从第三极到北极： 热喀斯特及其对碳循环影响研究进展

北半球多年冻土区储存着大量的土壤有机碳, 气候变暖加剧了多年冻土退化, 多年冻土退化最明显的特征是热喀斯特。热喀斯特会直接导致活动层及多年冻土层土壤有机质暴露, 并改变水文、 植被和土壤生物环境条件, 对生态系统碳循环具有重要影响。热喀斯特对碳循环的影响是评估多年冻土碳循环和气候变化关系不确定性的关键问题之一。然而, 在气候变暖背景下热喀斯特地貌的发育及其对碳循环影响有多大, 目前对这个问题仍然缺乏足够的认识。通过综合比较第三极和北极热喀斯特相关研究, 分析了第三极和北极地区热喀斯特地貌特征及其变化趋势, 阐述了热喀斯特对植被演替、 土壤碳损失和生态系统温室气体排放过程的影响, 并提出了未来热喀斯特研究可能遇到的挑战。认识热喀斯特碳循环过程, 是评估气候变化对多年冻土碳循环影响的关键环节, 有助于加强多年冻土区生态系统碳循环与气候变暖之间反馈关系的认知。     

气候变暖对多年冻土区土壤有机碳库的影响

多年冻土区存储了大量土壤有机碳。气候变暖、 多年冻土退化导致其长期封存的有机碳逐渐或快速释放, 进入大气圈或水系统, 改变原有多年冻土区碳循环, 并可能显著加速气候变暖。通过综述气候变暖对多年冻土区碳库的影响研究进展, 主要包括多年冻土碳库储量、 降解机理及变化预测, 研究表明： 北半球多年冻土区的碳储量巨大, 但不确定性很高, 尤其是海底多年冻土和水合物碳库储量的评估; 多年冻土碳库对气候变暖的响应速度受土壤水热特性、 土壤有机质C/N比、 有机碳含量和微生物群落特征等多种环境因素的控制或影响; 目前, 关于北半球多年冻土碳库对气候变暖响应模拟结果说明, 多年冻土退化短期内不会导致经济和生产方面的灾难性后果。但是, 无论是针对多年冻土碳库评估, 还是多年冻土有机碳库对气候变暖的响应模拟研究结果, 都有较大的不确定性。未来多年冻土碳库变化的模拟和预测研究应更多考虑多年冻土快速退化和多年冻土区水合物分解, 如中小尺度热喀斯特的生态环境和碳的源汇效应。准确的多年冻土区有机碳排放模拟可为未来多年冻土碳与气候反馈的预估提供重要支持。     

21世纪初极端天气气候事件研究进展

由于极端天气气候事件的严重影响，越来越多的研究开始关注其变化情况。从观测分析到模拟研究，几乎都发现极端气温、降水事件发生了显著变化，而且在全球变暖的大背景下，未来有些极端事件可能会发生频数更高或强度更强。当然，研究结论也存在一定程度的不确定性，从模式模拟来看，目前模拟结果仍存在不确定性，不同模式的结果间常常存在较大的差异；而从观测分析来看，研究主要局限于20世纪后半叶，如果对更长时间作分析，结论或许会有所不同。文章从最基本的极端天气气候事件的定义出发，结合观测事实和模拟研究两个主要方面来介绍近几年来极端事件研究取得的主要进展，最后简单地总结了这些进展，并提出了进一步研究的思路。      

国际南极冰盖与海平面变化研究述评

海平面上升是全球变暖的主要后果之一。尽管有少数冰川学家认为,气候变暖并不能确保雪积累量的显著增加,同时可能出现冰流的突然变化,因此南极冰盖在未来海平面变化中的作用存在很大的不确定性。但近几十年来南极半岛气温的急剧上升,已使大量的冰架崩解。冰架崩解并不对海平面产生真正的影响,但反映出南极洲气候与冰川存在急剧变化的可能。     

