Institutions,indigenous peoples,and climate change adaptation in the Canadian Arctic

GeoJournal - Climate change impacts on Indigenous peoples in remote regions pose unique institutional challenges and opportunities for governments. Reducing vulnerability and enabling collaborative...     

Noble gas and isotope geochemistry in western Canadian Arctic watersheds: tracing groundwater recharge in permafrost terrain

In Canada’s western Arctic, perennial discharge from permafrost watersheds is the surface manifestation of active groundwater flow systems with features including the occurrence of year-round open water and the formation of icings, yet understanding the mechanisms of groundwater recharge and flow in periglacial environments remains enigmatic. Stable isotopes (δ¹⁸O, δD, δ¹³C_DIC), and noble gases have proved useful to study groundwater recharge and flow of groundwater which discharges along rivers in Canada’s western Arctic. In these studies of six catchments, groundwater recharge was determined to be a mix of snowmelt and precipitation. All systems investigated show that groundwater has recharged through organic soils with elevated P_CO2, which suggests that recharge occurs largely during summer when biological activity is high. Noble gas concentrations show that the recharge temperature was between 0 and 5 °C, which when considered in the context of discharge temperatures, suggests that there is no significant imbalance of energy flux into the subsurface. Groundwater circulation times were found to be up to 31 years for non-thermal waters using the ³?H-³He method.     

Sea ice variations in the central Canadian Arctic Archipelago during the Holocene

A sea ice record for Barrow Strait in the Canadian Arctic Archipelago (CAA) is presented for the interval 10.0–0.4 cal. kyr BP. This Holocene record is based primarily on the occurrence of a sea ice biomarker chemical, IP₂₅, isolated from a marine sediment core obtained from Barrow Strait in 2005. A core chronology is based on ¹⁴C AMS dating of mollusc shells obtained from ten horizons within the core. The primary IP₂₅ data are compared with complementary proxy data obtained from analysis of other organic biomarkers, stable isotope composition of bulk organic matter, benthic foraminifera, particle size distributions and ratios of inorganic elements. The combined proxy data show that the palaeo-sea ice record can be grouped according to four intervals, and these can be contextualised further with respect to the Holocene Thermal Maximum (HTM). Spring sea ice occurrence was lowest during the early–mid Holocene (10.0–6.0 cal. kyr BP) and this was followed by a second phase (6.0–4.0 cal. kyr BP) where spring sea ice occurrence showed a small increase. Between 4.0 and 3.0 cal. kyr BP, spring sea ice occurrence increased abruptly to above the median and we associate this interval with the termination of the HTM. Elevated spring sea ice occurrences continued from 3.0 to 0.4 cal. kyr BP, although they were more variable on shorter timescales. Within this fourth interval, we also provide evidence for slightly lower and subsequently higher spring sea ice occurrence during the Mediaeval Warm Period and the Little Ice Age respectively. Comparisons are made between our proxy data with those obtained from other palaeo-climate and sea ice studies for the CAA.     

Periglacial sediment variations controlled by late Quaternary climate and lake level change at Elgygytgyn Crater, Arctic Siberia

Late Quaternary sediments in a permafrost environment recovered from the Elgygytgyn Impact Crater were studied to determine regional palaeoenvironmental variability and infer past water-level changes of the crater lake. Stratigraphic analysis of a 5 m long permafrost core is based on various lithological (grain size, total organic carbon, magnetic susceptibility) and hydrochemical (oxygen isotope composition, major cation content) properties and pore ice content. The results show that alluvial sediments accumulated on top of cryogenically weathered volcanic rock. Changes in the hydrochemical properties reflect different stages of cryogenic weathering. The lithological characteristics mark the transition from an erosive site to a site with accumulation. This environmental change is linked to a relative lake level highstand at >13 000 yr BP, when a shoreline bar was formed leading to slope sedimentation. Lake level dropped by 4 m during the Holocene.     

