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1.
近600年来北极与中国气候变化的对比 总被引：2，自引：2，他引：0
许娟 《地理学报(英文版)》2004,14(3):289-295
A compilation of paleoclimate records from lake sediments, trees, ice cores, and historical documents provide a view of China and Arctic environmental changes in the last 600 years. Many of these changes have also been identified in sedimentary and geochemical signatures in deep-sea sediment cores from the North Atlantic Ocean, Arctic and Greenland and ice cores from the Qinghai-Tibet Plateau, confirming the linkage of environmental changes of different time scales between the Arctic and China. It is shown that the changes of precipitation, temperature and sea ice cover in Arctic were correlated with climate changes in China. This paper also developed a comparative research on the climate changes between Arctic and China both during the Little Ice Age (LIA) and the instrumental observation period. Cycles and trend of temperature variations during LIA and temperature and precipitation during the instrumental observation period are performed. We found some similarities and differences of environmental changes between Arctic and China. 相似文献
2.
Climate records during the last millennium are essential in placing recent anthropogenic-induced climate change into the context of natural climatic variability. However, detailed records are still sparse in Alaska, and these records would help elucidate climate patterns and possible forcing mechanisms. Here we present a multiple-proxy sedimentary record from Kepler Lake in south-central Alaska to reconstruct climatic and environmental changes over the last 800?years. Two short cores (85 and 101?cm long) from this groundwater-fed marl lake provide a detailed stable isotope and sediment lithological record with chronology based on four AMS 14C dates on terrestrial macrofossils and 210Pb analysis. The ??18O values of inorganic calcite (CaCO3) range from ?17.0 to ?15.7???, with the highest values during the period of 1450?C1850 AD, coeval with the well-documented Little Ice Age (LIA) cold interval in Alaska. The high ??18O values during the cold LIA are interpreted as reflecting shifts in atmospheric circulation. A weakening of the wintertime Aleutian low pressure system residing over the Gulf of Alaska during the LIA would have resulted in 18O-enriched winter precipitation as well as a colder and possibly drier winter climate in south-central Alaska. Also, elevated calcite contents of >80?% during the LIA reflect a lowering of lake level and/or enhanced seasonality (warmer summer and colder winter), as calcite precipitation in freshwater lakes is primarily a function of peak summer temperature and water depth. This interpretation is also supported by high ??13C values, likely reflecting high aquatic productivity or increased residence times of the lake water during lower lake levels. The lower lake levels and warmer summers would have increased evaporative enrichment in 18O, also contributing to the high ??18O values during the LIA. Our results indicate that changes in atmospheric circulation were an important component of climate change during the last millennium, exerting strong influence on regional climate in Alaska and the Arctic. 相似文献
3.
Recently observed changes in the Arctic have highlighted the need for a better understanding of Arctic dynamics. This research addresses that need and is also motivated by the recent finding of two regimes of Arctic ice - ocean wind-driven circulation. In this paper, we demonstrate that during 1946-1997 the Arctic environmental parameters have oscillated with a period of 10-15 years. Our results reveal significant differences among atmosphere, ice, and ocean processes during the anticyclonic and cyclonic regimes in the Arctic Ocean and its marginal seas. The oscillating behaviour of the Arctic Ocean we call the Arctic Ocean Oscillation (AOO). Based on existing data and results of numerical experiments, we conclude that during the anticyclonic circulation regime the prevailing processes lead to increases in atmospheric pressure, in ice concentration and ice thickness, river runoff, and surface water salinity - as well as to decreases in air temperature, wind speed, number of storms, precipitation, permafrost temperatures, coastal sea level, and surface water temperature. During the cyclonic circulation regime the prevailing processes lead to increased air and water temperatures, wind speed, number of storms,open water periods, and to decreases in ice thickness and ice concentration, river runoff, atmospheric pressure, and water salinity. The two-climate regime theory may help answer questions related to observed decadal variability of the Arctic Ocean and to reconcile the different conclusions among scientists who have analysed Arctic data obtained during different climate states. 相似文献
4.
