Permafrost degradation under climate warming plays a crucial role in hydrological and ecological processes,including the regional water cycle and terrestrial carbon balance.The Tibetan Plateau(TP),which contains the l...Permafrost degradation under climate warming plays a crucial role in hydrological and ecological processes,including the regional water cycle and terrestrial carbon balance.The Tibetan Plateau(TP),which contains the largest expanse of high-altitude permafrost globally,remains understudied in terms of how permafrost degradation affects surface water resources and regional carbon dynamics.Using permafrost simulation models and quantitative analysis,we assess the spatiotemporal impacts of permafrost degradation on surface water resources and carbon dynamics.In the inner endorheic regions of the TP,ground ice meltwater contributed 12.6%of the total lake volume increase from 2000 to 2020,accelerating lake expansion and affecting nearby infrastructure and ecosystems.Cryospheric meltwater accounted for 4.6%of total runoff in the source areas of the Yangtze,Yellow,Lancang,Yarlung Zangbo,and Nujiang Rivers in 2002-2018.This cryospheric meltwater contribution is projected to peak in the 2030s-2040s,followed by a decline,with potentially profound implications for downstream water availability.From 2000 to 2020,carbon sequestration of alpine grassland in permafrost regions is 1.05-1.29 Tg C a^(-1)in 2000-2020.This estimate is underestimated by approximately 35.5%to 48.1%without considering the impact of permafrost degradation.Top-down thawing of permafrost from 2002 to 2050 is projected to release 129.39±21.02 Tg C a^(-1)of thawed soil organic carbon(SOC),with 20.82±3.06 Tg C a^(-1)decomposed annually.Additionally,permafrost collapse and thermokarst lake are estimated to reduce ecosystem carbon sinks by 0.41(0.29-0.52)Tg C a^(-1)in 2020.展开更多
In contrast to glaciological studies in Mexico,periglacial studies are very recent and limited to the analysis of the general permafrost cover in the high mountains of the country.Although some of the studies on the r...In contrast to glaciological studies in Mexico,periglacial studies are very recent and limited to the analysis of the general permafrost cover in the high mountains of the country.Although some of the studies on the reconstruction of Pleistocene glaciers in Mexico mention the existence of rock glaciers,to date no work has been done to study their physical properties or determining their state of conservation.Since rock glaciers are the most important visible indicators of mountain permafrost(along with features such as gelifluction lobes and patterned ground)and given that the“Nevado”rock glacier is the main example of its kind in Mexico,this study analyzes its internal temperature and assesses its state of conservation.The investigation was carried out by drilling and thermal monitoring of rock profiles as well as air.The results indicate that at present,the“Nevado”seems to lack permafrost inside.Although there is evidence of surface freezing during the winter months in the upper part of the rock glacier,in the lower portion it is almost unnoticed;and in both parts the internal temperature shows a tendency towards positive values as depth increases,a situation that predominates throughout the year.In addition,according to the records of the climatological station located in the lower part of the rock glacier,although the annual rainfall regime could be favorable for the formation and feeding of interstitial or segregated ice,the air temperature conditions throughout the year prevent permanent freezing.The sum of the above determines that at present the“Nevado”could be considered as an inactive and relict-type rock glacier;the presence of vegetation on the surface of the debris that make it up corroborates its inactivity.展开更多
Permafrost,a critical component of Earth’s climate system,is increasingly subject to abrupt thaw events,which jeopardize infrastructure,reshape landforms,alter hydrological regimes,and disrupt ecosystems,thereby posi...Permafrost,a critical component of Earth’s climate system,is increasingly subject to abrupt thaw events,which jeopardize infrastructure,reshape landforms,alter hydrological regimes,and disrupt ecosystems,thereby posing substantial threats to global sustainability.However,the underlying mechanisms that trigger these abrupt transitions remain incompletely understood.Here,we present decade-long in-situ observations from HRQ1,a marginal permafrost site in the Headwater Area of the Yellow River,northeastern Qinghai-Xizang Plateau.These data reveal the formation and growth of a talik,indicative of a permafrost tipping point.Absent before 2017,the talik subsequently formed and progressively deepened,extending to the maximum observation depth of 300 cm by 2024.The transition from perennially frozen to thawed conditions was accompanied by a substantial increase in mean annual soil temperature(MAST)throughout the entire soil profile.From 2015 to 2023,MAST in the upper 200 cm rose from sub-zero(−0.30 to−0.49℃)to consistently above 0℃(0.07 to 1.08℃).Concurrently,maximum daily soil temperatures in deeper layers(200–300 cm)became positive,indicating thaw propagation into the relict permafrost.This warming coincided with a marked increase in unfrozen soil moisture,particularly within the expanding talik.The rapid,non-linear deepening of the talik,far exceeding rates attributable to conductive heat transfer alone,was driven by a strong convective mechanism(Rayleigh-Darcy instability).This advective process was triggered when the soil profile became fully saturated,a condition resulting from the convergence of intensified rainfall and enhanced water retention linked to decadal vegetation greening.Intriguingly,despite the accelerated subsurface warming,the annual amplitude of ground surface temperature decreased from 29.0±2.8℃ to 24.5±3.6℃ following talik formation,likely due to the buffering effect of increased vegetation cover,which modified the surface energy balance.Our results demonstrate that climatic warming and wetting can initiate a cascade of internal feedbacks,propelling marginal permafrost beyond an abrupt tipping point.These findings emphasize the acute vulnerability of marginal permafrost and highlight the urgent necessity for sustained monitoring to assess ecosystem stability and quantify associated greenhouse gas emissions.展开更多
In 2022,the Russian Federation commenced development of a national system for permafrost monitoring.The conceptual design of this system reflects three objectives:(1)to collect data on the impact of climate change on ...In 2022,the Russian Federation commenced development of a national system for permafrost monitoring.The conceptual design of this system reflects three objectives:(1)to collect data on the impact of climate change on permafrost,(2)to provide data for evaluation of climate-permafrost feedback,and(3)to provide input to a model-based permafrost data assimilation system.It is intended that the system will eventually consist of 30 active layer monitoring sites and 140 boreholes situated near existing weather stations.As of October 2024,the network comprised 38 sites spanning from the High Arctic islands to the Altai Mountains and across western and eastern Siberia.Among these sites,the lowest recorded temperature at the depth of zero annual amplitude is-11.3℃and the minimum active layer thickness is 0.3 m,as observed on the New Siberian Archipelago.In most boreholes,a positive vertical temperature gradient exists below the depth of zero annual amplitude,indicative of ongoing warming of the upper permafrost layer attributable to climate change.The annual maximum active layer thickness is observed in September with only two exceptions:at the High Arctic sites on Franz Josef Land and Wiese Island and in the low-latitude Sayan Mountain region,where maximum thawing is observed at the end of August.Talik was found in boreholes in Salekhard and Altai where the upper boundary of the permafrost is located at depth of 6-10 m.展开更多