火山活动的气候影响及其冰芯记录研究进展

系统地总结了不同时间尺度内火山活动影响气候的机理,回顾了不同区域冰芯记录火山喷发物质沉积信号的研究历史,阐述了不同气候模式对火山活动影响气候的数值模拟结果,并指出了相关研究中存在的不确定性.结果表明:火山活动通过释放大量的火山物质气溶胶影响气候波动,在年际至年代际时间尺度上,这种影响是显著的;然而,在更长的时间尺度上这种影响是否仍然存在,尚需更多研究的证实.冰芯中火山喷发物质沉积记录为研究历史时期火山活动及其气候影响提供了必要的参考资料,相关的气候模式利用该沉积记录较好地模拟了火山活动对区域乃至全球尺度气候的影响,为我们认识火山活动影响气候变化的机理提供了重要的理论支持,同时也为研究未来火山活动对气候的可能影响提供了参照.但是,冰芯中火山喷发物质沉积记录研究及数值模式模拟结果中尚存在诸多的问题和不确定性.     

全球气候变化的几个关键问题辨析

基于对全球气候变化事实与国家气候变化行动的分析,就当前全球气候变化科学认识和行动中的几个关键问题的不同观点与争论进行了辨析。指出：①应以比较确定的科学事实和“共同但有区别的责任”作为应对气候变化的出发点;②全球增温的幅度被高估了;③近百年全球变暖主要归因于人类活动的论断科学证据不足;④全球变暖的影响有利有弊,具体问题需具体分析;⑤气候预估不等于气候预测,气候预测尚待时日,气候预估的不确定性也非常大;⑥当前应对全球变暖的行动应采取“适应为主、减缓为辅”的战略。     

气候变暖对湖泊热力及溶解氧分层影响研究进展

气候变暖对湖泊物理、化学、生物和生态系统有着复杂而深刻的直接和间接影响,而具体影响随研究区域和水体表现不尽相同。气候变暖通过改变湖泊热力和溶解氧分层进而影响湖泊生物过程和生态系统结构与功能。从全球湖泊变暖趋势、长期缓慢气温上升、极端高温事件以及气候情景模拟等方面详细综述了气候变暖对湖泊热力及溶解氧分层影响的研究进展。研究表明,全球不同区域湖泊均存在不同程度的变暖趋势;长期缓慢气温上升和短期极端高温均会造成湖泊热力分层提前,分层结束推迟,分层时间延长,混合层和温跃层深度下降,以及热稳定性增加;相伴随的是溶解氧扩散深度和氧跃层深度明显下降,加剧了湖泊底部好氧和厌氧环境。除了这种直接影响外,气候变暖引起的流域降水、入湖物质的变化以及风速的变化也会对湖泊热力和溶解氧分层产生许多间接的影响,因此未来仍然需要更多的实验证据、经验和数值模型来验证和预测气候变暖对湖泊热力及溶解氧分层的影响。     

融水径流分割研究回顾及展望

全球气候变暖引起雪冰（积雪/冰川）消融、冻土退化,融水径流量显著增加。不同融水径流分割方法可以量化河流径流的融水比例,反映高寒区雪冰变化及其对气候变暖的响应。评述了不同径流分割方法的原理及其优缺点,并着重介绍了同位素/化学径流分割的计算方法及示踪剂选择。对比分析各研究流域融水径流分割结果,详细讨论影响融水径流变化的主要因素。针对同位素径流分割方法的理想化假设,提出了量化不确定性的的拓展研究。最后,阐述了随着高频采样技术的完善,同位素径流分割研究的发展前景。     

青藏高原气候变化若干前沿科学问题

在全球变化的背景下,青藏高原冰冻圈和大气圈正在发生快速变化,对“亚洲水塔”和“第三极”的生态环境带来深刻影响。研究并梳理了近年来青藏高原气候变化的若干前沿科学问题的研究进展,如高原极端气候事件变化及其与大气环流的关系;高原变暖放大效应及海拔依赖型变暖的物理机制;再分析资料在高原气候变化应用的适用性;气候模式在高原资料稀缺地区的模拟偏差特征及不确定性;以及不同升温阈值下高原气候变化的预估及其风险等。同时展望了高原气候变化研究的前沿问题和科学难点。认清高原气候变化研究的前沿科学问题,可为“一带一路”倡议顺利实施提供科学依据。     

