Long-term variability in Arctic sea surface temperatures

In this study, we used 30 years of an operational sea surface temperature (SST) product, the NOAA Optimum Interpolation (OI) SST Version 2 dataset, to examine variations in Arctic SSTs during the period December 1981–October 2011. We computed annual SST anomalies and interannual trends in SST variations for the period 1982–2010; during this period, marginal (though statistically significant) increases in SSTs were observed in oceanic regions poleward of 60°N. A warming trend is evident over most of the Arctic region, the Beaufort Sea, the Chuckchi Sea, Hudson Bay, the Labrador Sea, the Iceland Sea, the Norwegian Sea, Bering Strait, etc.; Labrador Sea experienced higher temperature anomalies than those observed in other regions. However, cooling trends were observed in the central Arctic, some parts of Baffin Bay, the Kara Sea (south of Novaya Zemlya), the Laptev Sea, the Siberian Sea, and Fram Strait. The central Arctic region experienced a cooling trend only during 1992–2001; warming trends were observed during 1982–1991 and 2002–2010. We also examined a 30-yr (1982–2011) record of summer season (June–July–August) SST variations and a 29-yr (1982–2010) record of September SST variations, the results of which are discussed.     

Modeling Arctic Ocean heat transport and warming episodes in the 20th century caused by the intruding Atlantic Water

This study investigates the Arctic Ocean warming episodes in the 20th century using both a high-resolution coupled global climate model and historical observations .The model,with no flux adjustment,reproduces well the Atlantic Water core temperature(AWCT) in the Arctic Ocean and shows that four largest decadal-scale warming episodes occurred in the 1930s,70s,80s,and 90s,in agreement with the hydrographic observational data.The difference is that there was no pre-warming prior to the 1930s episode,while there were two pre-warming episodes in the 1970s and 80s prior to the 1990s,leading the 1990s into the largest and prolonged warming in the 20th century.Over the last century,the simulated heat transport via Fram Strait and the Barents Sea was estimated to be,on average,31.32 TW and 14.82 TW,respectively,while the Bering Strait also provides 15.94 TW heat into the western Arctic Ocean.Heat transport into the Arctic Ocean by the Atlantic Water via Fram Strait and the Barents Sea correlates significantly with AWCT(C=0.75 ) at 0- lag.The modeled North Atlantic Oscillation(NAO) index has a significant correlation with the heat transport(C=0.37).The observed AWCT has a significant correlation with both the modeled AWCT(C=0.49) and the heat transport(C=0.41). However,the modeled NAO index does not significantly correlate with either the observed AWCT(C=0.03) or modeled AWCT(C=0.16) at a zero-lag,indicating that the Arctic climate system is far more complex than expected.     

Early Holocene deglaciation of the eastern coast of Hudson Bay

The final stage of deglaciation of Hudson Bay was a major Holocene catastrophic event marked by the drainage of Lake Agassiz/Ojibway at ~ 8.47 ka cal BP and the rapid collapse of the Laurentide Ice Sheet. Previous work undertaken in the Nastapoka River area (eastern Hudson Bay) demonstrated that during the relative sea level highstand that shortly followed the drainage of the lake, the western margin of the Québec–Labrador ice sector rapidly retreated eastward to reach a stillstand position in a coastal hill range. In this study, an analysis of Landsat 7TM images has allowed a mapping of large-scale glacial landforms (outwash deposits, eskers, flutings, and De Geer and Rogen moraines) between Kuujjuaraapik (SE Hudson Bay) and Puvirnituq (NE Hudson Bay). The key results from this mapping are: i) ice-contact outwash deposits mapped along the entire arc-shaped coastline of the eastern Hudson Bay outline a major ice stillstand phase in the coastal hills that extended at least from Kuujjuaraapik to Inukjuak. The presence of these hills allowed a stabilisation of the ice margin that led to the accumulation of thick and extensive ice-contact submarine fans. ii) The position of these deposits on the down ice side (west) of large sets of flutings indicates an important phase of sediment delivery by a rapid ice flow phase toward a marine-based ice margin. iii) A second system of outwash deposits observed farther inland indicates a subsequent phase of stabilisation of the ice margin during its retreat toward central Québec–Labrador.     

