Klimaänderung—Was weiß die Wissenschaft?

In the Intergovernmental Panel for Climate Change (IPCC), scientists worldwide are working on a holistic view of climate development. This accommodates highly complex interactions between natural occurrences, their effects and human activity as far as possible. Uncertainties are expressed in terms of confidence levels. The Third Assessment Report presents the following cases: Human activities have generally increased the atmospheric concentrations of green-house gases and their radiative forcings during the 20^th century. The resulting radiative forcing is positive (warming) with a small uncertainty range; that from the direct aerosol effects is negative (cooling) and smaller; whereas the negative forcing from the indirect effects of aerosols (clouds and water cycle) might be large but is not well quantified. An increasing body of observations gives a collective picture of a warming earth and other changes in the climate system. Observed changes in regional climate during the past 50 years have affected biological and hydrological systems in many parts of the world. There are preliminary indications that social and economic systems have also been affected. Local, regional and global environmental problems are often interlinked in ways that, in total, affect the sustainable satisfaction of human needs. The Projections of all SRES scenarios show an increase of the globally averaged surface temperature within the 21^st century at a rate which is very likely to be without precedent during at least the last 10,000 years, based on paleoclimate data. Adaptation is a necessary strategy at all scales to complement climate change mitigation efforts. Together they can contribute to sustainable development objectives.     

热带增宽及其对中国东部亚热带森林植被的影响

全球气候变暖已是不争的事实,现今气候变暖的趋势已由每百年（1901--2000）增加0．6℃的记录升高为0．74℃（1906—2005）。其中高纬度地区增温特别显著,成为世界关注的热点。与之对比,热带地区的气候变化以及热带森林对它的反应报道甚少。事实上,自1970s中期以来,热带温度是每lO年升高0．26oC;同时气候模型预测到本世纪末热带地区温度将上升2．1-4．5℃。这些预测是有根据的,但究竟不是直接的证据。因此,本文综合了许多专家对热带地球物理学和大气层特性的多年观测、分析和研究的成果,其结论认为：至少自1979年以来许多热带大气层固有的特征发生变化并向地球极地推进和位移,这些根据是：（1）热带高空的哈德利环流增强并向极地扩展;（21位于热带边缘的亚热带射流向极地移动;（3）热带亚热带对流层顶高度和位置的变化;（4）热带高空平流层臭氧柱总量浓度的变化。据上述特征的变化证明数十年来热带向极地增宽纬度2°～5°（～8°）,一般确认为2．5°。由于热带增宽的驱动,广东50年的气温记录表明气候持续变暖,按增暖趋势推算,预估到2020年,现在的雷州半岛南部可能变成中热带;广东东南沿海将由目前的南亚热带变为北热带（占全省面积约1／3）;其余大部分地区为南亚热带;中亚热带基本上将退出广东（仅剩下东北角一偶）。此预测意味着南岭地区将成为南亚热带的边缘地。     

中国东南部太阳辐射变化特征、影响因素及其对区域气候的影响

基于8个站点1961年以来的长期太阳辐射及其它气象观测数据,通过线性回归、相关分析等方法,探讨近半个世纪以来中国东南部太阳辐射的变化特征,并分析了太阳辐射变化的影响因素以及对区域气候的影响。结果表明：该地区地表总太阳辐射自1961年以来呈下降趋势,变化率为-10.17MJ·m-2·a-1。太阳辐射下降主要集中在1961到1990年间,该时间段的下降趋势达到-39.43MJ·m-2·a-1,主要表现为直接辐射显著下降,散射辐射则变化不大;1990年代以后,地表总太阳辐射开始呈现上升趋势,变化率为13.21MJ·m-2·a-1。该地区太阳辐射变化与全球范围内太阳辐射＂变暗＂及＂变亮＂的变化是一致的。从云量对太阳辐射的作用来看,该地区太阳辐射的变化很有可能是受到低云量变化的影响;而太阳辐射的这种变化直接导致气温发生变化,使得最高气温和最低气温的变化出现不一致,日较差随之发生改变。     