气温变化对多年冻土斜坡稳定性的影响

受气温变化影响,浅层冻土滑坡失稳涉及水分的固液相态转换,是一个复杂的水热力耦合过程。为揭示气温变化对多年冻土斜坡稳定性的影响,基于冻土水热力耦合数值模型,模拟了2020—2024年青海省多年冻土区斜坡水热力演化过程。研究结果表明：水分迁移速率呈周期性变化,每年5—10月活动层融化程度高,总体积含水率变化趋势显著;夏季多年冻土上限以下的高含冰量土层融化产生厚度约15 cm的富水层,孔隙水压难以消散;4年间多年冻土上限下移10.4 cm,导致活动层和富水层的厚度增大,上覆融土下滑力增大、抗滑力减小,土体抗剪强度进一步下降;活动层土体每年产生数厘米冻胀融沉变形,抗剪强度不断劣化,坡脚处最容易形成薄弱带。     

Hydraulic geometry change of a large river: a case study of the upper Yellow River

Study on hydraulic geometry can reveal the response of river systems to basin attributes, and the trends in channel change. Based on 35 years of data collected at 10 hydrological stations (cross-sections), the hydraulic geometry relations between cross-sectional variables and discharge were established, and the derived parameters were analyzed. The channel behavior of the mountainous bedrock reach (from riverhead to Xunhua cross-section) and the alluvial reach (from Xunhua to Toudaoguai cross-sections) differed significantly over the past decades in response to dramatic water and sediment changes. The hydraulic geometry quasi-equilibrium was achieved through equally adjusting water depth and flow velocity in the mountainous bedrock reach; while primarily through flow velocity in the alluvial reach. The change rate of river width with varying discharge was relatively small in the whole upper Yellow River. Compared with the lower Yellow River and other rivers in the world, both similarity and differences existed, indicating the general adjustment direction of hydraulic quasi-equilibrium and also the importance of considering other influencing factors in hydraulic geometry studies. In addition, dams played an important role in affecting the changes of hydraulic geometry exponents.     

Evidence for the enhanced lability of dissolved organic matter following permafrost slope disturbance in the Canadian High Arctic

Arctic landscapes are believed to be highly sensitive to climate change and accelerated disturbance of permafrost is expected to significantly impact the rate of carbon cycling. While half the global soil organic matter (SOM) is estimated to reside in Arctic soils, projected warmer temperatures and permafrost disturbance will release much of this SOM into waterways in the form of dissolved organic matter (DOM). The spring thaw and subsequent flushing of soils releases the highest contributions of DOM annually but has historically been undersampled due to the difficulties of sampling during this period. In this study, passive samplers were placed throughout paired High Arctic watersheds during the duration of the 2008 spring flush in Nunavut, Canada. The watersheds are very similar with the exception of widespread active layer detachments (ALDs) that occurred within one of the catchments during a period of elevated temperatures in the summer of 2007. DOM samples were analyzed for structural and spectral characteristics via nuclear magnetic resonance (NMR) and fluorescence spectroscopy as well as vulnerability to degradation with simulated solar exposure. Lignin-derived phenols were further assessed utilizing copper(II) oxide (CuO) oxidation and gas chromatography/mass spectrometry (GC/MS). The samples were found to have very low dissolved lignin phenol content (∼0.07% of DOC) and appear to originate from primarily non-woody angiosperm vegetation. The acid/aldehyde ratios for dissolved vanillyl phenols were found to be high (up to 3.6), indicating the presence of highly oxidized lignin. Differences between DOM released from the ALD vs. the undisturbed watershed suggest that these shallow detachment slides have significantly impacted the quality of Arctic DOM. Although material released from the disturbed catchment was found to be highly oxidized, DOM in the lake into which this catchment drained had chemical characteristics indicating high contributions from microbial and/or primary productivity. The resulting pool of dissolved carbon within the lake appears to be more biologically- and photochemically-labile than material from the undisturbed system. These disturbances may have implications for projected climate warming; sustained elevated temperatures would likely perpetuate widespread ALDs and further affect carbon cycling in this environment.     