全球变暖“停滞”现象辨识与机理研究

观测表明全球温室气体浓度持续快速增加,但21世纪以来全球表面平均温度升高有减缓趋势,呈现变暖"停滞"现象,这对已有的全球变暖认识带来挑战。围绕"变暖‘停滞’机理及其可预测性"这一国际前沿科学问题,国家重点研发计划"全球变暖‘停滞’现象辨识与机理研究"主要研究内容有:1辨识变暖"停滞"的时空特征,阐明外部强迫和内部自然变率的相对贡献;2阐明全球变暖停滞背景下,大气在气候系统能量热量再分配过程中的作用及机理;3阐明全球变暖"停滞"背景下,海洋动力热力过程对能量热量再分配的调制机理;4探讨全球变暖"停滞"现象的可预测性,对其未来变化及重要区域气候影响进行预测预估。以期通过变暖"停滞"研究回答人们所关心的目前变暖停滞现象未来发展及其对我国及周边的"一带一路"核心区和南北极重要区域的影响,为我国未来气候政策的制定提供参考依据,为国家参与全球气候治理及国际气候谈判提供科学支撑。     

Impact of climate change on hydrological conditions of Rhine and Upper Danube rivers based on the results of regional climate and hydrological models

The main objective of the Effects of Climate Change On the Inland waterway Networks (ECCONET) EU FP7 project was to assess the effect of climate change on the inland waterway transport network with special emphasis on the Rhine and Upper Danube catchments. The assessment was based on consolidation and analysis of earlier and existing research work as well as application of existing climate change and hydrological modelling tools. A key premise at the planning stage of the project had been that all impact studies conducted within ECCONET should be comparable with each other. This can be guaranteed by the common meteorological and hydrological basis. The climate model simulations, which are the most physics- and process-oriented tools for projecting the future climate evolution, include several uncertainties. In addition, uncertainties exist in the hydrological model simulations. In ECCONET, an effort was made to quantify the uncertainty range by using “representative projections” that represent both the lower and upper signals of hydrological low-flow parameters for 2021–2050 over the Rhine catchment. Their evaluation indicated that the finally chosen two regional climate model simulations could be applied also for the Upper Danube catchments as representative projections. The raw climate model outputs have been corrected to the observation data set through application of the linear scaling and the delta-change method. The first impact studies carried out after validation of the hydrological models resulted in discharge scenarios used as input to the economic models in ECCONET.     

气候变化对江河流量变化趋势影响研究进展

气候变化对基于自然稳定气候假定的流量变化趋势的检测和水资源评价方法提出了挑战。在流量变化趋势的检测中分离出气候变化的影响,不仅对水资源管理和水利工程设计有重要的应用价值,而且有助于了解气候变化以何种方式、在何时、何地、已经或尚未对水文循环产生影响,对改进气候模型的模拟与预测有重要的科学价值。 统计方法是检验流量变化趋势显著性的有效工具。直接用气候模型模拟和预测未来径流变化的可靠性取决于模型对当代降水模拟的可信度。多个气候模型集合分析有可能在一定程度上减少模型对降水、径流模拟的不确定性。近年发展起来的多个气候模型集合分析与统计显著性检验技术结合的方法,有可能模拟并预测出气候强迫导致大尺度径流空间分布的变化。随着气候模型尤其是陆—气耦合的区域气候模型对降水模拟的改进,可以预见径流变化的检测、归因和预测的趋同化模拟已为期不远。将温室气体外强迫导致的水文气候变化作为一个因子引入到水资源评价中,对于水资源管理经济与生态评估,以及未来的发展规划将是一件十分重要的变革。      

Visualization of Climate Change and Economic Research Hotspots:Integrating Cited References and Burst Keywords

The study of the economic impact of climate change has received extensive attention from governments and scholars around the world. This paper based on 14 796 literatures that related to climate change and economic from the core database of Web of Science. Integrating the method of co-citation network and burst keywords co-occurrence network to analyze the temporal and spatial changes of research hotspots on climate change and economic impact. The results show that the global literature's number keep a exponential growth trend, rapidly after 2007. Before 2007, the research hotspots primarily centered on the climate change attribution analysis (increased CO₂ emissions from fossil fuels, land use changes, etc.), the impact on natural ecosystems (agricultural production, food security, Arctic ice caps, coastal zones, etc.) and socio-economic System (human health, energy, industry, etc.), and the assessment of economic impac and then focused on the future scenarios of climate change and CO₂ abatement and how to adapt and mitigate the climate change. After 2007, with the introduction of IPCC AR4 and Stern report, further strengthened the research on cost-effective assessment of climate change impact, vulnerability, bioenergy and so on. The research hotspots focus on economics of climate change and trade. In space, the literatures of research hotspots were mainly come from the United States, Canada, Western European countries (UK, France, Germany, Italy, Netherlands), Australia and China.     

