Rapid changes in the level of Kluane Lake in Yukon Territory over the last millennium

The level of Kluane Lake, the largest lake in Yukon Territory, was lower than at present during most of the Holocene. The lake rose rapidly in the late seventeenth century to a level 12 m above present, drowning forest and stranding driftwood on a conspicuous high-stand beach, remnants of which are preserved at the south end of the lake. Kluane Lake fell back to near its present level by the end of the eighteenth century and has fluctuated within a range of about 3 m over the last 50 yr. The primary control on historic fluctuations in lake level is the discharge of Slims River, the largest source of water to the lake. We use tree ring and radiocarbon ages, stratigraphy and sub-bottom acoustic data to evaluate two explanations for the dramatic changes in the level of Kluane Lake. Our data support the hypothesis of Hugh Bostock, who suggested in 1969 that the maximum Little Ice Age advance of Kaskawulsh Glacier deposited large amounts of sediment in the Slims River valley and established the present course of Slims River into Kluane Lake. Bostock argued that these events caused the lake to rise and eventually overflow to the north. The overflowing waters incised the Duke River fan at the north end of Kluane Lake and lowered the lake to its present level. This study highlights the potentially dramatic impacts of climate change on regional hydrology during the Little Ice Age in glacierised mountains.     

Analysis of dynamic changes and influence factors of Lake Balkhash in the last twenty years

Lake Balkhash is the third largest inland lake in Central Asia after the Caspian Sea and the Aral Sea. The Ili River-Balkash Lake Basin resides in the southeastern part of the Republic of Kazakhstan and the western part of China's Ili Prefecture, which belongs to the arid and semi-arid region. In the middle to late 20th century, the Ili River-Balkash Lake Basin was affected by climate change and human activities, and the problems of water ecology and water resources became increasingly prominent, which became the focus of attention for China and Kazakhstan. In this study, the water level derived from radar altimeter data, the water surface area extracted from Landsat data, and the temperature and precipitation data in the basin were comprehensively utilised. Data analysis of the time course and correlation of hydrological, meteorological elements in the lake basin, water dynamic changes, and influencing factors of Lake Balkhash was studied. The results show that the cyclical change of regional climate is the main factor affecting the change of lake water, and human activities in the short term can regulate the change of water volume in Lake Balkhash. The research results in this paper can provide a scientific basis for the solution of water disputes in cross-border rivers between China and Kazakhstan.     

Late-Holocene paleoenvironmental change at mid-elevation on the Caribbean slope of the Cordillera Central,Dominican Republic: a multi-site,multi-proxy analysis

High-resolution proxy records from the circum-Caribbean region indicate significant variation in Late Holocene climate, especially precipitation, attributed primarily to shifts in the mean annual position of the Intertropical Convergence Zone (ITCZ). The paleoenvironmental and cultural impacts of this Late-Holocene climate variability have been analyzed intensively in the western Caribbean, and to a lesser extent in the southern Caribbean. However, the occurrence and impacts of Late Holocene climate shifts in the eastern Caribbean, especially in island interiors, has not been well documented. Here we present sediment records of Late-Holocene paleoenvironmental change from two lakes located on the Caribbean slope of the Cordillera Central in the Dominican Republic that span the last ～3000 years. Sediment characteristics, pollen, charcoal, biogenic carbonate assemblages and isotopic composition, and bulk sedimentary carbon isotope values in Laguna Castilla and Laguna de Salvador indicate extreme shifts in hydrology, vegetation, and disturbance regimes in response to climate change and human activity in the lake watersheds. Close correspondence between the hydrological histories of the lakes and trace metal concentrations in sediments of the Cariaco Basin indicate that precipitation variability here responds to the same controls, and may similarly reflect shifts in the mean annual position of the ITCZ. Human occupation of the watersheds appears to be closely linked to severe dry periods and may indicate larger scale cultural responses to precipitation variability on the island of Hispaniola. Prehistoric human populations strongly affected vegetation and disturbance regimes in the lake watersheds. Impacts may have lasted several centuries and may have been more severe than impacts of modern populations.     