大气CO2升高对土壤碳循环影响的研究进展

土壤有机碳是陆地碳库的重要组成部分,其积累和分解的变化直接影响全球的碳平衡。据估计,全球土壤（表层1m）有机碳积累总量相当于大气中碳总量的2～3倍。土壤是温室气体的源或汇,土壤碳库的变化将影响大气C02的浓度,因此,土壤碳库对人类活动的响应也是全球碳循环和全球变化研究的热点。在全球变化的大背景下,大气CO2升高导致植被生态系统碳平衡的改变进而对土壤碳循环产生影响。总结了陆地生态系统碳循环对大气C02浓度升高响应的主要生物学机制及过程,简述了大气C02浓度升高对影响土壤碳输入和输出的各因素的研究进展,并指出未来研究的主要方向。在大气C02浓度升高条件下,陆地生态系统碳循环的变化主要反映在以下几个方面：1）不同类型植物群落的净初级生产力（NPP）显著增加,但湿地植物的净初级生产力也有可能降低;2）光合产物向根系分配的数量增加,地上／地下生物量降低,根系形态发生变化,根系周转速率和根系分泌等过程的碳流量提高;3）植物含氮量降低,C／N提高,次生代谢产物增加,微生物生长受到抑制,植物残体分解速率降低;4）土壤呼吸速率显著增加,提高幅度受植物类型与土壤状况的影响;5）进入土壤的植物残体及分泌物的数量和性质影响土壤酶的活性,脱氢酶和转化酶活性增加,酚氧化酶和纤维素酶受植物类型与环境条件的影响;6）土壤中真菌的数量的增加幅度要高于细菌;7）CH4释放量增加,在植物的生长期表现更为明显。由于陆地生态系统碳循环的复杂性,研究结果仍有很大的不确定性。大气C02浓度升高与全球变化的其它表现间的交互作用将是今后研究的重点,同时由于土壤碳循环是一个由微生物介导的生物地球化学循环过程,因此,加强陆地生态系统碳循环的微生物机制研究也将为全面理解碳循环的过程提供更加准确的研究理论基础。     

三江平原气候变暖的进一步认识:最高和最低气温的变化

利用三江平原17个站1951-2000年的平均最高、最低气温和气温日较差资料，采用线性倾向估计和几种突变检测方法，定量研究了最高、最低气温和气温日较差变化趋势的空间分布，比较了最高、最低气温变化特征的差异性。结合前期的相关研究结果，对研究区20世纪70年代中期以来的三江平原气候变暖过程和成因有了进一步的认识。1975—2000年的变暖时期主要由两个阶段构成：1975—1987年为第一阶段，以夜间升温为主要特征，相对应的是气温日较差明显减小，超过一定面积的湿地开垦是该阶段气候变暖的主要驱动力之一；1987-2000年为第二阶段，以白天和夜间同时升温且幅度相当，气温日较差没有明显的变化趋势为特点，这一阶段的升温是对全球气候变暖同步的区域响应。     

湿地碳汇功能探讨:以泥炭地和芦苇湿地为例

大量研究表明湿地是地球表层系统中的重要碳汇,对于吸收大气中的温室气体,减缓全球气候变暖有重要作用.由于近几十年来全球气候变暖和人类活动的影响,湿地碳汇功能不断减弱.文章以泥炭地和芦苇Phragmites australis湿地为例来分析湿地的碳汇功能发现:农业排水、土地利用方式的改变、大气中CO2体积分数升高、全球气候变化等人为和自然因素影响了泥炭地的碳汇功能,泥炭地的碳蓄积能力下降,逐渐由"碳汇"转变为"碳源";尽管芦苇湿地是CH4的重要来源,但其对CO2具有较强的碳汇作用,综合来看芦苇湿地的仍是温室气体的净汇;人工芦苇湿地污水净化系统的温室气体排放量高于天然芦苇湿地.分析表明,研究泥炭地和芦苇湿地在全球气候变化下的响应及反馈机制,确定合理的湿地开发模式将是未来湿地碳汇研究的主要方向.     

Can ocean acidification affect population dynamics of the barnacle Semibalanus balanoides at its southern range edge?

The global ocean and atmosphere are warming. There is increasing evidence suggesting that, in addition to other environmental factors, climate change is affecting species distributions and local population dynamics. Additionally, as a consequence of the growing levels of atmospheric carbon dioxide (CO2), the oceans are taking up increasing amounts of this CO2, causing ocean pH to decrease (ocean acidification). The relative impacts of ocean acidification on population dynamics have yet to be investigated, despite many studies indicating that there will be at least a sublethal impact on many marine organisms, particularly key calcifying organisms. Using empirical data, we forced a barnacle (Semibalanus balanoides) population model to investigate the relative influence of sea surface temperature (SST) and ocean acidification on a population nearing the southern limit of its geographic distribution. Hindcast models were compared to observational data from Cellar Beach (southwestern United Kingdom). Results indicate that a declining pH trend (-0.0017 unit/yr), indicative of ocean acidification over the past 50 years, does not cause an observable impact on the population abundance relative to changes caused by fluctuations in temperature. Below the critical temperature (here T(crit) = 13.1 degrees C), pH has a more significant affect on population dynamics at this southern range edge. However, above this value, SST has the overriding influence. At lower SST, a decrease in pH (according to the National Bureau of Standards, pHNBs) from 8.2 to 7.8 can significantly decrease the population abundance. The lethal impacts of ocean acidification observed in experiments on early life stages reduce cumulative survival by approximately 25%, which again will significantly alter the population level at this southern limit. Furthermore, forecast predictions from this model suggest that combined acidification and warming cause this local population to die out 10 years earlier than would occur if there was only global warming and no concomitant decrease in pH.     

