Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： As the “water tower” of Asia, the Tibetan Plateau provides basic water resources for the regional ecosystems. Among the variety of water resources, natural precipitation is most relevant to ecosystems, and temperature also affects soil moisture availability by regulating evapotranspiration, thus affecting ecosystem process. From the aspects of community composition and structure, vegetation phenology, coverage and productivity, and water conservation function by ecosystems, this paper reviewed the series of impacts caused by changed water resources on the Tibetan Plateau ecosystems in recent years, and the underlying mechanism was further revealed. The shifted water conditions led to changes in community coverage, species diversity, and relative importance of each species, thereby driving community succession. The strengthened preseason precipitation advanced spring phenology, and postponed autumn phenology. The preseason precipitation also adjusted the responses of vegetation phenology to temperature. Under global changes, the vegetation coverage increased and ecosystem productivity strengthened on the Tibetan Plateau, but with high spatial heterogeneities. The incongruous changes of temperature and precipitation complicated their effects on vegetation, as exhibited by their distinct relative determination effects in different areas. Water conservation by ecosystems stems from interactions among soil-vegetation-atmosphere, which is influenced by climate, vegetation, soil, human activities, etc. The future studies need to pay mounting attentions to the coupling effects of climates and vegetation cover on water conservation of ecosystems, and also attribute the separate contribution from each factor.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： The Tibetan Plateau and surrounding mountains contain the largest glacier storage outsides the north and south polar regions. Under the global warming, recently glaciers in China are generally experiencing rapid melting and shrinkage. This rapid glacier change impacts the water resource that supplied by melt-water, and also favors glacial hazards, such as glacier collapse, glacier surging, glacial debris flow, and glacial lake outburst flood. Those glacial hazards show their spatio-temporal distribution characters, dynamic processes and mechanisms. Accompanying with the recent rapid glacier change, which reduces the glacier stability by warming, glacial hazards become more frequent. Furthermore, since global warming continues and human activity intensifies, the uncertainty and risk of glacial disasters will intensify. Therefore, scientific solution and countermeasures are needed based on the researches on glacial changes and hazards.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： The Tibetan Plateau is the source zone of major rivers, which provide water resources for more than 2 billion people downstream. Compared with runoff, riverine sediment load is considered as a more sensitive variable in response to climate and land surface process changes, and also as an important index to quantify regional land degradation and soil resource changes. In this study, 8 major rivers originated in the Tibetan Plateau, including Yerqiang River, Shule River, Heihe River, Yarlung Tsangpo River, Nujiang River, Yellow River, Yangtze River, and Lancang River, were selected to study the variation of sediment load in the source zone or upper reaches. Firstly, the general amount and spatial variation of runoff and sediment load of these rivers were explored. Secondly, the changes of riverine sediment load in recent decades (1960–2017) were analyzed, with the spatial and temporal variations of sediment load compared to climate (temperature, precipitation) and land surface process (glacier, frozen soil, vegetation cover) factors. Thirdly, the uncertainty of sediment load variation associated with interaction of multi-factors was discussed. Finally, the significant impacts of sediment load variation on the ecological environment and the safety of hydropower projects was pointed out with typical cases. Nowadays, the scarcity of hydrometeorological data is a major challenge to understand the variation of riverine sediment load from the Tibetan Plateau and assess the impacts. It is urgent to strengthen observation and modeling studies to reveal the complex mechanism of sediment transport changes, so as to provide scientific basis for the sustainable utilization of water and soil resources on the Tibetan Plateau and the downstream water resources management, so as to serve the national ecological security.