全球变化及其相关科学概念的发展与比较

在回顾全球变化科学产生和发展历史的基础上,针对当前全球变化、全球气候变化、全球环境变化、地球系统科学在概念和内涵上存在混淆的情况,就全球变化等概念的内涵、产生的过程及其联系进行了综述、分析和比较。提出全球变化是指对人类现在和未来生存与发展有重要的直接或潜在影响、由自然因素或人类因素驱动在全球范围内所发生的地球环境的变化,或与全球环境有重要关联的区域环境的变化。气候变化和全球环境变化的研究范畴包含在全球变化之中,但又各有其关注领域和交叉部分;而地球系统科学是解决全球变化问题的科学理念、思维方式和解决方案。]     

Field Survey and Research Approaches at Apine Treelines

A tree line, as the altitudinal or latitudinal limit of erect trees, is considered as a sensitive ecological indicator of climate change, and becomes one of the hot issues in the studies of global change ecology. During the last decade, rapid progress has been made in tree line studies. However, field survey and research methods may vary significantly among tree line literatures, limiting the evaluation of mountainous forest response and feedback to climate change at regional or global scale. Herein, we reviewed the research progress regarding the field survey and research methods on tree lines, evaluated the advantages and disadvantages of each method, and pointed out the current research frontiers. Field survey and research methods in tree line literatures mainly include: Repeat landscape photography, remote sensing image analysis, land line transect method, circular sampling plot, rectangular or square sampling plot, spatial point pattern analysis, tree line dynamic model, controlled experiment, and transplant experiment. Repeat landscape photography and remote sensing image analysis can provide an intuitive reference for treeline dyanmics, but some uncertainties remain. Compared with selective sampling approach (e.g., line transect method, circular sampling plot and square small plot), sample-total method (rectangular large plots including the whole tree line ecotone, i.e., encompassing the current timberline and the tree line) provides more robust results regarding tree line structure and shifts. Spatial point pattern analysis has been used to establish the linkage between the ecological patterns and processes of the tree line ecotone. Tree line dynamic models can be used to reveal temporal patterns of position and structure of tree line ecotones and their driving mechanisms. Controlled or transplant experiment has advantages in exploring the critical drivers of tree line dynamics. In future studies, sample-total method and its protocol are recommended when exploring variations in structure and position of tree lines; regular monitoring of fixed large tree line plot is worth carrying out; controlled or transplant experiment can be set up at diverse tree lines across a regional scale; researchers should attempt to develop new tree line dynamic models with good transplantation capability.     

A Profile of International Climate Change Science in the Past One Hundred Years*

Climate change is one of the most active research fields currently, which has attracted extensive attention from the international community. In order to better understand the development situation and research status of international climate change science, in this paper we took the SSCI and SCI databases as data sources, collected the relevant literatures since 1900 based on the key words related to climate change, and made some statistics and analysis of the literatures of the past one hundred years to reveal the development process of climate change research as well as the development and evolution of its research topics and hot spots. The results showed that the climate change research began in the late 18 th century and early 19 th century, and the academic debate about global warming and global cooling started in the early 1970s. The international programs and projects led by a range of international organizations and intergovernmental bodies have contributed significantly to the rapid development of climate change research. The United States and the United Kingdom have long been the core countries of climate change research. The proportion of Chinese papers has risen rapidly in the last decade. The intensity and scope of scientific research cooperation are constantly expanding. Current research focuses on climate model/modeling, climate simulation, climate policy, climate sensitivity, climate change impacts, climate change adaptation, climate change mitigation, and rate of climate change.     

