the influence of debris cover and glacial lakes on the recession of glaciers in sikkim himalaya india we investigated area changes in glaciers covering an area of similar to 200 km 2 in the tista basin sikkim eastern indian himalaya between similar to 1990 and 2010 using landsat thematic mapper tm and indian remote sensing satellite irs images and related the changes to debris cover supraglacial lakes and moraine dam lakes the glaciers lost an area of 3 3 0 8 between 1989 90 and 2010 more detailed analysis revealed an area loss of 2 00 0 82 2 56 0 61 and 2 28 2 01 km 2 for the periods 1989 97 1997 2004 05 and 2004 2009 10 respectively this indicates an accelerated retreat of glaciers after 1997 on further analysis we observed 1 the formation and expansion of supraglacial lakes on many debris covered glaciers and 2 the merging of these lakes over time leading to the development of large moraine dam lakes we also observed that debris covered glaciers with lakes lose a greater area than debris covered glaciers without lakes and debris free glaciers the climatic data for 24 years 1987 2011 measured at the gangtok meteorological station 1812 m a s l showed that the region experienced a 1 0 degrees c rise in the summer minimum temperature and a 2 0 degrees c rise in the winter minimum temperature indicating hotter summers and warmer winters there was no significant trend in the total annual precipitation we find that glacier retreat is caused mainly by a temperature increase and that debris covered glaciers can retreat at a faster rate than debris free glaciers if associated with lakes

paleo glacier reconstruction in southwestern british columbia canada a glaciovolcanic model abstract volcanic rocks erupted within glacial environments offer powerful paleoenvironmental insights these glaciovolcanoes and their deposits serve as proxies that inform on the paleo presence distribution and thickness of past glaciers we investigate the paleoenvironmental implications of three mid to late pleistocene volcanic deposits in the garibaldi volcanic belt of southwestern british columbia canada we use these data to inform a simple geometric model that constrains paleo glacier distributions in the southern canadian cordillera the three volcanoes are used to recover i a coalesced mountain ice sheet in late marine isotope stage mis 4 and possibly into mis 3 up to 49 1 5 5 ka ii major and rapid degradation of glaciers during the late mis 6 to 5e transition by 141 12 9 ka and iii a coalesced mountain ice sheet or continental ice sheet that existed during mis 15 598 7 5 ka

hydrological regimes under the conjunction of westerly and monsoon climates a case investigation in the astore basin northwestern himalaya in a changing climate river basins with limited summer precipitation but abundant snow and glacier melt water are affected severely by reductions and seasonal alterations in annual stream flows however high altitude glacio hydrological observations and investigations to address the linkage between the timing of glacier changes and river runoff fluctuations remain ambiguous particularly in the northwestern himalayan region of pakistan in this context the hydrological regime of the astore basin a sub catchment of the upper indus river basin was comprehensively investigated by employing in situ hydro meteorological observations in combination with satellite remote sensing data two thirds of the annual precipitation in the astore basin falls in winter and spring mainly deposited by westerly winds whereas summer and autumn precipitation deposited by the monsoon and local jet streams accounts for only one third some 14 of the basin area is covered by glaciers and added to the accumulated seasonal snow deposited by westerly circulations this can reach 80 85 of the basin area therefore more than 75 of the annual basin runoff depends on melt water produced by the predominant seasonal snow and glacier ablation the non parametric mann kendall trend test was applied to the whole time series of hydro meteorological data this indicated a lowering of annual and summer mean temperatures during the period 1980 1995 and slight warming during the 1996 2010 period similarly annual winter and summer precipitation and annual mean discharge increased from 1980 to 1995 but in contrast a slight decrease in annual and summer precipitation was observed during the 1996 2010 period however discharge evidence is slight making any increase in this period insignificant in addition the spearman and mann kendall correlation results depict annual stream flow fluctuations during the 1980 2010 decades in the astore river that were predominantly influenced by precipitation variations but not by any alteration in catchment temperatures and so not governed by enhanced glacier ablation and retreat the results of the analysis presented here were also substantiated by satellite remote sensing investigation which points to evidence of stable conditions in the astore basin glaciers during this period

