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Meteorological disasters are one of the major risks to agricultural production, causing huge losses to agriculture. Agricultural insurance is an important part of the agricultural security system and can effectively spread agricultural risks and losses. Weather index insurance, which emerged in the late 1990s, has received a lot of attention, research, and applications due to its objectivity, standardization, and robust liquidity. In this paper, authors analyzed the advantages and disadvantages of weather index insurance compared to traditional agricultural insurance. The development of weather index insurance technology at home and abroad was reviewed. Authors introduced the development and practical application of weather index insurance model for Anhui grain crops (winter wheat, one season rice, summer corn), and discussed and prospected the future development of weather index insurance. [ABSTRACT FROM AUTHOR]

Climate change will lead to an increase in extreme weather events and economic losses, which will further affect financial stability and require timely assessment and response by relevant departments. Therefore, it is of great theoretical and practical significance to construct a reasonable climate financial analysis framework, analyze how climate change affects financial variables in detail, and formulate targeted policies and measures in combination with transmission paths. This paper constructs a DSGE model including carbon cycle, climate change factors, and multiple economic entities under the framework of financial accelerator and simulates the impact of climate change on output, asset prices, corporate default rate, and total credit. The results show that: ① The impact of climate change reduces output, capital price, and return on capital, increases the level of external financing premium, and pushes up the leverage ratio and credit default rate of enterprises, which in turn leads to a credit crunch and reduced investment. ② The impact of carbon intensity increases output, capital price, and return on capital, reduces the level of external financing premium, reduces the leverage ratio of enterprises and the default rate of corporate credit, and then causes credit expansion and investment increase. ③ The impact of emission reduction intensity mainly affects the macro-economy through cost drives. In the short term, the economy is negatively affected by the impact of emission reduction. In the long term, with the rapid recovery of output, the demand for investment and credit increases, thus promoting economic growth. Based on this, this paper puts forward the following suggestions: ① Assess the scale of climate change risk in the financial system timely and accurately, and prevent the impact of non-traditional systemic risks on the financial market. ② Actively promote the rapid development of green and low-carbon technologies, and promote the win-win results of pollution and carbon reduction and output increase. ③ Improve the analysis framework of the economic model of climate change and enhance its practical explanatory power and theoretical guidance. [ABSTRACT FROM AUTHOR]

Under the background of climate change, vegetation restoration in arid area ecosystem is faced with great challenges, which has important research value and is also an important research direction of ecology. In this paper, CiteSpace software was used to carry out data mining and econometric analysis on the research progress of vegetation restoration in arid area ecosystem. Besides, the number of papers published under this topic, the trend of change, the main research strength and the development path of the research topic were presented. The study found that (1) the overall volume of papers showed a significant growing tendency on the whole, and generally experienced three growth stages of slow, steady and rapid growth. The research hotspots were different at different stages. At present, the research mainly focuses on clustering topics such as “soil moisture”, “abandoned farmland”, “biological soil skinning” and “layered soil”, and the cross-study of engineering, hydrology, geosciology and other related disciplines is increasing day by day. (2) China, the United States and Spain were the countries with the largest number of publications, and the Chinese Academy of Sciences was the research institution with the largest number of publications. Li Xinrong and others constituted the core group of authors under the research topic. (3) The strategies of vegetation restoration in response to drought stress and the changing rules of the structure and function of different restored ecosystems under the background of climate change may be the research hotspots of vegetation restoration in arid areas in the near future. [ABSTRACT FROM AUTHOR]

Assuming responsibility for emission reduction is an important part of participating in the global governance of climate change. Countries with a carbon neutrality target now cover about 75% of global greenhouse gas emissions. Carrying out fairness evaluations of their carbon neutrality targets provide a strong basis for the global carbon inventory. In this paper, the target years of carbon neutrality for major countries and regions under the global target of 2 °C and 1.5 °C are studied using the burden sharing model. On this basis, this paper simulates the possible pathways of carbon neutrality and evaluates the ambition of emission reduction targets in terms of annual emission reduction, per capita emission, and cumulative per capita emission. The results show that, from the perspective of equity, most of the developing countries cannot meet the global goal of 1.5 °C. The United States and the European Union nations could achieve carbon neutrality by 2050 by continuing their annual emission reductions under their existing NDC targets. However, to achieve carbon neutrality by 2060, China's annual emission reduction rate from 2030 to 2050 will be 6.7%, and the annual amount of emission reduction accounts for 51% of the global amount under the 1.5 °C target. Meanwhile, China would become the main force behind global cumulative emissions in the following decades. Thus, the emission reduction pathways China chooses will have an important impact on global climate mitigation progress. Based on the above research conclusions, this paper proposes that developed countries and developing countries should explore bilateral or multilateral cooperation in technology and finance in the field of climate change. Under the great pressure to achieve carbon neutrality, China needs to carry out research on the overall emission reduction pathways as soon as possible and clarify the paths at the scale of sectors, industries, provinces, and time stages. [ABSTRACT FROM AUTHOR]

In the context of climate change, nature-based solutions (NbS) are an advanced concept for human society to cope with climate risks and challenges; they can also help to build a scientific and standardized management system and an efficient and green social and economic system for the achievement of sustainable and high-quality development goals. Besides, it provides the fundamental guidelines and directions for the Xiong' an New Area, which has been planned and constructed with high standards and provides an important realistic scenario for the study of stormwater management modes. This paper introduces the concept and development process of NbS, summarizes its principles and approaches, and systematically analyzes the characteristics of rainstorm and flood disasters in the Xiong' an New Area and the tight situation of water supply and demand caused by rapid socioeconomic development against the background of frequent extreme weather events caused by climate change. Based on the moderate greenhouse gas emission scenario (RCP4.5) of the regional climate model, the numerical simulation results of 1980--2099 with a horizontal resolution of 25 km, and the reference period of 1986--2005, the future climate change prediction analysis and rainstorm and flood risk assessment in the Xiong' an New Area were carried out. According to the Xiong' an New Area' s stormwater management and the current extreme rainfall situation, the paper combines the future social and economic development and urban-rural ecological spatial pattern of the Xiong' an New Area, as well as the concept and construction goals of 'building an ecological city where human and nature coexist harmoniously in the lake city featuring blue sky and verdant fields,' and proposes nature-based solutions to strengthen climate risk management in the area and reduce the risk of extreme precipitation. The proposed stormwater management model for the Xiong' an New Area based on NbS includes three dimensions: ① We should adhere to the overall plan of ecological protection and restoration of the whole basin and improve the capacity of systemic climate governance. ② We should advocate the multi-scale vertical system design at the city level and improve the carrying capacity of urban resilience. ③ We should adhere to the general principle of seeking advantages and avoiding disadvantages and strengthen the development of ecological infrastructure. On the basis of effective engineering and institutional defense measures, actively implementing the concept of nature-based solutions in the stormwater management of the Xiong' an New Area is conducive to fully exploring and rationally utilizing the special water system conditions of the area and the integrated environmental advantages of urban lakes, seeking advantages and avoiding disadvantages, and minimizing the impact of extreme precipitation on the stable operation of the cities and the safety of people' s lives and property. [ABSTRACT FROM AUTHOR]

Since the signing of the United Nations Framework Convention on Climate Change in 1992, the United States has shown a sometimes conservative and sometimes radical pendulum in its position on several key subsidiary climate treaties. For example, in 1997, the United States Congress refused to approve the Kyoto Protocol signed by former US vice president Al Gore. In 2015, President Obama used executive power to bypass Congress to sign the Paris Agreement. In 2017, President Trump announced the withdrawal of the US from the Paris Agreement. These seemingly confusing behaviors actually reflect the contradictions and conflicts in the formulation of climate policy of the United States. Using neoclassical realism theory as the analytical framework, the authors of this paper explore how such several key variables as leader image and perception, partisan politics, and civil society and lobbying groups shape the climate policy of the United States. [ABSTRACT FROM AUTHOR]

In the context of climate change, economic globalization and rapid urbanization, the multi-hazard risk has become a major threat to human society. Risk assessment is the foundation of risk prevention. Based on an in-depth examination of literature, this paper summarizes the theories and methodologies for assessing multi-hazard risk in the past two decades. The compre‐ hensive risk assessment has two significant theory foundations: the conceptual models which in‐ dicate the combination way of multi-hazards and the risk frameworks which describe the risk ele‐ ments and their relationships as well as developing the assessment models. The key to multi-haz‐ ard risk assessment is the integration of single hazard risk, and the method for integration can be classified to two categories: integration of risk values and integration of hazard processes. It de‐ serves closer attention to investigate both the complex relationship between various disasters and risk elements as well as the complex impact of environmental changes on disaster risk. The sce‐ nario-based modeling and risk assessing method may be a better choice for meeting the demands of the current era. It is feasible to take the single hazard risk analysis as a starting point, the in‐ terrelationships between various hazards as traction, and the scenario analysis method as a pro‐ pellant to implement multi-hazards risk assessment. [ABSTRACT FROM AUTHOR]

he ' Scientific Understanding of Climate Change' part of China' s Fourth National Assessment Report on Climate Change reflects a series of new evidence and new understanding of climate change in China since 2015, based on scientific analyses such as climate system observations, paleoclimate archives, theoretical research, and climate modeling. This report summarizes the basic climatic variables of the atmosphere, ocean, cryosphere, and biosphere, as well as the characteristics of climate change seen in extreme events and typical regions in China. It also analyzes the changes in natural and human driving factors affecting climate change and estimates the future trends of climate change in China. Compared with the Third National Assessment Report on Climate Change, this paper identifies the new features of this assessment report in terms of the structure and conclusions. At the same time, it is pointed out that the system of China' s climate change assessment report is continuously enriched and the understanding of scientific basis is constantly deep -ened. The paper also makes a preliminary comparison between this report and the report of Working Group I to the Sixth Assessment of the Intergovernmental Panel on Climate Change (IPCC) and proposes solutions to issues concerning climate change monitoring and diagnosis, detection and attribution, simulation estimation, instruments, and methods that China may face in the future. [ABSTRACT FROM AUTHOR]