Analysis of indices of extreme temperature events at Apizaco,Tlaxcala, Mexico: 1952-2003

In recent years in Mexico and around the world, the scientific community has shown great interest in acquiring knowledge regarding the behavior of extreme climate events due to their increasing number and intensity. The objective of this research was to analyze variations in extreme temperature events using extreme climate indices. We conducted a case study for the municipality of Apizaco, Tlaxcala, Mexico, using data sets of the daily maximum and minimum temperatures for the period from 1952 to 2003. Six indices related to maximum and minimum temperatures were calculated: frost days, summer days, warm days, cool days, warm nights and cool nights. All of the index results were evaluated annually and only four of the indices were analyzed according to the seasons. A trend based on a linear least squares regression model was fit to the indices to determine their behavior. The index results showed that extreme events related to maximum temperatures corresponded to greater changes and an increased number of summer days and decreased cool days. Additionally, there was an increase of frost days, associated with a greater number of days with minimum temperatures below 0 °C. In general, the results indicated that warmer and colder extreme temperatures are occurring. The detection of those trends in the extreme events can be seen as a first step in any study of the attribution of those observed changes (e.g., land use change, regional climate change, etc.). This attribution aspect will not be discussed in the present study.     

Integrative Modeling and Strategic Planning for Regional Sustainability under Climate Change

Climate change and land use/land cover change have resulted in water shortage, degraded ecosystem services, and increased disaster risks across the world. Developing strategies and measures for achieving regional and global sustainability in the face of these environmental problems is a key topic of current climate change research. This paper provides an overview of the 973 project, entitled “Integrative Modeling and Strategic Planning for Regional Sustainability under Climate Change”, including its background, relative progresses, key scientific questions, major research elements, methodology, and expected outcomes. The proposed research is based on sustainability science, guided by the idea of Orderly Human Activities (OHA), and implemented through an integrated methodology of combining field observations, simulation experiments, and scenario analysis. The main objectives of the project are: to quantify the relationship between human activities and climate change, to assess the impacts of human activities on ecosystem services and human well being in the face of climate change, and to develop an integrated model of climate change, OHA, and regional sustainable development. The ultimate goal is to provide a landscape/regional-scale strategy for sustainable development in the face of climate change. The project is expected to help advance the science and application of landscape sustainability science and land system design, particularly in terms of linking climate change, ecosystem services, and human well-being in the dry land region of China.     

成都平原中—晚全新世环境考古研究进展*

自20世纪80年代以来,成都平原环境考古工作在聚落选址与地理环境、古气候与古蜀文明发展、灾变事件研究及史前人地关系综合研究等方面取得重要进展。研究表明: 成都平原史前城址群的出现与当时的地理环境应有很大关系;成都平原中—晚全新世以来气候整体温暖湿润,其中有多次气候波动和降温事件发生;古洪水、古地震等自然灾害与古蜀文明发展的关系很密切;基于成都平原诸多先秦遗址的人地关系综合研究表明,河流、地貌、气候等因素与史前聚落变迁有很大关系。总体上,成都平原环境考古工作经历了3个发展阶段。受限于研究材料和方法,目前仍然缺乏高分辨率古环境演变规律的研究成果;自然灾害与成都平原先秦时期古文化演变的一些重要节点的耦合关系仍不明确;今后还需要加强与河流地貌有关的聚落环境考古研究;利用地理信息系统和遥感技术分析环境变迁与人类活动关系以及定量和模型化研究史前人地关系也将是未来成都平原环境考古工作的重要内容。     

气候变化适应对策的评价方法和工具

气候变化影响和适应对策方法评估的研究目的主要是建立和应用先进有效的分析工具和评价方法对气候变化脆弱性和适应对策进行科学评估. 因此需要了解当前已经在自然资源和环境研究中广泛使用的决策分析工具,掌握和了解各种适应对策评估工具的关键特性及其优缺点. 首先介绍各种有关适应对策的定义及两大类适应评估方法途径, 同时举例介绍不同方法在气候变化影响和适应评估研究中的应用. 常规的适应对策评估分析主要以政府间气候变化专业委员会(IPCC)气候变化影响和适应对策评估技术指南中的方法工具为代表, 另一种适应对策研究则致力于改善各种对气候变化敏感系统的适应能力和复原能力. 文中对各种适应对策评估方法和工具进行了介绍和讨论,并提出气候变化适应研究的新方向.