glacier changes in southeast alaska and northwest british columbia and contribution to sea level rise 1 the digital elevation model dem from the 2000 shuttle radar topography mission srtm was differenced from a composite dem based on air photos dating from 1948 to 1987 to determine glacier volume changes in southeast alaska and adjoining canada srtm accuracy was assessed at 5 m through comparison with airborne laser altimetry and control locations measured with gps glacier surface elevations lowered over 95 of the 14 580 km2 glacier covered area analyzed with some glaciers thinning as much as 640 m a combination of factors have contributed to this wastage including calving retreats of tidewater and lacustrine glaciers and climate change many glaciers in this region are particularly sensitive to climate change as they have large areas at low elevations however several tidewater glaciers that had historically undergone calving retreats are now expanding and appear to be in the advancing stage of the tidewater glacier cycle the net average rate of ice loss is estimated at 16 7 4 4 km3 yr equivalent to a global sea level rise contribution of 0 04 0 01 mm yr

late holocene activity of sherman and sheridan glaciers prince william sound alaska abstract two adjacent glaciers in the chugach mountains of south central alaska have markedly different histories on decadal to perhaps centennial timescales sheridan glacier has advanced and retreated hundreds of metres during the latest holocene its recent fluctuations have markedly altered local base level of sherman river which drains sherman glacier and flows into sheridan lake sheridan glacier advanced to its greatest extent during the little ice age raising base level of sherman river and inducing aggradation there of up to 17 m of sediment retreat of sheridan glacier formed a series of lakes that have coalesced as lower lake outlets have become available base level of sherman river has dropped resulting in the evacuation of substantial volumes of sediment from sherman river valley in about 2000 the terminus of sheridan glacier began to disintegrate retreat accelerated dramatically in 2010 by 2016 the glacier had retreated an average of 600 m from its 2010 terminus although some areas retreated up to 1 9 km and others did not retreat at all meanwhile sherman glacier continued a slow advance initiated by a rock avalanche that blanketed much of its ablation area in the 1964 alaska earthquake

rock glaciers and mountain hydrology a review abstract in mountainous regions climate change threatens cryospheric water resources and understanding all components of the hydrological cycle is necessary for effective water resource management rock glaciers are climatically more resilient than glaciers and contain potentially hydrologically valuable ice volumes and yet have received less attention even though rock glacier hydrological importance may increase under future climate warming in synthesising data from a range of global studies we provide the first comprehensive evaluation of the hydrological role played by rock glaciers we evaluate hydrological significance over a range of temporal and spatial scales alongside the complex multiple hydrological processes with which rock glaciers can interact diurnally seasonally annually decadally and both at local and regional extents we report that although no global extent complete inventory for rock glaciers exists currently recent research efforts have greatly elaborated spatial coverage using these research papers we synthesise information on rock glacier spatial distribution morphometric characteristics surface and subsurface features ice storage and hydrological flow dynamics water chemistry and future resilience from which we provide the first comprehensive evaluation of their hydrological contribution we identify and discuss long intermediate and short term timescales for rock glacier storage allowing a more balanced assessment of the contrasting perspectives regarding the relative significance of rock glacier derived hydrological contributions compared to other water sources we show that further empirical observations are required to gain a deeper hydrological understanding of rock glaciers in terms of i their genesis and geomorphological dynamics ii total ice water volume iii water discharge and iv water quality lastly we hypothesise that at decadal and longer timescales under future climate warming degradation of ice within rock glaciers may represent an increasing hydrological contribution to downstream regions and thus increased hydrological significance while rock glacier water stores persist

glacier change of the columbia icefield canadian rocky mountains 1919 2009 we determined length area elevation and volume change of the columbia icefield using interprovincial boundary commission survey maps from 1919 eight sets of aerial photographs from 1948 to 1993 and satellite data from 1999 to 2009 over the period 1919 2009 glaciers on average retreated 1150 34 m and shrank by 2 4 0 2 km 2 total area loss was 59 6 1 2 km 2 23 5 and mean elevation change was 49 25 m w e resulting in a total volume loss of 14 3 2 0 km 3 w e large outlet glaciers experienced the greatest absolute ice loss while small detached glaciers lost the most relative length and area thinning rates of debris covered ice were 30 60 lower than those for clean ice all glacier changes were significantly correlated with each other p 0 01 with r values ranging from 0 54 to 0 82 temperature is correlated with length and area change over periods lagged 1 5 years p 0 05 and with elevation and volume change over periods lagged 9 18 years p 0 05 precipitation is correlated with glacier change over periods lagged 1 10 years p 0 05