Changes in air temperature over China in response to the recent global warming hiatus

The 1998-2012 global warming hiatus has aroused great public interest over the past several years. Based on the air temperature measurements from 622 meteorological stations in China, the temperature response to the global warming hiatus was analyzed at national and regional scales. We found that air temperature changed -0.221℃/10a during 1998-2012, which was lower than the long-term trend for 1960-1998 by 0.427℃/10a. Therefore, the warming hiatus in China was more pronounced than the global mean. Winter played a dominant role in the nationwide warming hiatus, contributing 74.13%, while summer contributed the least among the four seasons. Furthermore, the warming hiatus was spatial heterogeneous across different climate conditions in China. Comparing the three geographic zones, the monsoon region of eastern China, arid region of northwestern China, and high frigid region of the Tibetan Plateau, there was significant cooling in eastern and northwestern China. In eastern China, which contributed 53.79%, the trend magnitudes were 0.896℃/10a in winter and 0.134℃/10a in summer. In the Tibetan Plateau, air temperature increased by 0.204℃/10a, indicating a lack of a significant warming hiatus. More broadly, the warming hiatus in China may have been associated with the negative phase of PDO and reduction in sunspot numbers and total solar radiation. Finally, although a warming hiatus occurred in China from 1998 to 2012, air temperature rapidly increased after 2012 and will likely to continuously warm in the next few years.     

The role of Pacific water in the dramatic retreat of arctic sea ice during summer 2007

A model study is conducted to examine the role of Pacific water in the dramatic retreat of arctic sea ice during summer 2007.The model generally agrees with the observations in showing considerable seasonal and interannual variability of the Pacific water inflow at Bering Strait in response to changes in atmospheric circulation. During summer 2007 anomalously strong southerly winds over the Pacific sector of the Arctic Ocean strengthen the ocean circulation and bring more Pacific water into the Arctic than the recent(2000-2006) average.The simulated summer(3 months) 2007 mean Pacific water inflow at Bering Strait is 1.2 Sv,which is the highest in the past three decades of the simulation and is 20%higher than the recent average.Particularly ,the Pacific water inflow in September 2007 is about 0.5 Sv or 50%above the 2000-2006 average.The strengthened warm Pacific water inflow carries an additional 1.0×10~(20) Joules of heat into the Arctic,enough to melt an additional 0.5 m of ice over the whole Chukchi Sea.In the model the extra summer oceanic heat brought in by the Pacific water mainly stays in the Chukchi and Beaufort region,contributing to the warming of surface waters in that region.The heat is in constant contact with the ice cover in the region in July through September.Thus the Pacific water plays a role in ice melting in the Chukchi and Beaufort region all summer long in 2007,likely contributing to up to 0.5 m per month additional ice melting in some area of that region .     

对气候变暖问题争议的分析

综合评述和分析了近年来关于全球气候变暖问题的研究。重点是有关气候变暖的一些争议。目前的结论是:(1)19世纪中期以来全球平均地表气温上升了0.4～0.8℃;(2)全球气候变暖的论断得到了海洋温度、大气温度、钻孔温度、陆地雪盖、海冰及冰川资料的支持;(3)1998年是近一个半世纪有观测资料以来最暖的一年,对1961～1990年平均的距平为0.55℃。20世纪变暖的趋势为0.066℃/10a;(4)1990′s是20世纪最暖的10年,平均气温距平0.35℃,也可能是500a或者甚至1000a来最暖的10年。所以,20世纪气候的变暖是无可怀疑的。人类活动影响很可能是20世纪气候变暖的主要原因,至少是主要原因之一。     

中国气温变化对全球变暖停滞的响应

1998-2012年出现的全球变暖停滞（global warming hiatus）现象,近年来受到各界的广泛关注。基于中国622个气象站的气温数据,研究了全国及三大自然区气温变化对全球变暖停滞的响应。结果表明：① 1998-2012年间,中国气温变化率为-0.221 ℃/10 a,较1960-1998年增温率下降0.427 ℃/10 a,存在同全球变暖停滞类似的增温减缓现象,且减缓程度更明显,其中冬季对中国增温减缓的贡献最大,贡献率为74.13%,夏季最小;② 中国气温变化对全球变暖停滞的响应存在显著的区域差异,从不同自然区看,1998-2012年东部季风区和西北干旱区降温显著,其中东部季风区为中国最强降温区,为全国增温减缓贡献了53.79%,并且具有显著的季节依赖性,减缓期冬季气温下降了0.896 ℃/10 a,而夏季上升了0.134 ℃/10 a。青藏高寒区1998-2012年增温率达0.204 ℃/10 a,对全球变暖停滞的响应并不显著;③ 中国增温减缓可能受太平洋年代际振荡（PDO）负相位、太阳黑子数与太阳总辐照减小等因素的影响;④ 1998-2012年中国虽出现增温减缓现象,但2012年之后气温快速升高,且从周期变化看,未来几年可能持续升温。     

