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1.
By using,summer temperature data in 26 stations from 1951 to 2003, the variation characteristics of summer temperature in Northeast China （NET） were analyzed based on the background of climate wanning. The results showed that the warming in summer was 0.15~C/10a in Northeast China, which was higher than that on the global, Northern Hemisphere or Northeast Asia scale in the recent 50 years. The responses of NET to global warming were shown in 3 aspects mainly. Firstly, it became warm and the average temperature increased in summer; secondly, the temperature variability increased, which displayed the increase of climatic instability; thirdly, the disaster of low temperature decreased and high temperature damage increased obviously, but the disaster of low temperature still existed in some areas under global warming background, which would be worthy of notice further.  相似文献   

2.
在气候变化和全球治理挑战日益严峻的背景下,CO2排放及代价评估日益受到学术界和决策者的关注。当前全球范围包括联合国政府间气候变化专门委员会（IPCC）评估在内的几乎所有研究都是基于全球平均CO2浓度来驱动气候模式的,但基于全球CO2平均分布设定开展模拟影响评估在学术界多有争议。首先,综述了大气CO2非均匀分布的证据,评述了大气CO2浓度非均匀分布与地表升温过程的互馈机制。其次,从自然和人为2个维度,梳理了大气CO2浓度非均匀分布形成的原因,并评估了其对地表升温的影响。最后,评述了当前大气CO2浓度非均匀分布研究中存在的问题,进一步展望了其发展趋势,为把握全球与区域碳排放现状及气候变化影响提供科学判据。  相似文献   

3.
Mountain regions are sensitive to climate changes, which make them good indicators of climate change. The aim of this study is to investigate the spatial and temporal variability of air temperature and precipitation in the Polish Carpathians. This study consists of climatological analyses for the historical period 1851-2010 and future projections for 2021-2100. The results confirm that there has been significant warming of the area and that this warming has been particularly pronounced over the last few decades and will continue in the oncoming years. Climate change is most evident in the foothills; however, these are the highest summits which have experienced the most intensive increases in temperature during the recent period. Precipitation does not demonstrate any substantial trend and has high year-to-year variability. The distribution of the annual temperature contour lines modelled for selected periods provides evidence of the upward shift of vertical climate zones in the Polish Carpathians, which reach approximately 350 meters, on average, what indicates further ecological consequences as ecosystems expand or become extinct and when there are changes in the hydrological cycle.  相似文献   

4.
Based on the authors‘ 1986 to 1994 sporo-pollen assemblage analysis in the southern Yellow Sea area, data from 3 main cores were studied in combination with ^14C, palaeomagnetic and thermoluminescence data. The evolution of the paleoclimate environments in the southern Yellow Sea since 15ka B.P. was revealed that, in deglaciation of the last glacial period, the climate of late glaciation transformed into that of postglaciation, accompanied by a series of violent climate fluctuations. These evolution events happened in a global climate background and related to the geographic changes in eastern China. We distinguished three short-term cooling events and two warming events. Among them, the sporo-pollen assemblage of subzone A1 showed some cold climate features indicating that a cooling event occurred at about 15 - 14ka. B .P. in early deglaciation. This subzone corresponds to the Oldest Dryas. In subzone A3 , many drought-enduring herbal pollens and some few pollens of cold-resistant Picea, Abies, etc. were found, which indicated that a cooling event, with cold and arid climate, occurred at about 12- 11ka. B.P. in late deglaciation. This subzone corresponds to the Younger Dryas. The sporo-pollen assemblage of zone B showed warm and arid climate features in postglaciation. Although the assemblage of subzone B2 indicated a cold and arid climate environment, the development of flora in subzone B2 climate was less cold than that in A3 . Subzone B2 indicated a cooling event which occurred at about 9ka B.P. in early Holocene. Subzone A2, with some distinct differences from subzone A1 and A3 , indicated a warming event which occurred at 14 - 13ka. B.P. and should correspond to a warming fluctuation. The sporo-pollen assemblage of zone C showed features of warm-moist flora and climate, and indicated a warming event which universally occurred along the coast of eastern China at 8 - 3ka B.P. in middle Holocene, and its duration was longer than that of any climate events mentioned above. This period was climatic optimum and belonged to an altithermal period in postglaciation.  相似文献   

