrological resilience to drought over China during the period of 1982–2015, based on Standard Evapotranspiration Deficit Index as well as satellite-retrieved evapotranspiration (ET) and net primary production (NPP). Over the last three decades, the ecosystem water use efficiency (eWUE) increased in most regions of China (especially in Northeast China and North China Plain) in the context of climate change. The western China showed a significant wetting trend with ascending ET, GPP and eWUE. The SEDI and ET showed significantly increasing tendencies but the ecosystem GPP and eWUE did not exhibit obvious responses to regional wetting in the middle and lower reaches of Yangtze River basin. Most terrestrial ecosystems in China were found overall resilient to drought except for mild temperature-fully humid-warm summer at the climate type scale, water type at the land use scale, Northwest Rivers at the basin scale as well as Ningxia, Qinghai, Shanghai and Hong Kong at the province scale. These findings would facilitate the identification of most drought-vulnerable regions for ecosystem management and taking reasonable adaptation measures (e.g., use of alternative water resources or reuse water, water conservation and smart irrigation) to ensure the sustainability of terrestrial ecosystems during the drought periods over China. Unlabelled Image • Eco-hydrological resilience to drought was first assessed over Chinese ecosystems at multiple scales. • Most ecosystems were resilient to drought in China except for some local ecosystems. • Necessary adaptation measures were suggested for non-resilient ecosystems under drought stresses. [ABSTRACT FROM AUTHOR]

• A framework for decomposing the contributing factors of extreme droughts is developed for China. • Extreme droughts attributed to rises in temperature, net radiation, precipitation variability. • A smaller rise in extreme droughts per Kelvin in high-latitude regions is due to their high sensitivity to precipitation. Climate change in mean-state or variability could lead to more/less frequency of extreme drought. In this study, we developed a new framework for decomposing the contributing factors of changes in future extreme drought frequency in China in accordance to the Palmer Drought Severity Index (PDSI). We performed a series of numerical experiments to ensure that the sensitivity of trend and variability in individual climatic variables can be distinguished. In addition, an extreme drought rate with warming (EDRW , unit: %·K−1) is defined to quantify the relative change in extreme drought frequency per Kelvin. Overall, the EDRW will increase dramatically by an average of 27.71%·K−1. The ascended EDRW are attributed to increases in temperature (+56.90%·K−1), net radiation (14.80%·K−1) and precipitation variability (+8.23%·K−1); a decrease in relative humidity (+4.61%·K−1), but is partly offset by an increase in precipitation (i.e., "wetting", −60.12%·K−1). A smaller increase in the frequency of extreme droughts is found in high-latitude regions due to their enhanced sensitivity to "wetting". [ABSTRACT FROM AUTHOR]

Declining pan evaporation (Epan) across many continents in the past decades despite global warming is gaining attention of hydrology and climate science communities. While Geo‐detector is considered useful for attributing the spatio‐temporal variation of a certain geography‐related element, it has not been applied for Epan attribution. Based on the Geo‐detector, we first attribute the spatio‐temporal variation of Epan across China in 1961–2001. The results show that relative humidity is the primary factor influencing the temporal dynamics of Epan, followed by sunshine duration, maximum air temperature and wind speed. In the northwest China (south China and east China), wind speed, air temperature and relative humidity (relative humidity, sunshine duration, wind speed and air temperature) are the dominant factors of Epan variations. The results obtained are comparable to the previous studies using other statistical methods (i.e., the partial differential method, Pearson correlation coefficient and multiple regression), which reveal the usefulness of Geo‐detector for attributing and diagnosing the spatio‐temporal variations of Epan. Moreover, more detailed spatial information and interactions among meteorological elements can be obtained using Geo‐detector. These findings should provide helpful references for understanding the mass and energy budgets at different spatial–temporal scales under global warming. [ABSTRACT FROM AUTHOR]

Highlights • Wind resource assessment using the most complete wind speed data in China. • We examined the spatiotemporal distribution of wind resources in China. • We identify wind energy features and suitable areas for power generation in China. Abstract To achieve sustainable socioeconomic development as part of the global community, China has set ambitious goals for developing wind power within its national energy security framework. Existing wind power density maps in China present some knowledge gaps (e.g., lack of spatiotemporal resolution/characteristics and estimates at the height of a typical wind turbine). To address them, we combine the advantages of large network of wind speed observations (2430 meteorological stations; 2006–2015) and the grid-based method in order to create the spatiotemporal distributions of wind resource at the hub height. We found that the spatiotemporal variability of wind resources in China is apparent. Nationally, the annual mean wind speed and wind power density are 4.09 m s−1 and 164.1 W m−2, respectively. Spatially, Northeast China has the highest wind potential with annual mean wind speed and power density 4.64 m s−1 and 204 W m−2, while South China has the lowest wind potential annual mean wind speed and power density 3.55 m s−1 and 97.4 W m−2. Temporally, the wind resources over the entire China are higher in the cold season (spring and winter with peaks in April) than those in the warm season (summer and autumn with bottoms in August). Specifically, the wind power output in "Three North" region (including Northeast China, North China and Northwest China) in the cold season is 1.4 times higher than that in the warm season. Some coastal regions in East China have relatively high wind power density (>500 W m−2) and small seasonal variations. These findings should help decision-makers to identify the areas suitable for utilizing wind energy, and optimizing power generation and transmission across the grid for better system performance. [ABSTRACT FROM AUTHOR]