Kunming-Montreal Global Biodiversity Framework proposes to protect 30% and restore 30% of the land with high quality and maximize the goal of conserving biodiversity and mitigating climate change. Succession theory and vegetation restoration can serve the targets of 30% protection and restoration. Succession theory is the core theory in vegetation ecology. Succession refers to the process that the structure or composition of a group of different species in a site change with time. Vegetation restoration is the process of restoring or recovering or naturally renewing plant communities, mainly based on plant planting and configuration. Vegetation restoration is the process of changing the structure and function of ecosystem from simple to complex, from low level to high level, and the ultimate goal is to establish healthy and stable plant communities. Succession is the foundation of vegetation restoration, and vegetation restoration can be seen as the manipulation of the succession process to achieve the goal of restoring damaged vegetation ecosystem. Succession theory can guide vegetation restoration. Vegetation restoration is also beneficial to the development of succession theory. Succession theory and vegetation restoration differ in scale, theme and paradigms. Succession often emphasizes disturbances related to nature, while vegetation restoration focuses on disturbances related to humans. The succession can be divided into primary succession and secondary succession according to the nature of bare land. The restoration process is suggested to be regarded as the tertiary succession, which will help to understand the management options for promoting the success of vegetation restoration through human intervention, especially by emphasizing the management options which may improve success, especially by addressing environmental and biological legacies. Artificial intervention based on succession theory can accelerate vegetation restoration, avoid early positive promotion of degraded vegetation ecosystems to pre-degraded levels in poor habitats, and also avoid resource waste caused by disordered competition and low efficiency among communities. This paper also puts forward the scientific and technical issues on the theories of vegetation restoration and succession in the future. [ABSTRACT FROM AUTHOR]

In the process of vegetation restoration of mine slope, the slope direction has a great influence on the effect of plant regreening. In this paper, Parthenocissus quinquefolia(L.) Planch brocade was taken as the research object, planting troughs were arranged at the foot of the high and steep bedrock slope facing east, south, west, and north. Parthenocissus quinquefolia(L.) Planch was planted in the planting troughs. The slope heterogeneity and suitability of functional traits of Parthenocissus quinquefolia(L.) Planch leaves were studied by analysis of variance and principal component-membership function evaluation. Partial correlation analysis was used to reveal the effect of climatic factors on the changes of leaf functional traits to understand the adaptability of Parthenocissus quinquefolia(L.) Planch to slope climate change. The results showed that in the characteristics of leaf structure, the order of the leaf dry matter content(LDMC) was as east slope > west slope > north slope > south slope. Leaf water content (LWC) and specific leaf area(SLA) are north slope > east slope > west slope > south slope, leaf thickness(LT) is south slope > east slope = west slope > north slope, and leaf tissue density(LTD) is south slope > west slope > east slope > north slope. In the leaf photosynthetic characteristics, the order of net photosynthetic rate(Pn), stomatal conductivity(Gs), transpiration rate(Tr), and water utilization efficiency(WUE) was as east slope > west slope > north slope > south slope, intercellular CO2 concentration (Ci) was opposite to the order. In the leaf fluorescence characteristics, the initial fluorescence(Fo) on the south slope and est slope were large, and the value on the est slope and the north slope were small. Maximum fluorescence(Fm), PSⅡquantum efficiency (Fv/Fo), and PSⅡ maximum photochemical efficiency(Fv/Fm) were in the order of north slope > east slope > south slope > west slope. The comprehensive order of slope adaptability of Parthenocissus quinquefolia(L.) Planch was as follows: east slope (2.67) > north slope(1.66) > west slope(0.07) > south slope(-1.60). The effects of different climatic factors on the functional characters of Parthenocissus quinquefolia(L.) Planch leaves were different. The structural characteristics of leaves were greatly affected by environmental humidity, followed by photosynthetic radiation. The photosynthetic characteristics of leaves were greatly affected by environmental temperature, followed by photosynthetic radiation. The fluorescence characteristics of leaves were greatly affected by environmental humidity, followed by environmental temperature and water evaporation. From the above results, it can be known that in the environment of high and steep rock, the growth of Parthenocissus quinquefolia(L.) Planch grew the best on the east slope. Under the conditions of high temperature, strong evaporation, and strong photosynthetic radiation, the functional traits of Parthenocissus quinquefolia(L.) Planch leaves showed stress resistance. [ABSTRACT FROM AUTHOR]

The ability of methane-oxidizing bacteria to oxidize methane significantly affects the total global methane emissions. To study the response of methane-oxidizing bacteria community to temperature rise in river source wetland is helpful to further explore the methane cycling mechanism in river source wetland ecosystem. In this paper, high throughput sequencing method was used to study the changes of methane-oxidizing bacteria community characteristics in river source wetland of Qinghai Lake after temperature rise. Proteobacteria were the dominant phylum of methane-oxidizing bacteria in the headwater wetlands of Qinghai Lake; warming treatment did not significantly affect the community diversity of methane-oxidizing bacteria in the river source wetland. The community structure of methane-oxidizing bacteria in river source wetland responded significantly to temperature rise; warming significantly increased the dominant microflora at the genus level (relative abundance > 0.1%). LEfSe analysis showed that there were 23 different microflora between the warming group and the natural control group; the warming significantly increased the relative abundance of Methylococcus and significantly decreased the relative abundance of Methylobacter. The function of methane-oxidizing bacteria community was closely related to carbon and nitrogen metabolism in river source wetland. In general, the community structure of methane-oxidizing bacteria in river source wetland was more sensitive to temperature rise, and the relative abundance of some bacteria changed significantly. [ABSTRACT FROM AUTHOR]

Petrocodon Hance is one of the famous ornamental flowers, but most of them are assessed as extremely dangerous (CR), or at least above vulnerable (VU) due to climate turbulence and strong interference of human activities. To reconstruct the temporal and spatial changes of the potential suitable areas of Petrocodon since the last interglacial period, and explore the response of the suitable areas to environmental changes, which provided theoretical guidance for the origin of Petrocodon, the study of geographical differentiation, the conservation of unique germplasm resources in China, and the development and utilization of gardens. In this paper, combined with 120 distribution records and 17 environmental variables, the optimal MaxEnt model and geographic information technology (ArcGIS) were used to simulate the suitable areas and distribution pattern of Petrocodon in China and Indo-China Peninsula. Based on stepwise multiple linear regression analysis, redundancy analysis and Monte-Carlo test, the dominant variables affecting the current geographical distribution of Petrocodon were evaluated. The results were as follows: (1) The prediction accuracy of the optimized MaxEnt model was high, and the AUC value was greater than 0.96. The potential suitable areas of Petrocodon for the present distribution are continuous from Southwest China to North Vietnam, scattered in central and southern China and blocky in North Myanmar, of which the South Yunnan-Guizhou Plateau in China was the most suitable. (2) The environmental variables which restrict the geographical distribution of Petrocodon included precipitation of the driest month (bio14), precipitation of the warmest quarter (bio18), precipitation of the wettest quarter (bio16), SD of the temperature seasonality (bio4), min temperature of the coldest month (bio6) and altitude (alt). (3) Under the climate change scenario, the expansion and contraction areas of the suitable habitat of Petrocodon were located in the north and northeast of the current potential distribution area, which were sensitive areas susceptible to climate change. During the last interglacial period, the suitable area of Petrocodon expanded on a large scale, but there was almost no suitable distribution area of Petrocodon in the dry and cold environment during the last glacial maximum. After that, with the aggravation of climate warming, the suitable habitats of Petrocodon increased rapidly to high latitudes, while the suitable habitat in low latitudes decreased. (4) The centroid position of the suitable area for Petrocodon migrated northwards from Yongfu County, Guangxi (110.10° E, 24.69° N) to Chengbu County, Hunan (110.29° E, 26.05° N). To sum up, global warming has a positive impact on the potential distribution area of Petrocodon, but extreme warming will cause the suitable habitat of Petrocodon to shrink, and the niche of Petrocodon will narrow. Southwest China to North Vietnam, which has the advantage of mature karst landform, may be its main refuge. [ABSTRACT FROM AUTHOR]

The aims of this paper is to illustrate the importance of grain production in China's food security strategy based on the three Northeastern provinces (NEP) in the new period, which quantitative assessment of climate change under the background of the loss caused by meteorological disasters of regional food production is clarify. In this paper, using grain planting area, yield and agricultural disaster statistics from 1981 to 2020, comparison analysis grain production and disaster characteristics between NEP and the whole country respectively. The disaster-yield assessment model was used to estimate the disaster-yield loss and final yield of the NEP by inputting disaster data in recent 10 years, and the sensitivity and stability of the disaster-yield assessment model were re-tested. The results showed that :(1) from 1981 to 2020, the grain planting area and total output in NEP increased significantly, and the proportion of the total output of NEP increased steadily, and the proportion of the total output of the three northeast provinces reached 1/5 of the total output of the whole country by 2020. (2) The disaster situation in NEP showed a significant trend of first increasing and then decreasing. The incrasing of average grain yield during the past 40 years was 65.96kg⋅ha-1 and 252.5kg⋅ha-1 per year for NEP and the whole country, while the incrasing of average grain yield during the past 10 years was 52.6kg⋅ha-1 per year for NEP significantly. (3) From 2011 to 2020, the average affected area and affected area in China were 23704.5x10³ha and 11204.7x10³ha, respectively, and 3899.1x10³disasters of the whole country and the three northeastern provinces were significantly lower than those of the previous three years, making it the decade with the least severe disasters in 40 years. (4) The simulation accuracy of the disaster-yield assessment model was high. The linear regression coefficients (R²) of simulated grain yield and measured grain yield in Heilongjiang, Jilin and Liaoning provinces were 0.98, 0.90 and 0.88, respectively. The slopes were 1.05, 1.02 and 0.98 (P < 0.01), respectively. The loss rate of grain yield due to agro-disaster was 10.4%, 17.9% and 18.0% respectively in the three province, while which was more than 8.0%, 17.0% and 16.0% for 20a.years. (5) The model slightly overestimated the grain yield of Jilin and Liaoning in recent 10 years due to the overall light disaster situation. Based on the data from 1981 to 2010, the regional grain disaster loss assessment model was proved to be able to evaluate the loss of grain yield caused by meteorological disasters well, and had the performance of predicting grain yield, and has the feasibility of operational application. The impact of meteorological disasters on the grain output in northeast China is higher than the average level of disasters in the whole country. Considering that the grain output in Northeast China accounts for a high proportion of the national grain output, preventing the risk of agro-meteorological disasters in Northeast China in the new period is of great importance to guarantee the national food security. [ABSTRACT FROM AUTHOR]