Bacterial communities play a crucial role in permafrost biogeochemical cycling and ecosystem function maintenance.Bacterial interaction is one of the main factors in shaping soil bacterial communities.However,how woul...Bacterial communities play a crucial role in permafrost biogeochemical cycling and ecosystem function maintenance.Bacterial interaction is one of the main factors in shaping soil bacterial communities.However,how would bacterial interaction influence the bacterial communities in permafrost of the Qinghai-Tibet Plateau(QTP)remains largely unknown.Here we collected paired soil samples from both the active and permafrost layers of two typical QTP permafrost regions in October 2020 for Tuotuohe River(TTH)and May 2022 for Aerjin(ARJ),and investigated the bacterial communities and the role of interactions in structuring the bacterial community and its assembly process through amplicon sequencing of the 16S rRNA gene.Our study revealed distinct bacterial communities,with significant differences in the relative abundances of Proteobacteria(P<0.05),Acidobacteriota(P<0.001),Bacteroidota(P<0.05),and Planctomycetota(P<0.001)between the active layer and the permafrost layer.More importantly,we found that interspecies interactions,including both positive and negative associations,were strongly correlated with bacterial alpha-diversity and played a significant role in community variation and assembly process.Our findings also showed that the community assembly in both the active and permafrost layers was primarily driven by homogeneous selection of deterministic processes,with interspecies interactions accounting for more than 58%and 63%of all assembly mechanisms,respectively.This is the first study to quantify the contribution of bacterial interactions in shaping the bacterial community and its assembly process in permafrost of QTP,highlighting the importance of considering interspecies interactions in future modeling efforts.Our work also emphasizes the necessity of including interspecies interactions in microbial process projections to reduce uncertainty.展开更多
The thawing and warming of ice-rich permafrost present a considerable threat to the long-term stability of the Qinghai-Xizang Railway(QXR)on the roof of the world—that is,the Qinghai-Xizang Plateau(QXP).In this revie...The thawing and warming of ice-rich permafrost present a considerable threat to the long-term stability of the Qinghai-Xizang Railway(QXR)on the roof of the world—that is,the Qinghai-Xizang Plateau(QXP).In this review,we explore the extent of the observed permafrost degradation and embankment damage under the coupled impacts of climate change and engineering construction.The ice-rich permafrost beneath the embankment presents a substantial threat to the thermal-mechanical stability of the embankment due to the permafrost’s accelerated and amplified degradation.The observed embankment deformation has a potential high risk of thaw settlement,especially for 656 embankment-bridge sections,whose potential high risk of thaw settlement may be as great as 25%.Several techniques for roadbed cooling can be used to alleviate these impacts,including crushed rock structure embankments(CRSEs),thermosyphons,and reinforcement measures,which have been demonstrated to be successful in cooling the underlying permafrost and stabilizing an embankment.Under future climate change and permafrost degradation,however,the QXR still faces a high risk of embankment damage caused by permafrost degradation and requires more effective methods to reinforce the thermal-mechanical stability of permafrost.Therefore,a better understanding of such high-risk regions is needed,and roadbed cooling techniques will require further adaption in order to address the issues brought by climate change.展开更多
Thermal infrared satellite imagery is increasingly utilized in permafrost studies.One useful application of the land surface temperature(LST)products is classification and mapping of landscapes in permafrost regions,a...Thermal infrared satellite imagery is increasingly utilized in permafrost studies.One useful application of the land surface temperature(LST)products is classification and mapping of landscapes in permafrost regions,as LST values can help differentiate between frozen and unfrozen ground.This article describes a new approach to the use of LST.The essence of the new approach lies in the fact that in the territory where it is impossible to determine(indicate)the state of the underlying ground according to the same morphological characteristics(relief,vegetation,soil composition,etc.),the LST parameter,which reflects the thermal state of the landscape,allows as an additional criterion(indicator)identify frozen/un-frozen landscapes.In this work,using the above approach,a map has been compiled,which shows the permafrost natural-territorial complexes of the Elkon Massif,Eastern Siberia,including topography,slope aspect,slope angle,vegetation,snow cover and LST.The map provides a more detailed and updated description of permafrost distribution in the study area.展开更多
The distribution and variations of permafrost in the Xidatan region, the northern permafrost boundary of the Qinghai-Tibet Plateau, were examined and analyzed using ground penetrating radar(GPR), borehole drilling, an...The distribution and variations of permafrost in the Xidatan region, the northern permafrost boundary of the Qinghai-Tibet Plateau, were examined and analyzed using ground penetrating radar(GPR), borehole drilling, and thermal monitoring data. Results from GPR profiles together with borehole verification indicate that the lowest elevation limit of permafrost occurrence is 4369 m above sea level in 2012. Compared to previous studies, the maximal rise of permafrost limit is 28 m from 1975 to 2012. The total area of permafrost in the study region has been decreased by 13.8%. One of the two previously existed permafrost islands has disappeared and second one has reduced by 76% in area during the past ~40 years. In addition, the ground temperature in the Xidatan region has increased from 2012 to 2016, with a mean warming rate of ~0.004℃ a^(-1) and ~0.003℃ a^(-1) at the depths of 6 and 15 m, respectively. The rising of permafrost limit in the Xidatan region is mainly due to globalwarming. However, some non-climatic factors such as hydrologic processes and anthropic disturbances have also induced permafrost degradation. If the air temperature continues to increase, the northern permafrost boundary in the Qinghai-Tibet Plateau may continue rising in the future.展开更多
In boreal forest ecosystems, permafrost and forest types are mutually interdependent;permafrost degradation impacts forest ecosystem structure and functions. The Xing’an permafrost in Northeast China is on the southe...In boreal forest ecosystems, permafrost and forest types are mutually interdependent;permafrost degradation impacts forest ecosystem structure and functions. The Xing’an permafrost in Northeast China is on the southern margin of the Eastern Asia latitudinal permafrost body. Under a warming climate, permafrost undergoes rapid and extensive degradation. In this study, the frost-number (Fn) model based on air temperatures and ground surface temperatures was used to predict the distribution of the Xing’an permafrost, and, temporal and spatial changes in air and ground-surface temperatures from 1961 to 2019 are analyzed. The results show that Northeast China has experienced a rapid and substantial climate warming over the past 60 years. The rises in mean annual air and mean annual ground-surface temperatures were higher in permafrost zones than those in the seasonal frost zone. The frost numbers of air and ground-surface temperatures were calculated for determining the southern limit of latitudinal permafrost and for permafrost zonation. The southern limits of discontinuous permafrost, sporadic permafrost, and latitudinal permafrost moved northward significantly. According to the air-temperature frost-number criteria for permafrost zoning, compared with that in the 1960s, the extent of Xing’an permafrost in Northeast China had decreased by 40.6% by the 2010s. With an average rate of increase in mean annual air temperatures at 0.03 ℃ a^(−1), the extent of permafrost in Northeast China will decrease to 26.42 × 10^(4) by 2020, 14.69 × 10^(4) by 2040 and to 11.24 × 10^(4) km^(2) by 2050. According to the ground-surface temperature frost-number criteria, the southern limit of latitudinal permafrost was at the 0.463. From the 1960s to the 2010s, the extent of latitudinal permafrost declined significantly. Due to the nature of the ecosystem-protected Xing’an-Baikal permafrost, management and protection (e.g., more prudent and effective forest fire management and proper logging of forests) of the Xing’an permafrost eco-environment should be strengthened.展开更多