Based on temperature reconstruction and proxy data from 14 sites in the Northern Hemisphere, this paper focused on comparing the cycles of temperature variations between the Arctic and other areas, including Atlantic, Europe, China, Asia, Pacific, Indian Ocean, and America during the transition from the last Interstade to the Last Glacial Maximum, from the Last Glacial Maximum to megathermal period in Holocene and the transition of the Little Ice Age (LIA) by the methods of Singular Spectrum Analysis (SSA) and Maximum Entropy Spec-trum (MES). The results showed that environmental changes in the Arctic are most similar to that in the North American and better similar to Asia, Atlantic and Pacific, the least similar to Indian Ocean and Europe. The 1500-year oscillation of temperature existed both in Arctic and Europe. 相似文献
5.
Based on temperature reconstruction and proxy data from 14 sites in the Northern Hemisphere, this paper focused on comparing the cycles of temperature variations between the Arctic and other areas, including Atlantic, Europe, China, Asia, Pacific, Indian Ocean, and America during the transition from the last Interstade to the Last Glacial Maximum, from the Last Glacial Maximum to megathermal period in Holocene and the transition of the Little Ice Age （LIA） by the methods of Singular Spectrum Analysis （SSA） and Maximum Entropy Spectrum （MES）. The results showed that environmental changes in the Arctic are most similar to that in the North American and better similar to Asia, Atlantic and Pacific, the least similar to Indian Ocean and Europe. The 1500-year oscillation of temperature existed both in Arctic and Europe. 相似文献
6.
冰芯是重建古气候重要的信息载体,因具有分辨率高、保真性强、信息量大、时间尺度长等优点而成为研究热点。中国自1986 年在祁连山敦德获取第一支冰芯起,相继在青藏高原地区钻取了古里雅、马兰、达索普、普若岗日、东绒布等冰芯。本文重点回顾和总结了利用上述冰芯重建古气候的研究成果,分别论述了冰芯作为信息载体反映古气候的主要指标,包括氧同位素与温度、冰芯积累量与降水、大气气溶胶与古环境、微量元素与古环境、冰芯包裹体与古环境,以及冰芯内微生物与古环境的关系等。青藏高原地区冰芯对过去一些极端气候事件、中世纪暖期、小冰期、冰期—间冰期旋回、厄尔尼诺事件、太阳活动规律,以及工业革命以来的全球气候变暖均有不同程度的响应,但纬度差异导致青藏高原地区的响应机制有别于南北极地区;并进一步对比说明了受不同季风系统影响的冰芯在重建古气候上的异同。最后,基于当前研究状况,就加强多学科交叉与创新、新技术应用与代用指标开发、冰芯记录影响因素评估及量化模型构建等未来需要深入的研究方向进行了展望。 相似文献
7.
Banks Island (N.W.T.) has become a focal point for climate change studies in the Canadian Arctic. However, long-term climatic
and environmental data are very sparse from this large island, as they are for the entire southwestern region of the Canadian
Arctic Archipelago. In this paleolimnological study, diatom species assemblage shifts documented in cores collected from a
pond and a lake on Banks Island were interpreted to represent a response to climate warming commencing in the nineteenth century.
We found that, although the timing and overall nature of the species changes in the two cores were consistent, the signal
was muted in the deeper site likely as a result of differences in ice cover extent and duration between lakes and ponds. A
high-resolution study was also conducted from a second pond, at sub-decadal resolution, that only spanned the last ∼60 years.
In the deeper lake site, Fragilaria construens and F. pinnata dominated the assemblages, similar to those noted in other high Arctic regions where lakes are characterized by extended
ice cover. In contrast, Denticula kuetzingii dominated the shallower ponds and, in the case of the pond core representing the longer time period, this taxon increased
in the post-1850 sediments, likely coincident with climate warming. In all cores, diatom assemblages became more diverse and
Achnanthes species (particularly A. minutissima) increased from ∼1850 to the present, similar to changes documented in other Arctic regions. Beta diversity values calculated
for the diatom species changes indicated that assemblage shifts in the Banks Island cores were of similar magnitude to those
recorded in other Arctic regions with high species turnover, such as Ellesmere Island. A diatom-based Total Nitrogen (TN)
transfer function previously developed for Banks Island was applied to the three 210Pb dated cores as an exploratory tool for inferring past changes in nitrogen concentrations. In both the lake and pond cores,
diatom-inferred TN concentrations tended to increase in the more recent sediments, as may be expected with warming; however
these trends were not very distinct. 相似文献
8.
