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Agro-pastoral ecotone of northern China is the prominent area for agricultural production, but it is also the most typical ecological fragile area with frequent drought disasters. Taking Yulin City at Shaanxi Province in China as the case area, the paper aims to investigate the spatio-temporal changes of agricultural vulnerability to drought in China's agro-pastoral ecotone in the period 2000 to 2020. The results show that: 1) the agricultural vulnerability to drought in Yulin City has shifted from high vulnerability in the period 2000–2010 to low vulnerability in the period 2011–2020. 2) There exist obvious spatio-temporal differences of the agricultural vulnerability to drought in Yulin City during the research period. 3) Four sensitive events and 14 resilient events were identified in the research and the crops of Yulin had become more resilient to drought. Finally, the paper put forward with policy implications to make adaptive strategies of agriculture to climate change in China's agro-pastoral ecotone in the future, e.g., carrying out agricultural zoning based on agricultural production conditions, intensifying the construction of disaster prevention and relief system, and integrating with modern agricultural technology to develop new type agriculture. [ABSTRACT FROM AUTHOR]

Building a more resilient response system to climate change for sustainable development and reducing uncertainty in China's food markets, requires access to historical research gaps and mapping future research progress for decision making. However, the lack of quantitative and objective analyses to ensure the stability and development of agroecosystems increases the complexity of agro-climatic mechanisms, which leads to uncertainty and undesirable consequences. In this paper, we review the characteristics of climate change in China (1951–2020), reveal the mechanisms of agroecosystem structure in response to climate, and identify challenges and opportunities for future efforts in the context of research progress. The aim is to improve the scientific validity and relevance of future research by clarifying agro-climatic response mechanisms. The results show that surface temperature, precipitation, and frequency of extreme weather events have increased to varying degrees in major agricultural regions of China in 1951–2020. And they have strong geographic variation, which has resulted in droughts in the north and floods in the south. Moreover, climate change has complicated the mechanisms of soil moisture, Net Primary Productivity (NPP), soil carbon pool, and crop pest structure in agroecosystems. This lends to a reduction in soil water holding capacity, NPP, soil carbon content, and the number of natural enemies of diseases and insects, which in turn affects crop yields. However, human interventions can mitigate the deterioration of these factors. We have also realized that the methodology and theory of historical research poses a great challenge to future agroecosystem. Historical and projected climate trends identified current gaps in interdisciplinary integration and multidisciplinary research required to manage diverse spatio-temporal climate change impacts on agroecosystems. Future efforts should highlight integrated management and decision making, multidisciplinary big data coupling, and numerical simulations to ensure sustainable agricultural development, ecological security, and food security in China. [ABSTRACT FROM AUTHOR]

The decisions made by agricultural households to adjust to climate change (CC) in Iran are not well known. This study is intended to investigate the influence of perceptions and socioeconomic, institutional features on farmers' adaptation decisions about CC, which constitute the hypothetical statements of the study. We undertook a survey of 200 farm householders from 31 villages of Ilam Province, situated in the western Iran, as randomly selected. The result discloses that the proposed discriminant model matches the data-set well, with a strong effect size of partial eta-squared (η2 = 0.38). The analysis further signals that adapters are younger and more well-educated than non-adapters. Adapters are also knowledgeable about CC risks and institutional policy barriers. The adapters have subsidiary work, better access to credit, and have good contacts with expansion agents and specialists. The paper concludes that government authorities should provide farmers with the enriched capabilities and competencies enabling them to adapt to CC. [ABSTRACT FROM AUTHOR]

Xinjiang is located in the core China's 'Belt and Road' development, and northern Xinjiang is an important region for economic development. In recent years, due to the strong influence of global climate change and human disturbance, regional climate instability and ecological-economic-social system sensitivity have grown. In this paper, seasonal, interannual, interdecadal, spatial, abrupt, and periodic variations of temperature and precipitation in northern Xinjiang were analyzed using daily surface air temperature and precipitation data from 49 meteorological stations during 1961–2017. At the same time, the driving factors of climate change are discussed. Methods included linear regression, cumulative anomaly, the Mann-Kendall test, and Morlet wavelet analysis. The results indicated that during the study period, annual mean temperature and annual precipitation increased significantly at rates of 0.35°C/10 yr and 13.25 mm/10 yr, respectively, with abrupt changes occurring in 1994 and 1986. Annual mean temperature and annual precipitation in all four seasons showed increasing trends, with the maximum increases in winter of 0.42°C/10 yr and 3.95 mm/10 yr, respectively. The general climate in northern Xinjiang showed a trend towards increasingly warm and humid. In terms of spatial distribution, the temperature and precipitation in high mountainous areas increased the most, while basins areas increased only slightly. Periodic change analysis showed that annual mean temperature and annual precipitation experienced two climatic shifts from cold to warm and dry to wet, respectively. Population change, economic development and land use change are important factors affecting climate change, and more research should be done in this field. [ABSTRACT FROM AUTHOR]

Using the precipitation data in recent 40 years of 48 meteorological stations in Taklimakan area and neighboring areas, this paper analyzes the stage and periodicity of the wet-dry changes in a year and four seasons. The paper also compares the correlativity of precipitation between Taklimakan area and around Mountains, and obtained some statistic conclusions as follows. (1) The precipitation changes of a year and four seasons in Taklimakan area have different wet-dry periods and change periodicities. (2) Summer precipitation has well directive sense to annual precipitation in Taklimakan area with a correlation coefficient 0.901, and the negative correlation between precipitation and temperature in summer is very remarkable. (3) There is definite correlation between annual precipitation in Taklimakan area and position of polar vortex. When longitude of polar vortex is partial west in February and its latitude is partial north in September of the last year, annual precipitation is above its mean in the area. In addition, it is beneficial to obtain more summer precipitation in the area when position of polar vortex is partial west in February. [ABSTRACT FROM AUTHOR]

This paper attempts to assess the vulnerability to climate change of human communities in selected mouzas of Sagar Island, South 24 Parganas District of India. A primary household survey has been conducted to collect data on socio-demographic profile, livelihood strategy, health, food, water, social network, natural disaster and climate variation indicators, were selected for Livelihood Vulnerability Index (LVI) and Livelihood Vulnerability Index-Intergovernmental Panel on Climate Change (LVI-IPCC) analyses to measure and compare the vulnerability of mouzas (administrative unit) currently suffering from frequent flooding, coastal erosion and embankment breaching on an annual basis. Secondary data collected from the Indian Meteorological Department, the Water Resources Information System of India and the Global Sea Level Observing System have been used to identify dynamics of climate change by employing statistical and Geographic Information System (GIS) techniques. A GPS survey has been conducted to identify locations of embankment breaching, and satellite images obtained from the National Aeronautics and Space Administration and U.S. Geological Survey (NASA USGS) Government website have been applied to shoreline and land use change detection, using a supervised maximum likelihood classification. The results indicate that the study area has experienced increasing temperature, changing precipitation patterns, rise in sea level, higher storm surges, shoreline change, constant land loss, embankment breaching and changing land use, which have had impact on vulnerability, particularly of poorer people. The LVI (0.48 to 0.68) and LVI-IPCC (0.04 to 0.14) scores suggest that the populations of Dhablat, Bankimnagar, Sumatinagar, Muri Ganga and Sibpur mouzas are highly vulnerable (LVI scores of 0.60 to 0.68 and LVI-IPCC scores of 0.11 to 0.14) to climate change both because the communities are more exposed to it, and because poor access to food, health facilities and water makes them extremely sensitive to it and lowers their adaptive capacity. The findings of this study could be crucial to framing further development and adaptation strategies relating to climate change, and to safeguarding the estuarine ecosystem and the vulnerable population. [ABSTRACT FROM AUTHOR]