Clutch, egg and body size variation among common eiders breeding in Hudson Bay, Canada

The Hudson Bay common eider ( Somateria molissima sedentaria ) is a unique subspecies of eider that remains within the confines of Hudson Bay throughout the year. We compared clutch, egg and body size variation among populations of common eiders breeding in eastern and western Hudson Bay. Clutch size did not differ substantially among these populations. All eiders in Hudson Bay laid larger clutches than other subspecies in eastern North America. As Hudson Bay common eiders do not undergo extensive migrations, they may have more energy reserves available to them for egg production. Eiders nesting in eastern Hudson Bay laid larger eggs than eiders nesting in western Hudson Bay. Further, eiders in eastern Hudson Bay tended to be structurally larger, but had smaller bill processes. These differences may have a genetic basis. Smaller egg size and body size may arise in western Hudson Bay from mixing with the smaller borealis subspecies nesting to the north. Further work to resolve genetic affinities, determine levels of male and female dispersal, and examine variation in reproductive ecology are needed to resolve the sources of these differences.     

Response of Plant Community Carbon and Nitrogen Stoichiometry to Experimental Warming on the Qinghai-Tibet Plateau

Low temperature is an important limiting factor for alpine ecosystems on the Tibetan Plateau. This study is based on data from on-site experimental warming platforms (open top chambers, OTC) at three elevations (4300 m, 4500 m, 4700 m) on the Qinghai-Tibet Plateau. The carbon and nitrogen stoichiometry characteristics of plant communities, both above-ground and below-ground, were observed in three alpine meadow ecosystems in August and September of 2011 and August of 2012. Experimental warming significantly increased above-ground nitrogen content by 21.4% in September 2011 at 4500 m, and reduced above-ground carbon content by 3.9% in August 2012 at 4300 m. Experimental warming significantly increased below-ground carbon content by 5.5% in August 2011 at 4500 m, and the below-ground ratio of carbon to nitrogen by 28.0% in September 2011 at 4300 m, but reduced below-ground nitrogen content by 15.7% in September 2011 at 4700 m, below-ground carbon content by 34.3% in August 2012 at 4700 m, and the below-ground ratio of carbon to nitrogen by 37.9% in August 2012 at 4700 m. Experimental warming had no significant effect on the characteristics of community carbon and nitrogen stoichiometry under other conditions. Therefore, experimental warming had inconsistent effects on the carbon and nitrogen stoichiometry of plant communities at different elevations and during different months. Soil ammonium nitrogen and nitrate nitrogen content were the main factors affecting plant community carbon and nitrogen stoichiometry.     

1960—2019年西北地区气候变化中的Hiatus现象及特征

1998—2012年全球地表平均温度发生变暖停滞（Hiatus）,然而Hiatus现象是否在全球各地均存在尚有争议,其在西北地区的表现及特征缺乏深入研究。本文基于1960—2019年气温地面观测数据,利用累积距平曲线、Mann-Kendall突变检验、滑动t检验及Yamamoto检验进行气候突变分析,结合线性倾向估计进行气候变化趋势分析,对西北地区气候变化中的Hiatus现象及其特征进行了探讨。结果表明：① 西北地区年均气温在1986年、1996年和2012年分别突变,1996年突变升温后在1998—2012年间保持高位震荡;② 1998—2012年间西北地区年均温变化率为-0.20 ℃/10a,呈现明显Hiatus现象,分季节看,冬季降温幅度最大,夏季仍保持升温,春季均温比秋、冬季提前1年开始和结束停滞期,从空间上看,西北地区东南部降温最显著,青藏高原不存在Hiatus;③ 2012年Hiatus结束后西北地区气温普遍快速升高,季节上以冬季升温最快,空间上以南疆升温最快。综合来看,1998—2012年的Hiatus现象在除青藏高原外的西北地区表现明显,停滞后的快速升温值得高度关注。     