The role of declining Arctic sea ice in recent decreasing terrestrial Arctic snow depths 总被引：1，自引：1，他引：0
The dramatic decline in Arctic sea ice cover is anticipated to influence atmospheric temperatures and circulation patterns. These changes will affect the terrestrial climate beyond the boundary of the Arctic, consequently modulating terrestrial snow cover. Therefore, an improved understanding of the relationship between Arctic sea ice and snow depth over the terrestrial Arctic is warranted. We examined responses of snow depth to the declining Arctic sea ice extent in September, during the period of 1979–2006. The major reason for a focus on snow depth, rather than snow cover, is because its variability has a climatic memory that impacts hydrothermal processes during the following summer season. Analyses of combined data sets of satellite measurements of sea ice extent and snow depth, simulated by a land surface model (CHANGE), suggested that an anomalously larger snow depth over northeastern Siberia during autumn and winter was significantly correlated to the declining September Arctic sea ice extent, which has resulted in cooling temperatures, along with an increase in precipitation. Meanwhile, the reduction of Arctic sea ice has amplified warming temperatures in North America, which has readily offset the input of precipitation to snow cover, consequently further decreasing snow depth. However, a part of the Canadian Arctic recorded an increase in snow depth driven locally by the diminishing September Arctic sea ice extent. Decreasing snow depth at the hemispheric scale, outside the northernmost regions (i.e., northeastern Siberia and Canadian Arctic), indicated that Arctic amplification related to the diminishing Arctic sea ice has already impacted the terrestrial Arctic snow depth. The strong reduction in Arctic sea ice anticipated in the future also suggests a potential long-range impact on Arctic snow cover. Moreover, the snow depth during the early snow season tends to contribute to the warming of soil temperatures in the following summer, at least in the northernmost regions. 相似文献
9.
气候变化对径流的影响是全球变化研究领域的重点问题。论文采用BCC-CSM1-1模拟的过去千年(850—2012年)气候与水文变化数据,基于Budyko假设与傅抱璞公式开展了中世纪气候异常期(MCA)、小冰期(LIA)和现代暖期(MWP)黄河中、上游径流变化及其归因分析。结果表明：① 在3个气候特征期之间,上游地区径流与气候冷暖变化位相相同,MWP时期径流最高,LIA时期径流最低;中游地区径流则与气候冷暖变化位相相反,LIA径流最高,MCA径流最低。② 径流对各因子的敏感性不仅存在地理差异,而且受特征期之间气候冷暖转变的影响。中游地区径流对降水和潜在蒸发的弹性系数(绝对值)大于上游,且在冷转暖过程中的弹性系数(绝对值)略大于暖转冷过程。同时,持续偏暖过程中、上游地表变化的弹性系数(绝对值)均明显大于暖转冷与冷转暖过程。③ 3个特征期之间径流差异主要由降水主导,地表变化影响甚微,但潜在蒸发的作用存在地域差异,上游地区潜在蒸发部分抵消了降水变化的贡献而中游地区潜在蒸发则加强了降水导致的径流变化。研究量化了黄河流域各因子对过去千年百年尺度径流变化的贡献,明确了不同气候转变期各因子贡献的差异,为更好地研究径流量多尺度变化及其成因奠定了基础。 相似文献
10.
Glen MacDonald Benjamin Felzer Bruce Finney Steven Forman 《Journal of Paleolimnology》2000,24(1):1-13
Although paleoclimatic research in the Arctic has most often focused on variations in temperature, the Arctic has also experienced changes in hydrologic balance. Changes in Arctic precipitation and evaporation rates affects soils, permafrost, lakes, wetlands, rivers, ice and vegetation. Changes in Arctic soils, permafrost, runoff, and vegetation can influence global climate by changing atmospheric methane and carbon dioxide concentrations, thermohaline circulation, and high latitude albedo. Documenting past variations in Arctic hydrological conditions is important for understanding Arctic climate and the potential response and role of the Arctic in regards to future climate change. Methods for reconstructing past changes in Arctic hydrology from the stratigraphic, isotopic, geochemical and fossil records of lake sediments are being developed, refined and applied in a number of regions. These records suggest that hydrological variations in the Arctic have been regionally asynchronous, reflecting the impacts of different forcing factors including orbitally controlled insolation changes, changes in geography related to coastal emergence, ocean currents, sea ice extent, and atmospheric circulation. Despite considerable progress, much work remains to be done on the development of paleohydrological proxies and their application to the Arctic. 相似文献
11.