Objectives: As an emerging airborne remote sensing system, unmanned aerial vehicle (UAV) falls into multiple categories with various payloads, such as the multi ⁃ rotor and fixed ⁃ wing ones. Despite the harsh climatic condition, UAV is widely used in many Antarctic fields of basic and applied science, which still lacks a comprehensive and systematic literature review. Methods: We firstly discuss the special impact of Antarctic environmental conditions (meteorology, electromagnetic field, light, etc.) on the UAV operation. A comprehensive literature retrieval is subsequently presented on the current application of UAV in Antarctic research and expedition. We sort out 104 papers according to the time of publication, main journals, study areas, nations, and institutions. Representative literature is reviewed in seven application areas, including aeromechanics, atmosphere, sea ice and iceberg, glacier, geomorphology and geomagnetism, ecology-vegetation as well as ecology-animals. We retrospect the development and achievement of UAVs applications in the Chinese national Antarctic research and summarize the limitations of the research on the application of UAV in Antarctica. Results: A number of environmental factors need to be considered before the UAV missions, such as the meteorological conditions, electromagnetic field, solar radiations, and flight regulations. According to the review, half of the literature belongs to the journal paper, mostly in Polar Biology, Polar Science, and Remote Sensing. The earliest UAV research in Antarctica was published in 2004, followed by a productive period of International Polar Year in 2008. The first-tier countries including the USA, Australia, and Germany, led the progress in the research on UAVs in Antarctica. Meanwhile, the dominant role of top universities stood out via various collaborations. The UAV can also be classified into multiple categories according to the payload, such as the industrial⁃ or consumer-grade optical cameras, radiosonde, synthetic aperture radar, and light detecting and ranging （LiDAR), among which consumer-grade camera is widely used in Antarctic investigations. China􀆳s Antarctic expedition team initiated the Antarctic UAV program in 2007 and had carried out at least 18 flight missions by 2020. The flights covered Zhongshan Station, The Great Wall Station, Inexpression Island, and the inland ice sheet, from which the collected data were employed to support the glaciological, geomorphic, and biological studies. Conclusions: The UAV remote sensing, as the essential technology in the “Air ⁃Space ⁃Ground” polar observation system, has been increasingly upgraded in the recent decade. The flight experiments covered the primary research topics and research fields in Antarctic science. In general, the application and development of Antarctic UAV in China lie in the second tier, falling behind the USA and Australia. In the end, according to the current development of Antarctic UAV in China, this paper provides guidance for China's Antarctic expedition team in the future: (1) Develop new UAV models; (2) Make breakthroughs in the battery technology; (3) Couple multiple sensors; (4) Encourage trans ⁃disciplinary collaboration; (5) Pro-mote foreign communication and sharing; (6) Participate in the international management. [ABSTRACT FROM AUTHOR]

Climate warming has become the direction of future climate change. Climate warming and terrestrial ecosystem will interact and influence each other. Grassland ecosystem accounts for about 1/3 of land surface area. Observing and analyzing the responses of plant community and ecosystem carbon exchange in grasslands to climate warming will help to further predict changes in grassland ecosystem in the future. This paper reviewed the effects of climate warming on plant physiological and ecological processes, plant community and ecosystem carbon exchange of grasslands. Various results were obtained in different regions and by different experimental methods. Overall, climate warming had a positive effect on alpine grassland ecosystem, a negative effect on tropical grassland ecosystem, and positive/negative effects on temperate grassland ecosystem. In the future, long-term observational studies and mechanism studies on a global scale should be considered to further clarify the responses of grassland ecosystem to global warming. [ABSTRACT FROM AUTHOR]

To achieve the goal of 'Net-zero Europe' by 2050, the European Union (EU) has set up detailed policies in the fields of energy and climate. This paper summarizes the main characteristics of relevant policies in the EU and UK and their implications for China by reviewing these policies in the achievement of the carbon neutrality goal and other goals in the energy and climate fields. The characteristics of these energy and climate policies include: ① Top-down and bottom-up approaches are adopted to distribute the EU' s overall emission reduction targets to member states in accordance with the principle of fairness, and each member state formulates and adjusts its own goals to ensure the realization of the overall goals. ② Detailed transition plans are formulated for the power, industry, transportation, and building sectors; importance is attached to the application of new and renewable energy technologies such as solar, wind, and hydrogen energy; specific goals are set concerning coal power transition, nuclear energy development, energy efficiency improvement, carbon capture and storage, electrification, and building renovations; and the importance of energy security in transition planning is stressed. ③ A sound and mature emissions trading system and a fair transition mechanism are established to support the realization of the transition goals, and developing countries are helped to reduce emissions through technical dialogues and climate financing. To reach peak carbon emissions and achieve carbon neutrality, China should develop relevant roadmaps at national, sectoral, and provincial levels and strengthen R&D of key decarbonization technologies. At the same time, China should enhance its regulatory regime, and improve the carbon emissions trading system, the green financial system, and the just transition mechanism. [ABSTRACT FROM AUTHOR]

To explore the impact of climate change on the lake area of Selin Co, this paper used maximum likelihood method to extract the lake areas of Selin Co for the past 33 years (1988-2020) from Landsat data, then analyzed the variations in lake area, temperature, precipitation as well as snow cover depth in Selin Co basin using linear regression and Mann-Kendall test, and discussed the correlation between lake area and climate change by Pearson correlation. The results showed that, in the past 33 years, the Selin Co Lake expanded by 650. 70 km² at the rate of 203. 34 km²/ (10 a),mostly at northward and southward directions. The average annual temperature and precipitation increased significantly at the rates of 0. 50℃/ (10 a) and 17. 32 mm/ (10 a) (p<0. 05),while the average maximum snow cover depth decreased significantly at the rate of 0. 65 cm/ (10 a) (p<0. 05) during 1988-2020. An extremely significant correlation was found between the change of lake area and the rise of air temperature in the basin as well as the decreasing maximum snow cover depth in cold season (p<0. 001),indicating that the Selin Co lake’s expansion in the past 33 years was a consequence of the increasing water supply from ice-snow meltwater due to the rising air temperature in Selin Co basin. [ABSTRACT FROM AUTHOR]

The ' Policies and Actions to Address Climate Change' part of China' s Fourth National Assessment Report on Climate Change comprehensively summarizes the policies and actions implemented to tackle climate change during the middle and late stages of the 12th Five-Year Plan and the 13th Five-Year Plan, and makes an in-depth and systematic assessment of the effects of the policies. This paper mainly introduces the overall framework and main features of this part of the report, interprets its main conclusions, and proposes prospects for future policies. Since the middle and late stages of the 12th Five-Year Plan, China has adopted a series of policies and actions to tackle climate change, continued to promote the establishment and improvement of climate policies, and formed a policy system with distinctive Chinese characteristics involving the planning objectives, the administrative measures, the market-based policies, the pilot and demonstration actions, etc. During this period, China made great achievements in tackling climate change, fulfilled the 2020 carbon emission reduction target in advance, and reversed the rapid growth of carbon dioxide emissions. To achieve the goal of reaching peak carbon emissions by 2030 and achieving carbon neutrality by 2060, China needs to make climate change solutions a part of the overall goal and strategy for national modernization in the future, formulate and implement stronger climate policies, and put them into action. [ABSTRACT FROM AUTHOR]

Based on the assessment report of the Intergovernmental Panel on Climate Change (IPCC) and recent research literatures, from the perspective of the impacts and risks of climate change, this paper attempts to interpret several climate tipping points that may be exceeded due to global warming and explain mitigation measures such as carbon dioxide emission peak and carbon neutrality taken by the international community. The importance and urgency of adaptability research in different systems or regions are discussed. The main conclusions are as follows: ① In the past century, especially since the 1970s, global warming has been increasing rapidly, while the warming rate of China􀆳s land and sea is higher than that of the global average. ② In 2019, the atmosphere concentration of CO2, the main driver of global warming, has reached 410.5 ppm, which was 148% of the pre⁃industrial (1750) level and the highest at any time for at least 2 million years. ③ The risks of climate change will increase disproportionately as global temperature quickly increases. The climate tipping points (thresholds) of some systems may be exceeded or occur earlier than expected, causing abrupt and irreversible changes. ④ With the increase of global warming, nine global climate tipping points may being exceeded, including large⁃scale bleach⁃ ing and death of warm water coral reefs, accelerated melting of Greenland and Antarctic ice sheets, slowdown of the Atlantic Meridional Overturning circulation, etc., and there is also a risk of domino effect. ⑤ In order to address the impacts and risks of climate warming, it is necessary to limit global temperature rise in this century to 2 ℃ (preferably 1.5 ℃) above pre⁃industrial levels (1850-1900). Com⁃ pared with 2010, the global net anthropogenic CO2 emissions need to be reduced by about 25% (45%) by 2030 and achieve carbon neu⁃ trality in around 2070 (2050). ⑥ Taking warm water coral reefs as an example, this paper discusses and analyzes that the tipping point of damaged coral reefs in China may be firstly exceeded due to the high warming rate of the China Seas. Therefore, it is urgent to restore and strengthen the climate resilience of different systems or regions such as damaged coral reefs, so as to improve their ability to adapt to climate change. In addition, a breakthrough has recently been made in the research on in situ sexual reproduction and restoration of damaged coral reefs in China, which provides a positive prospect for reconstructing the resilience of damaged coral reefs. [ABSTRACT FROM AUTHOR]