The sideward permafrost along the Qinghai-Tibet Highway (QTH) contains massive ground-ice and is at a relatively high temperature.Under the influence of the steady increase of human activities,the permafrost environme...The sideward permafrost along the Qinghai-Tibet Highway (QTH) contains massive ground-ice and is at a relatively high temperature.Under the influence of the steady increase of human activities,the permafrost environment has been changed greatly for a long time.At present,the permafrost becomes warm and rapidly degenerates,including the decline of the permafrost table,rising of the ground temperature,shortening of the length of frozen section,and extension of range of melting region.Some thaw hazards (e.g.thaw slumping and thermokarst pond) have widely occurred along both sides of the roadbed.In addition,due to the incomplete construction management,the vegetation adjacent to the highway is seriously damaged or eradicated,resulting in the land desertification and ecosystem out of balance.The dust,waste and garbage brought by drivers,passengers,maintenance workers,and transportations may also pollute the permafrost environment.展开更多
This study proposes an equivalent-elevation method to evaluate the integrated effects of latitude and elevation on regional and local-scale permafrost distribution in the Qinghai-Tibet Plateau,and to model the general...This study proposes an equivalent-elevation method to evaluate the integrated effects of latitude and elevation on regional and local-scale permafrost distribution in the Qinghai-Tibet Plateau,and to model the general permafrost-distribution patterns in regional and local-scale area.It is found that the Gaussian curve―an empirical model describing the relation between variations of altitudinal permafrost lower limit (PLL) and latitude in the Northern Hemisphere―could be applied in regional-and local-scale areas in the Qinghai-Tibet Plateau in a latitude-sensitive interval of 30°-50°N.The curve was then used to evaluate the latitudinal effect on permafrost distribution through transforming the latitudinal effect into a kind of altitudinal difference of PLL.This study then calculated the local equivalent-elevation value by overlaying the altitudinal difference of PLL onto real elevation at a certain location.The equivalent-elevation method was verified in an experimental subwatershed of the Qinghai-Tibet Plateau.However,feasibility of the method should be further tested in order to extend for future studies.The use of equivalent-elevation values can build a platform for comparing the regional general permafrost distribution in the plateau,and for basing further evaluations of local factors' effects on regional permafrost distribution.展开更多
In high mountainous areas, the development and distribution of alpine permafrost is greatly affected by macro- and mi- cro-topographic factors. The effects of latitude, altitude, slope, and aspect on the distribution ...In high mountainous areas, the development and distribution of alpine permafrost is greatly affected by macro- and mi- cro-topographic factors. The effects of latitude, altitude, slope, and aspect on the distribution of permafrost were studied to under- stand the dislribution patterns of permafrost in Wenquan on the Qinghai-Tibet Plateau. Cluster and correlation analysis were per- formed based on 30 m Global Digital Elevation Model （GDEM） data and field data obtained using geophysical exploration and borehole drilling methods. A Multivariate Adaptive Regression Spline model （MARS） was developed to simulate permafrost spa- tial distribution over the studied area. A validation was followed by comparing to 201 geophysical exploration sites, as well as by comparing to two other models, i.e., a binary logistic regression model and the Mean Annual Ground Temperature model （IVlAGT）. The MARS model provides a better simulation than the other two models. Besides the control effect of elevation on permafrost distribution, the MARS model also takes into account the impact of direct solar radiation on permafrost distribution.展开更多
The Qinghai-Tibet Plateau(QTP)distributes the largest extent of high-altitude mountain permafrost in the world(Zou et al.,2017),which has different characteristics from high-latitude permafrost(Yang et al.,2010)and st...The Qinghai-Tibet Plateau(QTP)distributes the largest extent of high-altitude mountain permafrost in the world(Zou et al.,2017),which has different characteristics from high-latitude permafrost(Yang et al.,2010)and stores massive soil carbon.展开更多
Boreal peatlands represent a large global carbon pool. The relationships between carbon mineralization, soil temperature and moisture in the permafrost peatlands of the Great Hing＇an Mountains, China, were examined. ...Boreal peatlands represent a large global carbon pool. The relationships between carbon mineralization, soil temperature and moisture in the permafrost peatlands of the Great Hing＇an Mountains, China, were examined. The CO2 emissions were measured during laboratory incubations of samples from four sites under different temperatures （5, 10, 15, and 20℃） and moisture contents （0%, 30%, 60%, 100% water holding capacity （WHC） and completely water saturated）. Total carbon mineralization ranged from 15.51 to 112.92 mg C under the treatments for all sites. Carbon mineralization rates decreased with soil depth, increased with temperature, and reached the highest at 60% WHC at the same temperature. The calculated temperature coefficient （Q10） values ranged from 1.84 to 2.51 with the soil depths and moisture. However, the values were not significantly affected by soil moisture and depth for all sites due to the different peat properties （P 〉 0.05）. We found that the carbon mineralization could be successfully predicted as a two-compartment function with temperature and moisture （R^2 〉 0.96） and total carbon mineralization was significantly affected by temperature and moisture （P 〈 0.05）. Thus, temperature and moisture would play important roles in carbon mineralization of permafrost peatlands in the Great Hing＇an Mountains, indicating that the permafrost peatlands would be sensitive to the environment change, and the permafrost peatlands would be potentially mineralized under future climate change.展开更多
Qilian Mountain permafrost, with area about 10×10^4 km2, locates in the north of Qinghai- Tibet plateau. It equips with perfect conditions and has great prospecting potential for gas hydrate. The Scientific Drill...Qilian Mountain permafrost, with area about 10×10^4 km2, locates in the north of Qinghai- Tibet plateau. It equips with perfect conditions and has great prospecting potential for gas hydrate. The Scientific Drilling Project of Gas Hydrate in Qilian Mountain permafrost, which locates in Juhugeng of Muri Coalfield, Tianjun County, Qinghai Province, has been implemented by China Geological Survey in 2008-2009. Four scientific drilling wells have been completed with a total footage of 2059.13 m. Samples of gas hydrate are collected separately from holes DK-1, DK-2 and DK-3. Gas hydrate is hosted under permafrost zone in the 133-396 m interval. The sample is white crystal and easily burning. Anomaly low temperature has been identified by the infrared camera. The gas hydratebearing cores strongly bubble in the water. Gas-bubble and water-drop are emitted from the hydratebearing cores and then characteristic of honeycombed structure is left. The typical spectrum curve of gas hydrate is detected using Raman spectrometry. Furthermore, the logging profile also indicates high electrical resistivity and sonic velocity. Gas hydrate in Qilian Mountain is characterized by a thinner permafrost zone, shallower buried depth, more complex gas component and coal-bed methane origin etc.展开更多
The permafrost along the China-Russia Crude Oil Pipeline(CRCOP) is degrading since the pipeline operation in 2011. Heat dissipated from the pipeline, climate warming and anthropogenic activities leads to permafrost wa...The permafrost along the China-Russia Crude Oil Pipeline(CRCOP) is degrading since the pipeline operation in 2011. Heat dissipated from the pipeline, climate warming and anthropogenic activities leads to permafrost warming. The processes of permafrost warming along the CRCOP were studied based on the monitoring of air and soil temperatures, and electrical resistivity tomography(ERT) surveys. Results show that:(1) the mean annual air temperature(MAAT) in permafrost regions along the CRCOP increased with a rate of 0.21°C/10a–0.40°C/10 a during the past five decades;(2) the mean annual ground temperature(MAGT, at-15 m depth) of undisturbed permafrost increased by 0.2°C and the natural permafrost table remained unchanged due to the zero-curtain effect;(3) permafrost surrounding the uninsulated pipeline right-of-way warmed significantly compared with that in a natural site. During 2012–2017, the MAGT and the artificial permafrost table, 2 m away from the pipeline centerline, increased at rates of 0.063°C/a and 1.0 m/a. The thaw bulb developed around the pipe and exhibits a faster lateral expansion;(4) 80-mm-thick insulation could reduce the heat exchange between the pipeline and underlying permafrost and then keep the permafrost and pipe stable. The MAGT and the artificial permafrost table, 4.8 m away from the center line of the pipeline, increased by 0.3°C/a and 0.43 m/a, respectively. Due to the heat disturbance caused by warm oil, the degradation of wetland, controlled burn each autumn and climate warming, the permafrost extent reduced and warmed significantly along the CRCOP route. Field observations provide basic data to clarify the interactions between CRCOP and permafrost degradation and environmental effects in the context of climate change.展开更多