Extreme heat events have serious effects on human daily life. Accurately capturing the dynamic variance of extreme high-temperature distributions in a timely manner is the basis for analyzing the potential impacts of extreme heat, thereby informing risk prevention strategies. This paper demonstrates the potential application of multiple source remote sensing data in mapping and monitoring the extreme heat events that occurred on Aug. 8, 2013 in Jiangsu Province, China. In combination with MODIS products, the thermal sharpening (TsHARP) method and a binary linear model are compared to downscale the original daytime FengYun 2F (FY-2F) land surface temperature (LST) imagery, with a temporal resolution of 60 min, from 5 km to 1 km. Using the meteorological measurement data from Nanjing station as the reference, the research then estimates the instantaneous air temperature by using an iterative computation based on the Surface Energy Balance Algorithm for Land (SEBAL), which is used to analyze the spatio-temporal air temperature variance. The results show that the root mean square error (RMSE) of the LST downscaled from the binary linear model is 1.30°C compared to the synchronous MODIS LST, and on this basis the estimated air temperature has the RMSE of 1.78°C. The spatial and temporal distribution of air temperature variance at each geographical location from 06:30 to 18:30 can be accurately determined, and indicates that the high temperature gradually increases and expands from the city center. For the spatial distribution, the air temperature and the defined scorching temperature proportion index increase from northern to middle, to southern part of Jiangsu, and are slightly lower in the eastern area near the Yellow Sea. In terms of temporal characteristics, the percentage of area with air temperature above 37°C in each city increase with time after 10:30 and reach the peak value at 14:30 or 15:30. Then, they decrease gradually, and the rising and falling trends become smaller from the southern cities to the northern regions. Moreover, there is a distinct positive relationship between the percentage of area above 37°C and the population density. The above results show that the spatio-temporal distributions of heat waves and their influencing factors can be determined by combining multiple sources of remotely sensed image data. [ABSTRACT FROM AUTHOR]

Urban areas and its evolution are important anthropogenic indicators and human ecological footprints, and play decisive roles in environmental change analysis, global geo-conditional monitoring, and sustainable development. China has the highest rate of urban expansion and has emerged as an urban expansion hotspot worldwide. In this paper, the progress of studies on Chinese urban expansion based on remote sensing technology are summarized and analyzed from the aspects of urban area definition, remotely sensed imagery applied in urban expansion, monitoring methods of urban expansion, and urban expansion applications. Existing issues and future directions of Chinese urban expansion are discussed and proposed. Results indicate that: 1) The fusion of multi-source remotely sensed imagery is imperative to meet the needs of urban expansion with various monitoring terms and frequencies on different scales and dimensions. 2) To guarantee the classification accuracy and efficiency and describe urban expansion and its influences on local land use simultaneously, the combination of visual interpretation and automatic classification is the tendency of future monitoring methods of urban areas. 3) Urban expansion data have become the prerequisite for recognizing the urban development process, excavating its driving forces, simulating and predicting the future development directions, and also is conducive to revealing and explaining urban ecological and environmental issues. 4) In the past decades, Chinese scholars have promoted the application of remote sensing technology in the urban expansion field, with data construction, methods and models developing from the quotation stage to improvement and innovation stage; however, an independent and consistent urban expansion data on the national scale with long-term and high-frequency (such as annual monitoring) monitoring is still lacking. [ABSTRACT FROM AUTHOR]

The ground ice content in permafrost serves as one of the dominant properties of permafrost for the study of global climate change, ecology, hydrology and engineering construction in cold regions. This paper initially attempts to assess the ground ice volume in permafrost layers on the Qinghai-Tibet Plateau by considering landform types, the corresponding lithological composition, and the measured water content in various regions. An approximation demonstrating the existence of many similarities in lithological composition and water content within a unified landform was established during the calculations. Considerable knowledge of the case study area, here called the Source Area of the Yellow (Huanghe) River (SAYR) in the northeastern Qinghai-Tibet Plateau, has been accumulated related to permafrost and fresh water resources during the past 40 years. Considering the permafrost distribution, extent, spatial distribution of landform types, the ground ice volume at the depths of 3.0-10.0 m below the ground surface was estimated based on the data of 101 boreholes from field observations and geological surveys in different types of landforms in the permafrost region of the SAYR. The total ground ice volume in permafrost layers at the depths of 3.0-10.0 m was approximately (51.68 ± 18.81) km3, and the ground ice volume per unit volume was (0.31 ± 0.11) m3/m3. In the horizontal direction, the ground ice content was higher in the landforms of lacustrine-marshland plains and alluvial-lacustrine plains, and the lower ground ice content was distributed in the erosional platforms and alluvial-proluvial plains. In the vertical direction, the volume of ground ice was relatively high in the top layers (especially near the permafrost table) and at the depths of 7.0-8.0 m. This calculation method will be used in the other areas when the necessary information is available, including landform type, borehole data, and measured water content. [ABSTRACT FROM AUTHOR]

A new form of producing and sharing knowledge has emerged as an international (United States of America, Asia, and Europe) research collaboration, known as the Long-Term Ecological Research (LTER) Network. Although Africa boasts rich biodiversity, including endemic species, it lacks the long-term initiatives to underpin sustainable biodiversity managements. At present, climate change may exacerbate hunger and poverty concerns in addition to resulting in ecosystem degradation, land use change, and other threats in Africa. Therefore, ecosystem monitoring was suggested to understanding the effects of climate change and setting strategies to mitigate these changes. This paper aimed to investigate ecosystem monitoring ground sites and address their coverage gaps in Africa to provide a foundation for optimizing the African Ecosystem Research Network (AERN) ground sites. The geographic coordinates and characteristics of ground sites-based ecosystem monitoring were collected from various networks aligned with the LTER implementation in Africa. Additionally, climatic data and biodiversity distribution maps were retrieved from various sources. These data were used to assess the size of existing ground sites and the gaps in description, ecosystems and biomes. The results reveal that there were 1089 sites established by various networks. Among these sites, 30.5%, 27.5%, and 28.8% had no information of area, year of establishment, current status, respectively. However, 68.0% of them had an area equal to or greater than 1 km. Sites were created progressively over the course of the years, with 68.9% being created from 2000 to 2005. To date, only 41.5% of the sites were operational. The sites were scattered across Africa, but they were concentrated in Eastern and Southern Africa. The unbalanced distribution pattern of the sites left Central and Northern Africa hardly covered, and many unique ecosystems in Central Africa were not included. To sustain these sites, the AERN should be based on operational sites, seeking secure funding by establishing multiple partnerships. [ABSTRACT FROM AUTHOR]

To manage water resources effectively, a multiscale assessment of the vulnerability of water resources on the basis of political boundaries and watersheds is necessary. This study addressed issues on the vulnerability of water resources and provided a multiscale comparison of spatial heterogeneity under a climate change background. Using improved quantitative evaluation methods of vulnerability, the Theil index and the Shannon-Weaver index, we evaluated the vulnerability of water resources and its spatial heterogeneity in the Haihe River Basin in four scales, namely, second-class water resource regions (Class II WRRs), third-class water resource regions (Class III WRRs), Province-Class II WRRs, and Province-Class III WRRs. Results show that vulnerability enhances from the north to south in the different scales, and shows obvious spatial heterogeneity instead of moving toward convergence in multiscale assessment results. Among the Class II WRRs, the Tuhai-Majia River is the most vulnerable area, and the vulnerability of the Luanhe River is lower than that of the north of the Haihe River Basin, which in turn is lower than that of the south of the Haihe River Basin. In the scales of Class III WRRs and Province-Class III WRRs, the vulnerability shows obvious spatial heterogeneity and diversity measured by the Theil index and the Shannon-Weaver index. Multiscale vulnerability assessment results based on political boundaries and the watersheds of the Haihe River Basin innovatively provided in this paper are important and useful to characterize the real spatial pattern of the vulnerability of water resources and improve water resource management. [ABSTRACT FROM AUTHOR]

In this paper, a thin cloud removal method was put forward based on the linear relationships between the thin cloud reflectance in the channels from 0.4 μm to 1.0 μm and 1.38 μm. Channels of 0.66 μm, 0.86 μm and 1.38 μm were chosen to extract the water body information under the thin cloud. Two study cases were selected to validate the thin cloud removal method. One case was applied with the Earth Observation System Moderate Resolution Imaging Spectroradiometer (EOS/MODIS) data, and the other with the Medium Resolution Spectral Imager (MERSI) and Visible and Infrared Radiometer (VIRR) data from Fengyun-3A (FY-3A). The test results showed that thin cloud removal method did not change the reflectivity of the ground surface under the clear sky. To the area contaminated by the thin cloud, the reflectance decreased to be closer to the reference reflectance under the clear sky after the thin cloud removal. The spatial distribution of the water body area could not be extracted before the thin cloud removal, while water information could be easily identified by using proper near infrared channel threshold after removing the thin cloud. The thin cloud removal method could improve the image quality and water body extraction precision effectively. [ABSTRACT FROM AUTHOR]