中国绿洲喜温作物气候生长期对全球变暖停滞响应的时空差异

基于中国绿洲喜温作物分布区67个地面气象站1960—2016年逐日平均气温数据,运用线性趋势法、反距离加权（IDW）、Morlet小波分析法、Mann-Kendall检验等方法,分析了中国绿洲喜温作物气候生长期生长初、终日及生长期的时空变化对全球变暖停滞（globe warming hiatus）的响应。结果表明：1998—2012年中国绿洲喜温作物气候生长期生长初、终日及生长期变化倾向率分别为：-2.15 d·（10 a）^–1、2.76 d·（10 a）^–1、4.91 d·（10 a）^–1,与1960—2016年和1960—1998年相比呈现出初日提前、终日推迟、生长期延长的态势,没有出现对全球变暖停滞的响应;空间变化方面,仅有超过22%的站点有对全球变暖停滞的响应,整体响应不显著;但各绿洲对全球变暖停滞的响应却不尽相同,柴达木绿洲喜温作物气候生长期对全球变暖停滞的响应最为显著,其余绿洲则反之,也反映了青藏高原是气候变化的驱动器与放大镜。突变分析显示,研究区喜温作物生长初日、终日及生长期分别在2008年、2001年、2006年发生突变,突变年份多集中于变暖停滞期,之后的变化趋势显示对全球变暖停滞没有响应。Morlet小波分析表明其周期存在2.4~3.8 a的优势短周期,与2~4 a大气环流和厄尔尼诺事件2~7 a的周期相吻合,表明喜温作物气候生长期主要受大气环流与厄尔尼诺活动的影响。     

Recent decay of a single palsa in relation to weather conditions between 1996 and 2000 in Laivadalen, northern Sweden

This study presents the decay of a small palsa complex between 1996 and 2000 in Sweden's southernmost major palsa bog. The outline of the palsa was mapped during three summers in 1996, 1999 and 2000 and an automatic weather station measured air temperature, precipitation, snow depth, wind speed and wind direction between 1997 and 2000. The decay of the palsa was enormous in the dome–shaped part of the palsa complex: the height decreased during the observation period from 2.3 m to 0.5 m. In 2000, the palsa dome had almost totally disappeared: only some peat blocks in a palsa pond were left. The decay of the palsa was complex with a number of degradational processes, of which the main processes were block erosion, thermokarst and wind erosion. Thermal melting has occurred along the edges of the palsa and possibly below the frozen core of the palsa since 1998/99. Wind erosion was observed during summer and the maximum estimated deflation was 80 cm. The decay of the palsa dome was especially large between 1999 and 2000, probably due to a high mean annual temperature, high summer precipitation and the warming influence of the large pond surrounding the palsa. The present climate in the palsa bog with a mean annual temperature of −0.8°C is not favourable for palsa development and maintenance, despite a strong wind regime which can provide suitable conditions for snowdrift.     

Trends and variability of sea ice in Baffin Bay and Davis Strait, 1953–2001

The extent and duration of sea ice in Baffin Bay and Davis Strait has a major impact on the timing and strength of the marine production along West Greenland. The advance and retreat of the sea ice follows a predictable pattern, with maximum extent typically in March. We examine the area of sea ice in March in three overlapping study regions centred on Disko Bay on the west coast of Greenland. Sea ice concentration estimates derived from satellite passive microwave data are available for the years 1979-2001. We extend the record back in time by digitizing ice charts from the Danish Meteorological Institute, 1953-1981. There is reasonable agreement between the chart data and the satellite data during the three years of overlap: 1979-1981. We find a significant increasing trend in sea ice for the 49-year period (1953-2001) for the study regions that extend into Davis Strait and Baffin Bay. The cyclical nature of the wintertime ice area is also evident, with a period of about 8 to 9 years. Correlation of the winter sea ice concentration with the winter North Atlantic Oscillation (NAO) index shows moderately high values in Baffin Bay. The correlation of ice concentration with the previous winter's NAO is high in Davis Strait and suggests that next winter's ice conditions can be predicted to some extent by this winter's NAO index.     