Recently, the degradation of permafrost and marsh environments in the Da and Xiao Hinggan Mountains has become a great concern as more human activities and pronounced climate warming were observed during the past 30 y...Recently, the degradation of permafrost and marsh environments in the Da and Xiao Hinggan Mountains has become a great concern as more human activities and pronounced climate warming were observed during the past 30 years and projected for the near future. The distr/bution patterns and development mechanisms of the permafrost and marshes have been examined both in theories and in field observations, in order to better understand the symbiosis of permafrost and marshes. The permafrost and marshes in the Da and Xiao Hinggan Mountains display discernible zonations in latitude and elevation. The marsh vegetation canopy, litter and peat soil have good thermal insulation properties for the underlying permafrost, resulting in a thermal offset of 3 ℃ to 4℃ and subsequently suppressing soil temperature. In addition, the much higher thermal conductivity of frozen and ice-rich peat in the active layer is conducive to the development or in favor of the protection of permafrost due to the semi-conductor properties of the soils overlying the permafrost. On the other hand, because permafrost is almost impervious, the osmosis of water in marsh soils can be effectively reduced, timely providing water supplies for helophytes growth or germination in spring. In the Da and Xiao Hinggan Mountains, the permafrost degradation has been accelerating due to the marked climate warming, ever increasing human activities, and the resultant eco-environmental changes. Since the permafrost and marsh environments are symbiotic and interdependent, they need to be managed or protected in a well-coordinated and integrated way.展开更多
Based on data from six meteorological stations in the permafrost regions, 60 boreholes for long-term monitoring of permafrost temperatures, and 710 hand-dug pits and shallow boreholes on the Qinghai-Tibet Plateau （QT...Based on data from six meteorological stations in the permafrost regions, 60 boreholes for long-term monitoring of permafrost temperatures, and 710 hand-dug pits and shallow boreholes on the Qinghai-Tibet Plateau （QTP）, the spatiotemporal variability of permafrost degradation was closely examined in relation to the rates of changes in air, surface, and ground temperatures. The de- cadal averages and increases in the mean annual air temperatures （MAATs） from 1961-2010 were the largest and most persistent during the last century. MAATs rose by 1.3 ℃, with an average increase rate of 0.03 ℃/yr. The average of mean annual ground surface temperatures （MAGSTs） increased by 1.3 ℃ at an average rate of 0.03 ℃/yr. The rates of changes in ground temperatures were -0.01 to 0.07 ℃/yr. The rates of changes in the depths of the permafrost table were -1 to ＋10 cm/yr. The areal extent of permafrost on the QTP shrank from about 1.50× 10^6 km^2 in 1975 to about 1.26× 10^6 km^2 in 2006. About 60% of the shrinkage in area of permafrost occurred during the period from 1996 to 2006. Due to increasing air temperature since the late 1980s, warm （〉-1 ℃） permafrost has started to degrade, and the degradation has gradually expanded to the zones of transitory （-1 to -2 ℃） and cold （〈-2 ℃） permafrost. Permafrost on the southern and southeastem plateau degrades more markedly. It is projected that the degradation of permafrost is likely to accelerate, and substantial changes in the distributive features and thermal regimes of permafrost should be anticipated. However, regarding the relationships between degrading permafrost and the degradation of rangelands, it is still too early to draw reliable conclusions due to inadequate scientific criteria and evidence.展开更多
Many observations in and model simulations for northern basins have confirmed an increased streamflow from degrading permafrost,while the streamflow has declined in the source area of the Yellow River(SAYR,above the T...Many observations in and model simulations for northern basins have confirmed an increased streamflow from degrading permafrost,while the streamflow has declined in the source area of the Yellow River(SAYR,above the Tanag hydrological station)on the northeastern Qinghai-Tibet Plateau,West China.How and to what extent does the degrading permafrost change the flow in the SAYR?According to seasonal regimes of hydrological processes,the SAYR is divided intofour sub-basins with varied permafrost extents to detect impacts of permafrost degradation on the Yellow River streamflow.Results show that permafrost degradation may have released appreciable meltwater for recharging groundwater.The potential release rate of ground-ice melt-water in the Sub-basin 1(the headwater area of the Yellow River(HAYR),above the Huangheyan hydrological station)is the highest(5.6 mm per year),contributing to 14.4%of the annual Yellow River streamflow at Huangheyan.Seasonal/intra-and annual shifts of streamflow,a possible signal for the marked alteration of hydrological processes by permafrost degradation,is observed in the HAYR,but the shifts are minor in other sub-basins in the SAYR.Improved hydraulic connectivity is expected to occur during and after certain degrees of permafrost degradation.Direct impacts of permafrost degradation on the annual Yellow River streamflow in the SAYR at Tanag,i.e.,from the meltwater of ground-ice,is estimated at 4.9%that of the annual Yellow River discharge at Tanag,yet with a high uncertainty,due to neglecting of the improved hydraulic connections from permafrost degradation and the flow generation conditions for the ground-ice meltwater.Enhanced evapotranspiration,substantial weakening of the Southwest China Autumn Rain,and anthropogenic disturbances may largely account for the declined streamflow in the SAYR.展开更多
The soil moisture movement is an important carrier of material cycle and energy flow among the various geo-spheres in the cold regions.Thus, this research takes the north slope of Bayan Har Mountains in Qinghai-Tibet ...The soil moisture movement is an important carrier of material cycle and energy flow among the various geo-spheres in the cold regions.Thus, this research takes the north slope of Bayan Har Mountains in Qinghai-Tibet Plateau as a case study.The present study firstly investigates the change of permafrost moisture in different slope positions and depths. Based on this investigation, this article attempts to investigate the spatial variability of permafrost moisture and identifies the key influence factors in different terrain conditions. The method of classification and regression tree(CART) is adopted to identify the main controlling factors influencing the soil moisture movement. The relationships between soil moisture and environmental factors are revealed by the use of the method of canonical correspondence analysis(CCA). The results show that: 1) Due to the terrain slope and the freezing-thawing process, the horizontal flow weakens in the freezing period. The vertical migration of the soil moisture movement strengthens. It will lead to that the soil-moisture content in the up-slope is higher than that in the down-slope. The conclusion is contrary during the melting period. 2) Elevation, soil texture, soil temperature and vegetation coverage are the main environmental factors which affect the slopepermafrost soil-moisture. 3) Slope, elevation and vegetation coverage are the main factors that affect the slope-permafrost soil-moisture at the shallow depth of 0-20 cm. It is complex at the middle and lower depth.展开更多
基金supported by the National Natural Science Foundation of China(U2268215,41901074,42501162,and U21A2012)the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0905)+2 种基金the State Key Laboratory of Subtropical Building and Urban Science(2023ZB13)Guangdong Basic and Applied Basic Research Foundation(2024A1515030027)the Guangdong Provincial Key Laboratory of Modern Civil Engineering Technology(2021B1212040003).