Global climate change is becoming more and more serious, resulting in an increased risk of sea-level rising, extreme weather events, frequent forest fires, and so on. Despite the efforts made by all countries, the trend of global warming has not been stopped, and it is urgent to solve the climate problem. As the largest carbon emission country in the world, China has committed to the international community to achieve peak carbon emissions by 2030 and carbon neutrality by 2060. To explore the synergy mechanism and effect of China's climate policy and promote carbon emission reduction, this paper proposes the concept of 'Sector Consortium'. It is believed that due to the specialization of sector division, a single sector cannot effectively deal with complicated climate problems, and multi-sector climate policy synergy is imperative. Climate policy synergy runs through the process of policy objective formulation, policy detail determination, and policy implementation. All sectors should be fully mobilized to participate in the response to climate change and to enhance the capacity of climate governance by optimizing policy objectives, improving policy details, and strengthening policy implementation. The results show that differences between the central government and the provincial governments in the degree of climate policy synergy are obvious, the central government has a higher degree of climate policy synergy, and the provincial governments have a larger space to improve their climate policy synergy. Based on the provincial panel data from 2003 to 2017, this paper finds that climate policy synergy can reduce carbon emissions, but this influence is reflected by an indirect effect. Climate policy synergy will not have a direct impact on carbon emissions, but will play a role through four types of interaction mechanisms: the synergy of climate policy with measures such as strengthening financial investment, promoting technological innovation, optimizing industrial structure, and reducing energy intensity can reduce carbon emissions more effectively. China's experience of climate policy synergy has important implications for the construction of global carbon emission reduction mechanism. This paper proposes that the global climate governance synergy mechanism should be established based on the effectiveness of climate policy synergy and the behavior logic of 'Sector Consortium', so as to effectively promote global carbon emission reduction and slow down the process of climate change. [ABSTRACT FROM AUTHOR]

The essence of ecological security focuses on ecological risk and ecological vulnerability, and the study of ecological security is the hot points of low-carbon green development, which has important theoretical value and practical significance for optimizing landscape ecological spatial structure and maintaining ecological sustainability. Based on the interdisciplinary principles and methods involved in geography, ecology, remote sensing and GIS, this paper studies the characteristics and laws of climate change and landscape pattern, the coupling relationship between climate change and ecological process, landscape pattern and functional properties. The relationship between landscape pattern, climate factors and soil, hydrological processes and vegetation processes in the ecosystem is analyzed, and the effects of climate change on carbon storage, NPP and ecosystem services are studied to reveal the impact of climate change on ecological processes. The comprehensive analysis shows that climate factors affect the characteristics and changes of ecological security. Meanwhile, landscape pattern is the basis of restricting regional ecological security, and the effects of climate change and landscape pattern on ecological security mechanism are complex. [ABSTRACT FROM AUTHOR]

Excessive anthropogenic emissions of greenhouse gas have led to global climate change in recently years. Methane is an important greenhouse gas after carbon dioxide. Methane emissions increase with the global temperature, which further intensifies global warming. Soil is a huge source and sink of methane, and methanotrophic bacteria play a key role in reducing methane emissions. Exploring the effect of temperature on soil methane-oxidizing ability has been a research hotspot in recent years. This paper reviewed the effects of temperature on soil methane oxidation and methanotrophic bacteria; analyzes and compares the soil methane oxidation process and methanotrophic bacteria in various ecosystems at different temperatures, and the growth temperature range of methanotrophic bacteria strains. The results showed that various ecosystems have different temperature ranges for methane oxidation; the rate of methane oxidation increases with increasing temperature in their particular temperature ranges. When the cultivation temperature is closer to the in-situ temperature, the methane oxidation response will be faster. Similar to the effect of temperature on methane oxidation, the diversity and abundance of methanotrophic bacteria also increase with increasing temperature and are closely related to the magnitude of temperature increase and the adaptation temperature of dominant bacteria. Type II methanotrophic bacteria in the soil are more sensitive to temperature. As the temperature rises, the abundance of type II methanotrophs increases. Therefore, temperature affects the abundance and community structure of methanotrophs, thereby affecting the rate of methane oxidation and methane emissions. However, whether temperature can only change the methane oxidation capacity of the soil by regulating the replacement of dominant bacteria is still unconfirmed. This review discussed the response of methane oxidation to temperature and its microbial mechanism, in order to provides a comprehensive analysis for methane oxidation capacity under the context of future climate change. [ABSTRACT FROM AUTHOR]

Climate change potentially increases the severity, frequency, and duration of cyanobacterial blooms in freshwater lakes, thereby threatening the ecosystem service functions of these lakes and negatively impacting human health. This paper provides a comprehensive review of the external environmental factors and internal eco-physiological characteristics that may trigger these blooms. In particular, detailed discussions are provided to explain the processes leading to cyanobacterial blooms caused due to rising temperature, CO2 concentration, and extreme climate change. A preliminary research framework to determine the impact of climate change on the blooms, namely, the “mechanism analysis — model construction — simulated prediction — risk assessment” research framework, is established. Strategies for the control and prevention of bacterial blooms are developed. Several key future research themes, including the construction of big data monitoring platforms, mechanism models for development and risk prediction, and formulations of nutrient control standards and prevention policies, are proposed to tackle the current problem. This review provides scientific evidence for the prevention and control of cyanobacterial blooms in lakes. [ABSTRACT FROM AUTHOR]

Because of global climate change and human activities, the occurrence frequency of extreme precipitation events is increasing steadily, which causes devastating flood disasters. The stability of a human body can be compromised when exposed to floodwaters, which definitely threatens the life of a human being. Therefore, the investigation into mechanisms and criteria of human instability in floodwaters can provide scientific bases for urban flood risk assessments and hazard reduction measures, and can also benefit the ability of emergency response. This paper summarizes existing studies on instability mechanisms and criteria for people in floodwaters. Based on the summarization, the application scope, advantages and disadvantages of these existing criteria for human instability are evaluated in detail. Even though the calibrated formulas based on mechanical analysis and measured data involve some simplifications, they can reflect the critical mechanical condition of human instability in floodwaters, and therefore show better universality in practice. Given the limitations and shortcomings of the existing studies as well as major threats in current urban flood disasters, this study also presents key future research directions, including the instability mechanisms and criteria of pedestrian evacuation in actual flood conditions and from flooded stairs; using big data technologies to obtain and analyze online resources of flood instability videos and images, and reasonably estimate the critical instability state to construct a dataset of body instability in floodwaters; conduct in-depth studies on the influence of body posture adjustment on flood hazard degree. Besides, it is necessary to promote the application of human instability criteria in the field of urban flooding disaster prevention and reduction, in order to minimize the disadvantageous impacts of urban flood disasters. [ABSTRACT FROM AUTHOR]

Water option trading aims at solving the problem of uneven spatial and temporal distribution of water resources. With the change of global climate, rainfall has become an important factor leading to the uneven spatial and temporal distribution of water resources. In this paper, Markov chain is used to divide and forecast the rainfall scenarios. On the basis of rainfall forecast, the related costs of water option trading are determined. The forecast results of rainfall index are integrated into the determination of the ultimate overprice of water options. The improved Black- Scholes option pricing model is used to determine the rights of water options trading based on the forecast results of rainfall. Finally, the rationality of the calculation results is verified by using the extended linear expenditure model, which proves the rationality of the transaction price determined by the model. Taking Guangdong province as an example, this paper verifies the necessity of incorporating rainfall index into water option trading and the rationality of the related costs of water option trading determined by the model, and proves the superiority of fluctuating water price over stepped water price. Water option trading considering rainfall fully reflects the relationship between supply and demand in water market, and improves the scientificity of water option trading pricing in China. [ABSTRACT FROM AUTHOR]

As a primary tool in climate change research at the watershed scale, the role of horizontal resolution in regional climate simulations needs to be evaluated. This paper investigates the role over the Huang-Huai-Hai (HHH) River basin using a regional climate model, RegCM4, coupled with the National Center for Atmospheric Research (NCAR) Community Land Model, version 4.5 (CLM4.5) including the modules of CN and DV (RCM_CLM4.5). The model is driven by ERA-Interim reanalysis data, and the time period is 1990—2010. Model validation shows that RCM_CLM4. 5 at 50 km and 25 km resolutions can reproduce the present climate well, including the spatial distribution of winter and summer mean temperature and precipitation, the annual cycles of temperature and precipitation, and the climate extremes. However, some biases can also be found. For example, compared with the observation, cold and warm biases are found in the winter and summer mean temperature, respectively; wet biases are found in the precipitation. Comparison between the two simulations, better performance of the magnitude and spatial distribution of mean temperature is found in the simulation at 25 km resolution; while for precipitation, better performance is observed in the one at 50 km resolution; little difference is found for the climate extremes. In general, results from this study indicate a very low sensitivity of present climate in this region to model resolution and can provide a reference for the application of this model in future climate change research over the HHH River basin. [ABSTRACT FROM AUTHOR]

Under the background of climate change and water shortage, the study on the change of vegetation ecological water demand in the middle and lower reaches of Shule Riverbasin is of great significance for water resources allocation, ecosystem balance and sustainable development of Shule River oasis. In this paper, the area quota method and the phreatic evaporation method were adopted to calculate and analyze the temporal and spatial variation trend during the vegetation growth period（April-October） in the middle and lower reaches of Shule River basin from 1980 to 2018. The results show that the average annual ecological water demand of grassland（640 million m³） is higher than that of woodland（50 million m³） in the study area. On the annual, the total ecological water demand of vegetation fluctuated and increased with the change rate of 4 million m3/10 a, among which, the ecological water demand of grassland is increased（7 million m³/10 a） and the ecological water demand of forest is decreased（4 million m³/10 a). During the growing period, the vegetation water demand accounts for 63% of the total amount from April to July, reaches to the maximum value of 138 million m³ in July and gradually decreases from July to October. Spatially, the total water demand in the middle reaches is slightly higher than that of in the lower reaches, among which the ecological water demand of forest land is greater than that in the lower reaches and the water demand of grassland is basically the same as that in the lower reaches. [ABSTRACT FROM AUTHOR]