Precipitation extremes are expected to increase by 7% per degree of warming according to the Clausius–Clapeyron (CC) relation. However, this scaling behavior is inappropriate for high temperatures and short-duration precipitation extremes. Here, daily data from 702 stations during 1951–2014 and hourly data from 8 stations during 2000–15 are used to examine and explain this behavior in China. Both daily and hourly precipitation extremes exhibit an increase in temperature dependency at lower temperatures. The CC scaling transitions from positive to negative rates with temperatures greater than 25°C. Unlike the increase in daily data, which is similar to single-CC (1CC) scaling, the increase in hourly data resembles super-CC (2CC) scaling for temperatures greater than 13°C. Results show that the precipitation extremes are controlled by water vapor for a given temperature. At lower temperatures, precipitation extremes exhibit a positive linear dependence on daily actual vapor pressure whose value is almost equal to the saturated vapor pressure at a given temperature. At higher temperatures, actual vapor pressure has difficulty maintaining a consistent increasing rate because of the exponential increasing of the saturated vapor pressure. Higher temperatures result in larger vapor pressure deficits, which lead to sharp decreases in precipitation extremes. Similar scaling behaviors are obtained in 10 river basins over China, where the breaking point temperature increases from 17°C along the northwest inland area to 25°C along the southeast coast. These behaviors demonstrate that precipitation extremes are firmly linked to temperature when there is sufficient moisture at lower temperatures and limited by insufficient moisture at higher temperatures. Overall, precipitation extreme events require more attention in a warming climate. [ABSTRACT FROM AUTHOR]

Highlights • The ED approach can make robust improvement for the PD method. • The ED approach can better identify and quantify the contribution of meteorological observations. • The wind function: f q (u 2) = 3.977 × 10 - 8 (1 + 0.505 u 2) is recommended in the PenPan model in D20 E pan estimation. • The ED approach can be used in attribution analysis in complicated hydrological models. Abstract In predicting how droughts and hydrological cycles might change in a changing climate, change of pan evaporation (E pan) is one crucial element to be understood. The derived partial differential (PD) form of the PenPan equation is a prevailing attribution approach worldwide. However, small biases exist and the application of PD method is limited within the derivation of partial differential form of the equation, which impede the attribution analysis in hydrology. Here we designed a series of numerical experiments by detrending each climatic variable, i.e., an experimental detrending (ED) approach, to attribute changes of E pan over China. We compared the attribution results using these two methods and further analyzed the plausible advantages of ED approach. The comparison shows that both ED approach and PD method perform well in attributing changes of E pan and to the input meteorological variables in China over 1960–2017. The first advantage of ED approach is that it can help make robust adjustment for the PD method in attribution analysis. Another advantage lies in its ability to attribute to the observed meteorological variables in China, when the PD method fails to quantify the contribution of relative humidity and air temperature in net radiation in E pan attribution analysis. We highlight that the ED approach is recommended in attribution analysis for hydrologic research. Together with the adjusted PD method, both methods can assist a better understanding and prediction of water-energy cycles change in a changing climate. [ABSTRACT FROM AUTHOR]

High solid loading enzymatic hydrolysis (HSLEH) produces high sugar concentrations with low water and energy inputs. Adequate information has been provided to confirm the excellent enzymatic digestibility of pretreated bamboo biomass with the solid content below 10%. However, the utilization of bamboo biomass for producing high-concentration sugars solution via HSLEH is rarely reported. In this work, hydrogen peroxide/acetic acid (HPAC) pretreatment removed 79% of lignin from bamboo and HPAC-pretreated bamboo was rich in glucan (55.3%) and xylan (20.4%). In the HSLEH of HPAC-pretreated bamboo, xylanase could increase glucose production by 9.4%. Alkaline incubation could increase the glucose production of HPAC-pretreated bamboo by 6.3% and saved 75% cellulase. The addition of Tween 80 (0.03 g/L) could further increase the glucose production of HPAC-pretreated bamboo by 14.1%. As a result, 204.9 g/L glucose and 60.2 g/L xylose, corresponding to glucose and xylose yields of 75.8% and 65.4% respectively, were obtained from the resulting bamboo solid via 400 g/L HSLEH with 10 FPU cellulase/g dry matter and 0.03 g/L Tween 80, which was the highest concentration compared with the previous literatures. This work developed an integrated process to produce very high-concentration sugars solution from bamboo residue via HSLEH. [Display omitted] • Bamboo biomass provided sugars solution with very high concentration. • High solid loading enzymatic hydrolysis (HSLEH, 400 g/L) of bamboo was performed. • Highest sugars concentration included 204.9 g/L of glucose and 60.2 g/L of xylose. • Input of cellulase (10 FPU/g DM) was minimized during HSLEH of bamboo biomass. [ABSTRACT FROM AUTHOR]

Climate change and its potential threats on water security call for reliable predictions of evapotranspiration (ET) and runoff Q at different time scales, but current knowledge of the differences in their predictability between humid and nonhumid regions is limited.Based on spatially distributed catchments inChina, the authors characterized their predictability and provided plausible explanations. Using the Budyko framework, it was confirmed that annualET is predictable in nonhumid regions but less predictable in humid regions, and annualQ is predictable in humid regions but less reliable in nonhumid regions. Themain cause of the varied predictability lies in the variation of water storage change DS in the water balance equation. It affects both the estimation and the variability ofQin nonhumid catchmentsmore than that in humid catchments, which increases the challenge of predicting annual Q in nonhumid regions, while the opposite effect occurs in annual ET prediction between humid and nonhumid catchments.Moreover, the differences between the controlling factors of ET variability in different regions add more differences in their predictability. The dominant control of precipitation makes it easy to predict annual ET in nonhumid regions. By contrast, precipitation, potential evaporation, and their covariance take considerable effort to determine annualETvariations,which leads to less reliableETestimation and predictability in humid catchments. Therefore, one can accurately predict annual ET in nonhumid catchments andQ in humid catchments based on commonly used hydrological models.With proper consideration of ΔS, the predictability of annual ET and Q in both humid and nonhumid catchments can be improved. [ABSTRACT FROM AUTHOR]