《Polar Science》2014,8(2):86-95
Rapid environmental change has been observed in the De Long Islands, Siberian Arctic, where warming has extensively occurred over the area. To quantitatively evaluate glaciological changes since the 1980s, the climate, mass balance, and the equilibrium line altitude (ELA) of Toll Glacier on Bennett Island were analyzed. Air temperature has increased and solid precipitation has decreased since the 1960s, especially after 2000. The cumulative mass balance of Toll Glacier has had a negative trend since the 1960s and reached approximately −20 m water equivalent (w.e.) in 2000, which is one of the largest changes in the Arctic. These changes are much larger than those in the west Russian Arctic. The warming trend is also correlated with the sea ice distribution in the Siberian Arctic and may lead to feedback effects that cause further Arctic warming. 相似文献
12.
We inferred the temperature and environmental conditions of Smreczynski Staw Lake in the Tatra Mountains, southern Poland,
from a sediment record covering the last 1,500 years. Paleobiological methods (cladocera, chironomid, and diatom analyses)
were used together with sedimentological analysis and dating. These studies provide new information about the timing and character
of climate fluctuations during the Little Ice Age (LIA). The Medieval Warm Period ended in the Tatra region at the beginning
of the thirteenth century, followed by the first episode of the LIA. The LIA was a relatively long but unstable period. The
first part of the LIA was cold in the Tatra Mountains, without evidence of increasing precipitation, while the second part,
after AD 1540, was cold and humid. The LIA terminated in the Tatra Mountains at the beginning of the twentieth century, although
some aspects of its climatic and sedimentological regime continued until the 1920s. We also found some evidence of warming
and acidification during the twentieth century. 相似文献
13.
Carsten Braun D. R. Hardy R. S. Bradley 《Geografiska Annaler: Series A, Physical Geography》2004,86(1):43-52
Abstract Small, stagnating ice caps at high latitudes are particularly sensitive to climatic fluctuations, especially with regard to changes in ablation season temperature. We conducted mass balance measurements and GPS area surveys on four small High Arctic plateau ice caps from 1999–2002. We compared these measurements with topographic maps and aerial photography from 1959, and with previously published data. Net mass balance (bn) of Murray Ice Cap was ?0.49 (1999), ?0.29 (2000), ?0.47 (2001), and ?0.29 (2002), all in meters of water equivalent (m w.eq.). The mass balance of nearby Simmons Ice Cap was also negative in 2000 (bn=?0.40 m w.eq.) and in 2001 (bn=?0.52 m w.eq.). All four ice caps experienced substantial marginal recession and area reductions of between 30 and 47% since 1959. Overall, these icecaps lost considerable mass since at least 1959, except for a period between the mid‐1960s and mid‐1970s characterized regionally by reduced summer melt, positive mass balance, and ice cap advance. The regional equilibrium line altitude (ELA) is located, on average, above the summits of the ice caps, indicating that they are remnants of past climatic conditions and out of equilibrium with present climate. The ice caps reached a Holocene maximum and were several times larger during the Little Ice Age (LIA) and their current recession reflects an adjustment to post‐LIA climatic conditions. At current downwasting rates the ice masses on the Hazen Plateau will completely disappear by, or soon after, the mid‐21st century. 相似文献
14.