气候变暖背景下森林土壤碳循环研究进展

由人类活动引起的温室效应以及由此造成的气候变暖对森林牛态系统的影响已引起人们的普遍关注.森林土壤碳循环作为全球碳循环的重要组成部分,是决定未来陆地牛物嘲表现为碳源/碳汇的关键环节,揭示这一作用对于准确理解全球变化背景下陆地生态系统碳循环过程具有重要的指导意义.本文主要通过论述影响土壤碳循环过程的5个方面(土壤呼吸、土壤微生物、土壤酶活性、凋落物输入与分解、土壤碳库),综述了近10 a来全球气候变暖对土壤碳循环过程的影响.近年来,尽管已开展了大量有关土壤碳循环对气候变暖的响应及反馈机制的研究,并取得了一定的成果,但研究结果仍然存在很大的不确定性.整合各种密切关联的全球变化现象,完善研究方法和实验手段,加强根际微生态系统碳循环过程与机理研究将是下一步研究的方向和重点.参70     

The Future of Tropical Species on a Warmer Planet

Abstract: Modern global temperature and land cover and projected future temperatures suggest that tropical forest species will be particularly sensitive to global warming. Given a moderate greenhouse gas emissions scenario, fully 75% of the tropical forests present in 2000 will experience mean annual temperatures in 2100 that are greater than the highest mean annual temperature that supports closed‐canopy forest today. Temperature‐sensitive species might extend their ranges to cool refuges, defined here as areas where temperatures projected for 2100 match 1960s temperatures in the modern range. Distances to such cool refuges are greatest for equatorial species and are particularly large for key tropical forest areas including the Amazon and Congo River Basins, West Africa, and the upper elevations of many tropical mountains. In sum, tropical species are likely to be particularly sensitive to global warming because they are adapted to limited geographic and seasonal variation in temperature, already lived at or near the highest temperatures on Earth before global warming began, and are often isolated from cool refuges. To illustrate these three points, we examined the distributions and habitat associations of all extant mammal species. The distance to the nearest cool refuge exceeded 1000 km for more than 20% of the tropical and less than 4% of the extratropical species with small ranges. The biological impact of global warming is likely to be as severe in the tropics as at temperate and boreal latitudes.     

广东省自然物候对气候变暖的响应

利用广东省气象观测网14个观测站点1982年以来自然物候观测资料和气温资料,对广东省近30年木本植物木棉、苦楝和动物蚱蝉物候在气候变暖过程中的变化进行分析。结果表明：近30年广东省木本植物、动物春季物候期明显提前,植物、动物春季物候期的提前与推迟对温度的上升与下降的响应是非线性的。木本植物春季物候期、动物春季物候期分别与2—3月平均温度、3—4月平均温度有明显的负相关。动物春季物候期与物候期间〉10℃有效积温也有明显的负相关。预估到2020年我省木本植物春季物候期、动物春季物候期将分别提前2.9、2.2 d。     

Aktuelle Aerosoltrends an der GAW Globalstation Hohenpeißenberg und ihre Relevanz für Luftreinhaltung und Klima

Aim and Scope

This study was aimed at representing current aerosol trends measured at the GAW global station and their relevance for the present fine dust discussion and a possible impact on climate.

Results and Discussion

1) The intensive GAW measuring program at Hohenpeissenberg covers numerous parameters for the characterization of the physical, optical and chemical characteristics of the atmospheric aerosol. The time series of the number concentration of ultra fine particles with diameters of about 0.004 to 3 μm shows an increase of about 50% since 1995. 2) The introduction of soot particle filters would lower the dust mass only slightly since soot particles from diesel cars only about 8–10% contribute to the dust mass, but about 90% to the number concentration of particles. 3) The single scattering albedo (SSA) is a key parameter determining whether the existing aerosol mixture causes a cooling (negative radiative forcing) or a warming (positive radiative forcing) in the atmosphere. At Hohenpeißenberg the SSA changed from 0.85 to 0.91 in the time period 1999 to 2005, i.e. the regional aerosol as a whole is dominated by scattering rather than absorbing particles.