高应力区露天转地下开采岩体移动规律

以金川龙首矿为例,基于2003―2008年长达12期的GPS实测数据,按照时空分布比较分析总体变形趋势,得出整个矿区的地表沉降特征、平面位移特征、行线（勘探线）随时间变化的沉降和平面位移特征。据此分析了以水平构造应力为主导的高应力区露天转地下开采引起岩体的变形规律,并与该矿闭坑之初的变形规律比较,通过理论分析的方法对产生差异的原因进行初步解释,并用数值模拟的方法加以验证,其研究结果对认识露天转地下开采引起的岩体移动、破坏特征,指导矿区安全生产有积极意义     

Greenhouse gases mitigation against climate change: United States-Mexico border study case

Solar radiation is one of the most important energy resources of our planet. The interest in its use as a renewable and clean energy to mitigate the greenhouse gases (GHG) effects has increased significantly. This paper evaluates the measurements of global solar radiation and its energy potential and presents a comparison between both of them, as an example of the effort to reduce GHG emissions. The measurements were made with pyranometers installed in the city of Mexicali, Baja California, located in northwestern Mexico, and the city of Yuma, Arizona, located in the southwestern United States. Separated by a distance of 96 km, both cities have a sustained development and are climatically similar, since they present numerous sunny days, extreme hot temperatures and little precipitation. The results presented show differences in their behavior and in the solar radiation measurement values, especially for the critical spring and summer seasons, with values 15.73% (0.042 kW/m²) higher in Mexicali with respect to Yuma. Energy power is estimated, and it is discussed with some variables as global solar radiation, rainfall, air temperature, relative humidity and climatology of clear, partly cloudy, and cloudy days. With this estimation, the solar energy used and GHG avoided is projected for Mexicali. It is assessed that 291 tons of GHG are prevented. The Mexicali values of potential energy are higher than those of Yuma; therefore, this solar and energy comparative study provides reasons to develop these technologies in Mexico, but solar technologies should be deployed also in Yuma. The measured data at the regional level demonstrate their importance, and the relevance of the proposed mitigation strategy for climate change.     

Assessing storm surge impacts on coastal inundation due to climate change: case studies of Baltimore and Dorchester County in Maryland

Natural Hazards - Hurricane Isabel (2003) generated record flooding around Chesapeake Bay and caused extensive damage in rural Eastern Shore of Maryland and metropolitan cities like Baltimore....     

东北多年冻土地区地基承载力对气候变化敏感性分析

近年来,中国东北多年冻土地区正处于显著的增温过程中。由此导致多年冻土逐渐退化,并严重影响到构筑物的稳定性。以0.05 ℃的年平均气温上升率为背景,采用带有相变的传热学有限元方法,对中国东北多年冻土地区不同初始气温条件和不同含冰量类型冻土的地基温度状况以及季节活动层厚度变化进行了模拟;利用温度场有限元数值试验结果和已有承载力试验数据分析了不同类型冻土地基的力学性质对气温变化敏感性,评估了气温变化对各类冻土地基承载力的影响。气候变化对多年冻土地区构筑物稳定性影响程度取决于两个环节：其一,冻土地基温度状况对气候变化的响应;其二,冻土地基力学性质对地基温度变化的敏感性。研究结果表明,冻土地基含冰量和温度状态对其承载力随气温变化的敏感性具有显著的影响。含土冰层地基承载力对气温变化最为敏感,气温变化对高温冻土地区浅层地基承载力以及桩-土冻结强度影响较大;而深基础桩端冻土地基承载力受气候变化影响相对较小。     

Timing and prediction of climate change and hydrological impacts: periodicity in natural variations