1980—2019年中国西北地区降雪和融雪时空变化特征北大核心CSCDCSSCI

西北地区降雪和融雪特征的长期变化对于融雪洪水过程的准确模拟具有重要意义。本研究基于1961—1979年站点观测的日降水和气温等数据,首先对比了湿球温度法、KS方法和双临界气温法计算的降雪量,确定了精度最高的双临界气温方案,进而计算了1980—2019年的日雪雨比,最后分析了雪雨比、降雪开始日期和融雪开始日期的变化规律。结果包括:①春季平均气温呈显著上升趋势,随海拔上升升温速率减小,青藏高原地区、东南部半干旱区、半湿润区春季气温上升速率略低于北疆、南疆、河西走廊及内蒙古西部,春季雪雨比在海拔1000 m以上呈显著下降趋势,在青藏高原地区、东南部半干旱区、半湿润区呈显著下降趋势;秋季平均气温显著上升,随海拔上升升温速率增大,空间上在青藏高原地区上升速率最快,秋季雪雨比在不同海拔和部分气候分区都呈不显著下降趋势;冬季平均气温在海拔2000 m以上呈现显著升温,且随着海拔的升高升温速率加快,空间上在青藏高原地区、东南部半干旱区、半湿润区呈现显著升温,降雪量在1000~2000 m呈现显著增加趋势,空间上在北疆地区呈现显著增加趋势。②降雪开始日期随着温度的升高在所有区域都没有显著的推迟,每一年的降雪开始日期在不同高程带和不同气候区之间的差别没有变化,仍为30~40d。③融雪开始日期在所有海拔区间和气候分区都呈现出显著的提前趋势,每一年的融雪开始的日期在不同高程带和不同气候区的差别仍为25~30d。降雪和融雪特征的变化说明气候变化可能已经对融雪洪水的特征产生了明显的影响。     

气候变化对中亚天山山区水资源影响研究

本文结合资料分析和文献阅读,对全球气候变化背景下的中亚天山山区水文、水资源变化进行了讨论分析。在全球升温滞缓背景下,中亚天山山区在过去的10余年,气温却一直处于高位态波动状态;气候变暖及持续高位态波动加剧了山区冰川和积雪等固态水体的消融,导致山区降雪率降低,天山山区降雪率从1960-1998年的11%~24%降低到2000年以来的9%~21%,有97.52%的冰川表现为退缩状态,水储量呈明显减少趋势,减小幅度约为-3.72 mm/a;气候变暖直接影响区域水循环和水系统的稳定性,引起径流补给方式和水资源数量的改变,加大了水资源时空分布的不确定性。天山山区在短时期内因冰雪融水增多,会出现径流量增加现象。但在未来气候持续变暖、降水条件维持不变的条件下,河川径流量将会出现减少趋势。     

南极布兰斯菲尔德海峡沉积物的地磁场长期变与定年

对位于布兰斯菲尔德海峡东北部的沉积物岩心D1-7进行了初步环境磁学和古地磁研究,获得了连续的相对地磁场强度和方向。沉积物岩性总体为灰色软塑性粘土,中下部出现一层黑色火山灰层。结合该孔沉积物和有孔虫AMS¹⁴C测年结果（王汝建等未发表资料）,相对地磁场强度及其方向提供了12 ka以来连续的定年标尺,其中相对地磁场强度与具有相似沉积速率的南美Laguna Potrok Aike湖泊记录对比提供了六个对比点;同时特征剩磁倾角和磁偏角提供了另外六个对比点。磁化率各向异性分析揭示了全新世早、中和晚期岩心所在位置底流（南极深层水~1000 m）发生了阶段性显著变化,同时磁性矿物含量、粒度、沉积物湿密度等也发生了相应的变化。这些环境磁学和沉积学的变化主要受控于南极相应纬度处的太阳辐射量以及与辐射量相关的夏季季风降水量的变化,降水量增加导致磁性矿物粒度变细。D1-7也记录了一些千年尺度旋回变化,但是南极地区目前缺乏与之相似分辨率的气候参数记录,无法进一步探讨这些气候事件的缘起和分布范围。对比发现,地磁场长期变产生的年龄与沉积物全样有机碳AMS¹⁴C测年结果之间存在系统的差异,在6 ka以来比有机碳年龄年轻,在6 ka之前则比有机碳年龄老。南极布兰斯菲尔德海峡内各种不同水体的混合以及在全新世全球升温背景下冰川的动态变化和由此引起的中、深层水变化,都是造成水体性质复杂的原因。而地磁场强度和方向变化则不受水体性质的影响,因此可以提供更合理的年龄信息。自12 ka至今,25 cm/ka的平均沉积速率表明南极布兰斯菲尔德海峡地区整个全新世内稳定和丰富的沉积物供应。     