V.A. POHJOLA J. COLE-DAI G. ROSQVIST A.P. STROEVEN L.G. THOMPSON 《Geografiska Annaler: Series A, Physical Geography》2005,87(1):259-270
ABSTRACT. We have studied a 33.7 m deep ice core from a small polythermal Scandinavian ice cap to determine whether it is possible to recover pre-20th century climatic information from the glacier. Ice structural studies show a significant change from clear ice above 11 m depth (superimposed ice indicating refreezing) to bubbly ice below 11 m depth, indicating this is the transition between Little Ice Age (LIA) and 20th century ice. Calculations with a Nye-age model, along with a mass balance reconstruction, show that this structural boundary likely formed in the last part of the LIA, which in this region ended about 1910. The ice below this boundary was sampled and analysed for stable isotopic composition and ionic content, which both show significant variations with depth. The stable isotope record likely contains cycles of annual duration during the LIA. The chemistry in the ice core indicates that the information is useful, and can be used to interpret climatic and environmental variables during the LIA. A comparison of Riukojietna ion chemistry and oxygen isotope records with similar records from other glaciers in this region reveals a clear continental-maritime gradient. Changes in this gradient with time may be possible to resolve using such ice core records. Results from this study demonstrate that ice cores from glaciers in this climatic environment can be useful in revealing environmental conditions from climatically colder periods and yield pre-industrial benchmark values for chemical loading and oxygen isotopes, but that hiatuses complicate the depth-age relationship. 相似文献
15.
Glacier inventory compilation during the past 20 years and modifications of that for the Eastern Pamir and Banggong Lake indicate that there are 46,342 modern glaciers with a total area and volume of 59415 km^2 and 5601 km^3 respectively in China. These glaciers can be classified into maritime and continental (including sub-continental and extremely continental) types. Researches show that glaciers in China have been retreating since the Little Ice Age and the mass wastage was accelerated during the past 30 to 40 years. Being an important part of glaciological studies in China,ice core climatic and environmental studies on Tibetan Plateau and in the Antarctica have provided abundant, high resolution information about past climatic and environmental evolution over the Tibetan Plateau and Antarctica. Except for different parameters recorded in ice cores relating to climate and environment changes on Tibetan Plateau, records from ice cores extracted from different glaciers show that the discrepancies in climatic and environmental changes on the north and south parts of the plateau may be the consequence of different influencing effects from terrestrial and solar sources.Glaciological and meteorological phenomena imply that Lambert Glacier valley is an important boundary of climate in the east Antarctica, which is thought to be connected with cyclonic activities and Circum-polar Waves over the Antarctica. 相似文献
16.
LIU Shiyin WANG Ninglian DUAN Keqin XIAO Cunde DING Yongjian HAN Haidong 《地理学报(英文版)》2004,14(4):401-410
1IntroductionIn the early 1960s, glaciers in western China were classified into maritime- and continental-types by different glacial environment and physical characteristics (Shi and Xie, 1964). With extensive glaciological investigations in the western regions (Lanzhou Institute of Glaciology and Geocryology of CAS, 1988), Lai and Huang (1990) suggested a new classification of temperate, subpolar and quasipolar glaciers, corresponding to the maritime-, subcontinental- and extremely contin… 相似文献
17.
Glacier inventory compilation during the past 20 years and modifications of that for the Eastern Pamir and Banggong Lake indicate that there are 46,342 modern glaciers with a total area and volume of 59415 km2 and 5601 km3 respectively in China. These glaciers can be classified into maritime and continental (including sub-continental and extremely continental) types. Researches show that glaciers in China have been retreating since the Little Ice Age and the mass wastage was accelerated during the past 30 to 40 years. Being an important part of glaciological studies in China, ice core climatic and environmental studies on Tibetan Plateau and in the Antarctica have provided abundant, high resolution information about past climatic and environmental evolution over the Tibetan Plateau and Antarctica. Except for different parameters recorded in ice cores relating to climate and environment changes on Tibetan Plateau, records from ice cores extracted from different glaciers show that the discrepancies in climatic and environmental changes on the north and south parts of the plateau may be the consequence of different influencing effects from terrestrial and solar sources. Glaciological and meteorological phenomena imply that Lambert Glacier valley is an important boundary of climate in the east Antarctica, which is thought to be connected with cyclonic activities and Circum-polar Waves over the Antarctica. 相似文献
18.