As the melting of Arctic Sea ice because of global warming creates new shipping routes and energy resources, the post-Cold War peace and stability of the Arctic has been shattered. It has once again become a strategic location for multinational rivalries, attracting widespread attention in international geopolitical circles. Compared to other regions of the world, studying the Arctic region from a Western geopolitical perspective is at the forefront of international research. Although China, as a near-Arctic country, has developed geopolitical research on the Arctic in response to its practical needs, domestic research in this field started late, with room for improvement in its breadth and depth. Therefore, 98 papers in the Web of Science core database that are highly relevant to Arctic geopolitics are selected as the object of the study. Through a literature review, we summarize the development of Arctic research from a Western geopolitical perspective, and the shift in perspective and hot topics; we adopt a forward-looking perspective of future research development trends to provide reference for innovative research in this field in China. The results reveal the following: (1) Research on the geopolitics of the Arctic has been conducted in a wide range of fields and topics in Western academia, with some correlation among the topics, although the links among the studies are not strong, and the research scale generally shows a fluctuating growth trend. (2) The research content, composed of six major fields (boundary and territorial politics, Arctic shipping routes, Arctic resource development, Arctic geo-strategy, Arctic security and governance, and indigenous population issues), focus on politics and economics but is lack of cultural research. (3) Under the influence of aesthetic humanism and the "cultural and institutional turn," the trend in the cross-fertilization of geopolitical, geo-economic, and geo-cultural perspectives has increasingly become more obvious. (4) Research on the Arctic from a geopolitical perspective has been relatively fruitful, although there remain shortcomings in the depth of theoretical research, breadth of research scale, diversity of research methods, and geo-economic and geo-cultural research paradigms, which require further development. Future research will generate new ideas and directions in immaterial areas such as theoretical framework studies, interdisciplinary studies, and emotional culture, and will focus more on the role of multiple actors, such as indigenous peoples and NGOs, in geopolitical knowledge production and power competition. [ABSTRACT FROM AUTHOR]

The Yellow River is the mother river of China and the cradle of Chinese culture. The social-economic development of the entire Yellow River basin and the whole country is closely related to the changes in the water resources of the Yellow River. This study tries to disentangle the driving factors of the change in the Yellow River runoff across different reaches and in different periods of time. Using the restored natural runoff data, observed runoff data, rainfall data and potential evapotranspiration data of four typical hydrological stations of Lanzhou, Toudaoguai, Huayuankou and Lijin on the main stream of the Yellow River from 1960 to 2010, this paper analyzed the attribution of the change of the main stream of the Yellow River by using double mass curve and sensitivity coefficient methods based on the Budyko framework. The results show that human activities are the main reason for the significant decline of the Yellow River runoff after 1989 mid their contribution rate to the Yellow River runoff is more than 85%·, while the contribution rate of climate change is less than 15%, and the further downstream, the higher the contribution rate of human activities. In short, the climate change impact of the annual runoff is more prominent in the upstream than that of in the middle mid lower reaches. Finally, it discussed the theoretical and practical issues of the hydrological effects of climate change and human activities. [ABSTRACT FROM AUTHOR]

This paper is based on the meteorological observation data of the five meteorological stations (Shiquanhe, Gerze, Xianza, Bangoin and Amdo) near Qiangtang National Nature Reserve, the climate of Qiangtang National Nature Reserve from 1960 to 1990 and the estimated grid data in the future issued by IPCC5. The Miami model, Thornthwaite Memorial model, and tendency rate were used. The statistical analysis methods were used to study the spatiotemporal evolution of Net Primary Productivity in Qiangtang National Nature Reserve and its response to climate change. The results showed that: (1) the average annual temperature decreases from the west to the east, and the annual precipitation increases from the west to the east. The annual mean temperature(T) showed a significant increasing trend, while the annual precipitation(R) and annual evapotranspiration(E) showed a slight increasing trend. NPP of Temperature(NPPt) and NPP of precipitation(NPPr) showed a slight increasing trend at all stations, and NPP of evapotranspiration(NPPe) and standard NPP(NPPb) showed a slight increasing trend at most stations. (2) NPPt gradually decreased from the west to the east, NPPr gradually increased from the west to the east, NPPe and NPPb first increased and then decreased from the west to the east. The limiting factor of NPP was precipitation in Shiquanhe station and Gerze station, evapotranspiration in Xianza station and Bangoin station, and evapotranspiration or air temperature in Amdo station. (3) The NPPt, NPPr, NPPe and NPPb in different periods of the 21st century were significantly higher than those in all periods of the 20th century. The NPPt, NPPr, NPPe and NPPb were significantly increased in the future under different emission scenarios compared with those from 1960 to 1990. Under the trend of "warming and wetness" in the past 48 years and in the future, the NPP of vegetation increased, and the increase was larger in the cold and humid area in the southeast, but less in the cold and arid area in the northwest. The future climate is conducive to the improvement of local vegetation NPP and the improvement of local ecological environment. Assessing the possible impact of future climate change on the ecological environment of Qiangtang Plateau. The results not only provide a basic method for studying the Net Primary Productivity of vegetation in no man's land at regional scale, but also have important reference value for estimating ecological security research and ecological function planning. [ABSTRACT FROM AUTHOR]

Variations in streamflow are influenced by climate change and human activities. Hydrological research has been focused on analyzing the spatial and temporal variability of streamflow and quantifying their responses to climate change and human activities. This paper summarized the research advances of the methods of trend detection and attribution analysis for streamflow variation. Meanwhile, the representative research results at home and abroad had been reviewed. Advantages, limitations and applications of different methods also had been discussed. Finally, it further pointed out the weaknesses in this field and development trend of future research It is necessary to strengthen the study of streamflow variation in extreme hydrological events and areas without data by means of high and new technology. Additionally, the driving mechanism of climate change and human activities on streamflow variation remain to be explored. [ABSTRACT FROM AUTHOR]

Climate change in the arid area of Xinjiang is obvious in recent years.Whether there is a threshold value for grassland ecosystem response to atmospheric nitrogen deposition and climate change in this area needs to be further studied.This paper takes the four types of grassland (alpine meadow (AM), mid-mountain forest-meadow (MMFM), low-mountain dry grassland (LMDG) and plain desert grassland (PDG)) in the northern slopes of Tianshan Mountain as research object, based on the DNDC model, to reveal the influence of atmospheric nitrogen deposition and climate change on the grassland net primary productivity (NPP).The results showed that:1) there was a threshold value of NPP response to nitrogen deposition, and the response thresholds of PDG, LMDG, MMFM, and AM were 20±5.77, 60±26.46, 50±15.28, and 30±11.55 kg·hm-2, respectively;2) the hydrothermal condition was the main factor determining NPP;3) there was a threshold value of NPP response to temperature rise in PDG grassland, while no definite conclusion had been drawn for the other types in the current study;4) the NPP of PDG and LMDG grassland was positively correlated with precipitation, while the change of AM grassland NPP was negatively correlated with precipitation.The sensitivity of different grassland types to precipitation changes also varied greatly, with PDG being the largest, followed by LMDG, AM, and MMFM. [ABSTRACT FROM AUTHOR]

[Objective] Regional vegetation index is an important index to evaluate its ecosystem. Karst areas are vulnerable to climate change and human activities, vulnerable to damage and difficult to restore. The present paper aimed to explore the relationship between climate factors and vegetation change, and used the residual analysis to separate the impact of human activities on vegetation and quantitatively evaluate its contribution. [Method] Based on the normalized difference vegetation index data, meteorological data and land use data from 2001 to 2014, the trend analysis method and partial correlation analysis were used. [Result] The results showed that the NDVI in Chongqing karst areas showed a trend of fluctuation and increase in recent 14 years, with an annual growth rate of 0.0048/year. 78.9 % of the regional vegetation in the study area increased 17.14 %. Only less than 4 % of the regional vegetation was degraded; The impact of climate change on vegetation was much higher than that of human activities, and the correlation of temperature was higher than that of precipitation, mainly showing a positive correlation; The contribution rate of climate change was 94.6 %, and the contribution rate of human activities was 5.4 %. The average residual between the actual NDVI value and the simulated NDVI value in the study area was 0.0397. [Conclusion]The impact of human activities on vegetation was positive, and the ecological restoration project in Chongqing for karst areas has achieved initial results. [ABSTRACT FROM AUTHOR]

In order to improve the estimation accuracy of freeboard of Antarctic sea ice， this paper combined CryoSat⁃2 altimeter data, ASPeCt ship observational data and IceBridge airborne altimeter data to explore the optimal parameters for freeboard estimation using the minimum method, as well as analyzed spatiotemporal variation of sea ice freeboard from May to October，2011−2017 in the Weddell sea. The result indicates that the optimal parameter scheme for retrieving freeboard is to apply the average of the lowest 5% measurements as local sea surface height after eliminating the gross data using 0.8 times standard deviation within 10 km segment. Over the past seven years, sea ice freeboard in the Weddell sea presents a slightly thinning trend, and monthly average freeboard ranges from 17.9 cm to 27.4 cm. The distribution of sea ice freeboard of the Weddell sea is characterized by the thick sea ice located in the west Weddell sea and near the Antarctic Peninsula, while thin sea ice distributed in the east Weddell sea. This study could be beneficial for further studying the response of the Antarctic sea ice thickness to climate change. [ABSTRACT FROM AUTHOR]

In this paper, the maximum entropy model (Maxent) and geographic information system ( ArcGIS 10.3) softwares were used to predict the potential distribution areas of four Litsea species under the current and future climate conditions of China ( 2061 - 2080), and to analyze and classify their suitable habitats. The results were as follows: Litsea cubeba was widely distributed in the south to the Yangtze Hiver in China, and under the future climate with two ( HCP2.6, HCP8.5) carhon dioxide concentrations, during 2061-2080 the suitable anca for its distribution was reduced by 4.9%and 0.5%, respectively; L. coreana was mainly distributed in central and northern subtropical regions of China, and under the climate scenarios with two carbon dioxide concentrations, in 2061-2080 the total suitable area would be increased by 5.6% and 4.5%, respectively; L. greennumiana was mainly distributed in the south subtropical regions of China; L. mollis was widely distributed in the subtropical region. Under the future climate HCP2. 6 scenarios, the suitable area of the two species would be shrinked by 1.0% and 3.3%, respectively, and under the climale HCP8.5, the suitable area of the two species would be shrinked by 5.6% and 8.3%, respectively. These results reveal that due lo different ecological requirements, Litsea species will have different distributional responses to the future climate. the introduction and cultivation of Litsea species should consider the influences of climale change. [ABSTRACT FROM AUTHOR]