Although xylo-oligosaccharides production from lignocelluloses via lactic acid hydrolysis is advantageous in terms of high yields with less by-products, the use of high purity lactic acid inevitably increases the cost of xylo-oligosaccharides production. The utilization of lactic acid-rich fermentation broth for xylo-oligosaccharides production can avoid the separation and purification of lactic acid. However, the feasibility of lactic acid-rich fermentation broth for xylo-oligosaccharides production from lignocelluloses was unclear. In this work, the results indicated that the highest xylo-oligosaccharides yield of 72% was obtained from corncob by lactic acid-rich fermentation broth pretreatment and xylanase hydrolysis. Subsequently, monosaccharides-rich hydrolysate (90.9 g/L) was obtained from solid residues of corncob by cellulase hydrolysis. Lactic acid-rich fermentation broth was produced by Weizmannia coagulans fermentation of the monosaccharide-rich hydrolysate. Besides, the obtained xylo-oligosaccharides and lactic acid mixture might be used as feed additives, avoiding the purification and separation of lactic acid or xylo-oligosaccharides. Meanwhile, the production cost of feed grade xylo-oligosaccharides from this work was much lower than the current market price. Overall, this work proposed a new strategy for efficient and environmental-friendly production of xylo-oligosaccharides from corncob. [Display omitted] • A recycling process for the production of xylo-oligosaccharides was proposed. • Lactic acid-rich fermentation broth was firstly used for xylo-oligosaccharides production. • The obtained xylo-oligosaccharides and lactic acid mixture could be used as feed additives. • The production cost of xylo-oligosaccharides was lower than the current market price. [ABSTRACT FROM AUTHOR]

Atmospheric evaporative demand plays a pivotal role in global water and energy budgets, and its change is very important for drought monitoring, irrigation scheduling, and water resource management under a changing environment. Here, future changes of pan evaporation Epan, a measurable indicator for atmospheric evaporative demand, are first projected and attributed over China through a physically based approach, namely, the PenPan model, forced with outputs from 12 state-of-the-art climate models from phase 5 of the Coupled Model Intercomparison Project. An equidistant quantile mapping method was also used to correct the biases in GCMs outputs to reduce uncertainty in Epan projection. The results indicated that Epan would increase during the periods 2021-50 and 2071-2100 relative to the baseline period 1971-2000 under the representative concentration pathway (RCP) 4.5 and 8.5 scenarios, which can mainly be attributed to the projected increase in air temperature and vapor pressure deficit over China. The percentage increase of Epan is relatively larger in eastern China than in western China, which is due to the spatially inconsistent increases in air temperature, net radiation, wind speed, and vapor pressure deficit over China. The widely reported 'pan evaporation paradox' was not well reproduced for the period 1961-2000 in the climate models, before or after bias correction, suggesting discrepancy between observed and modeled trends. With that caveat, it was found that the pan evaporation has been projected to increase at a rate of 117-167 mm yr−1 K−1 (72-80 mm yr−1 K−1) over China using the multiple GCMs under the RCP 4.5 (RCP 8.5) scenario with increased greenhouse gases and the associated warming of the climate system. [ABSTRACT FROM AUTHOR]

This study developed a two-stage organosolv extraction process for the production of diverse components from tea oil fruit hull (TOFH) – a common lignocellulosic byproduct of tea oil processing industry. Results showed that a mild aqueous ethanol organosolv (AEO) extraction isolated 83.8% of tea saponin and 81.5% of tannin from the TOFH. Further, a severe atmospheric glycerol organosolv (AGO) extraction recovered the residual tea saponin and tannin. Meantime, the AGO process removed 40% of the hemicellulose and 35% of the lignin. The solid residual after the two-stage AEO-AGO extraction had a high cellulose hydrolyzability (>95%), much higher than that (only 40%) of one-step AEO extracted solid residual. Structural features of these undissolved solids were characterized by SEM, AFM and FT-IR. The two-stage organosolv extraction showed good potential in biorefining of the agroforestry biomass into value added bioproducts. [ABSTRACT FROM AUTHOR]

The Cel6A deficiency has become one of the limiting factors for cellulose saccharification in biochemical conversion of cellulosic biomass to fuels and chemicals. The work attempted to use codon optimization to enhance Trichoderma reesei Cel6A expression in Pichia pastoris . Two recombinants P. pastoris GS115 containing AOX1 and GAP promotors were successfully constructed, respectively. The optimal temperatures and pHs of the expressed Cel6A from two recombinants were consistent with each other, were also in the extremely similar range to that reported on the native Cel6A from T. reesei . Based on the shake flask fermentation, AOX1 promotor enabled the recombinant to produce 265 U/L and 300 mg/L of the Cel6A enzyme, and the GAP promotor resulted in 145 U/L and 200 mg/L. High cell density fed batch (HCDFB) fermentation significantly improved the enzyme titer (1100 U/L) and protein yield (2.0 g/L) for the recombinant with AOX1 promotor. Results have showed that the AOX1 promotor is more suitable than the GAP for the Cel6A expression in P. pastoris . And the HCDFB cultivation is a favorable way to express the Cel6A highly in the methanol inducible yeast. [ABSTRACT FROM AUTHOR]