The detection of glacial lake change in the Himalayas, Nepal is extremely significant since the glacial lake change is one of the crucial indicators of global climate change in this area, where is the most sensitive area of the global climate changes. In the Himalayas, some of glacial lakes are covered by the dark mountains' shadow because of their location. Therefore, these lakes can not be detected by conventional method such as Normalized Difference Water Index (NDWI), because the reflectance feature of shadowed glacial lake is different comparing to the ones which are located in the open flat area. The shadow causes two major problems: 1) glacial lakes which are covered by shadow completely result in underestimation of the number of glacial lakes; 2) glacial lakes which are partly identified are considered to undervalue the area of glacial lakes. The aim of this study is to develop a new model, named Detection of Shadowed Glacial Lakes (DSGL) model, to identify glacial lakes under the shadow environment by using Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) data in the Himalayas, Nepal. The DSGL model is based on integration of two different modifications of NDWI, namely NDWI model and NDWI model. NDWI is defined as integration of the NDWI and slope analysis and used for detecting non-shadowed lake in the mountain area. The NDWI is proposed as a new methodology to overcome the weakness of NDWI on identifying shadowed lakes in highly elevated mountainous area such as the Himalayas. The first step of the NDWI is to enhance the data from ASTER 1B using the histogram equalization (HE) method, and its outcome product is named ASTER. We used the ASTER for calculating the NDWI and the NDWI. Integrated with terrain analysis using Digital Elevation Model (DEM) data, the NDWI can be used to identify the shadowed glacial lakes in the Himalayas. NDWI value of 0.41 is used to identify the glacier lake (NDWI ≥ 0.41), and 0.3 of NDWI is used to identify the shadowed glacier lake (NDWI ≤ 0.3). The DSGL model was proved to be able to classify the glacial lakes more accurately, while the NDWI model had tendency to underestimate the presence of actual glacial lakes. Correct classification rate regarding the products from NDWI model and DSGL model were 57% and 99%, respectively. The results of this paper demonstrated that the DSGL model is promising to detect glacial lakes in the shadowed environment at high mountains. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a framework for evaluating the performance of ecosystem strategies prepared for enhancing vulnerability reduction in the face of hazards due to climate change. The framework highlights the positive effects of human activities in the coupled human and natural system (CHANS) by introducing adaptive capacity as an evaluation criterion. A built-in regional vulnerability to a certain hazard was generated based upon interaction of three dimensions of vulnerability: exposure, sensitivity and adaptive capacity. We illustrated the application of this framework in the temperate farming-grazing transitional zone in the middle Inner Mongolia of the northern China, where drought hazard is the key threat to the CHANS. Specific indices were produced to translate such climate variance and social-economic differences into specific indicators. The results showed that the most exposed regions are the inner land areas, while counties located in the eastern part are potentially the most adaptive ones. Ordos City and Bayannur City are most frequently influenced by multiple climate variances, showing highest sensitivity. Analysis also indicated that differences in the ability to adapt to changes are the main causes of spatial differences. After depiction of the spatial differentiations and analysis of the reasons, climate zones were divided to depict the differences in facing to the drought threats. The climate zones were shown to be similar to vulnerability zones based on the quantitative structure of indexes drafted by a triangular map. Further analysis of the composition of the vulnerability index showed that the evaluation criteria were effective in validating the spatial differentiation but potentially ineffective because of their limited time scope. This research will be a demonstration of how to combine the three dimensions by quantitative methods and will thus provide a guide for government to vulnerability reduction management. [ABSTRACT FROM AUTHOR]

This paper is a review of studies of abrupt climate changes (ACCs) during the Holocene published during the past ten years. North Atlantic cold events are indicators of ACCs. As indicated by North Atlantic ice-rafted debris (IRD), there were nine confirmed cold events during the Holocene, occurring at 11.1 kyr, 10.3 kyr, 9.4 kyr, 8.1 kyr, 5.9 kyr, 4.2 kyr, 2.8 kyr, 1.4 kyr, and 0.4 kyr respectively according to most representative results from Bond et al. (1997). However, the identification of chronology has been made with some uncertainties. Considerable climatic proxy data have shown that, during the cold events, substantial climate abnormalities have occurred widely across the globe, particularly in the areas surrounding the North Atlantic. These abnormalities were in the form of high-latitude cold in the both hemispheres, expansion of the Westerlies to low latitudes, drought in the monsoon regions, recession of summer monsoons, and intensification of the winter monsoons. Studies have indicated that the four ACCs occurring in the early Holocene may be related to freshwater pulses from ice melting in the northern part of the North Atlantic, and the other five ACCs that occurred during the middle and late Holocene may be related to the decreased solar activity. [ABSTRACT FROM AUTHOR]

Using wavelet analysis, regression analysis and the Mann-Kendall test, this paper analyzed time-series (1959–2006) weather data from 23 meteorological stations in an attempt to characterize the climate change in the Tarim River Basin of Xinjiang Uygur Autonomous Region, China. Major findings are as follows: 1) In the 48-year study period, average annual temperature, annual precipitation and average annual relative humidity all presented nonlinear trends. 2) At the 16-year time scale, all three climate indices unanimously showed a rather flat before 1964 and a detectable pickup thereafter. At the 8-year time scale, an S-shaped nonlinear and uprising trend was revealed with slight fluctuations in the entire process for all three indices. Incidentally, they all showed similar pattern of a slight increase before 1980 and a noticeable up-swing afterwards. The 4-year time scale provided a highly fluctuating pattern of periodical oscillations and spiral increases. 3) Average annual relative humidity presented a negative correlation with average annual temperature and a positive correlation with annual precipitation at each time scale, which revealed a close dynamic relationship among them at the confidence level of 0.001. 4) The Mann-Kendall test at the 0.05 confidence level demonstrated that the climate warming trend, as represented by the rising average annual temperature, was remarkable, but the climate wetting trend, as indicated by the rising annual precipitation and average annual relative humidity, was not obvious. [ABSTRACT FROM AUTHOR]

The scientific evidence that climate is changing due to greenhouse gas emission is now incontestable, which may put many social, biological, and geophysical systems in the world at risk. In this paper, we first identified main risks induced from or aggravated by climate change. Then we categorized them applying a new risk categorization system brought forward by Renn in a framework of International Risk Governance Council. We proposed that “uncertainty” could be treated as the classification criteria. Based on this, we established a quantitative method with fuzzy set theory, in which “confidence” and “likelihood”, the main quantitative terms for expressing uncertainties in IPCC, were used as the feature parameters to construct the fuzzy membership functions of four risk types. According to the maximum principle, most climate change risks identified were classified into the appropriate risk types. In the mean time, given that not all the quantitative terms are available, a qualitative approach was also adopted as a complementary classification method. Finally, we get the preliminary results of climate change risk categorization, which might lay the foundation for the future integrated risk management of climate change. [ABSTRACT FROM AUTHOR]

Traditionally, the mid-Holocene in most parts of China was thought to be warmer with higher precipitation, resulting from a strong Asian summer monsoon. However, some recent researches have proposed a mid-Holocene drought interval of millennial-scale in East Asian monsoon margin areas. Thus whether mid-Holocene was dry or humid remains an open issue. Here, Zhuyeze palaeolake, the terminal lake of the Shiyang River Drainage lying in Asian monsoon marginal areas, was selected for reconstructing the details of climate variations during the Holocene, especially mid-Holocene, on the basis of a sedimentological analysis. Qingtu Lake (QTL) section of 6.92m depth was taken from Zhuyeze palaeolake. Multi-proxy analysis of QTL section, including grain size, carbonate, TOC, C/N and δ13C of organic matter, was used to document regional climatic changes during 9–3 cal ka B.P. The record shows a major environmental change at 9.0–7.8 cal ka B.P., attributed to a climate trend towards warmth and humidity. This event was followed by a typical regional drought event which occurred during 7.8–7.5 cal ka B.P. And a warm and humid climate prevailed from 7.5 to 5.0 cal ka B.P., attributed to the warm/humid Holocene Optimum in this region. After that, the climate gradually became drier. Moreover, comparison of the climate record from this paper with the summer insolation at 30°N indicates that the climate pattern reflecting the Asian monsoon changes was caused by insolation change. [ABSTRACT FROM AUTHOR]