5.
Understanding of treeline ecotone ecophysiological adaptation to climate warming is still very limited. Furthermore, it is difficult to predict which plant species could dominate in the future. For this reason, a study was conducted in the treeline ecotone, East Tibetan Plateau to detect the adaptation of the dwarf willow(Salix eriostachya) to experimental warming. Compared to ambient conditions, the experimental warming advanced the bud break by 12 days, delayed the leaf abscission by20 days, and prolonged the growing period by 28 days.It also increased photosynthesis(47%), number of leaves(333%), leaf area(310%), and carbon sequestration of the dwarf willow. Experimental warming did not affect carbon use efficiency, but decreased water use efficiency significantly.Experimental warming enhanced the clonal ramets of Salix eriostachya(+ 3.7 shrubs m-2). The frequent air temperature fluctuations had minor effect on Salix eriostachya. Based on these findings, we highlighted that Salix eriostachya could dominate in the community treeline ecotone of east Tibetan Plateau in the future climate warming scenario.  相似文献   

6.
With trends indicating increase in temperature and decrease in winter precipitation, a significant negative trend in snow-covered areas has been identified in the last decade in the Himalayas. This requires a quantitative analysis of the snow cover in the higher Himalayas. In this study, a nonlinear autoregressive exogenous model, an artificial neural network （ANN）, was deployed to predict the snow cover in the Kaligandaki river basin for the next 30 years. Observed climatic data, and snow covered area was used to train and test the model that captures the gross features of snow under the current climate scenario. The range of the likely effects of climate change on seasonal snow was assessed in the Himalayas using downscaled temperature and precipitation change projection from - HadCM3, a global circulation model to project future climate scenario, under the AIB emission scenario, which describes a future world of very rapid economic growth with balance use between fossil and non-fossil energy sources. The results show that there is a reduction of 9% to 46% of snow cover in different elevation zones during the considered time period, i.e., 2Oll to 2040. The 4700 m to 52oo m elevation zone is the most affected area and the area higher than 5200 m is the least affected. Overall, however, it is clear from the analysis that seasonal snow in the Kaligandaki basin is likely to be subject to substantialchanges due to the impact of climate change.  相似文献   

7.
Warming trend in northern East China Sea in recent four decades   总被引：2，自引：0，他引：2  
Global warming has become a notable trend especially since an abrupt climate change in 1976. Response of the East China Sea (ECS) to the global warming trend, however, is not well understood because of sparse long-term observation. In this paper, hydrographic observation data of 1957–1996 are collected and reviewed to study climatological variability in northern ECS. Significant warming trends are found in both summer and winter. In summer, the average SST is about 0.46°C higher during the period of 1977-19...  相似文献   

8.
In arid regions, mountains fulfill important ecological and economic functions for the surrounding lowlands. In the scenario of global warming, mountain ecosystems change rapidly, especially in the arid region of northwestern China. This paper provides an assessment of the changes in temperature and precipitation in the historical records of climate on the northern slopes of the eastern Tianshan Mountains. A Mann-Kendall nonparametric trend and Sen＇s tests are employed to analyze the interannual changes and innerannual variability in temperature and precipitatiofi in the regions of low to high altitude. The present study finds that the largest increases in annual temperature are observed at stations in the low altitude regions. The significant increasing trends in temperature tend to occur mainly in late winter and early spring at stations from middle to high altitude, but in summer and autumn at stations of low altitudes. The increasing trends in annual precipitation are found from the middle to high altitude areas, but decreasing trends are found in the low altitude areas. The significant increasing trends in precipitation occur mostly in winter and earlier spring at stations from the middle to high altitudes, while the increasing and decreasing trend coexists at stations of low altitude with most of the significant trend changes occurring in March, June and August.  相似文献   

9.
WRF模式作为一个中尺度气候模式,其分辨率从几米到几千公里,其自身的双向嵌套特征也为进行动力尺度下推提供了有力条件。本文利用WRF模式和传统的统计方法对研究区的气温进行尺度下推。首先,通过动力下推得到不同分辨率下的气温空间分布,并选取15个气象站点进行点对点验证,为了更明显观察不同尺度间的差异,对不同尺度的输出与ANUSPLIN插值结果进行比对,结果显示动力尺度下推中,分辨率越高模拟效果越好。其次,我们采用传统的统计下推方法,从27km下推到3km分辨率,并与WRF和ANUSPLIN插值在该尺度的结果进行对比分析,结果显示统计下推结果的趋势与动力下推的插值结果是一致的,但具有明显的马赛克效果,通过分析认为,这与统计方法的尺度下推只考虑高程信息的变化对气温的影响,而未考虑其他因素有关,如若在下推时加入更多的变量,如对温度有较大影响的坡度、坡向、土地覆被类型等因素,综合分析不同尺度之间的关系,会使下推结果有所改善。  相似文献   