latest pleistocene and holocene behaviour of franklin glacier mt waddington area british columbia coast mountains canada franklin glacier is an 18 km long valley glacier that originates in a broad icefield below the west face of mt waddington in the central british columbia coast mountains canada radiocarbon dated

on the accuracy of glacier outlines derived from remote sensing data deriving glacier outlines from satellite data has become increasingly popular in the past decade in particular when glacier outlines are used as a base for change assessment it is important to know how accurate they are calculating the accuracy correctly is challenging as appropriate reference data e g from higher resolution sensors are seldom available moreover after the required manual correction of the raw outlines e g for debris cover such a comparison would only reveal the accuracy of the analyst rather than of the algorithm applied here we compare outlines for clean and debris covered glaciers as derived from single and multiple digitizing by different or the same analysts on very high 1 m and medium resolution 30 m remote sensing data against each other and to glacier outlines derived from automated classification of landsat thematic mapper data results show a high variability in the interpretation of debris covered glacier parts largely independent of the spatial resolution area differences were up to 30 and an overall good agreement for clean ice with sufficient contrast to the surrounding terrain differences 5 the differences of the automatically derived outlines from a reference value are as small as the standard deviation of the manual digitizations from several analysts based on these results we conclude that automated mapping of clean ice is preferable to manual digitization and recommend using the latter method only for required corrections of incorrectly mapped glacier parts e g debris cover shadow

accelerating shrinkage of patagonian glaciers from the little ice age ad 1870 to 2011 davies b j glasser n f 2012 accelerating shrinkage of patagonian glaciers from the little ice age similar to ad 1870 to 2011 journal of glaciology 58 212 1063 1084

hasty retreat of glaciers in northern patagonia from 1985 to 2011 mapping changes in glacier extent from repeat optical satellite data has revealed widespread glacier decline in nearly all regions of the world over the past few decades while numerous studies have documented the changes of the outlet glaciers of the northern and southern patagonia icefields npi spi information about glacier changes in the patagonian andes to the north of the npi is much scarcer here we present an assessment of area changes for glaciers mainly located in the palena district of chile based on glacier inventories for 1985 2000 and 2011 that were derived from two consecutive landsat scenes and a digital elevation model the analysis revealed a dramatic area decline for the largest glaciers and total area loss of 25 from 1985 to 2011 the lower parts of several larger glaciers 10 km 2 melted completely area loss below 1000 m elevation was 50 100 in both periods and 374 glaciers out of 1664 disappeared the number of proglacial lakes increased from 223 to 327 and their area expanded by 11 6 km 2 59 between 1985 and 2011 seasonal snow persisting at high elevations in the 2011 scene was a major obstacle to glacier delineation so the obtained area change rate of 1 a 1 over the entire period is a lower bound estimate the observed climate trends e g cooling in puerto montt are in contrast to the observed shrinkage

relation between the mass balance of western canadian mountain glaciers and meteorological data le bilan de masse les bilans d ete et d hiver et l altitude de la ligne d equilibre de 3 glaciers canadiens sont compares avec les donnees meteorologiques de stations avoisinantes pour la periode 1966 1984 presentation de reconstructions statistiques pour les 3 glaciers sur la base des equations de regression avec les enregistrements meteorologiques depuis 1938