Hydrological impacts from climate change are of principal interest to water resource policy-makers and practicing engineers. Predictive climatic models have been extensively investigated to quantify the impacts. Palaeoclmatic investigations, on the other hand, show unequivocal and strong periodicity of climate variations in proxy evidence. Yet how to use the periodicity in future hydroclimatic timing and forecasting has received less attention. This paper examines the periodicity in Pleistocene–Holocene glacial–interglacial events and in modern precipitation records, and discusses a way in which the periodicity is used for hydroclimatic predictions. The analysis, based on published CO₂, ΔT (δ²H) and δ¹⁸O proxy data of polar ice cores and deep oceanic benthic fossils, shows a periodicity in a ~100, ~40 or 25 kyear duration consistent with Milankovitch orbital regulations during the glacial–interglacial periods. On a fine time scale, millennium and multi-decadal periodicity is observed in high-resolution proxy variations of Greenland ice cores and in instrumental precipitation records of the contiguous USA. A basic periodicity of decadal and multi-decadal changes in ~20 and ~10–15 year duration is apparent in wavelet frequency analysis of both ice core proxy and precipitation data. While the kyear-scale periodicity is found of global prevalence, the millennium and decadal variations vary in space and are region-specific. Based on these findings, a generalized time-downscaling hierarchy of periodicity is proposed as a potential approach for timing and forecasting future hydroclimatic conditions at a resolution relevant to the water resources engineering and management.     

Regional variations in atmospheric deposition and sources of anthropogenic lead in lake sediments across the Canadian Arctic

Stable Pb isotope profiles in dated lake sediment cores were used to gauge the relative amounts and possible sources of anthropogenic Pb deposited from the atmosphere in different regions of the Canadian Arctic. A distinct north-south difference was found. In four High Arctic lakes (i.e., north of 66°N) in this study, recent Pb isotopic shifts or concentration increases attributable to anthropogenic Pb were negligible. The maximum possible contribution from anthropogenic Pb was 0 to 19% of acid-leachable Pb in the 1980s or 1990s. In contrast, two lakes in the Hudson Bay region displayed significantly lower Pb isotope ratios and threefold to fivefold increases of Pb concentrations in modern sediments, corresponding to anthropogenic Pb inputs of at least 72 to 91% of leachable Pb. Eurasian urban and industrial Pb is known to dominate the High Arctic atmosphere. A possible explanation for its negligible influence on northern lake sediments is that atmospheric Pb deposition at northern latitudes is reduced compared with southern regions and is small compared to local geological inputs. ²¹⁰Pb deposition declines with increasing latitude, apparently because of declining precipitation rates; stable Pb deposition may be similarly affected. Meteorological considerations and variations in the post-1900 Pb isotopic trajectories indicated that the predominant anthropogenic Pb source region in NW Hudson Bay was Eurasia, while in SE Hudson Bay, it was Canada and the United States, with a minor Eurasian component.     

Estimation of property loss and business interruption loss caused by storm surge inundation due to climate change: a case of Typhoon Vera revisit

This paper estimates property loss and business interruption loss under scenarios of storm surge inundation to explore the economic impact of climate change on Ise Bay, Japan. Scenarios-based analyses are conducted with respect to Typhoon Vera, which caused the most severe storm surge in the recorded history of Japan in 1959. Four different hazard scenarios are chosen from a series of typhoon storm surge inundation simulations: Typhoon Vera’s landfall with respect to the condition of the past seawall; Typhoon Vera’s landfall with respect to the condition of the current seawall; intensifying Typhoon Vera, but retaining its original tracks; and intensifying Typhoon Vera, but choosing the worst tracks from various possible typhoon tracks. Our economic loss estimation takes advantage of fine geographical scale census and economic census data that enable us to understand the spatial distribution of property loss and business interruption loss as well as identify the most potentially affected areas and business sectors on a sub-city scale. By comparing the property loss and business interruption loss caused by different hazard scenarios, the effect of different seawalls is evaluated and the economic impact of future climate change is estimated. The results indicate that although the current seawall can considerably reduce the scale of losses, climate change can cause Ise Bay to experience more serious storm surge inundation. Moreover, the resulting economic losses would increase significantly owing to a combination of climate change and the worst track scenario. It is, therefore, necessary to consider more countermeasures to adapt to climate change in this area.     