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： The Tibetan Plateau lakes, with more than 50% area of the total lakes in China, are an important part of the Asia Water Tower. From 1970s to 2018, the number and area of lakes increased obviously, but the changing rate was not uniform. Before 1990, the negative balance of lake water storage was caused by low temperature inhibition of melting water. From 1990 to 2000, lake water storage increased associated with increased melting water due to the rising of temperature. After 2000, precipitation was the main factor leading to the increase of lake water storage, but the continuous temperature rising during 2005 and 2013 strengthened evaporation and weakened the increasing rate of lake water storage. Nevertheless, in the central and western Tibetan Plateau, the increase of lake water storage during 2000 and 2013 was mainly contributed by glacier melt water. From 1970s to 2013, the spatial characteristics of the lake water storage changes on the Tibetan Plateau were consistent with that of precipitation in the westerly and Indian monsoon regions. The increase of air temperature and long-wave radiation make the lake water temperature increase obviously, and promote the transmission efficiency of food chain. With the lake water storage increase, the lake water salinity generally decreases, which conduce the increase of lake biological diversity and make the lake ecosystem structure relatively complex. In the next 20 years, the lake water storage in the inland closed lakes of the Tibetan Plateau will continue to increase while the increasing rate will decrease. For the “Asian Water Tower”, the lake study on the Tibetan Plateau should focus on macroscale water storage and water balance, the main physical and chemical properties of lake water and ecosystem parameters, as well as the water cycle process of lake changes in large-scale climate change.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： Snow cover over the Qinghai-Tibet Plateau (QTP) is a key element of Asian Water Tower. It is also an important indicator of weather and climate change. Its spatio-temporal changes can influence the regional climate and ecosystem. In this study, the spatiotemporal distribution and trends of snow cover were analyzed based on remote sensing data, and its hydrological and climate effects were also explored. The results show the followings: (1) Snow cover was dominantly distributed in mountainous areas, and the largest snow depth and Snow Cover Days (SCD) were found in the Dangla and Nianqing Dangla Mountains, with the average SCD of over 120 days, and annual average snow depth of over 10 cm; whilst there was few snow cover in the plain area and Qaidam Basin, e.g. ephemeral snow cover, with average SCD of less than 15 day and annual snow depth of less than 1 cm. (2) Snow cover days and depth were decreased in the period of 1980–2018, especially after the year of 2000. (3) There was large radiative forcing in the mountainous areas with deep snow and large SCD, and the maximum value beyond 15 W m−2; thus, the snow cover over QTP plays important feedbacks to the climate system. (4) The QTP is the source of runoff in headwater regions of many rivers, and snow melt water contributed to the soil moisture and river runoff in spring. (5) The frequency of snow disaster was increased by extreme weather events, and early warning system and protective measures should be enhanced to minimize the loss caused by snow disaster.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： Glaciers, an important part of Asia’s water tower, are extremely sensitive to climate change. The study on the spatiotemporal pattern of the changes of the glaciers in the Tibetan Plateau and surroundings in the context of global warming is helpful to identify the main water storage and supply areas of Asian Water Towers, which is of great significance for the rational planning and utilization of water resources. Through comprehensive analysis, it was revealed that the “Karakoram anomaly” might expand in different degrees to the Western Kunlun Mountains and the Pamirs, while the glaciers in the other parts of the Tibetan Plateau and surroundings were in an accelerated melting state recently. Moreover, we also illuminated the influences of the changes of the glaciers over the past 50 years and in different climate scenarios in the future on the basin water resources and sea level rise, and pointed out that the glacier observation and investigation should be carried out systematically, and a climate-ice-hydrological processes coupling model should be set up, in order to accurately assess the glacier melt water resources, which is an important basis for the green silk road construction.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： The Tibetan Plateau is known as the “Asian Water Tower”. In the past 50 years, global warming has accelerated the water cycle over the Asian Water Tower. The current understanding on the key processes of water vapor transport over the Asian Water Tower and the behind mechanisms are reviewed in this paper, via the climatology, long-term trend, and interannual variability, respectively. This review further suggests that it is urgent to understand the tempo-spatial changes, mechanisms, and impact of water vapor transport processes over the Asian Water Tower. Therefore, future research should improve capabilities on observation, diagnosis, dynamical mechanism, detection and attribution, as well as numerical simulation.