Over the last 2000 years, approximately 38 ancient cities were abandoned through desertification in Hexi Corridor, Northwest China. Among them, 21.05% were abandoned during the Northern and Southern Dynasties, 21.05% during the end of the Tang Dynasty and the Five Dynasties, and 57.9% during the Ming and Qing dynasties. At the same time, main lakes were shrinking rapidly from the 5th Century to the 6th Century and the end of the Qing Dynasty. The climate in these periods was relatively arid and cold with frequent dusts. The phase of these changes indicated that there were three periods of desertification enlargement in the northern China. They were Northern and Southern Dynasties, the end of Tang Dynasty and Five Dynasties, the Ming and Qing dynasties. The macro-process of desertification in the study area was controlled mainly by the climatic changes. But from the facts that the population density in the middle of Qing Dynasty had exceeded the critical index of population pressure in arid area and the usage rate of water resources had exceeded 40% in Hexi Corridor, this paper also suggests that human activities have played an important role in desertification processes of the study area mainly during the recent 300 years. [ABSTRACT FROM AUTHOR]

The grassland in the Hindu Kush Himalayan (HKH) region is one of the largest and most biodiverse mountain grassland types in the world, and its ecosystem service functions have profound impacts on the sustainable development of the HKH region. Monitoring the spatiotemporal distribution of grassland aboveground biomass (AGB) accurately and quantifying its response to climate change are indispensable sources of information for sustainably managing grassland ecosystems in the HKH region. In this study, a pure vegetation index model (PVIM) was applied to estimate the long-term dynamics of grassland AGB in the HKH region during 2000–2018. We further quantified the response of grassland AGB to climate change (temperature and precipitation) by partial correlation and variance partitioning analyses and then compared their differences with elevation. Our results demonstrated that the grassland AGB predicted by the PVIM had a good linear relationship with the ground sampling data. The grassland AGB distribution pattern showed a decreasing trend from east to west across the HKH region except in the southern Himalayas. From 2000 to 2018, the mean AGB of the HKH region increased at a rate of 1.57 g/(m2·yr) and ranged from 252.9 (2000) to 307.8 g/m2 (2018). AGB had a positive correlation with precipitation in more than 80% of the grassland, and temperature was positively correlated with AGB in approximately half of the region. The change in grassland AGB was more responsive to the cumulative effect of annual precipitation, while it was more sensitive to the change in temperature in the growing season; in addition, the influence of climate varied at different elevations. Moreover, compared with that of temperature, the contribution of precipitation to grassland AGB change was greater in approximately 60% of the grassland, but the differences in the contribution for each climate factor were small between the two temporal scales at elevations over 2000 m. An accurate assessment of the temporal and spatial distributions of grassland AGB and the quantification of its response to climate change are of great significance for grassland management and sustainable development in the HKH region. [ABSTRACT FROM AUTHOR]

Climate change can affect wind erosion power and hence induce changes in wind erosion rates. In this study, the wind erosion climate factor (C-factor), proposed by the Food and Agriculture Organization of the United Nations, was used to assess the impact of changes in climate on wind erosion climatic erosivity. The Mann-Kendall test was employed to detect trends in the C-factor during the period of 1961–2017 in the farming-pastoral zone of northern China. Sensitivity analysis was used to determine the sensitivity of the C-factor to changes in key climate factors. Furthermore, a comparison of the contributions of different climate factors was carried out to understand their impact on changes in the C-factor. The results indicated that most of the surveyed region exhibited decreasing trends in wind speed at a confidence level of 90%, while maximum and minimum temperatures showed increasing trends throughout the study area. As a consequence of decreasing wind speed, the annual C-factor exhibited significant decreasing trends, with a mean slope of −0.58/yr. Seasonal analysis revealed that in most regions, the changes in the C-factor had significant decreasing trends in spring, winter, and autumn, while in more than two-thirds of the study area, no significant change trends in the C-factor were detected in summer at a confidence level of 90%. Sensitivity analysis showed that the C-factor was most sensitive to wind speed, and that the sensitivity coefficients from July to September were much higher than those in other months. Contribution analysis revealed that, for most stations, wind speed (with greater values of sensitivity coefficients) was the dominant factor in the change of C-factor, while for some stations, the minimum temperature made the most contribution to the C-factor's change due to its dramatic changes during the study period. Although the minimum temperature sensitivity coefficient was the lowest of all the sensitivity coefficients, it is urgent to evaluate the expected impact of minimum temperature due to its possible changes in the future. [ABSTRACT FROM AUTHOR]

Reference evapotranspiration (ET0) is a vital component in hydrometeorological research and is widely applied to various aspects, such as water resource management, hydrological modeling, irrigation deployment, and understanding and predicting the influence of hydrologic cycle variations on future climate and land use changes. Quantifying the influence of various meteorological variables on ET0 is not only helpful for predicting actual evapotranspiration but also has important implications for understanding the impact of global climate change on regional water resources. Based on daily data from 69 meteorological stations, the present study analyzed the spatiotemporal pattern of ET0 and major contributing meteorological variables to ET0 from 1960 to 2017 by the segmented regression model, Mann-Kendall test, wavelet analysis, generalized linear model, and detrending method. The results showed that the annual ET0 declined slightly because of the combined effects of the reduction in solar radiation and wind speed and the increase in vapor pressure deficit (VPD) and average air temperature in the Loess Plateau (LP) during the past 58 yr. Four change points were detected in 1972, 1990, 1999, and 2010, and the annual ET0 showed a zigzag change trend of 'increasing-decreasing-increasing-decreasing-increasing'. Wind speed and VPD played a leading role in the ET0 changes from 1960 to 1990 and from 1991 to 2017, respectively. This study confirms that the dominant meteorological factors affecting ET0 had undergone significant changes due to global climate change and vegetation greening in the past 58 years, and VPD had become the major factor controlling the ET0 changes on the LP. The data presented herein will contribute to increasing the accuracy of predictions on future changes in ET0. [ABSTRACT FROM AUTHOR]

With global warming, the great changes in the patterns of plant growth have occurred. The conditions in early spring and late autumn have changed the process of vegetation photosynthesis, which are expected to have a significant impact on net primary productivity (NPP) and affect the global carbon cycle. Currently, the seasonal response characteristics of NPP to phenological changes in dryland ecosystems are still not well defined. This article calibrated and analyzed the normalized difference vegetation index (NDVI) time series of Advanced Very-High-Resolution Radiometer (AVHRR) data from 1982 to 2015 in the Loess Plateau, China. The spatial and temporal distributions of vegetation phenology and NPP in the Loess Plateau under semihumid and semiarid conditions were investigated. The seasonal variation in the NPP response to vegetation phenology under the climate change was also analyzed. The results showed that, different from the northern forest, there was distinct spatial heterogeneity in the effect of climate change on the dynamic change in vegetation growth in the Loess Plateau: 1) an advance of the start of the growing season (SOS) and a delay of the end of the growing season (EOS) significantly increased the NPP in spring and autumn, respectively, in the humid southeast; 2) in the arid northwest, the NPP did not significantly increase in spring and autumn but significantly decreased in summer. [ABSTRACT FROM AUTHOR]

Variations in vegetation are closely related to climate change, but understanding of their characteristics and causes remains limited. As a typical semi-humid and semi-arid cold plateau region, it is important to understand the knowledge of long term Normalized Difference Vegetation Index (NDVI) variations and find the potential causes in the source region of the Yangtze River. Based on four tree-ring width chronologies, the regional mean NDVI for July and August spanning the period 1665–2013 was reconstructed using a regression model, and it explained 43.9% of the total variance during the period 1981–2013. In decadal, the reconstructed NDVI showed eight growth stages (1754–1764, 1766–1783, 1794–1811, 1828–1838, 1843–1855, 1862–1873, 1897–1909, and 1932–1945) and four degradation stages (1679–1698, 1726–1753, 1910–1923, and 1988–2000). And based on wavelet analysis, significant cycles of 2–3 yr and 3–8 yr were identified. In additional, there was a significant positive correlation between the NDVI and the Palmer Drought Severity Index (PDSI) during the past 349 yr, and they were mainly in phase. However, according to the results of correlation analysis between different grades of drought/wet and NDVI, there was significant asymmetry in extreme drought years and extreme wet years. In extreme drought years, NDVI was positively correlated with PDSI, and in extreme wet years they were negatively correlated. [ABSTRACT FROM AUTHOR]