Numerical simulations of the influence of the seasonal snow cover on the occurrence of permafrost at high latitudes

It has repeatedly been reported that snow cover is a dominating factor in determining the presence or absence of permafrost in the discontinuous and sporadic permafrost regions. The temperature at the snow-soil interface by the end of winter, known as the bottom temperature of winter snow (BTS) method, has been used to detect the existence of permafrost in European alpine regions when the maximum snow depth is about 1.0 m or greater. A critical snow thickness of about 50 cm or greater can prevent the development of permafrost in eastern Hudson Bay, Canada. The objective of this study is to investigate the impact of snow cover on the presence or absence of permafrost in cold regions through numerical simulations. A one-dimensional heat transfer model with phase change and a snow cover regime is used to simulate energy exchange between deep soils and the atmosphere. The model has been validated against the in situ data in the Arctic. The simulation results indicate that both snow depth and the onset date of snow cover establishment are important parameters in relation to the presence or absence of permafrost. Early establishment of snow cover can make permafrost disappear, even with a relatively thin snow cover. Permafrost may survive when snow cover starts after the middle of December even with a snow thickness >1.0 m. This effect of snow cover on the ground thermal regime can be explained with reference to the pattern of seasonal temperature variation. Early establishment of snow cover enhances the insulating impact over the entire cold season, thus warming and eventually thawing the permafrost. The insulating effect is substantially reduced when snow cover starts relatively late and snowmelt in the spring creates a huge heat sink, resulting in a favorable combination for permafrost existence.     

Interannual variability in water masses in the Greenland Sea and adjacent areas

Oceanographic data covering the period 1950–1998 are used to determine interannual variations in the convection intensity and water mass structure in the Greenland Sea and adjacent areas. Extremely cold winters throughout 1965–1970 assisted intensification of the water vertical exchange in the Greenland and Norwegian seas. As a result, cold and fresh Greenland Sea Deep Water (GSDW) production was extremely high in the central Greenland Sea while in the southern Norwegian Sea warm and salty water spread downwards. The recent rapid warming in the Greenland Sea Gyre interior from 1980 originates, we argue, from an increase in the Atlantic Water (AW) temperature due to the advection of warm waters into the region with the Return Atlantic Current. The negative water temperature and salinity trends in the upper 300 m layer of the Atlantic Water in the Norwegian Sea prevailed during 1950–1990, whereas during 1980–1990 the water temperature trends are indicative of warming of that layer. Observation series obtained onboard the Ocean Weather Ship Mike confirmed the existence of layers with advectiondriven high oxygen concentrations in intermediate and deep layers. The depth of oxygen maxima and the values of oceanographic parameters at this horizon can be regarded as indicators of the convection intensity in the Arctic domain. A simultaneous rise in NAO index and GSDW temperature points to a link between atmospheric and thermohaline circulation. Weakening in water exchange with the North Atlantic could be the reason for the Polar Water recirculation increase within the Nordic seas.     

A fault plane solution using theoretical P seismograms

We use the method of Hudson and Douglas, Hudson & Blarney to compute seismograms which simulate the codas of 10 short period P -wave seismograms from a shallow earthquake. The polarities and relative amplitudes of P and pP measured from seven of the observed seismograms are used to compute a fault plane solution with confidence limits, assuming that the source radiates as a double couple. This solution is in approximate agreement with that given for the same earthquake by Sykes & Sbar, who used only the onset polarities of short-period P waves. The small difference between the two solutions can be explained by interference between the true first motion of P and microseismic noise at two stations.
The results show that, for some shallow earthquakes, the relative amplitude method has the following advantages over the first motions method. First, a P/pP amplitude ratio (with appropriate confidence limits) can always be measured, even in seismograms which are so noisy that the first motion of P is uncertain. Second, the fault plane solutions obtained from relative amplitudes have known confidence limits. Finally, by using more information from each seismogram, the relative amplitude method requires considerably fewer seismograms than the first motions method.     

Fifty years of meteo-glaciological change in Toll Glacier,Bennett Island,De Long Islands,Siberian Arctic

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.