文摘Permafrost degradation under climate warming plays a crucial role in hydrological and ecological processes,including the regional water cycle and terrestrial carbon balance.The Tibetan Plateau(TP),which contains the largest expanse of high-altitude permafrost globally,remains understudied in terms of how permafrost degradation affects surface water resources and regional carbon dynamics.Using permafrost simulation models and quantitative analysis,we assess the spatiotemporal impacts of permafrost degradation on surface water resources and carbon dynamics.In the inner endorheic regions of the TP,ground ice meltwater contributed 12.6%of the total lake volume increase from 2000 to 2020,accelerating lake expansion and affecting nearby infrastructure and ecosystems.Cryospheric meltwater accounted for 4.6%of total runoff in the source areas of the Yangtze,Yellow,Lancang,Yarlung Zangbo,and Nujiang Rivers in 2002-2018.This cryospheric meltwater contribution is projected to peak in the 2030s-2040s,followed by a decline,with potentially profound implications for downstream water availability.From 2000 to 2020,carbon sequestration of alpine grassland in permafrost regions is 1.05-1.29 Tg C a^(-1)in 2000-2020.This estimate is underestimated by approximately 35.5%to 48.1%without considering the impact of permafrost degradation.Top-down thawing of permafrost from 2002 to 2050 is projected to release 129.39±21.02 Tg C a^(-1)of thawed soil organic carbon(SOC),with 20.82±3.06 Tg C a^(-1)decomposed annually.Additionally,permafrost collapse and thermokarst lake are estimated to reduce ecosystem carbon sinks by 0.41(0.29-0.52)Tg C a^(-1)in 2020.
文摘In contrast to glaciological studies in Mexico,periglacial studies are very recent and limited to the analysis of the general permafrost cover in the high mountains of the country.Although some of the studies on the reconstruction of Pleistocene glaciers in Mexico mention the existence of rock glaciers,to date no work has been done to study their physical properties or determining their state of conservation.Since rock glaciers are the most important visible indicators of mountain permafrost(along with features such as gelifluction lobes and patterned ground)and given that the“Nevado”rock glacier is the main example of its kind in Mexico,this study analyzes its internal temperature and assesses its state of conservation.The investigation was carried out by drilling and thermal monitoring of rock profiles as well as air.The results indicate that at present,the“Nevado”seems to lack permafrost inside.Although there is evidence of surface freezing during the winter months in the upper part of the rock glacier,in the lower portion it is almost unnoticed;and in both parts the internal temperature shows a tendency towards positive values as depth increases,a situation that predominates throughout the year.In addition,according to the records of the climatological station located in the lower part of the rock glacier,although the annual rainfall regime could be favorable for the formation and feeding of interstitial or segregated ice,the air temperature conditions throughout the year prevent permanent freezing.The sum of the above determines that at present the“Nevado”could be considered as an inactive and relict-type rock glacier;the presence of vegetation on the surface of the debris that make it up corroborates its inactivity.
基金funded by the Science and Technology program of Gansu Province(Grant No.23ZDFA017)Longyuan Young Talents(D.Luo),Western Young Scholars Project of the Chinese Academy of Sciences(D.Luo)National Natural Science Foundation of China(U2243214).
文摘Permafrost,a critical component of Earth’s climate system,is increasingly subject to abrupt thaw events,which jeopardize infrastructure,reshape landforms,alter hydrological regimes,and disrupt ecosystems,thereby posing substantial threats to global sustainability.However,the underlying mechanisms that trigger these abrupt transitions remain incompletely understood.Here,we present decade-long in-situ observations from HRQ1,a marginal permafrost site in the Headwater Area of the Yellow River,northeastern Qinghai-Xizang Plateau.These data reveal the formation and growth of a talik,indicative of a permafrost tipping point.Absent before 2017,the talik subsequently formed and progressively deepened,extending to the maximum observation depth of 300 cm by 2024.The transition from perennially frozen to thawed conditions was accompanied by a substantial increase in mean annual soil temperature(MAST)throughout the entire soil profile.From 2015 to 2023,MAST in the upper 200 cm rose from sub-zero(−0.30 to−0.49℃)to consistently above 0℃(0.07 to 1.08℃).Concurrently,maximum daily soil temperatures in deeper layers(200–300 cm)became positive,indicating thaw propagation into the relict permafrost.This warming coincided with a marked increase in unfrozen soil moisture,particularly within the expanding talik.The rapid,non-linear deepening of the talik,far exceeding rates attributable to conductive heat transfer alone,was driven by a strong convective mechanism(Rayleigh-Darcy instability).This advective process was triggered when the soil profile became fully saturated,a condition resulting from the convergence of intensified rainfall and enhanced water retention linked to decadal vegetation greening.Intriguingly,despite the accelerated subsurface warming,the annual amplitude of ground surface temperature decreased from 29.0±2.8℃ to 24.5±3.6℃ following talik formation,likely due to the buffering effect of increased vegetation cover,which modified the surface energy balance.Our results demonstrate that climatic warming and wetting can initiate a cascade of internal feedbacks,propelling marginal permafrost beyond an abrupt tipping point.These findings emphasize the acute vulnerability of marginal permafrost and highlight the urgent necessity for sustained monitoring to assess ecosystem stability and quantify associated greenhouse gas emissions.
基金supported by the Key Innovative Project of National Importance“Unified National System for Monitoring Climate-active Substances”。
文摘In 2022,the Russian Federation commenced development of a national system for permafrost monitoring.The conceptual design of this system reflects three objectives:(1)to collect data on the impact of climate change on permafrost,(2)to provide data for evaluation of climate-permafrost feedback,and(3)to provide input to a model-based permafrost data assimilation system.It is intended that the system will eventually consist of 30 active layer monitoring sites and 140 boreholes situated near existing weather stations.As of October 2024,the network comprised 38 sites spanning from the High Arctic islands to the Altai Mountains and across western and eastern Siberia.Among these sites,the lowest recorded temperature at the depth of zero annual amplitude is-11.3℃and the minimum active layer thickness is 0.3 m,as observed on the New Siberian Archipelago.In most boreholes,a positive vertical temperature gradient exists below the depth of zero annual amplitude,indicative of ongoing warming of the upper permafrost layer attributable to climate change.The annual maximum active layer thickness is observed in September with only two exceptions:at the High Arctic sites on Franz Josef Land and Wiese Island and in the low-latitude Sayan Mountain region,where maximum thawing is observed at the end of August.Talik was found in boreholes in Salekhard and Altai where the upper boundary of the permafrost is located at depth of 6-10 m.