This paper presents a dynamic glacier model that simulates the processes in response of Glacier No. 1 in headwaters of the Ürümqi River to various future climatic scenarios. The results indicate that the Glacier No. 1 will continue retreating if current climatic conditions prevail, until it reaches an equilibrium state of 1600 m in length after 700 to 800 years. If air temperature raise 1°C, the glacier would become a hanging glacier with a length of 300 m after 700 to 800 years. Due to its retreat, cooling function of the glacier would be weakened, resulting in the air temperature in glaciated area higher than that in ice-free areas. The results also indicate that the current glacier melt runoff is in higher value period in comparison with the runoff in the equilibrium state under the current climatic condition. If the air temperature continues increasing, however, the runoff would still increase to a new peak and then decrease rapidly. [ABSTRACT FROM AUTHOR]

The impact of human carbon emissions on climate has generated widespread global concern. We selected 24 countries as research objects and analysed the changes in carbon emissions in different countries between the establishment of emission reduction actions in 1990 and 2014. Then, we selected 19 factors representing four categories (economy, population, technology and energy) to explore the key factors that led to changes in carbon dioxide (CO2) emissions in different countries. Emission reduction actions since 1990 did not lead to marked improvements, and only five countries (Russia, Germany, the United Kingdom, Italy and France) achieved reductions in carbon emissions. The factors that influenced CO2 emissions varied among countries. In most developing countries, reductions in CO2 emissions were caused by reductions in poverty and inherent natural conditions. Moreover, the extent of influence of a given factor on CO2 emissions differed among countries. The global economic crisis may cause similar fluctuations in CO2 emissions in many countries. Adjustments to energy and industrial structures are the main reason for the reduction in carbon emissions, whereas economic growth and urbanization are the two major contributors to the growth of carbon emissions. According to historical carbon emissions data, a green energy revolution must be implemented to address global climate change and ensure the sustainable development of human societies. [ABSTRACT FROM AUTHOR]

The alpine wetlands in QTP (Qinghai-Tibetan Plateau) have been profoundly impacted along with global climate changes. We employ satellite datasets and climate data to explore the relationships between alpine wetlands and climate changes based on remote sensing data. Results show that: 1) the wetland NDVI (Normalized Difference Vegetation Index) and GPP (Gross Primary Production) were more sensitive to air temperature than to precipitation rate. The wetland ET (evapotranspiration) across alpine wetlands was greatly correlated with precipitation rate. 2) Alpine wetlands responses to climate changes varied spatially and temporally due to different geographic environments, variety of wetland formation and human disturbances. 3) The vegetation responses of the Zoige wetland was the most noticeable and related to the temperature, while the GPP and NDVI of the Qiangtang Plateau and Gyaring-Ngoring Lake were significantly correlated with both temperature and precipitation. 4) ET in the Zoige wetland showed a significantly positive trend, while ET in Maidika wetland and the Qiangtang plateau showed a negative trend, implying wetland degradation in those two wetland regions. The complexities of the impacts of climate changes on alpine wetlands indicate the necessity of further study to understand and conserve alpine wetland ecosystems. [ABSTRACT FROM AUTHOR]

As an important means regulating the relationship between human and natural ecosystem, ecological restoration program plays a key role in restoring ecosystem functions. The Grain-for-Green Program (GFGP, One of the world's most ambitious ecosystem conservation set-aside programs aims to transfer farmland on steep slopes to forestland or grassland to increase vegetation coverage) has been widely implemented from 1999 to 2015 and exerted significant influence on land use and ecosystem services (ESs). In this study, three ecological models (InVEST, RUSLE, and CASA) were used to accurately calculate the three key types of ESs, water yield (WY), soil conservation (SC), and net primary production (NPP) in Karst area of southwestern China from 1982 to 2015. The impact of GFGP on ESs and trade-offs was analyzed. It provides practical guidance in carrying out ecological regulation in Karst area of China under global climate change. Results showed that ESs and trade-offs had changed dramatically driven by GFGP. In detail, temporally, SC and NPP exhibited an increasing trend, while WY exhibited a decreasing trend. Spatially, SC basically decreased from west to east; NPP basically increased from north to south; WY basically increased from west to east; NPP and SC, SC and WY developed in the direction of trade-offs driven by the GFGP, while NPP and WY developed in the direction of synergy. Therefore, future ecosystem management and restoration policy-making should consider trade-offs of ESs so as to achieve sustainable provision of ESs. [ABSTRACT FROM AUTHOR]

A thorough understanding of the vegetation succession in relation to both climatic changes and anthropogenic activities is vital for the formulation of adaptation strategies that address potential ecosystem challenges. Various climatic factors such as temperature, precipitation, and solar radiation, as well as anthropogenic factors such as ecological engineering and population migration, will affect the conditions for vegetation. However, the relationships among various factors remain unclear and the response of vegetation to climate change and anthropogenic activities in the Loess Plateau of China has not been well established. This study investigated the spatio-temporal characteristics and relationships between vegetation coverage and climatic factors in the Loess Plateau for the period of 1985–2015. Further analysis separated the anthropogenic and climatic factors on vegetation succession based on residual analysis. The results showed that the normalized difference vegetation index (NDVI) followed a significant upward trend with annual change rates of 0.15% during 1985–2015. The trend of human-induced NDVI increase was consistent with the spatial distribution of increasing forest areas in the eastern part of the Loess Plateau. Eco-restoration projects were the main driving factors that promoted vegetation coverage on the Loess Plateau. Furthermore, these results demonstrated that migrants to cities in the Loess Plateau could relieve ecological pressures and promote vegetation restoration. Therefore, the government should strive to increase population mobility and restore vegetation to sustain this particularly fragile ecological environment. [ABSTRACT FROM AUTHOR]

As is well known, clouds impact the radiative budget, climate change, hydrological processes, and the global carbon, nitrogen and sulfur cycles. To understand the wide-ranging effects of clouds, it is necessary to assess changes in cloud cover at high spatial and temporal resolution. In this study, we calculate global cloud cover during the day and at night using cloud products estimated from Moderate Resolution Imaging Spectroradiometer (MODIS) data. Results indicate that the global mean cloud cover from 2003 to 2012 was 66%. Moreover, global cloud cover increased over this recent decade. Specifically, cloud cover over land areas (especially North America, Antarctica, and Europe) decreased (slope =-0.001, R2 = 0.5254), whereas cloud cover over ocean areas (especially the Indian and Pacific Oceans) increased (slope = 0.0011, R2 = 0.4955). Cloud cover is relatively high between the latitudes of 36°S and 68°S compared to other regions, and cloud cover is lowest over Oceania and Antarctica. The highest rates of increase occurred over Southeast Asia and Oceania, whereas the highest rates of decrease occurred over Antarctica and North America. The global distribution of cloud cover regulates global temperature change, and the trends of these two variables over the 10-year period examined in this study (2003-2012) oppose one another in some regions. These findings are very important for studies of global climate change. [ABSTRACT FROM AUTHOR]

Global research progress on coastal flooding was studied using a bibliometric evaluation of publications listed in the Web of Science extended scientific citation index. There was substantial growth in coastal flooding research output, with increasing publications, a higher collaboration index, and more references during the 1995-2016 period. The USA has taken a dominant position in coastal flooding research, with the US Geological Survey leading the publications ranking. Research collaborations at institutional scales have become more important than those at global scales. International collaborative publications consistently drew more citations than those from a single country. Furthermore, coastal flooding research included combinations of multi-disciplinary categories, including ‘Geology’ and ‘Environmental Sciences & Ecology’. The most important coastal flooding research sites were wetlands and estuaries. While numerical modeling and 3S (Remote sensing, RS; Geography information systems, GIS; Global positioning systems, GPS) technology were the most commonly used methods for studying coastal flooding, Lidar gained in popularity. The vulnerability and adaptation of coastal environments, their resilience after flooding, and ecosystem services function showed increases in interest. [ABSTRACT FROM AUTHOR]