• Ecohydrological responses to the 1987 fire were re-examined in three forested basins. • A significant decline in most ecohydrological variables was detected in the 1987 fire. • The hydrological systems need longer time to recover from fire than NDVI, LAI and GPP. Understanding how bushfire affects basin-wide ecohydrological processes is critical for ecological restoration and water supply. However, the mechanisms responsible for post-fire streamflow remain poorly explored in forested basins of China due to complex scale-dependent relationships between fire-induced forest changes and ecohydrological processes, lack of reasonable design of paired watershed experiments, and especially data scarcity. Here, we re-examine ecohydrological responses of the Black Dragon fire (one of the largest and most damaging forest fires on record globally) on an annual scale in three forest basins (two fire-impacted basins, namely Emuer and Pangu, and a nearly unimpacted basin, Huma) in the Daxing'an Mountains using multiple most recent datasets and methods. We found that the Black Dragon fire decreased annual- and basin-averaged vegetation leaf area, evapotranspiration, interception loss, transpiration, soil moisture, runoff, and discharge capacity in 1987 in the two fire-impacted basins compared with the unimpacted basin. The annual- and basin-averaged evapotranspiration (runoff) did not reduce (increase) as much as that expected with decreased LAI given the precipitation amount in 1987 in the two fire-impacted basins, which properly linked to the quick postfire regrowth of vegetation in the growing season. Vegetation leaf area and productivity can quickly recover in the following two to three years postfire, but the hydrological systems need more than 10 years to adapt this disturbance. These findings improve the understanding of ecohydrological responses to bushfire disturbance and provide scientific evidence for ecological protection and water resources management under intensified natural and anthropogenic disturbances. [ABSTRACT FROM AUTHOR]

The potential of cellulase enzymes in the developing and ongoing “biorefinery” industry has provided a great motivation to develop an efficient cellulase mixture. Recent work has shown how important the role that the so-called accessory enzymes can play in an effective enzymatic hydrolysis. In this study, three newest Novozymes Cellic CTec cellulase preparations (CTec 1/2/3) were compared to hydrolyze steam pretreated lignocellulosic substrates and model substances at an identical FPA loading. These cellulase preparations were found to display significantly different hydrolytic performances irrelevant with the FPA. And this difference was even observed on the filter paper itself when the FPA based assay was revisited. The analysis of specific enzyme activity in cellulase preparations demonstrated that different accessory enzymes were mainly responsible for the discrepancy of enzymatic hydrolysis between diversified substrates and various cellulases. Such the active role of accessory enzymes present in cellulase preparations was finally verified by supplementation with β-glucosidase, xylanase and lytic polysaccharide monooxygenases AA9. This paper provides new insights into the role of accessory enzymes, which can further provide a useful reference for the rational customization of cellulase cocktails in order to realize an efficient conversion of natural lignocellulosic substrates. [ABSTRACT FROM AUTHOR]

• Calibration with only runoff may underestimate SCA while overestimating snowpack. • Including snow in the calibration improved both snow and runoff simulations. • 15% to 30% decline in runoff was projected in 2085s compared with 1985s. • Future runoff decline is due to mild rise in rain not enough to mitigate larger AE. Snow-affected mountainous areas are highly vulnerable to climate changes in arid and semi-arid regions. Previous studies have put more emphasis on runoff, however, research about snow hydrological processes is still insufficient. Based on the optimization of calibration strategies, this study aims to provide a more realistic simulation of snow hydrology by coupling both a lumped rainfall-runoff model (GR6J) and a semi-distributed snow model (CemaNeige). Compared with calibration using only runoff, the multi-objective calibration with both runoff and snow not only significantly improved the KGE (Kling-Gupta efficiency) of snow from 0.34/0.47 to 0.67/0.69 during the calibration/validation period, but also slightly improved the KGE of runoff from 0.84/0.75 to 0.86/0.78, respectively. Additionally, we also found that the calibration using only runoff may underestimate snow cover (41%) and overestimate snowpack (20%), while there is little discrepancy in snowmelt and runoff. Snowmelt runoff is 57.7 mm accounting for 26% of the annual runoff. In the historical period (1980–2011), the runoff varied with a positive trend of 2.15 mm year−1 (p < 0.1), while its tendency became negative in the future. A 15% to 30% decline in runoff was projected for SSP370 (SSP3-RCP7) and SSP585 (SSP5-RCP8.5) in the 2085s (2070–2100) compared with that in the 1985s (1970–2000). Through further study on seasonal variations, we found that the future runoff decline is probably due to mild rise in rain not enough to alleviate the larger AE (actual evaporation), and for the runoff and AE we also found the variations in summer dominated the annual changes. In response to global warming, SCED (snow cover end date) advances while SCOD (snow cover onset date) recedes in all four scenarios as the year increases. Generally, coupling different hydrological models and multi-objective calibration strategies is vital for understanding the hydrological processes in snow-affected catchments. [ABSTRACT FROM AUTHOR]

Given that the glycerol organosolv pretreatment (GOP) can effectively improve the hydrolyzability of various lignocellulosic substrates, physicochemical changes of the substrate before and after the pretreatment was characterized to elucidate what is responsible for it. The effect of GOP on the main components and hydrolyzability of wheat straw was revisited. Results demonstrate that the GOP should be a promising candidate for the current pretreatment. Then the composition and structure of substrates was measured at multi-dimensional scales by using various analytic equipment such as TGA, SEM, AFM, CLSM, FT-IR, XRD and solid-state CP/MAS 13 C NMR. This paper reports some new insights on the mechanism behind that, which can be beneficial for further development, optimization, and scale-up of the GOP process. [ABSTRACT FROM AUTHOR]