challenges and recommendations in mapping of glacier parameters from space results of the 2008 global land ice measurements from space glims workshop boulder colorado usa on 16 18 june 2008 the us national snow and ice data center held a glims workshop in boulder co usa focusing on formulating procedures and best practices for operational glacier mapping using satellite imagery despite the progress made in recent years there still remain many cases where automatic delineation of glacier boundaries in satellite imagery is difficult error prone or time consuming this workshop identified six themes for consideration by focus groups 1 mapping clean ice and lakes 2 mapping ice divides 3 mapping debris covered glaciers 4 assessing changes in glacier area and elevation through comparisons with older data 5 digital elevation model dem generation from satellite stereo pairs and 6 accuracy and error analysis talks presented examples and work in progress for each of these topics and focus groups worked on compiling a summary of available algorithms and procedures to address and avoid identified hurdles special emphasis was given to establishing standard protocols for glacier delineation and analysis creating illustrated tutorials and providing source code for available methods this paper summarizes the major results of the 2008 glims workshop with an emphasis on definitions methods and recommendations for satellite data processing while the list of proposed methods and recommendations is not comprehensive and is still a work in progress our goal here is to provide a starting point for the glims regional centers as well as for the wider glaciological community in terms of documentation on possible pitfalls along with potential solutions

structural diagenesis of siderite layers in black shales albian black flysch northern spain abstractin this study we describe the structural diagenesis of diluted turbidite and abyssal lutite deposits of the late albian black flysch western pyrenees northern spain we analyze and interpret an association of brittle and ductile soft sediment deformation structures to our knowledge some of them are described for the first time although they are known in other tectonic settings we reconstruct a diagenetic history that commenced with a generalized siderite cement precipitation after siliciclastic turbidite deposition siderite replaced the finer grained diluted uppermost turbidite parts siderite precipitation was followed by calcite cementation in turbidites and by soft sediment brittle thrust planes shear veins and microveins and ductile fault bend folds and culminations developed in relation to thrust ramp strain deformation structures this occurred before hosting lutite lithification by dewatering and compaction

temporal change of glaciers area and geomorphometric parameters in parbati valley himachal pradesh india temporal change in the glacier coverage is analyzed for the period between 1962 and 2003 in parbati valley himachal pradesh it is observed that the total glacier cover has been decreased by 17 ranging between 8 and 100 for individual glacier the pattern of de glaciation shows a high degree of shrinkage in outer zone of parbati valley while least shrinkage is observed in the inner valley the present study is conducted to establish relationship between glacio geomorphic parameters and glaciers shrinkage pattern to predict the future glacier cover in warming scenario a systematic change is observed for glacio geomorphic parameters associated with temporal change in glacier cover it is observed that mean and minimum elevation slope relief and duration of insolation have changed substantially maximum elevation plan profile curvatures and aspect have shown less change from 1962 to 2003 a correlation matrix between glacio geomorphic parameters for glaciers between 1962 and 2003 shows that the recent glaciers are much more controlled by terrain characteristics than that in the recent past

compilation of a glacier inventory for the western himalayas from satellite data methods challenges and results abstract due to their sensitive reaction to changes in climatic conditions glaciers have been selected as an essential climate variable ecv although a large amount of ice is located in the himalayas this region is yet only sparsely represented in global glacier databases accordingly a sound and comprehensive change assessment or determination of water resources was not yet possible in this study we present a new glacier inventory for the western himalayas compiled from landsat etm scenes acquired between 2000 and 2002 coherence images from alos palsar image pairs the srtm digital elevation model dem and the aster global dem gdem several specific challenges for glacier mapping were found in this region and addressed they are related to debris cover orographic clouds locally variable snow conditions and creeping permafrost features in cold dry regions additional to seven topographic parameters that are obtained from the aster gdem for each glacier we also determined the relative amount of debris cover on the glacier surface the inventory contains 11 400 glaciers larger than 0 02 km2 which cover a total area of 9 310 km2 analysis of the inventory data revealed characteristic patterns of mean glacier elevation and relative debris cover amounts that might be related to the governing climatic conditions the full dataset will be freely available in the glims glacier database to foster further analyses and modeling of the glaciers in this region