藏南羊卓雍错沉积物元素地球化学记录的过去2000年环境变化 总被引：1，自引：0，他引：1
以青藏高原南部的羊卓雍错（简称羊湖）沉积岩芯为研究对象,以较可靠的年代数据（ 210Pb和AMS 14C交叉定年）为框架,基于高分辨率的元素地球化学记录,通过数理统计分析方法提取环境信息,结合粒度和磁化率,重建该地区过去2000年来的环境变化。结果显示,该区黑暗时代冷期（DCAP）和小冰期（LIA）气候较为寒冷,降水量较高;而中世纪暖期（MWP）和现代暖期（CWP）气候较为温暖,降水量较低,气候具有冷湿—暖干的特征。其中,重建的温度显示,中世纪暖期的温暖程度似乎持平甚至超过20世纪暖期;小冰期期间可能存在一次百年尺度的温暖事件,而17世纪和18世纪可能是过去2000中最寒冷的一段时期。分析发现,过去2000年以来青藏高原南部存在着冷湿—暖干的气候模式;过去2000年青藏高原南部地区温度的变化可能主要受到太阳辐射的影响,而小冰期期间西风环流的南移和增强可能是导致区域降水增加的重要因素。另外,该时期羊湖的湖泊水位的变化受温度和降水共同控制：当温度降低,降水增加时,湖泊水位上升,反之亦然。 相似文献
19.
利用1961年以来美国国家环境预报中心(NCEP)月平均再分析风场、高度场、NOAA重构海表温度以及西北地区中部54个气象站6月逐日降水资料、1979年以来北极10个区域的海冰面积,通过分析2019年6月西北地区中部降水异常的成因,揭示出对该区域6月降水具有显著影响的关键海区海冰面积及时段、北大西洋三极子(NAT)关键影响时段,结合厄尔尼诺-南方涛动(ENSO)事件,分析其协同作用及影响机制。结果表明:1990年以来春季3-4月楚科奇海海冰面积异常容易激发欧亚中高纬度EU2(欧亚2型)遥相关型(即夏季EU(欧亚)遥相关型),有利于西北地区中部降水异常,1992年以来春季NAT对EU2遥相关型有明显影响,但其影响小于楚科奇海海冰面积的影响;当楚科奇海海冰面积偏少和NAT正位相(海冰面积偏多和NAT负位相)协同作用时,西北地区中部降水偏多(偏少)的概率明显增大;ENSO事件对西北地区中部6月降水无明显直接影响,但厄尔尼诺事件次年使得副热带高压异常偏强、偏西。2019年楚科奇海海冰面积异常偏少,春季NAT异常偏强,两者协同作用下使得EU2遥相关型正异常(“+-+-”),尤其使得贝加尔湖附近的阻塞高压异常偏强,鄂霍次克海和乌拉尔山附近低压异常深厚,厄尔尼诺事件使副热带高压异常偏强、偏西,将西太平洋的水汽输送至北太平洋,与鄂霍次克海附近的深厚低压相接,充足的冷空气和水汽导致西北地区中部出现异常降水。研究成果可为短期气候预测提供依据,同时,气-冰-海之间的相互作用需要更进一步研究。 相似文献
20.
近800年来内蒙古岱海地区古气温的定量重建 总被引：13，自引：5，他引：8
根据对现代湖水、现生介形类壳体以及湖泊沉积岩芯中同一种属介形类壳体的Sr/Ca分析,利用现代湖水Sr/Ca与湖水盐度的关系,确定了不同沉积时期湖水盐度;其次,在室内模拟实验,建立了湖水盐度与湖水氧同位素的函数关系;结合210Pb测定沉积速率和14C测年资料,利用沉积剖面的自生碳酸盐氧同位素及由湖水盐度推算的湖水氧同位素组成,定量恢复了不同时期的湖水温度,进而根据碳酸盐结晶时水温与年均气温关系推测了古气温。结果表明:在近800年内蒙古岱海地区的气温变化序列中,中世纪暖期、现代小冰期以及近百年增温均有明显表现。研究时段内,岱海地区中世纪暖期比当代30年的年均气温高1℃以上;在公元1240年左右突然降温过程表现特别突出,在其后约60年的时段内气温下降1.8℃;小冰期最大降温幅度2℃以上,大于华北其它地区。不同于我国西部古里雅冰芯的记录,岱海地区近百年增温程度仍没有达到中世纪暖期水平,预示气候变暖对我国西部地区的影响将大于东部。 相似文献