• Mutation was used to improve lipid production from dual carbon sources by Trichosporon dermatis. • Mutant L7 was used to produce lipid from enzymatic hydrolysate of pretreated sugarcane bagasse. • L7 produced 34.9 g/L cell mass and 20.2 g/L lipid in shake flask fed-batch cultivation. • L7 produced 51.5 g/L cell mass and 31.3 g/L lipid in fermenter fed-batch cultivation. • L7 is highly efficient in producing lipid from glucose and xylose mixture from lignocellulose. In this study, an oleaginous yeast Trichosporon dermatis was mutated by a sequential plasma and chemical mutagenesis approach. The best mutant (L7) was investigated to produce lipid from enzymatic hydrolysates derived from pretreated sugarcane bagasse at different scales and cultivation modes. The results showed that in shake flasks, L7 produced 26.7 g/L cell mass with 14.0 g/L lipid from the hydrolysate medium containing 80 g/L glucose/xylose (mass ratio of 2:1) in batch mode, and 34.9 g/L cell mass with 20.2 g/L lipid from the medium containing a total of 120 g/L glucose/xylose (2:1) in fed-batch mode, respectively. In a 5 L fermenter, L7 produced 33.3 g/L cell mass with 18.1 g/L lipid in batch mode and 51.5 g/L cell mass with 31.3 g/L lipid in fed-batch mode, respectively. This study demonstrates that L7 is highly efficient T. dermatis strain to produce lipid using glucose and xylose mixture derived from lignocellulose. [ABSTRACT FROM AUTHOR]

Considering the practical technology–economy of glycerol processing from oleochemicals industry, the ensuing work was proposed to further explore the atmospheric aqueous glycerol autocatalytic organosolv pretreatment (AAGAOP) to improve the enzymatic hydrolysis of lignocellulosic biomass. With the liquid–solid ratio of 20gg−1 at 220°C for 3h, the AAGAOP enabled wheat straw to remove ∼70% hemicelluloses and ∼65% lignin, with ∼98% cellulose retention. The pretreated fiber was achieved with ∼90% of the enzymatic hydrolysis yield after 48h. At oven-drying, dehydration was likely to cause the hornification of fiber, which was responsible for the low enzymatic hydrolysis of dried fiber. With SEM observations, the AAGAOP disrupted wheat straw into thin and fine fibrils, with a small average size and more surface area. The AAGAOP technique, as a novel strategy, enhanced the enzymatic hydrolysis of lignocellulosic biomass by removing the chemically compositional barrier and altering the physically structural impediment. [Copyright &y& Elsevier]

In order to defray the cost of biodiesel production, the ensuing work was to further investigate utilization of the crude glycerol (CG) from oleochemicals industry in the atmospheric autocatalytic organosolv pretreatment (AAOP) to enhance enzymatic hydrolysis. The AAOP–CG enabled wheat straw to achieve with reasonable enzymatic hydrolysis yields, reaching ⩾75% for the wet substrate and ⩽63% for the dried. Lipophilic compounds from the CG formed pitch deposition on the fiber, which was responsible for low delignification (⩽30%) and also troublesome in practical operation. Pitch deposits itself had no significant role on enzymatic hydrolysis. A striking finding of the lignin recondensation and/or lignin–carbohydrate complex helped explain why dried pretreated wheat straw had a low enzymatic hydrolysis yield. The CG was suitable for the AAOP to enhance enzymatic hydrolysis of lignocellulosic biomass. But it was advisable to remove lipophilic compounds from crude glycerol before utilization. [Copyright &y& Elsevier]

One crucial step in processing the recalcitrant lignocellulosic biomass is the fast hydrolysis of natural cellulose to fermentable sugars that can be subsequently converted to biofuels and bio-based chemicals. Recent studies have shown that lytic polysaccharide monooxygenase (LPMOs) with auxiliary activity family 9 (AA9) are capable of efficiently depolymerizing the crystalline cellulose via regioselective oxidation reaction. Intriguingly, the catalysis by AA9 LPMOs requires reductant to provide electrons, and lignin and its phenolic derivatives can be oxidized, releasing reductant to activate the reaction. The activity of AA9 LPMOs can be enhanced by in-situ generation of H 2 O 2 in the presence of O 2. Although scientific understanding of these enzymes remains somewhat unknown or controversial, structure modifications on AA9 LPMOs through protein engineering have emerged in recent years, which are prerequisite for their extensive applications in the development of cellulase-mediated lignocellulosic biorefinery processes. In this review, we critically comment on advances in studies for AA9 LPMOs, i.e., characteristic of AA9 LPMOs catalysis, external electron donors to AA9 LPMOs, especially the role of the oxidization of lignin and its derivatives, and AA9 LPMOs protein engineering as well as their extensive applications in the bioprocessing of lignocellulosic biomass. Perspectives are also highlighted for addressing the challenges. [ABSTRACT FROM AUTHOR]

The sediment load of the Yellow River, once the highest in the world, has decreased to a record low. The annual sediment load (ASL, t·yr−1) in the main stream of the Yellow River in the past 100 years (1919–2018) shows that the ASL was consistently high for the first 60 years and then decreased gradually until 1999, when the Green for Grain Project (GGP) launched on the Loess Plateau caused ASL to drop sharply. The annual runoff did not decrease as much as ASL from 1919 to 2018, while it decreased significantly in the middle reaches. With the construction of sediment storage dams, terraces, and reservoirs, especially after the GGP launched, the ASL of the Yellow River has been reduced to historic lows. For example, the annual average Normalized Difference Vegetation Index (NDVI) of the Yellow River Basin increased significantly from 1982 to 2016, and the ASL decreased exponentially with increasing NDVI. Although the annual precipitation has a stationary behavior in the Yellow River, the daily precipitation extremes affecting erosion showed an increase of 7% per degree of warming but did not change the trend of ASL reduction. Therefore, the effective management on the Loess Plateau can control the trend of the sediment load of the Yellow River. Erosion, sediment load, and runoff in changing environments are affected by flood control and drought resistance, so more attention should be paid to these hydrologic processes. Unlabelled Image • The sediment load of the Yellow River decreases significantly in recent 100 years. • The sediment (1919–2018) is unstationary, while it is stationary in first 60 years. • The main contribution of sediment reduction is human activities in Yellow River. [ABSTRACT FROM AUTHOR]