Analysis of dynamic changes and influence factors of Lake Balkhash in the last twenty years

Lake Balkhash is the third largest inland lake in Central Asia after the Caspian Sea and the Aral Sea.The Ili River-Balkash Lake Basin resides in the southeastern part of the Republic of Kazakhstan and the western part of China's Ili Prefecture,which belongs to the arid and semi-arid region.In the middle to late 20^thcentury,the Ili River-Balkash Lake Basin was affected by climate change and human activities,and the problems of water ecology and water resources became increasingly prominent,which became the focus of attention for China and Kazakhstan.In this study,the water level derived from radar altimeter data,the water surface area extracted from Landsat data,and the temperature and precipitation data in the basin were comprehensively utilised.Data analysis of the time course and correlation of hydrological,meteorological elements in the lake basin,water dynamic changes,and influencing factors of Lake Balkhash was studied.The results show that the cyclical change of regional climate is the main factor affecting the change of lake water,and human activities in the short term can regulate the change of water volume in Lake Balkhash.The research results in this paper can provide a scientific basis for the solution of water disputes in cross-border rivers between China and Kazakhstan.     

Timing and cause of water level fluctuations in Kluane Lake, Yukon Territory, over the past 5000 years

We reconstructed late Holocene fluctuations of Kluane Lake in Yukon Territory from variations in bulk physical properties and carbon and nitrogen elemental and isotopic abundances in nine sediment cores. Fluctuations of Kluane Lake in the past were controlled by changes in climate and glaciers, which affected inflow of Slims and Duke rivers, the two largest sources of water flowing into the lake. Kluane Lake fluctuated within a narrow range, at levels about 25 m below the present datum, from about 5000 to 1300 cal yr BP. Low lake levels during this interval are probably due to southerly drainage of Kluane Lake to the Pacific Ocean, opposite the present northerly drainage to Bering Sea. Slims River, which today is the largest contributor of water to Kluane Lake, only rarely flowed into the lake during the period 5000 to 1300 cal yr BP. The lake rose 7-12 m between 1300 and 900 cal yr BP, reached its present level around AD 1650, and within a few decades had risen an additional 12 m. Shortly thereafter, the lake established a northern outlet and fell to near its present level.     

Multi-level governance of climate change adaptation through regional partnerships in Canada and England

Adaptation to climate change is widely recognized as a multi-level governance challenge because expected impacts and respective measures cut across governmental levels, sectors and societal domains. The present paper analyses the role of regional adaptation partnerships in Canada and England in the multi-level governance of climate change adaptation. We describe and compare three partnerships per country with regard to their evolution, membership and governing structures, coordination across levels and societal domains, and their adaptation activities and outputs. Although both partnership schemes represent new collaborative approaches, their genesis and governance differ. While the Canadian collaboratives are a government-centred approach that originated and partly operated top-down through a national programme for the period 2009–2012, the English partnerships follow a more pluralistic stakeholder-centred approach that evolved bottom-up already in the early 2000s. Both schemes have in common that they mediate between governmental levels, foster networking between public and private actors, and eventually build adaptive capacities and inform adaptation policies. We conclude that regional adaptation partnerships represent a new governance approach that facilitates climate change adaptation, albeit with limits. Since state actors play(ed) key roles in both partnership schemes, they do not represent a new sphere of authority outside the state. Instead of blurring or destabilizing governmental levels they complement (and perhaps even stabilise) them with multi-level interactions.     

Mid-Holocene Hydrologic Model of the Shingobee Watershed, Minnesota

A hydrologic model of the Shingobee Watershed in north-central Minnesota was developed to reconstruct mid-Holocene paleo-lake levels for Williams Lake, a surface-water body located in the southern portion of the watershed. Hydrologic parameters for the model were first estimated in a calibration exercise using a 9-yr historical record (1990–1998) of climatic and hydrologic stresses. The model reproduced observed temporal and spatial trends in surface/groundwater levels across the watershed. Mid-Holocene aquifer and lake levels were then reconstructed using two paleoclimatic data sets: CCM1 atmospheric general circulation model output and pollen-transfer functions using sediment core data from Williams Lake.Calculated paleo-lake levels based on pollen-derived paleoclimatic reconstructions indicated a 3.5-m drop in simulated lake levels and were in good agreement with the position of mid-Holocene beach sands observed in a Williams Lake sediment core transect. However, calculated paleolake levels based on CCM1 climate forcing produced only a 0.05-m drop in lake levels. We found that decreases in winter precipitation rather than temperature increases had the largest effect on simulated mid-Holocene lake levels. The study illustrates how watershed models can be used to critically evaluate paleoclimatic reconstructions by integrating geologic, climatic, limnologic, and hydrogeologic data sets.     