Environmental efficiency standards are often used to evaluate the costs of oceanic economic development. A variety of statistical analyses were applied in this study to quantify the marine environmental efficiency of 11 Chinese coastal provinces and municipalities between 2000 and 2014. Results initially reveal that environmental efficiency measures that incorporate undesirable outputs are more consistent with real production conditions and thus the use of marine economic and environmental efficiencies supplement and complement one another. Second, overall marine environmental efficiency across China tends to be low and can be spatially characterized by a transformation such that the inefficiencies noted in 2000 have subsequently been transformed to comprise a three-tiered structure that encompasses northern, central, and southern cores. Third, variation in absolute and relative marine environmental efficiency differences for the coastal regions of China have been consistent over time; values initially decreased before increasing again in a fluctuating manner over the time period of this analysis. Fourth, data show that the Pearl River Delta area has experienced the highest rate of change in marine environmental efficiency over time when economic zones are used as basic research units, although values have nevertheless fluctuated significantly. Fifth, values for total factor productivity as well as technical efficiency and change across the Chinese marine economy all fluctuated over time but increased. Data show that changes in marine environmental efficiency across China can primarily be attributed to progress in marine science and technology. Finally, levels of capital investment and marine industrial pollution intensity are not significantly correlated with marine environmental efficiency. Indeed, both marine industrial structural levels and environmental protection technologies have had a positive effect on environmental efficiency while levels of investment in marine scientific research as well as the scale of economic development, the marine economy, and the degree of external openness have all exerted negative effects on this key variable. [ABSTRACT FROM AUTHOR]

Ecological migration is the process of increasing the population density in the immigration area and transferring the ecological pressure from emigration area to immigration area. This process may result in significant changes in land use and land cover in the area of immigration and have an important effect on ecosystem services. Therefore, scientifically revealing the effects and differentiation mechanisms of ecological migration on ecosystem services is becoming an important issue related to the implementation of the national ecological migration strategy in China. This study employed the Hongsibu District as a typical example of ecological migration. Hongsibu District is located in the central Ningxia steppe and desert steppe areas. Remote sensing data covering five periods from the period before ecological migration in 1995 and after migration in 2000, 2005, 2010, and 2015 was used to measure the value of ecosystem services (ESV). A geographical detector model and the value of ecosystem services model were used to diagnose the dynamic mechanism of the effects of land use change on ecosystem services. The results showed that: 1) The development of large-scale ecological resettlement has caused the area of cultivated land and urbanized land area to increase significantly in the area of immigration, while the grass area decreased significantly. 2) The overall value of the Hongsibu ecosystem services increased in a form of a ‘V’. Among them, during the period of 1995-2005, the overall ESV decreased and had an annual rate of change of −0.67%. During the period of development 2005-2015, the ESV increased steadily, with an annual rate of change of 0.79%. 3) The proportion and total ESV in soil formation and protection, waste treatment, and biodiversity conservation of the Hongsibu District decreased from 57.61% in 1995 to 56.17% in 2015, indicating that the region’s ecological regulation function slightly decreased. 4) The ESV in the Hongsibu District, showed a low distribution pattern of ecosystem services increasing from northeast to southwest, and the capacity of three townships, Hongsibu, Taiyangshan, and Liuquan, to provide ecosystem services gradually declined over time. The ecological service function of Xinzhuangji Township and Dahe Township gradually improved. 5) The sensitivity index of the ESV of each land use type was less than 1, indicating that the environment lacks flexibility in providing a strong ESV index in Hongsibu, which shows that the research results are reliable and believable. 6) During the study period, the decisive force of the change of land use on ecosystem services in Hongsibu District was: grassland (0.9934), climate regulation (0.9413), soil formation and protection (0.9321) and waste treatment (0.9241). [ABSTRACT FROM AUTHOR]

Understanding the temporal variations of extreme floods that occur in response to climate change is essential to anticipate the trends in flood magnitude and frequency in the context of global warming. However, long-term records of paleofloods in arid regions are scarce, thus preventing a thorough understanding of such events. In this study, a reconstruction of paleofloods over the past 300 years was conducted through an analysis of grain sizes from the sediments of Kanas Lake in the Altay Mountains of northwestern China. Results showed that grain parameters and frequency distributions can be used to infer possible abrupt environmental events within the lake sedimentary sequence, and two extreme flood events corresponding to ca. 1736-1765 AD and ca. 1890 AD were further identified based on canonical discriminant analysis (CDA) and coarse percentile versus median grain size (C-M) pattern analysis, both of which occurred during warmer and wetter climate conditions by referring to tree-ring records. These two flood events are also evidenced by lake sedimentary records in the Altay and Tianshan mountains. Furthermore, through a comparison with other records, the flood event from ca. 1736-1765 AD in the study region seems to have occurred in both the arid central Asia and the Alps in Europe, and thus may have been associated with changes in the North Atlantic Oscillation (NAO) index. [ABSTRACT FROM AUTHOR]

Market-based emission trading schemes (ETSs) are widely used in the developed world to reduce greenhouse gas (GHG) emissions which are perceived as the source of global climate change. China, as the largest GHG emitter in the world, is committed to introducing an ETS to reduce emissions. Here we reviewed existing ETSs and sustainable energy policies worldwide as well as China's pilot programs. These studies were conducted in order to propose recommendations for national initiatives and strategies to be implemented in China in relation to climate change adaptation and mitigation. It has been shown that setting emission caps in the context of a national emission intensity target is difficult. However, implementing reliable systems for measurement, reporting, and verification of emissions are essential. A two-level management system (by central and provincial governments) for carbon trading is beneficial to ensure uniform standards and compliance while maintaining flexibility. Persistent political support from, and effective coordination of, policies by the government are crucial. In addition, strengthening of institutional innovation, and the establishment of a national GHG emissions information system, are of equal importance. This vital information could provide a great opportunity for China to re-define its economic growth and take global leadership in combatting climate change. [ABSTRACT FROM AUTHOR]

River runoff is affected by many factors, including long-term effects such as climate change that alter rainfall-runoff relationships, and short-term effects related to human intervention (e.g., dam construction, land-use and land-cover change (LUCC)). Discharge from the Yellow River system has been modified in numerous ways over the past century, not only as a result of increased demands for water from agriculture and industry, but also due to hydrological disturbance from LUCC, climate change and the construction of dams. The combined effect of these disturbances may have led to water shortages. Considering that there has been little change in long-term precipitation, dramatic decreases in water discharge may be attributed mainly to human activities, such as water usage, water transportation and dam construction. LUCC may also affect water availability, but the relative contribution of LUCC to changing discharge is unclear. In this study, the impact of LUCC on natural discharge (not including anthropogenic usage) is quantified using an attribution approach based on satellite land cover and discharge data. A retention parameter is used to relate LUCC to changes in discharge. We find that LUCC is the primary factor, and more dominant than climate change, in driving the reduction in discharge during 1956-2012, especially from the mid-1980s to the end-1990s. The ratio of each land class to total basin area changed significantly over the study period. Forestland and cropland increased by about 0.58% and 1.41%, respectively, and unused land decreased by 1.16%. Together, these variations resulted in changes in the retention parameter, and runoff generation showed a significant decrease after the mid-1980s. Our findings highlight the importance of LUCC to runoff generation at the basin scale, and improve our understanding of the influence of LUCC on basin-scale hydrology. [ABSTRACT FROM AUTHOR]

Examining the direct and indirect effects of climatic factors on vegetation growth is critical to understand the complex linkage between climate change and vegetation dynamics. Based on the Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) data and meteorological data (temperature and precipitation) from 2001 to 2012, the trend of vegetation dynamics were examined in the Ziya-Daqing basins, China. The path analysis was used to obtain the information on the relationships among climatic factors and their effects on vegetation growth. It was found that the trends of growing season NDVI were insignificant in most plain dry land, while the upward trends were significant in forest, grass and dry land in Taihang Mountains. According to the path analysis, in 23% of the basins the inter-annual NDVI variation was dominated by the direct effect of precipitation, in 5% by the direct effects of precipitation and temperature, and in less than 1% by the direct effect of temperature or indirect effects of these two climatic factors. It indicated that precipitation significantly affected the vegetation growth in the whole basins, and this effect was not regulated by temperature. Precipitation increase (especially in July, August and September) was favorable to greenness enhancement. Summer temperature rising showed negative effect on plant productivity enhancement, but temperature rise in April was beneficial for the vegetation growth. When April temperature increases by 1°C, the onset date of greenness for natural vegetation will be 2 days in advance. There was a lag-time effect of precipitation or temperature on monthly NDVI for all land use types except grass. [ABSTRACT FROM AUTHOR]