Conclusion and Perspective

From current aerosol trends at the GAW global station Hohenpeißenberg it was possible to analyze their relevance for air pollution control and possible influences on climate. Dust mass is not a suitable parameter for accessing the contribution of diesel engined vehicles. Measuring the number concentration of particles much more reflects the influence of diesel engined vehicles and also shows, as expected, an upward trend due to a strong increase of the fraction of diesel vehicles in comparison to the total number of cars. Aerosol particles scatter and absorb solar radiation and thus cause a cooling or warming in the atmosphere. Calculated values of the single scattering albedo at Hohenpeissenberg show, that in the initial years the aerosol did not diminish the temperature rise, but rather caused it to increase. Only a data comparison from a global network like GAW can demonstrate, if the results are even representative for the large scale situation.     

土壤温度上升对某些土壤化学性质的影响

土壤温度变化导致微生物群落组成及其活性产生变化;某些微生物群落成员在较高温度时有能力代谢那些在较低温度时不能被利用的基质;因此,土壤温度上升将影响土壤生态系统中的C、N、S循环。大多数研究结果显示,温度对土壤溶液中的溶解态有机质和土壤有机磷组分有较大的影响。这些结论对预测全球气候变化对土壤的影响有重要的义。     

The Melting Himalayas: Cascading Effects of Climate Change on Water, Biodiversity, and Livelihoods

Abstract:  The Greater Himalayas hold the largest mass of ice outside polar regions and are the source of the 10 largest rivers in Asia. Rapid reduction in the volume of Himalayan glaciers due to climate change is occurring. The cascading effects of rising temperatures and loss of ice and snow in the region are affecting, for example, water availability (amounts, seasonality), biodiversity (endemic species, predator–prey relations), ecosystem boundary shifts (tree-line movements, high-elevation ecosystem changes), and global feedbacks (monsoonal shifts, loss of soil carbon). Climate change will also have environmental and social impacts that will likely increase uncertainty in water supplies and agricultural production for human populations across Asia. A common understanding of climate change needs to be developed through regional and local-scale research so that mitigation and adaptation strategies can be identified and implemented. The challenges brought about by climate change in the Greater Himalayas can only be addressed through increased regional collaboration in scientific research and policy making.     

Role of the natural and anthropogenic radiative forcings on global warming: evidence from cointegration–VECM analysis

Over the last few years there has been much debate about the hypothesis that anthropogenic emissions of CO₂ and other greenhouse gases increase global temperature permanently. By using recent advances in time series econometrics, this paper tries to answer the question on how human activity affects Earth’s surface temperatures. Bearing in mind this goal, we estimated the long-run cointegration relations between global temperatures and changes in radiative forcings by a set of perturbing factors. We found that the temperature response to a doubling in radiative forcing of anthropogenic greenhouse gases is + 2.94 °C [95 % CI: + 1.91, + 3.97], in perfect accordance with prior research, and that the orthogonalized cumulated effect over a 100 year time period, in response to a unit increase of size of one standard deviation in greenhouse gas radiative forcing, is + 3.86 °C [95 % CI: + 0.03, + 6.54]. Conversely, the amplitude of solar irradiance variability is hardly sufficient to explain observed variations in the Earth’s climate. Our results show that the combined effect of stochastic trends attributable to anthropogenic radiative forcing variations are driving the Earth’s climate system toward an ongoing phase of global warming, and that such long-run movement is unlikely to be transient.     

中国农田主要温室气体排放特征与控制技术

全球气候变化已成为不争的事实,已经引起了各国科学家和政府的高度重视。人类活动向大气中排放的二氧化碳（CO2）、甲烷（CH4）和氧化亚氮（N2O）等温室气体浓度的增加是导致气候变化的重要原因之一。农田土壤是这三种温室气体的重要来源。文章概述了农田土壤CO2、CH4和N2O三种主要温室气体的排放机制,系统总结了国内对这三种温室气体排放通量的观测研究,提出了相应的减排技术对策,并对目前的研究问题和未来的发展方向作了深入的探讨,以期为控制农田土壤温室气体排放、发展低碳农业提供参考依据。     

Innovation and the dynamics of global warming

Global warming and the carbon cycle are a dynamic system with positive feedbacks. Fossil fuels are exhaustible resources. These two facts mean that innovation in clean energy technology, rather than mitigating global warming, can lead to a permanently higher temperature path. This paper explores the impact of innovation in the simplest model linking the economic theory of exhaustible resources with positive feedback dynamics in the carbon cycle.     