基金supported by grants from the National Natural Science Foundation of China for Excellent Young Scientists Fund Program(No.42222105)the National Natural Science Foundation of China General Program(No.42171144)+1 种基金the Assessment of Ecosystem Carbon Stock and Turnover Patterns in Qinghai Province(No.2021-SFA7-1-1)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(No.2021QZKK0100)。
文摘Bacterial communities play a crucial role in permafrost biogeochemical cycling and ecosystem function maintenance.Bacterial interaction is one of the main factors in shaping soil bacterial communities.However,how would bacterial interaction influence the bacterial communities in permafrost of the Qinghai-Tibet Plateau(QTP)remains largely unknown.Here we collected paired soil samples from both the active and permafrost layers of two typical QTP permafrost regions in October 2020 for Tuotuohe River(TTH)and May 2022 for Aerjin(ARJ),and investigated the bacterial communities and the role of interactions in structuring the bacterial community and its assembly process through amplicon sequencing of the 16S rRNA gene.Our study revealed distinct bacterial communities,with significant differences in the relative abundances of Proteobacteria(P<0.05),Acidobacteriota(P<0.001),Bacteroidota(P<0.05),and Planctomycetota(P<0.001)between the active layer and the permafrost layer.More importantly,we found that interspecies interactions,including both positive and negative associations,were strongly correlated with bacterial alpha-diversity and played a significant role in community variation and assembly process.Our findings also showed that the community assembly in both the active and permafrost layers was primarily driven by homogeneous selection of deterministic processes,with interspecies interactions accounting for more than 58%and 63%of all assembly mechanisms,respectively.This is the first study to quantify the contribution of bacterial interactions in shaping the bacterial community and its assembly process in permafrost of QTP,highlighting the importance of considering interspecies interactions in future modeling efforts.Our work also emphasizes the necessity of including interspecies interactions in microbial process projections to reduce uncertainty.
基金financially supported in part by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(2021QZKK0205)the National Natural Science Foundation of China(42230512).
文摘The thawing and warming of ice-rich permafrost present a considerable threat to the long-term stability of the Qinghai-Xizang Railway(QXR)on the roof of the world—that is,the Qinghai-Xizang Plateau(QXP).In this review,we explore the extent of the observed permafrost degradation and embankment damage under the coupled impacts of climate change and engineering construction.The ice-rich permafrost beneath the embankment presents a substantial threat to the thermal-mechanical stability of the embankment due to the permafrost’s accelerated and amplified degradation.The observed embankment deformation has a potential high risk of thaw settlement,especially for 656 embankment-bridge sections,whose potential high risk of thaw settlement may be as great as 25%.Several techniques for roadbed cooling can be used to alleviate these impacts,including crushed rock structure embankments(CRSEs),thermosyphons,and reinforcement measures,which have been demonstrated to be successful in cooling the underlying permafrost and stabilizing an embankment.Under future climate change and permafrost degradation,however,the QXR still faces a high risk of embankment damage caused by permafrost degradation and requires more effective methods to reinforce the thermal-mechanical stability of permafrost.Therefore,a better understanding of such high-risk regions is needed,and roadbed cooling techniques will require further adaption in order to address the issues brought by climate change.
文摘Thermal infrared satellite imagery is increasingly utilized in permafrost studies.One useful application of the land surface temperature(LST)products is classification and mapping of landscapes in permafrost regions,as LST values can help differentiate between frozen and unfrozen ground.This article describes a new approach to the use of LST.The essence of the new approach lies in the fact that in the territory where it is impossible to determine(indicate)the state of the underlying ground according to the same morphological characteristics(relief,vegetation,soil composition,etc.),the LST parameter,which reflects the thermal state of the landscape,allows as an additional criterion(indicator)identify frozen/un-frozen landscapes.In this work,using the above approach,a map has been compiled,which shows the permafrost natural-territorial complexes of the Elkon Massif,Eastern Siberia,including topography,slope aspect,slope angle,vegetation,snow cover and LST.The map provides a more detailed and updated description of permafrost distribution in the study area.
基金supported by the National Natural Science Foundation of China (Grant no. 41601069) the State Key Program of National Natural Science of China (Grant No. 41730640)the Independent Project of the State Key Laboratory of Frozen Soils Engineering (SKLFSEZT-32 and SKLFSE-ZQ-37)
文摘The distribution and variations of permafrost in the Xidatan region, the northern permafrost boundary of the Qinghai-Tibet Plateau, were examined and analyzed using ground penetrating radar(GPR), borehole drilling, and thermal monitoring data. Results from GPR profiles together with borehole verification indicate that the lowest elevation limit of permafrost occurrence is 4369 m above sea level in 2012. Compared to previous studies, the maximal rise of permafrost limit is 28 m from 1975 to 2012. The total area of permafrost in the study region has been decreased by 13.8%. One of the two previously existed permafrost islands has disappeared and second one has reduced by 76% in area during the past ~40 years. In addition, the ground temperature in the Xidatan region has increased from 2012 to 2016, with a mean warming rate of ~0.004℃ a^(-1) and ~0.003℃ a^(-1) at the depths of 6 and 15 m, respectively. The rising of permafrost limit in the Xidatan region is mainly due to globalwarming. However, some non-climatic factors such as hydrologic processes and anthropic disturbances have also induced permafrost degradation. If the air temperature continues to increase, the northern permafrost boundary in the Qinghai-Tibet Plateau may continue rising in the future.
基金The project is fully funded by the Natural Science Foundation of China Program(Grant Nos.42001052 and 41871052)Startup Research Funding of Northeast Forestry University for Chengdong Outstanding Youth Scholarship(YQ2020-10)+1 种基金Chengdong Leadership(LJ2020-01)the State Key Laboratory of Frozen Soils Engineering Open Fund Project(Grant No.SKLFSE202008).
文摘In boreal forest ecosystems, permafrost and forest types are mutually interdependent;permafrost degradation impacts forest ecosystem structure and functions. The Xing’an permafrost in Northeast China is on the southern margin of the Eastern Asia latitudinal permafrost body. Under a warming climate, permafrost undergoes rapid and extensive degradation. In this study, the frost-number (Fn) model based on air temperatures and ground surface temperatures was used to predict the distribution of the Xing’an permafrost, and, temporal and spatial changes in air and ground-surface temperatures from 1961 to 2019 are analyzed. The results show that Northeast China has experienced a rapid and substantial climate warming over the past 60 years. The rises in mean annual air and mean annual ground-surface temperatures were higher in permafrost zones than those in the seasonal frost zone. The frost numbers of air and ground-surface temperatures were calculated for determining the southern limit of latitudinal permafrost and for permafrost zonation. The southern limits of discontinuous permafrost, sporadic permafrost, and latitudinal permafrost moved northward significantly. According to the air-temperature frost-number criteria for permafrost zoning, compared with that in the 1960s, the extent of Xing’an permafrost in Northeast China had decreased by 40.6% by the 2010s. With an average rate of increase in mean annual air temperatures at 0.03 ℃ a^(−1), the extent of permafrost in Northeast China will decrease to 26.42 × 10^(4) by 2020, 14.69 × 10^(4) by 2040 and to 11.24 × 10^(4) km^(2) by 2050. According to the ground-surface temperature frost-number criteria, the southern limit of latitudinal permafrost was at the 0.463. From the 1960s to the 2010s, the extent of latitudinal permafrost declined significantly. Due to the nature of the ecosystem-protected Xing’an-Baikal permafrost, management and protection (e.g., more prudent and effective forest fire management and proper logging of forests) of the Xing’an permafrost eco-environment should be strengthened.