Hydrological and nitrogen distributed catchment modeling to assess the impact of future climate change at Trichonis Lake, western Greece

According to regional climatic models, climate change may affect Mediterranean lakes significantly in terms of water availability and quality. Trichonis Lake catchment covers a semi-mountainous area of 403 km² including the largest Greek lake by volume (2.6?×?10⁹?m³), located in western Greece. The impact of climate change on the hydrology and water quality of the lake, in terms of lake water level and nutrient concentrations, has been assessed. Water balance estimates and geographical information system tools were then used to set up a physically based, spatially distributed model. The calibrated model was simulated for two future scenarios specified by the Intergovernmental Panel on Climate Change: A2 (pessimistic) and B2 (more optimistic), which involved temperature/evaporation/evapotranspiration increase and small precipitation decrease. The model was calibrated efficiently for the 1990–1992 period. The two basic climatic scenarios illustrated that the responses of the lake water levels will show a decrease of 24.2 and 12 cm, respectively, and an increase of total nitrogen concentrations by 3.4 and 10%, in relation to the early 1990s values. These important findings suggest that mitigation and optimum management plans should be developed to eliminate the aforementioned climate change impacts and further research should follow.     

Glacial hazards in the Rolwaling valley of Nepal and numerical approach to predict potential outburst flood from glacial lake

In recent years, climate change and retreating glaciers constitute a major hazard in the Himalaya of South Asia. Glacial lakes are rapidly developing or increasing due to climate change. The rapid development of the lake may cause outburst of the lake. The outburst discharge from the glacial lake can cause catastrophic flooding and disaster in downstream area. Therefore, it is necessary to investigate the impact of climate change on glacial lakes and to understand the characteristics of the glacial lake outburst. In this study, the field assessment of Tsho Rolpa Glacial Lake in the Himalaya of Nepal has been presented and the impact of climate change on this glacial lake has been discussed. The Tsho Rolpa Glacial Lake is the largest and most potentially dangerous glacial lake in Nepal. In addition, a numerical model has been also developed for computing the characteristics of glacial lake outburst due to moraine dam failure by seepage and water overtopping. The numerical model is tested for the flume experimental cases. The simulated results of the outburst discharge, the dam surface erosion, and the temporal variation of the moisture movement in the dam are compared with those obtained from the hydraulic model experiments. The moisture profile calculated by numerical model was agreeable with the experimental moisture profile. The simulated failure surface of the dam due to seepage by considering the suction in slope stability analysis gave more agreeable results than the Janbu's simplified method. The results of the outburst discharge and dam surface erosion also agreed with the experimental results.     

青海湖的形成与演化趋势

青海湖盆地形成于上新世,湖泊至晚在0.5 Ma前已经形成,在初期有流向贵德盆地的出口。湖泊发育主要划分为三个阶段:中更新世湖泊最盛期、晚更新世湖泊稳定期和全新世湖泊收缩期。晚更新世早期由于湖泊强烈沉陷,使河流出口处相对抬高,河水倒流而形成倒淌河。第四纪以来,我国西北地区有气候逐渐变干的趋势,导致全新世以来青海湖不断收缩。如不采取人工措施,青海湖还将继续收缩。     

A social justice framing of climate change discourse and policy: Adaptation,resilience and vulnerability in a Jamaican agricultural landscape

It is now widely recognized that climate change is likely to have detrimental impacts across the Caribbean region, with the burden likely to fall disproportionately on the most vulnerable segments of society. It is therefore an appropriate time to ask whether the frameworks that lie behind climate change discourse and policy are consistent with the demands of social and environmental justice. In this paper, we use climate justice as a lens for evaluating three prominent frameworks for addressing climate change, those of adaptation, resilience, and vulnerability. Each of these discursive frameworks, we argue, can contribute to our understanding of climate change, but they do not all incorporate justice concerns to the same degree. In order to illustrate this, we examine the justice implications of using each of the three frameworks to assess a case study of agricultural transformation in Southwestern Jamaica. Farmers in this region have adapted to changing climate conditions in a variety of ways, including the use of new agricultural technology. The ability of many farmers to take advantage of such innovations, however, is constrained by the underlying landscape of vulnerability within the region. After interpreting this example from the perspectives of adaptation, resilience and vulnerability, we conclude that all three paradigms are capable of calling attention to climate justice issues, but only in the vulnerability perspective are such issues intrinsic. We believe, therefore, that a greater attention to vulnerability within Caribbean climate policy holds the potential to advance the goals of climate justice within the region.     

巴尔喀什湖分湖水平衡及其影响与优化保护研究

巴尔喀什湖是中亚干旱区最大的湖泊生态系统之一,其保护对中亚地区具有重要意义,但同时对相关区域也产生了较大的水资源压力.分析其水量平衡,对提出合理的保障措施具有重要的理论与实践价值.根据巴尔喀什湖形态、水文特征,在分析识别其水量平衡主要影响因素与作用机制的基础上,根据水量平衡原理与东西湖分治的思想,反演了1936-200...     