Estimation of property loss and business interruption loss caused by storm surge inundation due to climate change: a case of Typhoon Vera revisit

This paper estimates property loss and business interruption loss under scenarios of storm surge inundation to explore the economic impact of climate change on Ise Bay, Japan. Scenarios-based analyses are conducted with respect to Typhoon Vera, which caused the most severe storm surge in the recorded history of Japan in 1959. Four different hazard scenarios are chosen from a series of typhoon storm surge inundation simulations: Typhoon Vera’s landfall with respect to the condition of the past seawall; Typhoon Vera’s landfall with respect to the condition of the current seawall; intensifying Typhoon Vera, but retaining its original tracks; and intensifying Typhoon Vera, but choosing the worst tracks from various possible typhoon tracks. Our economic loss estimation takes advantage of fine geographical scale census and economic census data that enable us to understand the spatial distribution of property loss and business interruption loss as well as identify the most potentially affected areas and business sectors on a sub-city scale. By comparing the property loss and business interruption loss caused by different hazard scenarios, the effect of different seawalls is evaluated and the economic impact of future climate change is estimated. The results indicate that although the current seawall can considerably reduce the scale of losses, climate change can cause Ise Bay to experience more serious storm surge inundation. Moreover, the resulting economic losses would increase significantly owing to a combination of climate change and the worst track scenario. It is, therefore, necessary to consider more countermeasures to adapt to climate change in this area.

     

Flood mapping under uncertainty: a case study in the Canadian prairies

In April 2013, a 7.0 Mw earthquake struck along the Longmen Shan fault in the city of Ya’an, Sichuan Province, China, causing serious damage. The invaluable contributions of the non-governmental organizations (NGOs) in dealing with this disaster highlighted the significance of government–NGO relationships in post-disaster reconstruction and the effect this has on the efficiency and quality of post-disaster reconstruction. This paper examines government–NGO relationships (GNR) in the post-Lushan earthquake period as a multi-stakeholder collaborative problem based on organizational lifecycle perspectives through the birth, growth, stability, and saturation stages. Two-year field research was conducted in the affected areas which identified the GNR as a bridged government–NGO relationship (BGNR) during the reconstruction period, with the Ya’an service center acting as the bridging organization. The BGNR’s experience was compared to the previous Wenchuan earthquake, and the general BGNR post-disaster reconstruction situation is discussed on two dimensions: mutuality and organizational identity.     

Rock burst assessment in multi-seam mining: a case study

To assess rock burst prone zones in the lower seam during multi-seam mining, a rock burst hazard assessment method for use in multi-seam mining was established. According to the observed geological evolution, the feasibility of using upper layer coal mining data to determine the rock burst risk zone of the lower coal seam is explained. Then, we established the energy density risk index (EDRI) and proved that the EDRI more accurately reflected the potential rock burst region than the multi-factor coupling analysis method. Finally, we established the rock burst hazard assessment method for use in multi-seam mining by using the EDRI of the upper coal to divide the rock burst risk zone in the lower coal. From the accuracy and validity analysis of this assessment method, we find that the critical energy induced rock burst, and the damage area of a rock burst in the lower coal seam were all located in the high-risk zone derived from this assessment method. To quantify the effectiveness and practicability of this assessment method, the structural similarity (SSIM) index, from image quality assessment research, was introduced. The SSIM index between predicted-high-risk map and actual high-risk map index was 0.8581, which shows that the established rock burst hazard assessment method in multi-seam mining can be used to predict rock burst risk zones in the lower seam.