Identifying the impacts of climate change is important for conservation of ecosystems under climate change, particularly in mountain regions. Holdridge life zone system and Köppen classification provide two effective methods to assess impacts of climate change on ecosystems, as typical climate-vegetation models. Meanwhile, these previous studies are insufficient to assess the complex terrain as well as there are some uncertainties in results while using the given methods. Analysis of the impacts of the prevailing climate conditions in an area on shifts of ecosystems may reduce uncertainties in projecting climate change. In this study, we used different models to depict changes in ecosystems at 1 km × 1 km resolution in Sichuan Province, China during 1961-2010. The results indicate that changes in climate data during the past 50 years were sufficient to cause shifts in the spatial distribution of ecosystems. The trend of shift was from low temperature ecosystems to high temperature ecosystems. Compared with Köppen classification, the Holdridge system has better adaptation to assess the impacts of climate change on ecosystems in low elevation (0-1000 m). Moreover, we found that changed areas in ecosystems were easily affected by climate change than unchanged areas by calculating current climate condition. [ABSTRACT FROM AUTHOR]

Human activities and climate changes are deemed to be two primary driving factors influencing the changes of hydrological processes, and quantitatively separating their influences on runoff changes will be of great significance to regional water resources planning and management. In this study, the impact of climate changes and human activities was initially qualitatively distinguished through a coupled water and energy budgets analysis, and then this effect was further separated by means of a quantitative estimation based on hydrological sensitivity analysis. The results show that: 1) precipitation, wind speed, potential evapotranspiration and runoff have a significantly decreasing trend, while temperature has a remarkably increasing tendency in the Weihe River Basin, China; 2) the major driving factor on runoff decrease in the 1970s and 1990s in the basin is climate changes compared with that in the baseline 1960s, while that in the 1980s and 2000s is human activities. Compared with the results based on Variable Infiltration Capacity (VIC) model, the contributions calculated in this study have certain reliability. The results are of great significance to local water resources planning and management. [ABSTRACT FROM AUTHOR]

Using the low-resolution (T31, equivalent to 3.75° × 3.75°) version of the Community Earth System Model (CESM) from the National Center for Atmospheric Research (NCAR), a global climate simulation was carried out with fixed external forcing factors (1850 Common Era. (C.E.) conditions) for the past 2000 years. Based on the simulated results, spatio-temporal structures of surface air temperature, precipitation and internal variability, such as the El Niño-Southern Oscillation (ENSO), the Atlantic Multi-decadal Oscillation (AMO), the Pacific Decadal Oscillation (PDO), and the North Atlantic Oscillation (NAO), were compared with reanalysis datasets to evaluate the model performance. The results are as follows: 1) CESM showed a good performance in the long-term simulation and no significant climate drift over the past 2000 years; 2) climatological patterns of global and regional climate changes simulated by the CESM were reasonable compared with the reanalysis datasets; and 3) the CESM simulated internal natural variability of the climate system performs very well. The model not only reproduced the periodicity of ENSO, AMO and PDO events but also the 3-8 years variability of the ENSO. The spatial distribution of the CESM-simulated NAO was also similar to the observed. However, because of weaker total irradiation and greenhouse gas concentration forcing in the simulation than the present, the model performances had some differences from the observations. Generally, the CESM showed a good performance in simulating the global climate and internal natural variability of the climate system. This paves the way for other forced climate simulations for the past 2000 years by using the CESM. [ABSTRACT FROM AUTHOR]

Rapid urbanization has led to dramatic changes in urban forest structures and functions, and consequently affects carbon (C) storage in cities. In this study, field surveys were combined with high resolution images to investigate the variability of C storage of urban forests in Changchun, Northeast China. The main objectives of this study were to quantify the C storage of urban forests in Changchun City, Northeast China and understand the effects of forest type and urbanization on C storage of urban forests. The results showed that the mean C density and the total C storage of urban forests in Changchun were 4.41 kg/m and 4.74 × 10 kg, respectively. There were significant differences in C density among urban forest types. Landscape and relaxation forest (LF) had the highest C density with 5.41 kg/m, while production and management forest (PF) had the lowest C density with 1.46 kg/m. These differences demonstrate that urban forest type is an important factor needed to be considered when the C storage is accurately estimated. Further findings revealed significant differences in different gradients of urbanization, and the mean C density decreased from the first ring (6.99 kg/m) to the fourth ring (2.87 kg/m). The total C storage increased from the first ring to the third ring. These results indicate that C storage by urban forests will be significantly changed during the process of urbanization. The results can provide insights for decision-makers and urban planners to better understand the effects of forest type and urbanization on C storage of urban forests in Changchun, and make better management plans for urban forests. [ABSTRACT FROM AUTHOR]

Under global climate change, drought has become one of the most serious natural hazards, affecting the ecological environment and human life. Drought can be categorized as meteorological, agricultural, hydrological or socio-economic drought. Among the different categories of drought, hydrological drought, especially streamflow drought, has been given more attention by local governments, researchers and the public in recent years. Identifying the occurrence of streamflow drought and issuing early warning can provide timely information for effective water resources management. In this study, streamflow drought is detected by using the Standardized Runoff Index, whereas meteorological drought is detected by the Standardized Precipitation Index. Comparative analyses of frequency, magnitude, onset and duration are conducted to identify the impact of meteorological drought on streamflow drought. This study focuses on the Jinghe River Basin in Northwest China, mainly providing the following findings. 1) Eleven meteorological droughts and six streamflow droughts were indicated during 1970 and 1990 after pooling using Inter-event time and volume Criterion method. 2) Streamflow drought in the Jinghe River Basin lagged meteorological drought for about 127 days. 3) The frequency of streamflow drought in Jinghe River Basin was less than meteorological drought. However, the average duration of streamflow drought is longer. 4) The magnitude of streamflow drought is greater than meteorological drought. These results not only play an important theoretical role in understanding relationships between different drought categories, but also have practical implications for streamflow drought mitigation and regional water resources management. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various articles within the issue on topics including effects of China's national ecological restoration programs on ecosystem or soil carbon storage, soil carbon process and their intrinsic correlations, and climate change mitigation.

The northeastern China is an important commodity grain region in China, as well as a notable corn belt and major soybean producing area. It thus plays a significant role in the national food security system. However, large-scale land reclamation and non-optimum farming practices give rise to soil degradation in the region. This study analyzed the food security issues coupled with global climate change in the northeastern China during 1980-2000, which is the period of modern agriculture. The results of statistical data show that the arable land area shrank markedly in 1992, and then increased slowly, while food production generally continually increased. The stable grain yield was due to the increase of applied fertilizer and irrigated areas. Soil degradation in the northeastern China includes severe soil erosion, reduced soil nutrients, a thinner black soil layer, and deterioration of soil physical properties. The sustainable development of the northeastern China is influenced by natural-artificial binary disturbance factors which consist of meteorological conditions, climate changes, and terrain factors as well as soil physical and chemical properties. Interactions between the increasing temperature and decreasing precipitation in the region led to reduced accumulation of soil organic matter, which results in poor soil fertility. Human-induced factors, such as large-scale land reclamation and non-optimum farming practices, unsuitable cultivation systems, dredging, road building, illegal land occupation, and extensive use of fertilizers and pesticides, have led to increasingly severe soil erosion and destruction. Solutions to several problems of soil degradation in this region requiring urgent settlement are proposed. A need for clear and systematic recognition and recording of land use changes, land degradation, food production and climate change conditions is suggested, which would provide a reference for food security studies in the northeastern China. [ABSTRACT FROM AUTHOR]