• The annual precipitation remained stationary during 1958–2018 over the basin. • The annual water level and discharger remained stationary for period 1890–1970. • We analyzed the hydrological regime of the Changjiang River during the past 100. • The water level and discharge were in perfect synchronization prior to 1980. • About 50% discharge change in flood and non-flood seasons was attributed to TGD. The assumption that natural system changes in a constant range runs through the practice of water resources application. However, under the changing environment, whether hydrological characteristics have changed is a crucial and important foundation for flood control and drought resistance. Based on daily water level, discharge, and precipitation for the last 100 or 60 years, this study analyzed the hydrological characteristics and their changes as results of the operation of the Three Gorges Dam (TGD) in the Changjiang (Yangtze) River. Results showed that the monthly precipitation did not significantly change for the longer period and the annual precipitation remained stationary during 1959–2018. However, the water level and discharge significantly increased during most months from January to March and significantly decreased from August to November. Yichang station, the nearest station to the TGD, changed the most, which annual runoff and water level series (1959–2018) showed obvious non-stationarity behavior. The same results were showed in period 1890–2018, while the process remained stationary for the period 1890–1970. 50.15% of the discharge at Yichang station decrease from June to November was attributed to water storage of the TGD and 57.57% of its increase during other months was attributed to recharge of the TGD. The TGD had a greater impact on the discharge, while the water level was affected by both the TGD and Gezhouba Dam. The trends of the water level and discharge were in perfect synchronization prior to 1980, but went out of sync in terms of a different direction or rate after 1980 given the operation of Gezhouba Dam. The non-stationarity behavior of discharge and water level and the change of their laws make it difficult to directly apply the relationship among precipitation-discharge-water level in the past, which brings great challenges to the planning and management of water resources. [ABSTRACT FROM AUTHOR]

The use of heterogeneous catalysts in the transesterification reaction is an eco-friendly and cost-effective approach for biodiesel production as compared to the homogeneous catalyst-based processes. In this study, a heterogeneous cobalt doping Zn/Al complex oxide was prepared by a simple birch-templating method, and successfully applied to the transesterification of jatropha oil with methanol. The catalyst had strong diffraction peaks of ZnAl 2 O 4 spinel crystal with substitutional doping of amorphous cobalt atom. It had a tendency to achieve a high base strength whilst increasing the specific surface area in the presence of cobalt. By contrast to the impregnation and coprecipitation methods, the crystalline particles from templating method were uniformly distributed on the catalyst surface, thus forming a well-defined tiled network with large amounts of grain-free pores. The exposure of available activity sites resulted in a biodiesel yield of 91.4%. After used several times and recycled, the regenerated catalyst also exhibited good catalytic potency without obvious deactivation. The transesterification kinetics satisfied the Pseudo first order model that controlled by the reaction temperature and catalyst dosage. The thermodynamic parameters of Δ H of 16.7 kJ/mol, Δ S of −284.6 J/mol/K, and Δ G of 140.0 kJ/mol suggested an endothermic, endergonic, and non-spontaneous nature of the reaction. [Display omitted] • Co doped Zn-Al spinel was prepared for biodiesel production by different methods. • Templating method had high specific surface area with pores evenly distributed. • Efficient biodiesel yield above 90% was achieved with low levels of residual metal. • The catalyst exhibited good catalytic potency and reusability after reactivation. • Kinetic and thermodynamic properties of biodiesel production were assessed. [ABSTRACT FROM AUTHOR]

In the context of global warming, the increasing frequency of compound dry–hot extremes pose varying degrees of threats to the natural environment and human society. However, due to the lack of long‐term and high‐accuracy meteorological observations, the characteristics and drivers of compound dry–hot extremes over a century‐long period is still poorly investigated in China. Here we characterize the spatiotemporal variations of growing‐season (May–September) compound dry–hot events (CDHEs) over China using Standardized Dry and Hot Index (SDHI) calculated by monthly temperature and precipitation during 1901–2017. The influences of precipitation and temperature extremes, as well as large‐scale climate indices (i.e., El Niño–Southern Oscillation Index [ENSO], Atlantic Multidecadal Oscillation [AMO], North Atlantic Oscillation [NAO], Pacific Decadal Oscillation [PDO] and North Pacific [NP]) on CDHEs were then explored using the relative contribution analysis, Pearson correlation analysis and cross‐wavelet spectrum analysis. Our findings reveal a significant increase in the occurrence of different severity levels of CDHEs in China with their spatial extent gradually increase, practically since the end of the 20th century. Due to the exacerbation of drought conditions in China since the mid‐20th century, the regions where the Standardized Precipitation Index (SPI) has a more prominent contribution to the SDHI have gradually expanded, predominantly in the eastern, northern and northwestern parts of China. The significant influence of large‐scale climate indices, particularly ENSO and AMO, on the occurrence of compound dry–hot extremes in China is noteworthy, as these indices control the variability of precipitation and temperature, respectively. The study findings demonstrate that AMO exhibits a more significant correlation with SDHI in all subregions of China, while ENSO exhibits marginally stronger periodic coherence with SDHI than the other indices. This study offers valuable insights and references for unravelling long‐term development process of and the underlying influence mechanisms of significant climate patterns on the growing‐season CDHEs in China. [ABSTRACT FROM AUTHOR]