The East Asian summer monsoon brings a large amount of precipitation in East China every year, which is the main source of water resources for China. At the same time, it often causes the severe flooding disasters. The Chinese meteorologists and hydrologists have realized that the moisture transport intensity, the extent and persistence of summer monsoon may play a crucial role in extreme rainstorm processes. This branch of moisture transport belt may be termed as the East Asian summer monsoon moisture transport belt. It can be categorized in the atmospheric river (AR) coined internationally, but it is not a fully same conception, due to its unique regional feature of the East Asian summer monsoon. The monsoon moisture transport belt is a main producer of excessively heavy rainfalls and disastrous floods in this region. Based on the data of the past hundred years, this paper made an update re view of the characteristics and formation reasons of the East Asian summer monsoon moisture transport belt. Taking the five strongest continuous heavy rain processes in the Haihe River, Yellow River, Huaihe River and Yangtze River in the past hundred years as examples, the important role of the monsoonal moisture transport belt is analyzed. Finally, it is proposed that climate warming can affect the global water cycle through four aspects, including holding more water vapor in the atmosphere, changes of the atmospheric circulations and radiation forcing with climate warming as well as the regional impact of aerosols. [ABSTRACT FROM AUTHOR]

The significant changes in the cryosphere have produced a series of effects on the cryospheric hydrological processes. This paper comprehensively reviews the recent 20 years, especially the new progress in the research on the changes in cryospheric hydrological processes in China, which mainly include glacial meltwater, snow melt runoff, and frozen ground hydrology. The main progresses in the study on changes in glacial melt water manifest as: a comprehensive study on glacial meltwater at different scales was carried out, it was found that the glacial meltwater showed continuously increase, and whether the "peak point" of the glacial meltwater have appeared has scientifically identified and some basic understandings has obtained, and the modelling on glacial melt water process had made significant progress. In the study on snowmelt runoff changes, the snowmelt runoff contribution rate to river runoff in various basins were basically grasped by estimating the snowmelt runoff and found that the snowmelt runoff changes in China vary greatly, and it increased in some basins while decreased in some basins. The changes in the start melting period in China are universal with other basins in the world, and the prominent feature is the advance of the peak value. In the study of frozen ground hydrology, the studies on the relationship between surface water, interflow in active layer soil, supra- permafrost water revealed the coupling mechanism of gravity and thermodynamics in the formation of runoff in permafrost regions. The impacts of permafrost change on surface runoff has already appeared, which mainly appears as increase in the winter ( dry season) runoff. It also found that the permafrost degradation has a direct replenishment effect on river runoff, and the amount of recharge may have reached a certain level in some basins. [ABSTRACT FROM AUTHOR]

This paper focuses on the analysis and assessment of ocean changes including the offshore area of China (hereafter, offshore China) and adjacent seas in the context of climate change and its impact on China's climate. The results show that: (1) Over the period of 1958-2018, the global oceans and offshore seas in China have warmed significantly, especially since the late 1970s, and warming in offshore China is greater than the global average during the same period, which is mainly due to the interdecadal strengthening of Kuroshio warm water intrusion into offshore China shelf. Under different climate scenarios such as greenhouse gas emissions from low to high (RCP2. 6, 4.5, 8.5), it is very likely that offshore China, especially the East China Sea (ECS) (including the Bohai Sea, Yellow Sea and East China Sea), would become one of the most warming areas in the global oceans. Since the mid-1970s, the sea surface salinities in the ECS and the South China Sea have experienced a decreasing trend. The oceanic circulation in offshore China has changed greatly since the late 1970s, e.g., the interdecadal strengthening intrusion of Kuroshio into the eastern offshore China shelf and the South China Sea through the Luzon Strait, and the decadal weakening of Yellow Sea warm currents and the upper circulation of the South China Sea in winter. (2) Since the beginning of the 20th century, the rate of global sea level rise has been about 1.5 ±0.4 mm yr-1, mainly due to the thermal expansion and the melting of terrestrial glacier ice sheets. Since 2006, the global sea level rise has accelerated significantly, reaching 3. 6 mm yr. The rate of sea level rise along coastal China is 3.4 mm yr between 1980 and the present, which is greater than the global average in the same period. Under different RCP emission scenariosy, sea level will continue to rise, and the current once per century extreme sea level events in coastal areas will occur more frequent. (3) The strong interannual air-sea interaction signal such as El Nino in the tropical Pacific has experienced an interdecadal shift since the 1970s, with a significant stronger and longer duration; particularly, the central El Nino pattern has become more frequent after 1990, with less precipitation and higher temperature in the Yangtze River area in the summer of its developing year, and less precipitation in southern China in the following spring, which is generally contrary to the impact of the eastern El Nino pattern. The projection of El Nino and its impact on China's climate in the future remain uncertain. The interdecadal warming of the Indian Ocean basin has been observed, which could induce frequent high summer temperature in eastern China. Extreme ocean climate events such as super typhoon (hurricane) and Marine Heat Wave (MHW) around the global oceans have become more frequent and stronger since 1911. (4) The distribution patterns of carbon source and sinks, and the long-term changes of ocean acidification in offshore China are still unclear, although offshore China may be a source of atmospheric CO2, which releases about 6 ~9.5 TgC yr-1. Additionally, the Yangtze River Estuary, the Pearl River Estuary, and their adjacent waters have been acidified over the past decades, with long-term reduction of dissolved oxygen concentration. This analysis indicates that sea salinity, oceanic circulation, strong typhoons and MHW as well as the distribution pattern of ocean carbon source and sinks, acidification and dissolved oxygen in offshore China need to be further observed and studied in the future. [ABSTRACT FROM AUTHOR]

Biological invasions seriously threat the global biodiversity and ecosystem health, causing great losses to global environment and economy. However, rapid climate change could significantly affect the diffusion and invasion of alien species. To explore the development situation of biological invasions under climate change could be helpful for better understanding the status and hot spots in this field, and also the benefitial for understanding the invasion mechanism and making effective management measures. In our study, we studied the Web of Science(WOS)database for publications pertaining to the biological invasions under climate change between the years 1990-2016, we then used the Thomson Data Analyzer(TDA)to operate the systematic analysis. We found that there were total 1 736 published papers in recent 27 years. The number of publications increased annually, while it rapidly increased since 2009. This research area related to several subjects such as environmental science and ecology, biodiversity protection, botany, etc. Prof. Chown SL form Monash University had the largest amounts of publications. USA had the maximum total papers, highly cited and high impact factor papers. California University published the most papers among international research institutes, while the Chinese Academy of Science(CAS)ranked the 10th. Biological Invasions was the academic journal which had the largest publications. Recent studies focused primarily on topics related to species distribution models, biodiversity, global warming and risk assessment. China totally published 52 articles, Chinese Academy of Science had the largest amounts of papers, while Institute of Zoology, Wuhan Botanical Garden, Institute of Botany ranking Top 3 among the branch organizations of CAS. In the future, China should give more attentions on the high level research papers and international cooperation of biological invasions under climate change. In addition, we need to focus on prediction and risk assessment of alien species, relationships between biological invasions and biodiversity, system evolution of invaders, relationships among multiple trophic levels of invaded ecosystem, marine biological invasion, influence of invasion on human health, etc under a rapid global climate change. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the spatial and temporal variation characteristics of the potential evapotranspiration (ET0) and its response to climate change using the collected data from the daily weather observation of 23 meteorological stations in the Beijing-Tianjin-Hebei region for 57 years from 1960-2016. The specific parameters of dataset included the daily average air temperature, the maximum and minimum air temperature, relative humidity, wind speed and sunshine hours. We chose the Penman-Monteith formula to calculate the daily ET0 at each site, and then analyzed the spatial and temporal variation characteristics of the calculated ET0. A sensitivity coefficient was used to quantitatively study the sensitivity of ET0 to various meteorological elements and its spatial and temporal distribution. The contribution rate was set to evaluate the influence of meteorological elements changes on the variation of ET0 during the calculation. The results show that: 1) The spatial distribution of ET0 shows a decreasing trend from south to north across the Beijing-Tianjin-Hebei region, except a high ET0 in the central region, such as Tanggu, Huangye and Baoding stations. There was a linear decline rate of -0.92mm /a. e in the whole distribution of ET0. The spatial distribution of ET0 MK (Penman-Monteith) decreased from the northwest to southeast. In temporal characteristics, spring has the most obvious decrease, followed by autumn, summer, and winter. 2) The sensitivity coefficient of ET0 to the average air temperature, sunshine hours, relative humidity and wind speed are 0.26, 0.28, 0.31 and -044, respectively, indicating the most sensitive to the changes of relative humidity in the Beijing-Tianjin-Hebei region, followed by the wind speed and sunshine hours. The sensitivity coefficient of ET0 to meteorological elements presents in a fluctuating trend from1960-2016, the sensitivity coefficient of ET0 to the wind speed and relative humidity in a downward trend, while the sensitivity coefficient of ET0 to average temperature and sunshine hours in an upward trend. The spatial distribution of the sensitivity coefficient from northwest to southeast: the wind speed and average temperature gradually increased, while the sunshine hours and relative humidity gradually decreased. The spatial distribution characteristics of the sensitivity coefficient of ET0 to relative humidity and average temperature were the opposite situation, where the high sensitivity zone of average temperature belongs to the low sensitive zone of relative humidity. The opposite phenomenon also occurred in the spatial distribution characteristics of the sensitivity coefficient of ET0 to sunshine hours and wind speed sensitivity, i.e., the high sensitivity zone of sunshine hours belongs to the low sensitive zone of wind speed. 3) The contribution rate of meteorological elements to ET0 depends on the sensitivity coefficient and the relative change of meteorological elements. ET0 has the most sensitivity to the changes of relative humidity, but the change rate of the relative humidity was small. ET0 has the lower sensitive to the changes of wind speed, but the change rate of the wind speed was large, resulting the most contribution to ET0 in the whole region was the wind speed. However, the stations number of the wind speed as the dominant factor decreased with the measure time, whereas the stations number of the average temperature as the dominant factor increased with the measure time, especially in the period of 2010—2014 to 2010s, 12 stations with the average temperature as the dominant factor. The stations number of the sunshine hours as the dominant factor also increased with the measured time. It infers that the average temperature and sunshine hours have much significant influences on ET0 in recent years. From 2013 to 2016, the correlation coefficients of the winter average air temperature, sunshine hours, relative humidity, wind speed and PM2.5 concentration were -0.44, -0.53, 0.42 and -0.35, respectively, while the correlation coefficients of ET0 and PM2.5 concentration were -0.37. Therefore, it is possible that the haze, especially winter haze, has a certain impact on meteorological elements, and thereby on ET0 in the Beijing-Tianjin-Hebei region. [ABSTRACT FROM AUTHOR]