基金Project(KZCX2-YW-Q03-04) supported by the Important Orientation Projects of the Chinese Academy of SciencesProject(41030741) supported by the National Natural Science of ChinaProject(2010CB434813) supported by the National Basic Research Program of China
文摘The sideward permafrost along the Qinghai-Tibet Highway (QTH) contains massive ground-ice and is at a relatively high temperature.Under the influence of the steady increase of human activities,the permafrost environment has been changed greatly for a long time.At present,the permafrost becomes warm and rapidly degenerates,including the decline of the permafrost table,rising of the ground temperature,shortening of the length of frozen section,and extension of range of melting region.Some thaw hazards (e.g.thaw slumping and thermokarst pond) have widely occurred along both sides of the roadbed.In addition,due to the incomplete construction management,the vegetation adjacent to the highway is seriously damaged or eradicated,resulting in the land desertification and ecosystem out of balance.The dust,waste and garbage brought by drivers,passengers,maintenance workers,and transportations may also pollute the permafrost environment.
基金Under the auspices of Major State Basic Research Development Program of China(No.2010CB951402)National Natural Science Foundation of China(No.41101067)+1 种基金Foundation for Excellent Youth Scholars of Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences(No.Y184A91001)Research Program of State Key Laboratory of Frozen Soil Engineering of Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences(No.SKLFSE-ZQ-10)
文摘This study proposes an equivalent-elevation method to evaluate the integrated effects of latitude and elevation on regional and local-scale permafrost distribution in the Qinghai-Tibet Plateau,and to model the general permafrost-distribution patterns in regional and local-scale area.It is found that the Gaussian curve―an empirical model describing the relation between variations of altitudinal permafrost lower limit (PLL) and latitude in the Northern Hemisphere―could be applied in regional-and local-scale areas in the Qinghai-Tibet Plateau in a latitude-sensitive interval of 30°-50°N.The curve was then used to evaluate the latitudinal effect on permafrost distribution through transforming the latitudinal effect into a kind of altitudinal difference of PLL.This study then calculated the local equivalent-elevation value by overlaying the altitudinal difference of PLL onto real elevation at a certain location.The equivalent-elevation method was verified in an experimental subwatershed of the Qinghai-Tibet Plateau.However,feasibility of the method should be further tested in order to extend for future studies.The use of equivalent-elevation values can build a platform for comparing the regional general permafrost distribution in the plateau,and for basing further evaluations of local factors' effects on regional permafrost distribution.
基金supported financially by the Special Basic Research Program of China(Grant No.2008FY110200)partially by Open Programme of State Key Laboratory(No.SKLFSE201009)
文摘In high mountainous areas, the development and distribution of alpine permafrost is greatly affected by macro- and mi- cro-topographic factors. The effects of latitude, altitude, slope, and aspect on the distribution of permafrost were studied to under- stand the dislribution patterns of permafrost in Wenquan on the Qinghai-Tibet Plateau. Cluster and correlation analysis were per- formed based on 30 m Global Digital Elevation Model （GDEM） data and field data obtained using geophysical exploration and borehole drilling methods. A Multivariate Adaptive Regression Spline model （MARS） was developed to simulate permafrost spa- tial distribution over the studied area. A validation was followed by comparing to 201 geophysical exploration sites, as well as by comparing to two other models, i.e., a binary logistic regression model and the Mean Annual Ground Temperature model （IVlAGT）. The MARS model provides a better simulation than the other two models. Besides the control effect of elevation on permafrost distribution, the MARS model also takes into account the impact of direct solar radiation on permafrost distribution.
基金financially supported by the National Natural Science Foundation of China(41871064)the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0304)。
文摘The Qinghai-Tibet Plateau(QTP)distributes the largest extent of high-altitude mountain permafrost in the world(Zou et al.,2017),which has different characteristics from high-latitude permafrost(Yang et al.,2010)and stores massive soil carbon.
基金supported by the National Natural Science Foundation of China (No. 40671013,40871245)
文摘Boreal peatlands represent a large global carbon pool. The relationships between carbon mineralization, soil temperature and moisture in the permafrost peatlands of the Great Hing＇an Mountains, China, were examined. The CO2 emissions were measured during laboratory incubations of samples from four sites under different temperatures （5, 10, 15, and 20℃） and moisture contents （0%, 30%, 60%, 100% water holding capacity （WHC） and completely water saturated）. Total carbon mineralization ranged from 15.51 to 112.92 mg C under the treatments for all sites. Carbon mineralization rates decreased with soil depth, increased with temperature, and reached the highest at 60% WHC at the same temperature. The calculated temperature coefficient （Q10） values ranged from 1.84 to 2.51 with the soil depths and moisture. However, the values were not significantly affected by soil moisture and depth for all sites due to the different peat properties （P 〉 0.05）. We found that the carbon mineralization could be successfully predicted as a two-compartment function with temperature and moisture （R^2 〉 0.96） and total carbon mineralization was significantly affected by temperature and moisture （P 〈 0.05）. Thus, temperature and moisture would play important roles in carbon mineralization of permafrost peatlands in the Great Hing＇an Mountains, indicating that the permafrost peatlands would be sensitive to the environment change, and the permafrost peatlands would be potentially mineralized under future climate change.
文摘Qilian Mountain permafrost, with area about 10×10^4 km2, locates in the north of Qinghai- Tibet plateau. It equips with perfect conditions and has great prospecting potential for gas hydrate. The Scientific Drilling Project of Gas Hydrate in Qilian Mountain permafrost, which locates in Juhugeng of Muri Coalfield, Tianjun County, Qinghai Province, has been implemented by China Geological Survey in 2008-2009. Four scientific drilling wells have been completed with a total footage of 2059.13 m. Samples of gas hydrate are collected separately from holes DK-1, DK-2 and DK-3. Gas hydrate is hosted under permafrost zone in the 133-396 m interval. The sample is white crystal and easily burning. Anomaly low temperature has been identified by the infrared camera. The gas hydratebearing cores strongly bubble in the water. Gas-bubble and water-drop are emitted from the hydratebearing cores and then characteristic of honeycombed structure is left. The typical spectrum curve of gas hydrate is detected using Raman spectrometry. Furthermore, the logging profile also indicates high electrical resistivity and sonic velocity. Gas hydrate in Qilian Mountain is characterized by a thinner permafrost zone, shallower buried depth, more complex gas component and coal-bed methane origin etc.
基金funded by the National Key Research and Development Program(2016YFC0802103)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA2003020102)+3 种基金National Natural Science Foundation of China(Grants Nos.U1703244,41672310,41630636 and 41702333)the Research Project of the State Key Laboratory of Frozen Soils Engineering(Grant No.SKLFSE-ZY-16)the Major Program of Bureau of International Cooperation of CAS(131B62KYSB20170012)the STS research project of CAS(HHS-TSS-STS-1502)
文摘The permafrost along the China-Russia Crude Oil Pipeline(CRCOP) is degrading since the pipeline operation in 2011. Heat dissipated from the pipeline, climate warming and anthropogenic activities leads to permafrost warming. The processes of permafrost warming along the CRCOP were studied based on the monitoring of air and soil temperatures, and electrical resistivity tomography(ERT) surveys. Results show that:(1) the mean annual air temperature(MAAT) in permafrost regions along the CRCOP increased with a rate of 0.21°C/10a–0.40°C/10 a during the past five decades;(2) the mean annual ground temperature(MAGT, at-15 m depth) of undisturbed permafrost increased by 0.2°C and the natural permafrost table remained unchanged due to the zero-curtain effect;(3) permafrost surrounding the uninsulated pipeline right-of-way warmed significantly compared with that in a natural site. During 2012–2017, the MAGT and the artificial permafrost table, 2 m away from the pipeline centerline, increased at rates of 0.063°C/a and 1.0 m/a. The thaw bulb developed around the pipe and exhibits a faster lateral expansion;(4) 80-mm-thick insulation could reduce the heat exchange between the pipeline and underlying permafrost and then keep the permafrost and pipe stable. The MAGT and the artificial permafrost table, 4.8 m away from the center line of the pipeline, increased by 0.3°C/a and 0.43 m/a, respectively. Due to the heat disturbance caused by warm oil, the degradation of wetland, controlled burn each autumn and climate warming, the permafrost extent reduced and warmed significantly along the CRCOP route. Field observations provide basic data to clarify the interactions between CRCOP and permafrost degradation and environmental effects in the context of climate change.