The co‐occurrence of hot and dry extremes (compound hot and dry extreme, CHDE) has attracted much attention due to the amplified impact on wildfire occurrence, agriculture production and human health. Most existing studies have reported the spatiotemporal variations of CHDE, changes in CHDE on different land surface conditions are barely discussed. The study investigated the spatial and temporal differences of CHDE over different regions and land covers in China during 1957–2018. On average over China, both day‐ and night‐time CHDEs have increased with a more rapid (2.6 times faster) and significant (p <.05) increasing trend in night‐time ones. Increasing trends are mainly distributed in north China with decreasing trends in central China. Moreover, increasing trends in night‐time mildly dry (0.07 per decade) and moderately hot (0.06 per decade) CHDEs are the largest among all dry and hot CHDEs. Regionally, the frequency of CHDE is the highest over the humid and sub‐humid regions for night‐ and day‐time CHDEs, but the lowest for both over the arid region. Meanwhile, CHDE has increased over the humid and sub‐humid regions in the recent decade but decreased over the arid region since 1957. For different land covers, the frequency of CHDE is the highest over forest but the lowest over grassland. Day‐time CHDEs of different hot magnitudes indicate the largest increasing trends over grassland caused by the largest increasing trends of day‐time heatwave. Significant (p < 0.05) increasing trends of day‐ and night‐time CHDEs over forest may increase the risks of tree mortality or forest fires after 2010 and larger increasing trends in night‐time CHDEs over urban may negatively impact human health. [ABSTRACT FROM AUTHOR]

• Raw material selected reduces the difficulty of removing aromatic amino acids. • The preparation process improves controllability, repeatability, and can be scaled-up. • High Fischer's ratio corn oligopeptides improve medical value of raw material. • Efficacy of liver injury repair of high Fischer's ratio corn oligopeptides is superior. • High Fischer's ratio corn oligopeptides can prevent early liver injury. Directed hydrolysis of corn crude peptides was performed by sequential digestion with α-chymotrypsin and carboxypeptidase A. With the additional step of adsorption of aromatic amino acids by activated carbon, corn oligopeptides with a Fischer's ratio of 41.87 and low bitterness were prepared. The fraction with molecular weight of 180–1000 Da was found to constitute 71.37% of these oligopeptides, where the proportion of Phe and Tyr among all amino acid residues was only 0.73%. In addition, a model of liver injury induced by carbon tetrachloride was established. Through the analysis of the body–mass index, liver index, liver histopathological features, and various serum biochemical indicators of liver function, high Fischer's ratio corn oligopeptides were found to be safe and slightly superior in terms of liver injury repair when compared with a commercial high Fischer's ratio amino acid product. Crude corn peptides (raw material) and skimmed milk powder had no effect on repairing liver injury. [ABSTRACT FROM AUTHOR]

Compound extreme events, such as events with concurrent extreme temperature and precipitation, are often more devastating than single events occurring independently with serious impacts on human society. In this study, we analyzed the future evolution of compound extreme summer days, namely, compound hot–dry days (CHDDs) and compound hot–wet days (CHWDs), in China and explored the relative changes in population and economic exposure based on climate simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6). The results showed that compound extreme days will be more frequent and severe under different scenarios in which the frequency of CHDDs is relatively high with a relatively high growth rate of CHWDs. The frequency of compound extreme days will continue to increase under the SSP2–4.5 and SSP5–8.5 scenarios but decline after 2070 under the SSP1–2.6 scenario. In general, the growth rate of population exposure to moderate/severe CHDDs ranges from 0 to 10%/30 to 50%. Meanwhile, the increasing rate of population exposure to moderate/severe CHWDs ranges from 0 to 30%/30 to 100%. GDP exposure to moderate/severe CHDDs would increase by 0–50%/100–400%, and severe CHWDs increased GDP exposure by more than 800%. Socioeconomic exposure to CHWDs will increase at a faster rate in the future. Due to the increase in compound extreme days and population decline, the relative contribution of climate change to population exposure is larger. Economic development alongside an increase in the number of compound extreme days will contribute relatively more to the interaction of climate and GDP, increasing GDP exposure. This study offers useful insights into mitigation and adaptation measures for compound extreme events and potential climate change in China. [ABSTRACT FROM AUTHOR]

Dilute acid (DA) pretreatment of biomass generates multiple inhibitory compounds within the pretreated hydrolysates. These compounds subsequently contribute to the formation of pseudo-lignin on the surface of the substrate, consequently impeding the efficiency of enzymatic digestibility. To detoxify the DA pretreated hydrolysates, post-incubation with non-catalytic proteins (amaranth protein, AP; soy protein, SP; bovine serum albumin, BSA) was performed in the present study. The enzymatic digestibility of DA-pretreated substrates was increased from 40.0% (without non-catalytic proteins) to 64.9, 53.8, and 56.4%, respectively, in the presence of AP (50 mg g−1), SP (65 mg g−1), and BSA (50 mg g−1). The post-incubation of pretreated substrates with non-catalytic proteins led to high hydrophobicity, contact angle, and accessibility, likely due to less formation of pseudo-lignin. Furthermore, gas chromatography/mass spectrometry analysis revealed that AP, SP, and BSA could lower the inhibitor concentrations in the pretreated hydrolysates by 39–100%, 5–100%, and 3–100%, respectively. The detoxification of the pretreated hydrolysates by AP demonstrated superior effectiveness compared to SP and BSA. To assess the affinity between inhibitors and non-catalytic proteins, surface plasmon resonance analysis was conducted, revealing the following affinity rates: AP (18.65 nM) > SP (17.04 nM) > BSA (16.87 nM). Additionally, molecular docking analysis revealed numerous molecular binding sites (i.e., hydrogen, polar, acidic, basic, and greasy contacts) with strong binding affinity ranging from −36.17 to −76.98 kcal mol−1 between the inhibitors and the amino acids of AP. Thus, this study highlights the potential application of AP as a cost-effective strategy for achieving a viable biorefinery. Also, the findings provide valuable insights that can be utilized to advance the development of (hemi)cellulases that exhibit enhanced resistance to lignin and inhibitors. [ABSTRACT FROM AUTHOR]