The West Liaohe River Basin (WLRB) is one of the most sensitive areas to climate change in Chi⁃ na. Here we use the terrestrial water fluxes derived from the Gravity Recovery and Climate Experiment (GRACE) satellites, precipitation dataset, and in situ runoff records, to calculate the actual evapotranspira⁃ tion (ET) in the WLRB based on the water balance equation. We find that during the drought period of 2005-- 2011, the mean annual ET is 350.5 mm, which is 9.8 mm more than the mean annual precipitation during the same time period. This difference can be explained by the groundwater depletion in the WLRB (about 6.8 mm/ a). We also find that the ET products from remote sensing both underestimate the actual ET in the WLRB, compared with the GRACE⁃based ET results. However, the ET simulated by the global land data assimila⁃ tion system version 2.1 (GLDAS⁃2.1) Noah is overestimated. This paper highlights the capability of GRACE to monitor actual ET in the WLRB and to validate different ET products from remote sensing and models. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms underlying drying-wetting cycles and their consequence for vegetation dynamic is important for sustainable eco-environmental development in alpine regions. We investigated these in this paper by taking the Yarlung Zangbo River (YZR) basin in southeast Qinghai-Tibet Plateau as an example. The standardized precipitation evapotranspiration index (SPEI) in the region was calculated using the global land data assimilation system (GLDAS) from 1982 to 2015 to represent the drying-wetting cycles. The spatiotemporal variation of the dry-wet cycles and the responsive vegetation dynamic was investigated using the remotely sensed NDVI (normal difference vegetation index) from GIMMS (global inventory modeling and mapping studies). The results showed that: 1) Spatiotemporal variation of both precipitation and surface air temperature calculated from GLDAS agreed well with the ground-truth data. 2) The spatiotemporal changes in the dry-wet cycles calculated from the SPEI from 1982 to 2015 showed that the YZR basin became increasingly wet from 1982-1999 but changed course in 2000 and has been become increasingly drier since. In particular, the arid areas showed a tendency of wetting whereas the humid areas tended to become drying. 3) The overall vegetation calculated from the NDVI had been in increase from 1982 to 2000 but changed course in 2000 and has been in decline since. In terms of spatial distribution, areas with higher NDVI value represented vegetation degradation, while areas with lower NDVI represented an improvement in vegetation. 4) Approximately 71.83% of the areas saw a positive correlation between the SPEI and NDVI, mainly in the middle and low reaches of the basin which have a high vegetation coverage. Areas showing negative correlation between SPEI and NDVI were small and not statistically significant. The high consistency between spatiotemporal variation of the NDVI and SPEI indicated that the drying-wetting cycles played an important role in vegetation dynamics. 5) The driving forces of the dry-wet cycles were precipitation, surface air temperature, potential evapotranspiration and soil water content, which were consistent with that estimated from SPEI. In addition, the SPEI showed that soil water content was the dominant factor impacting the drying-wetting in 92.17% of the areas in the region. Results of this study have important implications for evaluating water cycles and the associated vegetation dynamics in alpine regions. [ABSTRACT FROM AUTHOR]

Evaluation of the healthy productivity of cultivated land in China, analysis of key problems of different regions that endangers cultivated land health is of great significance to explore sustainable cultivated land utilization path and safeguard national food security and ecological security. The evaluation of cultivated land healthy productivity should be executed base on integration of existing evaluation indicators system and evaluation method achievements and clarification of key factor states and driving processes that affecting cultivated land health from the perspective of cultivated land components. And interaction characteristics between cultivated land health and cultivated land productivity should be analyzed by coupling them with each other. In this paper, we selected 65 counties (cities) nationwide as research regions with considering the difference of climate conditions in different regions of China, and used 5 categories of indicators including topographic characteristics, soil properties, tillage conditions, environmental conditions and biological characteristics to present the cultivated land health status. And on that basis, we defined critical health threshold and critical sub-health threshold of different indicators by analyzing counties’ indicator standard deviation convergence characteristics and scoring rules. We divided all pilot counties into three statuses: Health, sub-health and unhealth, and analyzed spatial distribution features of counties with different health status. Furthermore, regional climate conditions indicator, cultivated land natural conditions indicator and tillage technique level indicator had been synthetically integrated to evaluate the productivity of cultivated land, and regional cultivated land health-productivity interaction characteristic had been analyzed. Experimental result showed that counties whose cultivated land in sub-healthy or unhealthy status expressed significant regional features, and the key factors of limiting cultivated land health were different among pilot counties. On the one hand, the sub-health status cases caused by inferior farming conditions indicator were more common (accounting for nearly 40% of pilot counties) than other indicators, which was not only manifested by serious fragmentation of cultivated land and imperfect farmland infrastructure, but also reflected the urgent requirement for promoting high-standard farmland construction. On the other hand, the form of biological characteristics was severe, indicating that under the interaction of climatic conditions, soil structure and tillage technology, the ability of cultivated land to guarantee the healthy growth of animals was facing degradation. Furthermore, through coupling analysis of cultivated land health and cultivated land productivity, we divided the cultivated land healthy productivity characteristics of pilot counties into six categories: “health-high productivity”, “health-low productivity”, “sub-health-high productivity”, “sub-health-low productivity”, “unhealth-high productivity” and “unhealth-low productivity”, and respectively analyzed the regional farmland protection directions for each category. “Sub-health/unhealth-high productivity” type was widely distributed, which was the core region for implementation of “storing grain on land and storing grain in technology” strategy in China. Therefore, it is necessary to give consideration to the health and productivity of cultivated land in this region, and strengthen the research and practice on methods to improve the health of cultivated land. This study provides scientific basis for improving cultivated land healthy productivity and provides effective support for designing protection paths of cultivated land resources in different regions. [ABSTRACT FROM AUTHOR]

Drought has become a problem that is universally faced by global terrestrial ecosystems. Northeast China is dominated by a temperate monsoon climate and located in an area sensitive to global climate changes, and one of the main impacts of climate changes in Northeast China is manifested as drought in growing seasons. The drought area has a gradual increase trend, and drought has become the main agro-meteorological disaster in this region which is also the main maize planting area in China. Drought normalization seriously restricts the stable development of maize production in Northeast China. So in this paper, we took spring maize in Liaoning Province as an example and made clear the drought variation characteristics in different growth stages by using the data of MODIS, FY-3A, relative soil moisture and growth stages and the methods of RS, GIS and statistical analysis. Then we analyzed the correlation between multi-time scale remote sensing indexes and relative soil moisture in different soil depth, and established the remote sensing monitoring index set and models of relative soil moisture for each growth stage and soil depth. The accuracy of the monitoring models was verified and the application research of monitoring the drought of spring maize in Liaoning Province was studied. The results showed that: From 1993 to 2012, drought occurred in each growth stage of spring maize in Liaoning Province and the highly frequent drought occurred in the period from 1999 to 2002. The drought grade in each year was mainly light drought, and the drought was the most serious at milk stage, followed by heading stage. There was no significant correlation between the monitoring indexes and relative soil moisture at sowing and emergence stage, but there was a significant or extremely significant correlation between them at three-leaf and maturity stage. The monitoring index LSWI (land surface water index) had a strong ability to monitor relative soil moisture, followed by WI (water index). Multi-index coordination could improve the monitoring ability of relative soil moisture by remote sensing means, and the monitoring ability at 10-day scale was generally higher than that at 5-day scale and 20-day scale. Based on the monitoring models of soil relative humidity, the drought condition of partial growth stages and soil depth from 2001 to 2004 was monitored. The overall monitoring accuracy was 73.32%, in which the monitoring accuracy of jointing and three-leaf stage was more than 85%. The dynamic monitoring of drought grades in different growth stages in 2000 was realized. The monitoring results were consistent with the agro-meteorological observation records in terms of the growth stages and space. This study would be very significant to improve the capacity of disaster prevention and mitigation by monitoring spring maize accurately and synchronously on a large range. [ABSTRACT FROM AUTHOR]