identification of alpine glaciers in the central himalayas using fully polarimetric l band sar data to study the applicability of full polarimetric synthetic aperture radar sar data to identify alpine glaciers in the central himalayas six polarimetric decomposition methods were used to obtain 20 polarimetric characteristic parameters based on the advanced land observing satellite 2 alos 2 phased array type l band sar palsar data object oriented multiscale segmentation was performed on a landsat 8 operational land imager oli image prior to classification and the vector boundaries of different types of training samples were selected from the segmented results we performed a support vector machine svm based classification on the characteristic parameters from each polarimetric decomposition all 20 parameters were then screened and combined according to different requirements the degree of separability of different types of training samples and the type of scattering mechanisms the results show that the classification accuracy of the incoherent decomposition characteristics based on the covariance matrix is the best reaching 87 and it can exceed 91 after adding the local incidence angle to the suite of classifiers eventually more than 93 accuracy was achieved using a combination of multiple polarimetric parameters which reduced the misclassification between bare ice and rock we also analyzed the use of controlling factors on the accuracy of alpine glacier identification and found that the polarimetric information and aspect of the glacier surface are the most important factors the former is the main basis for identification but the latter will confuse the feature distributions of different categories and cause misclassification

late holocene glacial activity at bromley glacier cambria icefield northern british columbia coast mountains canada retreating and downwasting glaciers in the british columbia coast mountains are exposing the remains of forests buried during holocene age glacial advances despite recent progress in discerning th

perspectives on the production of a glacier inventory from multispectral satellite data in arctic canada cumberland peninsula baffin island the consequences of global warming on land ice masses are difficult to assess in detail as two dimensional glacier inventory data are still missing for many remote regions of the world as the largest future temperature increase is expected to occur at high latitudes the glaciers and ice caps in the arctic will be particularly susceptible to the expected warming this study demonstrates the possibilities of space borne glacier inventorying at a remote site on cumberland peninsula a part of baffin island in arctic canada thereby providing glacier inventory data for this region our approach combines landsat etm and terra aster satellite data an aster derived digital elevation model dem and geographic information system based processing we used thresholded ratio images from etm bands 3 and 5 and aster bands 3 and 4 for glacier mapping manual delineation of little ice age trimlines and moraines has been applied to calculate area changes for 225 glaciers yielding an average area loss of 11 a size distribution has been obtained for 770 glaciers that is very different from that for alpine glaciers numerous three dimensional glacier parameters were derived from the aster dem for a subset of 340 glaciers the amount of working time required for the processing has been tracked and resulted in 5 min per glacier or 7 years for all estimated 160 000 glaciers worldwide

comparison of new and existing global digital elevation models aster g dem and srtm 3 1 a new global elevation dataset known as g dem based on the aster satellite imagery will be released in late 2008 g dem will be the best freely available global digital elevation model dem at a horizontal resolution of 1 arc second we assess the quality of g dem in comparison with 3 arc second srtm dem the best current global elevation dataset basic geomorphometric parameters elevation slope and curvature were examined for a pre release version of g dem and srtm dem for western japan g dem has fewer missing cells than srtm dem particularly in steep terrain also g dem gives smoother and more realistic representations of lowlands valleys steep slopes and mountain ridges whereas srtm dem includes many local spikes and holes and tends to overestimate valley floor elevation and underestimate ridge elevation g dem will be commonly used in geoscientific studies because of its higher resolution fewer missing data and better topographic representation than srtm dem

remote sensing based assessment of hazards from glacier lake outbursts a case study in the swiss alps glacier lakes are a common phenomenon in high mountain areas outbursts from glacier lakes have repeatedly caused the loss of human lives as well as severe damage to local infrastructure in several high mountain ranges around the world a grave uncertainty about the hazard potential of glacier lakes still exists especially with respect to the effects of accelerating rates of glacier retreat as a consequence of atmospheric warming area wide detection and modeling of glacier lake hazard potentials is therefore a major challenge in this study an approach integrating three scale levels allows for the progressive focus on critical glacier lakes remote sensing methods for application in glacier lake hazard assessment are presented and include channel indexing data fusion and change detection each method matches the requirements of a certain scale level for estimating potential disaster amplitudes assessments must be made of maximum discharge and runout distance of outbursts floods and debris flows existing empirical relations are evaluated and complementary ones as derived from available data are proposed tests with observations from a recent outburst event from a moraine dammed lake in the swiss alps show the basic applicability of the proposed techniques and the usefulness of empirical relations for first hazard assessments in particular the observed runout distance of the debris flow resulting from the outburst does not exceed the empirically estimated maximum runout distance a list of decision criteria and related remote sensing techniques are discussed in conclusion such a list is an essential tool for evaluating the hazard potential of a lake a systematic application of remote sensing based methods for glacier lake hazard assessment is recommended