10.
Alpine treeline, as a prominent ecological boundary between forested mountain slopes and alpine meadow/shrub, is highly complex in altitudinal distribution and sensitive to warming climate. Great efforts have been made to explore their distribution patterns and ecological mechanisms that determine these patterns for more than 100 years, and quite a number of geographical and ecophysiological models have been developed to correlate treeline altitude with latitude or a latitude related temperature. However,on a global scale, all of these models have great difficulties to accurately predict treeline elevation due to the extreme diversity of treeline site conditions.One of the major reasons is that "mass elevation effect"(MEE) has not been quantified globally and related with global treeline elevations although it has been observed and its effect on treeline elevations in the Eurasian continent and Northern Hemisphere recognized. In this study, we collected and compiled a total of 594 treeline sites all over the world from literatures, and explored how MEE affects globaltreeline elevation by developing a ternary linear regression model with intra-mountain base elevation(IMBE, as a proxy of MEE), latitude and continentality as independent variables. The results indicated that IMBE, latitude and continentality together could explain 92% of global treeline elevation variability, and that IMBE contributes the most(52.2%), latitude the second(40%) and continentality the least(7.8%) to the altitudinal distribution of global treelines. In the Northern Hemisphere, the three factors’ contributions amount to 50.4%, 45.9% and 3.7% respectively; in the south hemisphere, their contributions are 38.3%, 53%, and 8.7%, respectively. This indicates that MEE, virtually the heating effect of macro-landforms, is actually the most significant factor for the altitudinal distribution of treelines across the globe, and that latitude is relatively more significant for treeline elevation in the Southern Hemisphere probably due to fewer macro-landforms there.  相似文献   

11.
The global climate is intimately connected to changes in the polar oceans. The variability of sea ice coverage affects deep-water formations and large-scale thermohaline circulation patterns. The polar radiative budget is sensitive to sea-ice loss and consequent surface albedo changes. Aerosols and polar cloud microphysics are crucial players in the radiative energy balance of the Arctic Ocean. The main biogenic source of sulfate aerosols to the atmosphere above remote seas is dimethylsulfide (DMS). Recent research suggests the flux of DMS to the Arctic atmosphere may change markedly under global warming. This paper describes climate data and DMS production (based on the five years from 1998 to 2002) in the region of the Barents Sea (30–35°E and 70–80°N). A DMS model is introduced together with an updated calibration method. A genetic algorithm is used to calibrate the chlorophyll-a (CHL) measurements (based on satellite SeaWiFS data) and DMS content (determined from cruise data collected in the Arctic). Significant interannual variation of the CHL amount leads to significant interannual variability in the observed and modeled production of DMS in the study region. Strong DMS production in 1998 could have been caused by a large amount of ice algae being released in the southern region. Forcings from a general circulation model (CSIRO Mk3) were applied to the calibrated DMS model to predict the zonal mean sea-to-air flux of DMS for contemporary and enhanced greenhouse conditions at 70–80°N. It was found that significantly decreasing ice coverage, increasing sea surface temperature and decreasing mixed-layer depth could lead to annual DMS flux increases of more than 100% by the time of equivalent CO2 tripling (the year 2080). This significant perturbation in the aerosol climate could have a large impact on the regional Arctic heat budget and consequences for global warming.  相似文献   

12.
Tropical Atlantic climate change is relevant to the variation of Atlantic meridional overturning circulation (AMOC) through different physical processes. Previous coupled climate model simulation suggested a dipole-like SST structure cooling over the North Atlantic and warming over the South Tropical Atlantic in response to the slowdown of the AMOC. Using an ocean-only global ocean model here, an attempt was made to separate the total influence of various AMOC change scenarios into an oceanic-induced component and an atmospheric-induced component. In contrast with previous freshwater-hosing experiments with coupled climate models, the ocean-only modeling presented here shows a surface warming in the whole tropical Atlantic region and the oceanic-induced processes may play an important role in the SST change in the equatorial south Atlantic. Our result shows that the warming is partly governed by oceanic process through the mechanism of oceanic gateway change, which operates in the regime where freshwater forcing is strong, exceeding 0.3 Sv. Strong AMOC change is required for the gateway mechanism to work in our model because only when the AMOC is sufficiently weak, the North Brazil Undercurrent can flow equatorward, carrying warm and salty north Atlantic subtropical gyre water into the equatorial zone. This threshold is likely to be model-dependent. An improved understanding of these issues may have help with abrupt climate change prediction later.  相似文献   