Carbon dioxide and methane emission from subsurface peatlands and its controlling factors北大核心CSCD

Peatland is an efficient carbon dioxide (CO2) sink on the continent and plays an important role in global carbon cycle. Climate change and human activities, two of the notable global environmental issues, have accelerated the degradation of peatlands during recent years. Global warming will increase the rate of aerobic decomposition in the surface of peatlands. Carbon stored in the subsurface of peatlands will be metabolized if the climatic conditions become favorable for decomposition. This study reviewed the carbon circle of subsurface peatland in natural environment and in environments disturbed by human activity or climate change. Furthermore, the major factors (environmental and human factors) that affect the carbon cycle were also discussed. According to a previous study, subsurface peatland will rapidly participate in the carbon cycle when the peatland is degraded. Water level, vegetation, and temperature were the main natural factors affecting the carbon cycle, whereas drainage, farming, and grazing were the main anthropogenic factors. Further studies should focus on different soil layer carbon dynamics, inorganic carbon content, and conservation and restoration of peatlands. The study methods should be a combination of macro with micro scale and focus on developing deep peat research techniques. Most of the previous studies focused on greenhouse gas emission and their response factors in short-term experiments. Thus, the mechanism and process of subsurface carbon are not clear and needs further study. © 2018 Science Press. All rights reserved.     

Impacts of changing frost regimes on Swedish forests: Incorporating cold hardiness in a regional ecosystem model

Understanding the effects of climate change on boreal forests which hold about 7% of the global terrestrial biomass carbon is a major issue. An important mechanism in boreal tree species is acclimatization to seasonal variations in temperature (cold hardiness) to withstand low temperatures during winter. Temperature drops below the hardiness level may cause frost damage. Increased climate variability under global and regional warming might lead to more severe frost damage events, with consequences for tree individuals, populations and ecosystems. We assessed the potential future impacts of changing frost regimes on Norway spruce (Picea abies L. Karst.) in Sweden. A cold hardiness and frost damage model were incorporated within a dynamic ecosystem model, LPJ-GUESS. The frost tolerance of Norway spruce was calculated based on daily mean temperature fluctuations, corresponding to time and temperature dependent chemical reactions and cellular adjustments. The severity of frost damage was calculated as a growth-reducing factor when the minimum temperature was below the frost tolerance. The hardiness model was linked to the ecosystem model by reducing needle biomass and thereby growth according to the calculated severity of frost damage. A sensitivity analysis of the hardiness model revealed that the severity of frost events was significantly altered by variations in the hardening rate and dehardening rate during current climate conditions. The modelled occurrence and intensity of frost events was related to observed crown defoliation, indicating that 6-12% of the needle loss could be attributed to frost damage. When driving the combined ecosystem-hardiness model with future climate from a regional climate model (RCM), the results suggest a decreasing number and strength of extreme frost events particularly in northern Sweden and strongly increasing productivity for Norway spruce by the end of the 21st century as a result of longer growing seasons and increasing atmospheric CO₂ concentrations. However, according to the model, frost damage might decrease the potential productivity by as much as 25% early in the century.     

Effects of Warming Conditions in Eastern North American Forests on Red-Backed Salamander Morphology

Abstract:  Several studies have reported climate-associated changes in phenotypically plastic traits of amphibians, yet it remains unknown whether amphibians can manifest an evolutionary response to global climate change at the rate and magnitude that it is occurring. To assess this issue, we examined temporal change in the morphology of the red-backed salamander ( Plethodon cinereus ), a small, abundant woodland salamander distributed widely in eastern North America with two distinct morphotypes: striped individuals associated with cooler microclimates and unstriped individuals associated with warmer microclimates. We compiled morph frequencies for 50,960 individual salamanders from 558 sites as recorded in the published literature and in unpublished field notes of herpetologists between 1908 and 2004. We observed that striping probability increased with increasing latitude, longitude, and elevation and decreased (from 80% to 74% range wide) with time. The combined forces of regional climate warming and, particularly, forest disturbance have evidently been sufficient to cause morphological evolution in this amphibian over the last century.     

大气气溶胶研究新动向

本文概述了近年大气气溶胶研究的四个主要方面:大气气溶胶的表征、大气化学过程与气候变化、健康效应等的概况.阐明了当今大气气溶胶研究的趋向,主要着重于PM_(10)和PM_(2.5)细颗粒(可吸入颗粒物或二次颗粒物)的物理化学特性与环境行为、生态效应,更重视气溶胶的非均相化学反应过程;其研究范围,从平流层向对流层发展,并密切结合气候变化、健康影响等有关的一些实际问题,进行深层次的综合性研究.大气气溶胶化学已成为当今大气化学研究最前沿的领域.