recent volume loss of british columbian glaciers canada 1 we use the shuttle radar topography mission srtm data and digital terrain models from aerial photography to quantify the change of glacier volume in british columbia bc canada for the period 1985 1999 we note substantial elevation bias in the srtm elevations typically on the order of 12 m km 1 the bias corrected thinning rate is 0 78 0 19 m a 1 which yields an annual volume loss of 22 48 5 53 km 3a 1 this rate of glacier volume loss is 65 of the estimate uncorrected for elevation bias 34 7 km 3a 1 and cautions against the use of uncorrected srtm data for glacier change studies glacier recession in bc could account for ca 0 67 0 12 mm of sea level rise over the period 1985 1999 0 05 0 009 mm yr 1 or about 8 3 of the contribution from mountain glaciers and ice caps the recent rate of glacier loss in the coast mountains 17 0 km 3a 1 is approximately double that observed for the previous two decades

tree ring based reconstructions of north american glacier mass balance through the little ice age contemporary warming transition abstract glacier mass balance reconstructions provide a means of placing relatively short observational records into a longer term context in western north america mass balance records span four to five decades and capture a relatively narrow window of glacial behavior over an interval that was dominated by warming and ablation we use temperature and moisture sensitive tree ring series to reconstruct annual mass balance for six glaciers in the pacific northwest and alaska mass balance models rely on the climatic sensitivity of tree ring chronologies and teleconnection patterns in the north pacific the reconstructions extend through the mid to latter portions of the little ice age lia and explore the role of climate variability in forcing mass balance across multiple environmental gradients synchronous positive mass balance intervals coincide with regional moraine building and solar minima whereas differences in lia glacier behavior are related to synoptic climate forcing secular warming in the late 19th century to present corresponds with the only multi decadal intervals of negative mass balance in all glacier reconstructions this suggests that contemporary retreat in western north america is unique with respect to the last several centuries and that regional patterns of glacier variability are now dominated by global climate forcing

evolution of a debris covered glacier in the western himalaya during the last four decades 1971 2016 a multiparametric assessment using remote sensing and field observations abstract this study assesses the response of the panchi nala glacier bhaga basin western himalaya to climate change by monitoring multiple glacier parameters namely length area debris cover snowline altitude sla surface ice velocity siv and surface elevation change h these parameters were analysed using high resolution satellite images corona kh 4b and sentinel 2 msi and medium resolution ones landsat tm etm oli and terra aster acquired between 1971 and 2016 along with extensive field observations considering only dimensional changes the glacier appears to have low rates of recession 4 54 2 56 m y 1 and deglaciation 0 11 0 04 y 1 over the study period 1971 2016 however siv and h values reveal a significant slowdown 33 87 1992 93 2015 16 and an extensive lowering 1 62 0 06 m y 1 2000 2013 on the glacier the debris cover area and sla also increased by 23 50 1 74 and 287 63 m respectively during 1971 2016 increase in the mean winter minimum temperature and decrease in the winter snowfall are probably the main drivers of glacier depletion we conclude that the significant slowdown extensive surface lowering development of a proglacial lake and appearance of the supraglacial lakes collectively indicate a severe glacier degeneration this forewarns that the glacier may experience an accelerated pace of wastage in the future

area and mass changes of siachen glacier east karakoram here we present a comprehensive assessment of siachen glacier east karakoram in terms of its area and elevation change velocity variations and mass budget utilizing different satellite datasets including landsat hexagon cartosat i shuttle radar topography mission envisat advanced synthetic aperture radar and japanese advanced land observing satellite phased array type l band sar the total areal extent of siachen glacier did not change significantly between 1980 and 2014 however the exposed ice area decreased during that period the terminus of the glacier has experienced substantial downwasting on average 30 m over the period of 1999 2007 followed by a retreat of the transition between exposed and debris covered ice by a distance of 1 3 km during the short span 2007 14 the spatial patterns of the elevation difference and velocity are heterogeneous over the large areal extent of siachen glacier the average velocity of the entire glacier as computed between 11 december 2008 and 26 january 2009 was 12 3 0 4 cm d 1 while those estimated separately for the accumulation and ablation regions were 9 7 0 4 cm d 1 and 20 4 0 4 cm d 1 respectively the mass budget of siachen glacier is estimated to be 0 03 0 21 m w e a 1 for the period of 1999 2007