基金Under the auspices of National Natural Science Foundation of China (No. 40701031,40225001,J0630966)3rd-term Knowledge Innovation Program of Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences (No. O650445)
文摘Recently, the degradation of permafrost and marsh environments in the Da and Xiao Hinggan Mountains has become a great concern as more human activities and pronounced climate warming were observed during the past 30 years and projected for the near future. The distr/bution patterns and development mechanisms of the permafrost and marshes have been examined both in theories and in field observations, in order to better understand the symbiosis of permafrost and marshes. The permafrost and marshes in the Da and Xiao Hinggan Mountains display discernible zonations in latitude and elevation. The marsh vegetation canopy, litter and peat soil have good thermal insulation properties for the underlying permafrost, resulting in a thermal offset of 3 ℃ to 4℃ and subsequently suppressing soil temperature. In addition, the much higher thermal conductivity of frozen and ice-rich peat in the active layer is conducive to the development or in favor of the protection of permafrost due to the semi-conductor properties of the soils overlying the permafrost. On the other hand, because permafrost is almost impervious, the osmosis of water in marsh soils can be effectively reduced, timely providing water supplies for helophytes growth or germination in spring. In the Da and Xiao Hinggan Mountains, the permafrost degradation has been accelerating due to the marked climate warming, ever increasing human activities, and the resultant eco-environmental changes. Since the permafrost and marsh environments are symbiotic and interdependent, they need to be managed or protected in a well-coordinated and integrated way.
基金supported by the China Key Research Project for Global Change (No.2010CB951404) the China National Science Foundation (No.40821001)
文摘Based on data from six meteorological stations in the permafrost regions, 60 boreholes for long-term monitoring of permafrost temperatures, and 710 hand-dug pits and shallow boreholes on the Qinghai-Tibet Plateau （QTP）, the spatiotemporal variability of permafrost degradation was closely examined in relation to the rates of changes in air, surface, and ground temperatures. The de- cadal averages and increases in the mean annual air temperatures （MAATs） from 1961-2010 were the largest and most persistent during the last century. MAATs rose by 1.3 ℃, with an average increase rate of 0.03 ℃/yr. The average of mean annual ground surface temperatures （MAGSTs） increased by 1.3 ℃ at an average rate of 0.03 ℃/yr. The rates of changes in ground temperatures were -0.01 to 0.07 ℃/yr. The rates of changes in the depths of the permafrost table were -1 to ＋10 cm/yr. The areal extent of permafrost on the QTP shrank from about 1.50× 10^6 km^2 in 1975 to about 1.26× 10^6 km^2 in 2006. About 60% of the shrinkage in area of permafrost occurred during the period from 1996 to 2006. Due to increasing air temperature since the late 1980s, warm （〉-1 ℃） permafrost has started to degrade, and the degradation has gradually expanded to the zones of transitory （-1 to -2 ℃） and cold （〈-2 ℃） permafrost. Permafrost on the southern and southeastem plateau degrades more markedly. It is projected that the degradation of permafrost is likely to accelerate, and substantial changes in the distributive features and thermal regimes of permafrost should be anticipated. However, regarding the relationships between degrading permafrost and the degradation of rangelands, it is still too early to draw reliable conclusions due to inadequate scientific criteria and evidence.
基金the Chinese Academy of Sciences Strategic Priority Research Program(XDA20100103)Ministry of Science and Technology of China Key R&D Program(2017YFC0405704)CAS Overseas Professorships of Victor F Bense and Sergey S Marchenko at the former Cold and Arid Regions Environmental and Engineering Research Institute(now renamed to Northwest Institute of Eco-Environment and Resources),CAS during 2013-2016.
文摘Many observations in and model simulations for northern basins have confirmed an increased streamflow from degrading permafrost,while the streamflow has declined in the source area of the Yellow River(SAYR,above the Tanag hydrological station)on the northeastern Qinghai-Tibet Plateau,West China.How and to what extent does the degrading permafrost change the flow in the SAYR?According to seasonal regimes of hydrological processes,the SAYR is divided intofour sub-basins with varied permafrost extents to detect impacts of permafrost degradation on the Yellow River streamflow.Results show that permafrost degradation may have released appreciable meltwater for recharging groundwater.The potential release rate of ground-ice melt-water in the Sub-basin 1(the headwater area of the Yellow River(HAYR),above the Huangheyan hydrological station)is the highest(5.6 mm per year),contributing to 14.4%of the annual Yellow River streamflow at Huangheyan.Seasonal/intra-and annual shifts of streamflow,a possible signal for the marked alteration of hydrological processes by permafrost degradation,is observed in the HAYR,but the shifts are minor in other sub-basins in the SAYR.Improved hydraulic connectivity is expected to occur during and after certain degrees of permafrost degradation.Direct impacts of permafrost degradation on the annual Yellow River streamflow in the SAYR at Tanag,i.e.,from the meltwater of ground-ice,is estimated at 4.9%that of the annual Yellow River discharge at Tanag,yet with a high uncertainty,due to neglecting of the improved hydraulic connections from permafrost degradation and the flow generation conditions for the ground-ice meltwater.Enhanced evapotranspiration,substantial weakening of the Southwest China Autumn Rain,and anthropogenic disturbances may largely account for the declined streamflow in the SAYR.
基金supported by the National Natural Science Foundation of China(Grant No.41501079 and 91647103)Funded by State Key Laboratory of Frozen Soil Engineering(Grant No.SKLFSE-ZQ-43)+1 种基金the Chinese Academy of Sciences(CAS)Key Research Program(Grant No.KZZD-EW-13)the Foundation for Excellent Youth Scholars of NIEER,CAS
文摘The soil moisture movement is an important carrier of material cycle and energy flow among the various geo-spheres in the cold regions.Thus, this research takes the north slope of Bayan Har Mountains in Qinghai-Tibet Plateau as a case study.The present study firstly investigates the change of permafrost moisture in different slope positions and depths. Based on this investigation, this article attempts to investigate the spatial variability of permafrost moisture and identifies the key influence factors in different terrain conditions. The method of classification and regression tree(CART) is adopted to identify the main controlling factors influencing the soil moisture movement. The relationships between soil moisture and environmental factors are revealed by the use of the method of canonical correspondence analysis(CCA). The results show that: 1) Due to the terrain slope and the freezing-thawing process, the horizontal flow weakens in the freezing period. The vertical migration of the soil moisture movement strengthens. It will lead to that the soil-moisture content in the up-slope is higher than that in the down-slope. The conclusion is contrary during the melting period. 2) Elevation, soil texture, soil temperature and vegetation coverage are the main environmental factors which affect the slopepermafrost soil-moisture. 3) Slope, elevation and vegetation coverage are the main factors that affect the slope-permafrost soil-moisture at the shallow depth of 0-20 cm. It is complex at the middle and lower depth.