Elm ( Ulmus pumila), widely distributed in the north temperate zone, contributes to a special savanna-like woodland in typical grassland region in the northeastern China. This woodland performs a variety of ecological functions and environmental significance, such as decreasing soil erosion, stabilizing sand dunes, preserving species diversity. However, in the last approximate 30 years, the species composition, productivity and distribution area of elm woodland has decreased severely. A series of studies have been carried out to find out whether the climate changes or human disturbances caused the degradation of elm woodland and how these factors affected elm woodland. In this study, undisturbed, plowing and grazing elm woodland were investigated in 1983 and 2011 by using Point-Centered Quarter method. The relationship between vegetation changes and environmental factors was analyzed by Bray-Curtis ordination. The results show that in 2011, species diversity and understory productivity of undisturbed elm woodland decrease slightly compared to those of undisturbed elm woodland in 1983. However, nearly 60% of the species is lost in the plowing and grazing elm woodland relative to the species undisturbed elm woodland in 1983. Interestingly, plowing stimulates the growth of elm and certain understory species through furrowing soil and accelerating soil nutrient turnover rate. Grazing disturbance not only leads to species loss and productivity decrease, but also induces changes in elm growth (small, short and twisted). The mean age of the elm was 29 ± 2 yr in undisturbed and plowing elm woodland, while only 15 yr in the grazing elm woodland. The results of Bray-Curtis ordination analysis show that all sample stands clustered to three groups: Group I including the undisturbed sample stands of 83UE (undisturbed elm woodland in 1983) and 11UE (undisturbed elm woodland in 2011); Group II including sample stands of PE (elm woodland disturbed by plowing); Group III including samples stands of GE (elm woodland disturbed by grazing). The results indicate that the long time disturbance of the plowing and grazing have converted elm woodland to different community types. Climate change is not the primary reason causing the degradation of elm woodland, but plowing and grazing disturbance. Both plowing and grazing decrease the vegetation composition and species diversity. Grazing further decreases vegetation productivity and inhibits the growth of elm tree. Therefore, we suggest that reasonable plowing and exclusive grazing would be favorable for future regeneration of degraded elm woodland. [ABSTRACT FROM AUTHOR]

Based on runoff, air temperature, and precipitation data from 1960 to 2010, the effects of climate change on water resources in the arid region of the northwestern China were investigated. The long-term trends of hydroclimatic variables were studied by using both Mann-Kendall test and distributed-free cumulative sum (CUSUM) chart test. Results indicate that the mean annual air temperature increases significantly from 1960 to 2010. The annual precipitation exhibits an increasing trend, especially in the south slope of the Tianshan Mountains and the North Uygur Autonomous Region of Xinjiang in the study period. Step changes occur in 1988 in the mean annual air temperature time series and in 1991 in the precipitation time series. The runoff in different basins shows different trends, i.e., significantly increasing in the Kaidu River, the Aksu River and the Shule River, and decreasing in the Shiyang River. Correlation analysis reveals that the runoff in the North Xinjiang (i.e., the Weigan River, the Heihe River, and the Shiyang River) has a strong positive relationship with rainfall, while that in the south slope of the Tianshan Mountains, the middle section of the north slope of the Tianshan Mountains and the Shule River has a strong positive relationship with air temperature. The trends of runoff have strong negative correlations with glacier coverage and the proportion of glacier water in runoff. From the late 1980s, the climate has become warm and wet in the arid region of the northwestern China. The change in runoff is interacted with air temperature, precipitation and glacier coverage. The results show that streamflow in the arid region of the northwestern China is sensitive to climate change, which can be used as a reference for regional water resource assessment and management. [ABSTRACT FROM AUTHOR]

The thermal-environment effect exists in the field of rapid urbanization. It has adverse effects on the urban atmosphere, regional climate, energy consumption, and public health. Shenzhen, a representative of rapidly urbanizing cities in China, was selected as a case for pattern dynamics analysis of the thermal environment. The surface temperature was acquired from the thermal infrared data of Landsat TM and ETM+ images in 1986, 1995, and 2005 by Jiménez-Muñoz and Sobrino's generalized single-channel method, which was used in assessing the distribution and spatial patterns of the thermal environment. The relative thermal environment curve (RTC) was combined with Moran's I analysis to assess the pattern dynamics of the thermal environment in different urbanization periods. Moran's I index and the RTC represent a process of aggregation-fragmentation-aggregation, which shows the aggregation pattern of a decrease during the rapid urbanization period and then an increase during the steady urbanization period. High-temperature areas gradually expanded to a uniform and scattered distribution in the rapid urbanization period; while the high thermal-environment effect was gradually transformed into a steady spatial pattern in the stable urbanization period. To characterize the increasing development in this multiple-center city, we chose profiles along an urban-development axis. The results suggest that heat islands have expanded from internal urban to external urban areas. Four profiles were obtained showing differences in shape due to spatial differences in the process of development. [ABSTRACT FROM AUTHOR]

The impacts of future climate change on streamflow of the Dongliao River Watershed located in Jilin Province, China have been evaluated quantitatively by using a general circulation model (HadCM3) coupled with the Soil and Water Assessment Tool (SWAT) hydrological model. The model was calibrated and validated against the historical monitored data from 2005 to 2009. The streamflow was estimated by downscaling HadCM3 outputs to the daily mean temperature and precipitation series, derived for three 30-year time slices, 2020s, 2050s and 2080s. Results suggest that daily mean temperature increases with a changing rate of 0.435°C per decade, and precipitation decreases with a changing rate of 0.761 mm per decade. Compared with other seasons, the precipitation in summer shows significant downward trend, while a significant upward trend in autumn. The annual streamflow demonstrates a general downward trend with a decreasing rate of 0.405 m/s per decade. The streamflow shows significant downward and upward trends in summer and in autumn, respectively. The decreasing rate of streamflow in summer reaches 1.97 m/s per decade, which contributes primarily to the decrease of streamflow. The results of this work would be of great benifit to the design of economic and social development planning in the study area. [ABSTRACT FROM AUTHOR]

In the mid-latitude regions of the Asian continent, Zhuye Lake is located in the northwest margin of the Asian monsoon, where the modern climate is affected by the Asian monsoon and Westerlies. In this study, we investigated the absolutely dated Holocene records in Zhuye Lake for detecting the Holocene climate cycles. Totally, 14 C dates and 6 optically simulated luminescence (OSL) dates are obtained from the QTH01 and QTH02 sections. The proxies of grain-size, total organic carbon content (TOC), C/N and δC are used for wavelet analysis, and the results show obvious ∼256, ∼512 and ∼1024-year climate cycles, which are consistent with the Holocene millennial and centennial scale climate cycles in the typical Asian summer monsoon domain. In different parts of the Zhuye Lake, the Holocene sediments show variable climate cycles that are affected by the lake basin topography. In the Zhuye Lake, the Holocene climate cycles are mainly correlated with the solar-related Asian summer monsoon variability and the North Atlantic ice-rafting events. [ABSTRACT FROM AUTHOR]

Variations and trends in extreme climate events are more sensitive to climate change than the mean values, and so have received much attention. In this study, twelve indices of temperature extremes and 11 indices of precipitation extremes at 32 meteorological stations in Hengduan Mountains were examined for the period 1961-2008. The results reveal statistically significant increases in the temperature of the warmest and coldest nights and in the frequencies of extreme warm days and nights. Decreases of the diurnal temperature range and the numbers of frost days and ice days are statistically significant. Regional averages of growing season length also display the trends consistent and significant with warming. At a large proportion of the stations, patterns of temperature extremes are consistent with warming since 1961: warming trends in minimum temperature indices are greater than those relating to maximum temperature. As the center of the Shaluli Mountain, the warming magnitudes decrease from inner to outer. Changes in precipitation extremes is low: trends are difficult to detect against the larger inter-annual and decadal-scale variability of precipitation, and only the wet day precipitation and the regional trend in consecutive dry days are significant at the 0.05 level. It can be concluded that the variation of extreme precipitation events is not obvious in the Hengduan Mountains, however, the regional trends generally decrease from the south to the north. Overall, the spatial distribution of temporal changes of all extreme climate indices in the Hengduan Mountains illustrated here reflects the climatic complexity in mountainous regions. [ABSTRACT FROM AUTHOR]