湖泊沉积物不同粒级组分的元素含量特征及其环境指示意义①——以内蒙古黄旗海为例

黄旗海湖泊柱状沉积物的全样、77~20 μm、<20 μm粒级的钛(Ti)、锰(Mn)、锶(Sr)、銣(Rb)、钡(Ba)、锆(Zr)等元素含量分析表明,元素在湖泊沉积物各粒级组分的丰度存在较大差异:Ti、Zr倾向于在粗颗粒中富集,Mn、Sr、Rb倾向于在细颗粒中富集,Ba的富集粒级不明显。Ti、Zr与Mn、Rb的颗粒粒级富集倾向可能是其硅酸盐矿物颗粒碎化过程的结果,而Sr则与湖泊自生碳酸盐有关。元素比值Zrc/（Rbc+Bac）、Zrc/Rbc与Ti、Zr的粒度效应Tic/Tif、Zrc/Zrf指示了沉积物重、轻矿物的相对比率,是流域侵蚀强度与湖泊涨缩的信息指示;Ba、Rb与Sr在细粒级的含量之比Baf/Srf、Rbf/Srf指示了硅酸盐与碳酸盐矿物的相对含量,是流域风化、侵蚀搬运强度与湖泊过程（包括物理/化学/生物）等混合信息指示,没有明确的环境指向性。     

云南大理地区1989—2019年期间气候变化及对洱海水质的影响

依据1989年至2019年云南大理地区所辖12个气象站点的气候数据和洱海水质监测资料等文献,分析大理地区气候变化特征和洱海富营养化变化趋势,并总结洱海水质综合营养状态指数与降水量、气温的相互关系。结果表明,1989年至2019年期间,大理地区的年平均气温呈波动上升趋势,气候变暖明显,冬季气温升温幅度最大;年降水量总体呈波动下降趋势,秋季降水量减少最为显著。洱海水质的综合营养状态指数及单因子总氮、总磷、高锰酸盐指数等总体呈升高趋势,而水体透明度呈降低趋势;进一步可分成2个阶段,即2003年之前呈快速上升或下降变化趋势;2003年之后呈波动稳定趋势。洱海综合营养状态指数与年平均气温呈正相关,与年降水量呈负相关关系;总氮、水体透明度分别与年平均气温正相关和负相关,与年降水量则呈负相关和正相关;而总磷与冬季平均气温、高锰酸盐指数与夏季或冬季平均气温均呈正相关关系。年内变化上,洱海污染指数、综合营养状态指数在最近的2015—2019年期间呈现6—10月份明显增高,显示非汛期水质明显好于汛期状况。总之,1989—2019年期间,受大理地区气温升高、降水量减少导致入湖水量减少的影响,洱海综合营养状态指数呈升高趋势,湖泊富营养化进程加剧状况没有得到改善,洱海水环境仍然比较脆弱。     

Human impacts, climate change, and aquatic ecosystem response during the past 2000 yr at Lake Wandakara, Uganda

Analyses of carbon and hydrogen isotope ratios of terrestrial leaf waxes and the carbon and nitrogen abundance, ratio, and isotopic composition of bulk sediments from Lake Wandakara, a crater lake in western Uganda, East Africa, document human and climatic controls on the aquatic system and on the surrounding terrestrial vegetation during the past two millennia. Our data indicate that Wandakara was a relatively stable, productive lake surrounded by C₃ vegetation from AD 70 to 1000. Abrupt changes in the δ¹³C of terrestrial leaf waxes indicate a series of abrupt shifts in the relative abundance of C₃ and C₄ vegetation caused by a combination of climate change and human activities around Wandakara beginning at AD 1000. Abrupt shifts in bulk sediment organic geochemistry, particularly C/N ratios and δ¹⁵N, indicate that human activities at this time caused permanent changes in the limnology of Lake Wandakara, including eutrophication. Our results suggest that the biogeochemistry of Lake Wandakara was more sensitive to shifting human impacts than to climate variations during the past millennium, highlighting the importance of understanding the intensity of pre-colonial human impacts on Africa's aquatic ecosystems.     