the high mountain asia glacier contribution to sea level rise from 2000 to 2050 we estimate all the individual glacier area and volume changes in high mountain asia hma by 2050 based on randolph glacier inventory rgi version 4 0 using different methods of assessing sensitivity to summer temperatures driven by a regional climate model and the ipcc a1b radiative forcing scenario a large range of sea level rise variation comes from varying equilibrium line altitude ela sensitivity to summer temperatures this sensitivity and also the glacier mass balance gradients with elevation have the largest coefficients of variability amounting to 50 among factors examined prescribing ela sensitivities from energy balance models produces the highest sea level rise 9 2 mm or 0 76 of glacier volume a 1 while the ela sensitivities estimated from summer temperatures at chinese meteorological stations and also from 1 x1 gridded temperatures in the berkeley earth database produce 3 6 and 3 8 mm respectively different choices of the initial ela or summer precipitation lead to 15 uncertainties in modelled glacier volume loss rgi version 4 0 produces 20 lower sea level rise than version 2 0 more surface mass balance observations meteorological data from the glaciated areas and detailed satellite altimetry data can provide better estimates of sea level rise in the future

recent glacier and glacial lake changes and their interactions in the bugyai kangri southeast tibet glaciers in the bugyai kangri are located in a transition zone from southeast tibet where monsoonal temperate glaciers dominate to inner tibet where continental glaciers dominate here we analyze glacier and glacial lake changes in this region using multi year inventories based on landsat images from 1981 2013 results show that the total area of 141 glaciers in the region decreased by 30 44 0 89 km 2 from 198 35 9 54km 2 1980s to 167 93 4 52 km 2 2010s the annual area shrinkage rate 0 48 a 1 is lower than that reported for southeastern tibet but higher than that of inner tibet both the number and total area of glacial lakes increased between 1981 and 2013 among all lakes proglacial lakes contribute most similar to 81 to the expansion the total area of ten proglacial lakes increased by 150 3 13 17 and of these ten lakes the four that expanded most sharply showed increased calving at their upper margins resulting in more rapid retreat of lake terminating glaciers than land terminating glaciers owing to rapid calving several lakes may undergo further growth in the near future increasing the potential risk of glacial lake outburst floods

glacier change in western north america influences on hydrology geomorphic hazards and water quality the glaciers of western canada and the conterminous united states have dominantly retreated since the end of the little ice age lia in the nineteenth century although average rates of retreat varied from strong in the first half of the twentieth century with glaciers stabilizing or even advancing until 1980 and then resuming consistent recession this retreat has been accompanied by statistically detectable declines in late summer streamflow from glacier fed catchments over much of the study area although there is some geographical variation over recent decades glaciers in northwest bc and southwest yukon have lost mass dominantly by thinning with relatively low rates of terminal retreat and glacier fed streams in that region have experienced increasing flows in many valleys glacier retreat has produced geomorphic hazards including outburst floods from moraine dammed lakes mass failures from oversteepened valley walls and debris flows generated on moraines in addition to these hydrologic and geomorphic changes evidence is presented that glacier retreat will result in higher stream temperatures possibly transient increases in suspended sediment fluxes and concentrations and changes in water chemistry with climate projected to continue warming over the twenty first century current trends in hydrology geomorphology and water quality should continue with a range of implications for water resources availability and management and hydroecology particularly for cool and cold water species such as salmonids copyright 2008 john wiley sons ltd