13.
Seventeen coupled general circulation models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) are employed to assess the relationships of interannual variations of sea surface temperature (SST) between the tropical Pacific (TP) and tropical Indian Ocean (TIO). The eastern/central equatorial Pacific features the strongest SST interannual variability in the models except for the model CSIRO-Mk3-6-0, and the simulated maximum and minimum are produced by models GFDL-ESM2M and GISS-E2-H respectively. However, It remains a challenge for these models to simulate the correct climate mean SST with the warm pool-cold tongue structure in the equatorial Pacific. Almost all models reproduce El Niño-Southern Oscillation (ENSO), Indian Ocean Dipole mode (IOD) and Indian Ocean Basin-wide mode (IOB) together with their seasonal phase lock features being simulated; but the relationship between the ENSO and IOD is different for different models. Consistent with the observation, an Indian Ocean basin-wide warming (cooling) takes place over the tropical Indian Ocean in the spring following an El Niño (La Niña) in almost all the models. In some models (e.g., GFDL-ESM2G and MIROC5), positive ENSO and IOB events are stronger than the negative events as shown in the observation. However, this asymmetry is reversed in some other models (e.g., HadGEM2-CC and HadGEM2-ES).  相似文献   

14.
Based on a coupled ocean-atmosphere model, the response of the Indian Ocean Dipole (IOD) mode to global warming is investigated with a six member ensemble of simulations for the period 1850–2100. The model can simulate the IOD features realistically, including the east-west dipole pattern and the phase locking in boreal autumn. The ensemble analysis suppresses internal variability and isolates the radiative forced response. In response to increasing greenhouse gases, a weakening of the Walker circulation leads to the easterly wind anomalies in the equatorial Indian Ocean and the shoaling thermocline in the eastern equatorial Indian Ocean (EEIO), and sea surface temperature and precipitation changes show an IOD-like pattern in the equatorial Indian Ocean. Although the thermocline feedback intensifies with shoaling, the interannual variability of the IOD mode surprisingly weakens under global warming. The zonal wind feedback of IOD is found to weaken as well, due to decreased precipitation in the EEIO. Therefore, the atmospheric feedback decreases much more than the oceanic feedback increases, causing the decreased IOD variance in this model.  相似文献   

15.
Understanding of treeline ecotone ecophysiological adaptation to climate warming is still very limited. Furthermore, it is difficult to predict which plant species could dominate in the future. For this reason, a study was conducted in the treeline ecotone, East Tibetan Plateau to detcct the adaptation of the dwarf willow (Salix eriostachya) to experimental warming. Compared to ambient conditions, the experimental warming advanced the bud break by 12 days, delayed the leaf abscission by 20 days, and prolonged the growing period by 28 days. It also increased photosynthesis (47%), number of leaves (333%), leaf area (310%), and carbon sequestration of the dwarf willow. Experimental warming did not affect carbon use efficiency, but decreased water use efficiency significantly. Experimental warming enhanced the clonal ramets of Salix eriostachya (+ 3.7 shrubs m-2). The frequent air temperature fluctuations had minor effect on Salix eriostachya. Based on these findings, we highlighted that Salix eriostachya could dominate in the community treeline ecotone of east Tibetan Plateau in the future climate warming scenario.  相似文献   

16.
The Atlantic meridional overturning circulation (AMOC) is a vital component of the global ocean circulation and the heat engine of the climate system. Through the use of a coupled general circulation model, this study examines the role of synoptic systems on the AMOC and presents evidence that internally generated high-frequency, synoptic-scale weather variability in the atmosphere could play a significant role in maintaining the overall strength and variability of the AMOC, thereby affecting climate variability and change. Results of a novel coupling technique show that the strength and variability of the AMOC are greatly reduced once the synoptic weather variability is suppressed in the coupled model. The strength and variability of the AMOC are closely linked to deep convection events at high latitudes, which could be strongly affected by the weather variability. Our results imply that synoptic weather systems are important in driving the AMOC and its variability. Thus, interactions between atmospheric weather variability and AMOC may be an important feedback mechanism of the global climate system and need to be taken into consideration in future climate change studies.  相似文献   