Excessive heat can cause discomfort, stress even mortality to humans. We investigate the multifaceted characteristics of summer heat and the affected population across China using a composite heat index (HI) based on meteorological observations and the Coupled Model Intercomparison Project Phase 6 climate models. We highlight that HI is only applicable when maximum air temperature is above 26.7 ℃. From 1961 to 2014, China has experienced increasing heat days (1.05 day/10a) and severity (0.15 ℃/10a) with more population influenced by expanding heat extent. Simultaneously, increases in the frequency (7.58–14.80 times), duration (0.46–1.23 days) and intensity (1.00–1.42 ℃/day) of heat events are detected with increased population exposure (9.33 × 105–5.59 × 106 times·persons). In the future, increases in heat severity, spatial extent, and the affected population would be aggravated from 1.5 to 2 to 3 ℃ warming. Dangerous heat events would experience increases in frequency (12.67–70.81 times), duration (0.85–7.21 days), intensity (1.78–8.57 ℃/day), and population exposure (2.06 × 106–3.18 × 107 times·persons) under a warming climate. Some regions over the Tibetan Plateau and southwest China would be affected by expanding cautionary and extremely cautionary heat. Northwest China would experience intensified dangerous heat events whereas southeastern China would face longer-lasting heat events with stronger intensity. Precautionary strategies are essential for these regions under risk. [ABSTRACT FROM AUTHOR]

A letter to the editor is offered in response to the article "Ocean salinities reveal strong global water cycle intensification during 1950 to 2000," by P. J. Durack and team in the April 27, 2012 issue.

With increasing demand for energy, broaden renewable energy of income and reduce expenditure is becoming more and more important. Diffuse radiation ( R d ) is an important consideration in building energy saving. Hundreds of methods were developed to calculate R d because it is seldom available in many countries and its spatial-pattern is strongly station-dependent. There are only 13 stations that monitor both global solar radiation ( R s ) and R d after 1993 across China. Based on 812640 measurements of daily R s and R d collected from 80 stations across China during 1957–2014, we wished to calibrate and validate a simple approach, which can be easily used to predict R d over both daily and monthly periods for all locations in China and gave the accurate values of parameters. The approach, of the case study method, is based on R s and extra-terrestrial solar radiance ( R a ). Results showed that the daily method can be employed well, while the monthly approach was applied well in the Southern Region (SR) only. The monthly approach of the Northern Region (NR) was improved using its regional characteristics. The methods achieved can effectively estimate R d and strongly apply in engineering for only two parameters, which accurate values for all stations has been offered. [ABSTRACT FROM AUTHOR]

Acid/base conjugate of acetic acid/sodium acetate solution (AC/SA) can efficiently produce xylooligosaccharides (XOS) with relatively high purity from poplar. The lignin in poplar is an important factor limiting the hydrolysis of xylan using enzymes and dilute acids. Until now, the effect of lignin content of poplar on XOS production by AC/SA hydrolysis is not clear. This work examined the relationship between lignin removal and XOS production from poplar by AC/SA hydrolysis. It was revealed that lignin removal of poplar enhanced XOS yield almost linearly (R2 = 0.95) in AC/SA hydrolysis. Under the optimal conditions (0.15 M AC/SA at a molar ratio of 3.0, 170 °C, 60 min), the highest XOS yield of 55.7% with a low xylose yield of 4.1% was obtained from poplar at a preferential lignin removal of 84.0%. Compared to the optimal XOS production from raw poplar, the XOS yield was increased by 32.3% and xylose production was decreased by 41.4%. Cellulase hydrolysis of the poplar residue produced a satisfying glucose yield of 92.8% and a xylose yield of 88.4%. This work proved that preferential delignification of poplar was vital in XOS and monosaccharides production by AC/SA hydrolysis combined with enzymatic hydrolysis. [Display omitted] • Lignin removal and XOS yield obtained by AC/SA hydrolysis was positively related. • The highest XOS yield of 55.7% was obtained from poplar with 84.0% lignin removal. • By-product of xylose was reduced by 41.4% when poplar was delignified by 84.0%. • Both delignification and AC/SA hydrolysis improved the hydrolyzability of poplar. [ABSTRACT FROM AUTHOR]

Compound hot and dry extremes have drawn extensive attention given the devastating impacts on natural ecosystem and social economy. However, the substantial dependence of compound hot and dry extremes upon individual ones is barely discussed at the daily level. In this study, we present the dependence of compound hot and dry days (CHDDs) and events (CHDEs) upon individual ones using summer (June–July–August) daily temperature and precipitation across China during 1961–2014. Results show more CHDDs and CHDEs over regions from northeast to southwest China, with stronger intensity over the transitional area between Northwest China (NW) and the Tibetan Plateau. Simultaneously, the period with the occurrence of compound extremes generally extends since compound extremes start earlier and end later. On average over China, hot extremes are significantly (p < 0.01) influential on the frequency (r = 0.42–0.83) of compound extremes, which contribute 55–78% to changes in the frequency. Dry extremes are significantly (p < 0.01) influential on the intensity (r = 0.60–0.79) and contribute 63–70% to changes in the intensity. Both hot and dry extremes are influential on the start and end of compound extremes. More importantly, largely influenced by the high probability of dry extremes in North China, the joint probability of compound extremes is higher in NW followed by Inner Mongolia. These findings highlight the new insights into compound extremes defined by relative thresholds at the daily level. • More compound extremes occur from NE to SW, with stronger intensity over the transitional area between NW and TP. • Hot (dry) extremes are more influential on the frequency (intensity) of compound extremes. • Influenced by dry extremes, the joint probability of compound extremes is higher in NW followed by IM. [ABSTRACT FROM AUTHOR]