Evaluation of the healthy productivity of cultivated land in China, analysis of key problems of different regions that endangers cultivated land health is of great significance to explore sustainable cultivated land utilization path and safeguard national food security and ecological security. The evaluation of cultivated land healthy productivity should be executed base on integration of existing evaluation indicators system and evaluation method achievements and clarification of key factor states and driving processes that affecting cultivated land health from the perspective of cultivated land components. And interaction characteristics between cultivated land health and cultivated land productivity should be analyzed by coupling them with each other. In this paper, we selected 65 counties (cities) nationwide as research regions with considering the difference of climate conditions in different regions of China, and used 5 categories of indicators including topographic characteristics, soil properties, tillage conditions, environmental conditions and biological characteristics to present the cultivated land health status. And on that basis, we defined critical health threshold and critical sub-health threshold of different indicators by analyzing counties’ indicator standard deviation convergence characteristics and scoring rules. We divided all pilot counties into three statuses: Health, sub-health and unhealth, and analyzed spatial distribution features of counties with different health status. Furthermore, regional climate conditions indicator, cultivated land natural conditions indicator and tillage technique level indicator had been synthetically integrated to evaluate the productivity of cultivated land, and regional cultivated land health-productivity interaction characteristic had been analyzed. Experimental result showed that counties whose cultivated land in sub-healthy or unhealthy status expressed significant regional features, and the key factors of limiting cultivated land health were different among pilot counties. On the one hand, the sub-health status cases caused by inferior farming conditions indicator were more common (accounting for nearly 40% of pilot counties) than other indicators, which was not only manifested by serious fragmentation of cultivated land and imperfect farmland infrastructure, but also reflected the urgent requirement for promoting high-standard farmland construction. On the other hand, the form of biological characteristics was severe, indicating that under the interaction of climatic conditions, soil structure and tillage technology, the ability of cultivated land to guarantee the healthy growth of animals was facing degradation. Furthermore, through coupling analysis of cultivated land health and cultivated land productivity, we divided the cultivated land healthy productivity characteristics of pilot counties into six categories: “health-high productivity”, “health-low productivity”, “sub-health-high productivity”, “sub-health-low productivity”, “ill-health-high productivity” and “ill health-low productivity”, and respectively analyzed the regional farmland protection directions for each category. “Sub-health/ill-health-high productivity” type was widely distributed, which was the core region for implementation of “storing grain on land and storing grain in technology” strategy in China. Therefore, it is necessary to give consideration to the health and productivity of cultivated land in this region, and strengthen the research and practice on methods to improve the health of cultivated land. This study provides scientific basis for improving cultivated land healthy productivity and provides effective support for designing protection paths of cultivated land resources in different regions. [ABSTRACT FROM AUTHOR]

Atmospheric carbon dioxide( CO2) enrichment constitutes as one of the primary components of human-induced global change, significantly shaping soil carbon( C)and nitrogen( N)biogeochemieal cycles. Plant photosynthesis and growth are expected to increase under elevated atmospheric CO2 and ultimately promote the enhancement of soil Cstorage. On the other hand, soil C input enhanced by elevated atmospheric CO2 may also increase soil CO2 emissions, stimulating some soil Orelease back to the atmosphere. However, to what extent the capacity of terrestrial ecosystems acting as a sink under elevated CO2may be offset by the enhancement of soil source strength of greenhouse gases( GHG) emissions remains largely uncertain. Hence, a deep insight into the response and feedback of terrestrial C and N cycling to elevated CO2 would be of great importance for quantifying the terrestrial and soil C sequestration potential under global change scenarios. This paper fully reviewed the mechanisms and controls on terrestrial C and N cycling response to elevated CO2. We found that elevated CO2 significantly increased the accumulation of plant biomass C, production and release of soil GHG, and soil C and N pools, while decreased the supply of soil labile N. Klevated CO2 decreased upland uptake of CH4. Klevated CO2-enhanced emission source of soil GHG to the atmosphere completely offset the soil C sink capacity, and also more than half of the terrestrial C sequestration potent ial, which showed a declining trend with CO2 enrichment levels. Meanwhile, we proposed the potential h iotie and abiotie faetors influencing soil GHG exchanges between terrestrial ecosystems and atmosphere under enriched C02. This review would provide an important theoretical basis for estimation of terrestrial carbor i balance. [ABSTRACT FROM AUTHOR]

The greenhouse climate model has the characteristics of nonlinearity, strong disturbance and time variance. The commonly used methods to deal with the complex model are to linearize the original nonlinear models or to do some offline identification research. Without considering the complex characteristics completely, the usual modeling methods cannot predict the greenhouse climate dynamic behaviour effectively. In this paper, on account of the complex characteristics of greenhouse climate system, taking the temperature model as the example, the continuous-discrete recursive error algorithm was used to identify combined parameter and state online. Firstly, describe the greenhouse temperature model. The greenhouse temperature is affected by the heat load imposed on the greenhouse by the sun, the energy lost to the external air because of transmission through the greenhouse cover, the heat transfer between the internal air and soil, the heat loss by crop transpiration, the heat lost through natural ventilation of the roof windows and the energy supply from the heating system. In all of the model parameters, due to the fact that external solar radiation has a great effect on greenhouse temperature, radiation conversion factor changes over time and the parameters related to heating and ventilation are fundamental but difficult to obtain, this paper attempted to estimate and update 5 key parameters online. Secondly, continuous-discrete recursive prediction error algorithm to estimate combined parameters and states online was developed. This algorithm is appropriate for a continuous-discrete system, which is defined as a dynamic system with a continuous state function, and the observation function is discrete. The algorithm estimates the parameters and states by minimizing the error sum of squares between predicted values and measured values, which is usual in this technology. Compared with other traditional estimation algorithm such as the extended Kalman filter, the big difference of the algorithm is that there is no need to set the initial value of system noise precisely. It defines the system noise in real time by introducing an extra parameter as gain matrix and estimating it online. The algorithm adjusts the system noise to match the model predicted values and actual values by regulating the gain matrix. As estimating the system noise for the greenhouse temperature system beforehand is extremely difficult, the advantage of the proposed algorithm enhances the feasibility of its application in practice. At last, in order to test the developed algorithm, the model identification results were compared between the continuous-discrete recursive prediction error algorithm and the extended Kalman filter in MATLAB. The simulation was based on the measured data containing outside temperature, outside solar radiation, control inputs and temperature of an experiment greenhouse. The results showed that the proposed algorithm could lead to a higher model fit value of 93.7% compared with 89.5% of the extended Kalman filter. The gain matrix varied from zero to non-zero, and it nearly maintained stable at a non-zero constant in the end of each test day. The changing process indicated that there were errors between the model predicted value and the measured value in the initial, and the errors could be compensated by regulating the gain matrix. The different values of gain matrix in 2 days showed that system noise may vary largely in different condition and it should not be set as a constant. From the simulation results and the data analysis, it can be known that the proposed continuous-discrete recursive prediction error algorithm can estimate the temperature well and improve the model accuracy and validity. [ABSTRACT FROM AUTHOR]

Based on CROPWAT, ArcGIS and Matlab, this paper analyzed spatial-temporal distribution of water footprint for winter wheat and summer maize in Haihe River basin during the period of 1990-2014, simulated the yield under climate change during 2020-2050 and explored contributions of meteorological factors to water footprint. The main results show that, a) the blue water footprint and green water foot-print occupy 36.2% and 63.8% of the water footprint of summer maize respectively, while blue water footprint and green water footprint occupy 77.5% and 22.5% in the water footprint of winter wheat respectively. The high value of blue and green water footprint for winter wheat and summer maize appear in the northwest and middle east of the region, while high value of the total water footprint appears in the middle and southeast of the region； b) there is little difference between spatial distribution of blue and green water footprint in the period of 2020-2050 and the period of 1990-2014. There exists decrease and increase of the water footprint of for summer maize and winter wheat respectively. The total water footprints of these two crops show substantial increase during 2020-2050. [ABSTRACT FROM AUTHOR]

Over the past hundred years, remarkable changes occurred around global climate. Two significant characteristics of climate changes are temperature mutation and warming hiatus, which led to a variety of extreme climate events of all scales, such as in the north of China. Therefore, revealing the features and rules of temperature mutation and warming hiatus in northern China could provide some basis to deeply understand climate changes, prevent and mitigate disasters as well as improve ecological environment in northern China and in the whole world. Based on the seasonal (monthly) average minimum temperature, average temperature and average maximum temperature data at 357 meteorological stations in northern China and surrounding areas during 1951-2014, this paper analyzes the spatio- temporal variation of three types of seasonal temperature (the average minimum temperature, average temperature and average maximum temperature) mutation and warming hiatus over northern China by using Mann-Kendall test, slide t test and other methods. The results indicate: according to the average minimum temperature, average temperature and average maximum temperature, the abrupt change of temperature and warming hiatus became late and the cycle from abrupt change to warming hiatus became short as the latitude reduces. In spring and winter, the temperature mutation and warming hiatus in the Northeast China were the earliest (1970s- 1980s, 1993- 2002), in North China were the second and in the Northwest China were the latest (1990s-2000s, 1996- 2010). While in summer and autumn, the temperature mutation and warming hiatus in North China were the earliest, in Northeast China were the second and in Northwest China were the latest (1990s- 2010s). There was little distinction among areas in warming hiatus year. Meteorological stations with no mutation and no hiatus were centralized in mountainous regions, high- latitude areas and southern part of North China Plain where the surrounding areas were relatively late in mutation and warming hiatus. The mutations and warming hiatus of same kinds of temperature became late in the order of winter (1981- 1990), spring, autumn and summer (1994-2008) and winter (1995-2008), autumn, summer and spring (1998-2010). The cycle from temperature mutated to warming hiatus became short in the sequence of winter, spring, autumn and summer, during which the average minimum temperature period was the longest in winter (9- 24 a). The average minimum temperature mutated earliest in spring, summer and winter, which occurred during 1972-1999, 1987-1999 and 1971-2000, the average temperature was the second to mutate, while the average maximum temperature was the latest to mutate which occurred during 1975- 2008, 1994- 2008, 1972- 2006. However, in autumn, the mutation of the average temperature was the earliest (1982-2001), the mutation of the lowest average temperature was the second, and the mutation of the highest average temperature was the latest (1987-2001). The warming hiatus of the average minimum temperature, average temperature and average maximum temperature in spring and summer became late successively, which were during 1994- 2008, 1997-2008 and 1997-2010, respectively, while the sequence was opposite in autumn and winter. The lengths of periods from temperature mutation to warming hiatus in each season in order were that of the average minimum temperature (9-18 a), that of the average temperature and that of the average maximum temperature (5- 12 a). In particular, the three kinds of temperatures all mutated earliest in the southern of North China in summer, which is inconsistent with the rule in the whole area that the mutation became late as latitude decreases, and the temperature at most stations in this area did not mutate, which is also inconsistent with the general rule in the whole area. [ABSTRACT FROM AUTHOR]