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： The Tibetan Plateau and surroundings, also known as the Third Pole, is widely acknowledged as the Asian Water Tower. It holds glaciers with an area about 100 000 km2, and lakes with an area about 50 000 km2. It gives birth to more than ten big rivers in Asia including the Yangtze River, Yellow River, Yarlung Tsangpo, Indus, Ganges, Mekong, Amu Darya, Tarim River, etc. Its environmental changes affect water resources utilization in China and water securities in many nations involved in the Belt and Road initiative. The Asian Water Tower is undergoing dramatic changes characterized with unbalance in a warming climate. Accelerated glacier retreats, permafrost degradation, lake expansion, as well as increase of glacial melt to runoff are all related to the unbalance change of the Asian Water Tower. These have put the Tibetan Plateau and its surrounding regions at risk and caused many water-related hazards such as glacier collapse. Asian Water Tower change would even be amplified through the atmosphere and hydrosphere to affect global climate and water cycle, thus coupling and interacting with changes on the Arctic and Antarctica. The Second Tibetan Plateau Scientific Expedition and Research program (STEP) and Pan-Third Pole Environment study for a Green Silk Road program (Pan-TPE) will focus on the study of Asian Water Tower change and its local to regional impacts in the past half century, conduct comprehensive field expeditions and research, and advise on science policy to confront Asian Water Tower change and impacts. The ultimate goal of the STEP and Pan-TPE is to provide scientific advice to China and nations around on water resources regulations and sustainable development, thus serving global ecological environment and a community with a shared future for mankind.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： Landslides and debris flows caused significant threat to the China-Pakistan Economic Corridor. This study introduced the spatial pattern of the relevant mountainous hazards and assessed the hazards risks, predicted the development trends, and proposed the relevant countermeasures as well. 584 landslides, 116 collapses, and 1669 mudslides in total were identified, which mainly distributed in the mountainous areas in the northern part of the corridor. The hazards were divided into five grades: extremely high, high, medium, low, and extremely low and the northern area is highly dangerous. The vulnerability assessment was carried out with traffic, economy, and population as indicators, and then the risk assessment results were comprehensively obtained. In general, the risk is higher in the northern part and lower in the southeast. In the future, as the intensity of earthquakes increases, the area of high-susceptibility landslides will gradually increase from 0.01% to 1.4% of the studied area, and these hazards are mainly distributed between the northern segment of Aikenert fault and Kazitaert fault, the northern segment of Miya fault and the central region of Bulunkou fault. According to the trend that rainfall and temperature increase, the susceptibility of debris flows in most river basins has increased. It is recommended to strengthen basic data collection and detailed investigation of key disaster points, and carry out early risk assessment and monitoring and early warning, while formulating emergency plans, which serves the safe construction of major projects along the Belt and Road.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： Remote sensing of cryosphere, as an important branch of cryospheric science, is a new interdiscipline, involving the knowledge of both cryospheric science and remote sensing techniques. This paper overviews the objects and basic methods of cryospheric remote sensing, introduces the progresses by using representative case studies, and especially, describes the research status of Chinese cryospheric remote sensing. Finally, we propose several recommendations for the development of remote sensing of cryosphere. In particular, we discuss the potential paths to the scientific programme of Earth’s three poles.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： Ice core is an important carrier of the past climatic and environmental change information. In this paper, we firstly introduced how ice cores record past climatic and environmental changes. Then, we elaborated the achievements of ice core research in the past climate change, levels of atmospheric greenhouse gases, solar activity, volcanic eruptions, and human activities. Thirdly, the role of ice core research in promoting relevant environmental policy making was stated, such as the ban on Pb additives in gasoline and greenhouse gas emission reduction policies. And finally, it was suggested that the state should establish a National Ice Core Facility to drill and store the ice cores from the Three Poles (Antarctic, Arctic, and the Third Pole) to serve the future scientific research and national development.
Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： Cryospheric chemistry is a new discipline and one of important branch of cryospheric science. Pollutant emissions from anthropogenic activities have greatly altered the status of chemical components in the cryospheric environment since the Industrial Revolution. When this scenario is coupled with the rapid shrinkage of cryosphere under global warming, both anthropogenic activity and global warming have cooperatively influenced the biogeochemical cycling in the cryosphere and even on a global scale, which results in significant effects on climate and environment. In this paper, firstly, the role of cryospheric chemistry in the cryospheric science is introduced, and the discipline framework and research focuses of cryospheric chemistry are summarized. Secondly, the coupling relationship among cryospheric chemistry and climate/environmental changes, and anthropogenic activities, with emphasis on this relationship in the research field of global change, was exemplified. Lastly, we summarize a review and prospect of hot topics in the current research of cryospheric chemistry. The rapid development of cryospheric chemistry will provide important scientific and technological support for tackling the climate and environmental issues that challenge human survival and development.
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2020-06-21 Cooperative journals: 《干旱区研究》
Abstract：利用中国区域地面气象要素数据集(CMFD) 和GLDAS数据集的1979—2017年格点气温(2 m)、降水、比湿、风速(10m)、太阳辐射资料，运用线性回归、累积距平、滑动平均及Mann-Kendall突变检验方法，研究了近39 a来色林错流域气候特征和时空变化规律。结果表明：色林错流域多年平均气温为-1.8℃，降水量为389.4mm，比湿为3.2g·kg-1，太阳辐射为236.2W·m-2，风速为3.7m·s-1。色林错流域的月平均气温仅在5—9月高于0℃，流域平均气温以0.049℃·a-1的速率呈显著升高之势。流域降水集中在6—9月，占全年降水量的80%以上，流域平均年降水量以4.65mm·a-1的速率显著增大。气温的升高和降水的增加暗示了色林错流域在近几十年来呈现显著的暖湿气候背景。1979—2017年，流域年均风速变化在空间上表现为南部增大、北部减小，减小速率以流域东北部最大。多年平均太阳辐射空间分布整体呈自东向西逐渐增大的趋势，时间变化以-0.29W·m-2·a-1的速率显著减小，1980s中期至2000s中期减小尤为明显。流域的年均比湿变化趋势并不显著，但2006年开始呈显著减小之势。本研究结果对该流域的湖泊扩张机制、生态系统对气候变化的响应以及物候变化等研究具有指示意义。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2019-03-07 Cooperative journals: 《干旱区地理》
Abstract： 利用2015年8月至2016年7月在印度河上游流域Bagrot山谷降水稳定同位素（δ18O和δD）观测结果以及当地气象资料，利用同位素示踪及统计分析方法，并结合HYSPLIT模型，对研究区降水稳定同位素变化特征、大气水线以及水汽来源进行了分析。结果表明，观测期间Bagrot山谷降水稳定同位素的季节变化明显，δ18O与δD秋冬季偏低，春夏季偏高，且与气温变化一致，存在显著的温度效应，而降水量效应不明显。而且发现，研究区局地大气水线截距和斜率均低于全球的，反映了降水过程中云下二次蒸发作用较为强烈，特别是，不同的降水形态导致该研究区局地大气水线的斜率和截距不同。当液态降水（降雨）发生时，由于在较为干旱的气候环境下，雨滴在降落的过程中受到二次蒸发相对较强，使得局地大气水线的斜率和截距偏低；而当固态降水（降雪）发生时，由于温度较低，受再循环水汽和二次蒸发的影响较小，导致局地大气水线的斜率和截距均偏高。Bagrot山谷及其周边地区，从南到北局地大气水线的斜率相差不大，而其截距总体上随着纬度升高而降低，可能与云下二次蒸发导致稳定同位素发生的不平衡分馏逐渐强烈有关。通过Bagrot山谷站点降水稳定同位素观测结果并结合HYSPLIT模型的后向追踪，研究还发现，研究区全年主要受西风环流以及局地环流的影响。但与研究区以北的临近站点（慕士塔格、和田等）相比有所不同，由于Bagrot山谷位置更靠南，其仍然偶尔受到来自南方的海洋性水汽影响。这一研究结果可能对该地区树轮稳定同位素记录的解译具有一定的指示意义。
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