Assessment of land use/land cover dynamics vis-à-vis hydrometeorological variability in Wular Lake environs Kashmir Valley,India using multitemporal satellite data

Wular Lake, one of the largest freshwater lakes of Jhelum River Basin, is showing signs of deterioration due to the anthropogenic impact and changes in the land use/land cover (LULC) and hydrometeorological climate of the region. The present study investigated the impacts of temporal changes in LULC and meteorological and hydrological parameters to evaluate the current status of Wular Lake environs using multisensor, multitemporal satellite and observatory data. Satellite images acquired for the years 1992, 2001, 2005, and 2008 were used for determining changes in the LULC in a buffer area of 5 km² around the Wular Lake. LULC mapping and change analysis using the visual interpretation technique indicated significant changes around the Wular Lake during the last two decades. Reduction in lake area from 24 km² in 1992 to 9 km² in 2008 (?62.5 %) affected marshy lands, the habitat of migratory birds, which also exhibited drastic reduction from 85 km² in 1992 to 5 km² in 2008 (?94.117 %). Marked development of settlements (642.85 %) in the peripheral area of the Wular Lake adversely affected its varied aquatic flora and fauna. Change in climatic conditions, to a certain extent, is also responsible for the decrease in water level and water spread of the lake as witnessed by decreased discharge in major tributaries (Erin and Madhumati) draining into the Wular Lake.     

岱海湖开发利用中存在问题及对策研究

岱海湖位于内蒙古自治区乌兰察布市凉城县境内,是内蒙古第三大湖泊.近年来,受干旱气候和人类活动的影响,湖水成化、湖盆萎缩,流域内水土流失、水体污染加剧,生态环境问题突出.为促进岱海湖环境发展,分析岱海湖开发利用中存在问题,提出流域治理与环境保护的对策具有十分重要的意义.     

青海湖滩坝分布规律及其古气候意义

青海湖是我国最大的内陆湖盆,对气候变化十分敏感,而滩坝是青海湖滨浅湖带最为发育的沉积类型之一,其滩坝分布规律对晚更新世以来的古气候演化具有重要指示意义。在对青海湖一郎剑剖面进行实地考察的基础之上,对滩坝的分布规律及沉积特征进行精细解剖。通过分析总结前人相关测年数据,并与青海湖滩坝分布规律进行对比,发现青海湖湖平面升降对滩坝分布有明显的控制作用,建立了18 ka以来青海湖滩坝的演化过程,并将近18 ka以来青海湖湖平面升降史分为4个阶段:(1)更新世末温湿期,湖平面在海拔3 197～3 202 m附近波动;(2)全新世冷干期,湖平面近乎干涸;(3)全新世大暖期,湖平面处于全新世以来的最高值,约为3 212 m;(4)全新世凉湿期,湖平面回落到3 200 m附近,并在近2. 5 ka湖平面加速下降。在晚更新世和晚全新世时,湖平面在海拔3 202 m附近波动时间较长,在该海拔范围内,形成了规模较大的复合滩坝;在早全新世,青海湖平面最低,多发育风成黄土和潟湖沉积;在中全新世,湖平面最高,形成了距离现今湖平面最远的数列单体滩坝。     

粒度和元素证据指示的居延海1.5kaBP来环境演化

居延海是黑河的终端湖, 在最近3 000 a来已由原来面积 800 km2逐渐萎缩而最终干涸, 同时其周边环境也发生了巨大的变化.东居延海(索果诺尔)湖相沉积的粒度和元素资料研究结果表明: 明清以前湖泊的变化主要受气候变化的影响, 温暖时期, 气候偏湿, 入湖水量增多, 湖泊面积扩大, 流域化学风化作用增强; 寒冷时期, 气候偏干, 入湖水量减小, 湖泊萎缩, 流域化学风化作用减弱.明清之后特别是近40 a来, 由于黑河上中游地区大规模的土地开发及水资源利用, 入湖水量不断减小, 甚至河流断流, 最终导致了目前居延海的干涸.     

Effects of climatic changes and anthropogenic activities on lake eutrophication in different ecoregions

Climatic changes and anthropogenic activities could affect nutrients?? status significantly in the different lake ecosystems. Nutrients in Lake Hulun and Lake Taihu, two largest shallow cyanobacteria-blooming lakes in northern and southern China, respectively, were at eutrophicated levels in 2009. The concentrations of total nitrogen and total phosphorus were 3.346 and 2.250?mg/L as well as 0.435 and 0.062?mg/L, respectively, in these two lakes with different causes of eutrophication. For Lake Hulun, it was the decreased amount of water as a result of the warming and drying climate that accounted for the abrupt increase of total nitrogen and total phosphorus levels through inspissation. In addition, the icebound effects, no outflows, low nutrients sequestration by the sediment and the reduction of aquatic productivity made the situation even worse. On the contrary, high population densities, the rapid development of agriculture and industry as well as urbanization have increased the nitrogen and phosphorus loads on Lake Taihu. Therefore, higher criteria of total nitrogen and total phosphorus should be applied in Lake Hulun given the difficulties in controlling climatic changes while much more rigorous standards should be established for Lake Taihu since the anthropogenic impacts on nutrient status are relatively easy to control.