17.
Climate change will affect the geographic distribution and richness of species at different spatial and temporal scales. We applied Maximum entropy(MaxEnt) modeling to predict the potential influence of climatic change on the current and future distribution of the important mountainous tree species Moringa peregrina(Forssk.) Fiori. The Maxent model performed better than random models for the species with the training and test AUC(Area Under the receiver-operating characteristic Curve) values of 0.96 and 0.90, respectively. Jackknife test and response curves showed that the distribution of the species negatively correlates with higher altitudes and precipitation in October and November. Moreover, it positively correlates with the total annual precipitation and precipitation in January. Under current and future climatic conditions, our model predicted habitat gains for M. peregrina towards the coastal northern and southern limits of its distribution. The potentially suitable habitats, under future climate projections, are currently characterized by elevations of 1000 m a.s.l. and total annual precipitation of 80-225 mm/year. Moderate and high potential habitat suitability will increase by 5.6%-6% and 2.1%-2.3%, under RCP2.6 and RCP4.5 scenario, respectively. The results indicated that the habitat suitability of M. peregrina would increase with increasing climate warming, particularly under RCP2.6 scenario. We recommend sustainable conservation and cultivation of Moringa peregrina in its current habitats along the Red Sea mountains.  相似文献   

18.
The paper presents a numerical two-dimensional model (with a realistic sea basin and wind fields as exter nal forcing) to simulate the basic features of the wintertime circulation in the Bohai and Huanghai (Yellow) Seas (BHS) and to show how the circulation can be driven by wind. The main results can be summarized as follows (1) The basic features of the BHS wintertime circulation can be depicted by the wind-driven barotropi'c motion. (2) The traditionally named Huanghai Sea Warm Current (HSWC) is actually generated by the north wind field, at least in winter. (3) The southward coastal current off the Korean west coast plays a more significant role in the southern Huanghai Sea wintertime circulation than traditionally believed. (4) Though the coastal landform and bottom topography play important roles in the wintertime BHS circulation pattern, the wind is a primary forcing.  相似文献   

19.
Timely and proper backfilling of open-pits in strip coal-mines has been an effective measurement for the recovery of the hydrothermal regimes and ecological environment in permafrost regions. In this study, numerical simulations and statistical regressions were applied for analyzing the recovery processes of the backfill and its major influencing factors for the thermal equilibrium in recently backfilled open pits at the Gulian strip coalmine in Mo'he, Northeast China. Results show that the thermal recovery time of backfilled areas is positively correlated to the backfill depth(BD) of the soils, the backfilled soil temperature(BST), and the mean annual ground surface temperature(MAGST); meanwhile, climate warming can impact on thermal regimes of the backfill area. The impact of climate warming on ground temperature of the backfill will show up significantly in about 50 years afterbackfilling(BD at 10.0 and 20.0 m, BST at 20.0°C) under the climate warming scenario(CWS) of 0.025°C·year ~(-1). Grey-relation analyses show that the sensitivity of the backfill recovery time declines in the order of the BD, BST and MAGST. On the basis of the abovementioned studies, the layer-by-layer backfilling in cold seasons is advised for more effective and more rapid recovery of thermal regimes of the backfilled open-pits in cold regions.  相似文献   

20.
燃烧形成的黑碳粒子进入大气中可影响辐射平衡,导致全球气候变暖,其沉降在河流、湖泊、海洋、土壤等环境中对全球生物地球化学循环起到重要的作用,成为当前国际地球科学研究的热点问题。综述了黑碳的定义及排放、沉降、降解过程,并总结了其在现在及过去环境和气候系统中的重要作用与研究意义。黑碳是全球惰性有机碳库的重要组成部分,在全球慢速碳循环中发挥潜在作用。因其具有很强的吸光特性,它在区域气候变暖过程中扮演重要角色。沉降在不同地质载体中的黑碳难以降解,可以保存几百万年,为地质历史时期古气候和古环境重建研究提供重要信息。海洋沉积物过去数百万年的黑碳记录指示了天然火的演化信息,晚第四纪黄土剖面黑碳也指示了天然火的变化信息,最近千年的湖泊和冰芯黑碳记录既反映了天然火的信息,也指示人类活动的信号。未来黑碳研究应进一步关注标准测量方法,以真正理解黑碳在全球气候与环境系统中的作用。  相似文献   

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