a new glacier inventory for the svartisen region norway from landsat etm data challenges and change assessment glaciers are widely recognized as key indicators of climate change and their meltwater plays an important role in hydropower production in norway since the last glacier inventory was compiled in northern norway in the 1970s marked fluctuations in glacier length and mass balance have been reported for individual glaciers and the current overall glacier state is thus not well known within the framework of the global land ice measurements from space glims initiative we have created a new inventory for 489 glaciers in the svartisen region northern norway using a landsat enhanced thematic mapper plus etm satellite scene from 7 september 1999 and automated multispectral glacier mapping thresholded band ratios in addition visual inspection and correction of the generated glacier outlines has been applied adverse snow conditions and uncertain drainage divides made glacier mapping challenging in some regions of the study site glacier outlines from 1968 as digitized from a topographic map were used for a quantitative change assessment for a selection of 300 glaciers the overall area change of this sample from 1968 to 1999 was close to zero but with a strongly increasing scatter towards smaller glaciers large area gains 50 for small glaciers 1 km 2 and an unexpected stronger relative area loss towards the wetter coast the overall size changes are small 1 for the three largest ice masses in the study region vestisen ostisen and blamannsisen

landsat based inventory of glaciers in western canada 1985 2005 abstract we report on a glacier inventory for the canadian cordillera south of 60 n across the two western provinces of british columbia and alberta containing 30 000 km2 of glacierized terrain our semi automated method extracted glacier extents from landsat thematic mapper tm scenes for 2005 and 2000 using a band ratio tm3 tm5 we compared these extents with glacier cover for the mid 1980s from high altitude aerial photography for british columbia and from landsat tm imagery for alberta a 25 m digital elevation model dem helped to identify debris covered ice and to split the glaciers into their respective drainage basins the estimated mapping errors are 3 4 and arise primarily from seasonal snow cover glaciers in british columbia and alberta respectively lost 10 8 3 8 and 25 4 4 1 of their area over the period 1985 2005 the region wide annual shrinkage rate of 0 55 a 1 is comparable to rates reported for other mountain ranges in the late twentieth century least glacierized mountain ranges with smaller glaciers lost the largest fraction of ice cover the highest relative ice loss in british columbia 24 0 4 6 occurred in the northern interior ranges while glaciers in the northern coast mountains declined least 7 7 3 4

glacier change 1958 1998 in the north cascades national park complex washington usa the spatial characteristics for all glaciers in the north cascades national park complex usa were estimated in 1958 and again in 1998 the total glacier area in 1958 was 117 3 1 1 km 2 by 1998 the glacier area had decreased to 109 1 1 1 km 2 a reduction of 8 2 0 1 km 2 7 estimated volume loss during the 40 year period was 0 8 0 1 km 3 of ice this volume loss contributes up to 6 of the august september stream flow and equals 16 of the august september precipitation no significant correlations were found between magnitude of glacier shrinkage and topographic characteristics of elevation aspect or slope however the smaller glaciers lost proportionally more area than the larger glaciers and had a greater variability in fractional change than larger glaciers most of the well studied alpine glaciers are much larger than the population median so global estimates of glacier shrinkage based on these well studied glaciers probably underestimate the true magnitude of regional glacier change

the january 2018 to september 2019 surge of shisper glacier pakistan detected from remote sensing observations abstract this study analysed the actively surging shisper glacier in the karakoram region of pakistan using earth observation data from landsat 8 oli and planet images changes in the surface glacier velocity supraglacial moraines and debris cover were assessed using landsat 8 data at monthly time steps from january 2018 to may 2019 high resolution data from planet labs was used to precisely detect the snout advance and ice dammed lake expansion downstream cross section profiles of the valley were generated using a moderate resolution digital elevation model to assess the inundation in the event of rapid ice dammed lake drainage correlation image analysis software working on the principle of normalized cross correlation was used to generate time series monthly surface velocity profiles for shisper glacier manual digitization at 1 30000 scale was used to delineate supraglacial moraines and supraglacial debris cover the glacier surface velocity profiles indicate that the ablation zone of the glacier continues to be in an active surge phase resulting in advance of the snout and expansion of the ice dammed lake surface glacier velocities are as high as 48 m d 1 between 18 december 2018 and 8 may 2019 the glacier snout advanced at 6 m d 1 with a total overall advance of 860 m the lake formed due to damming of an outflow stream from mochowar glacier expanded to its maximum area 29 69 ha in may 2019 before drainage started on 23 june 2019 our estimates indicate that the peak discharge in case of rapid drainage could vary between 5033 m3 s 1 and 6167 m3 s 1 and potentially affect infrastructure downstream

ice volume and subglacial topography for western canadian glaciers from mass balance fields thinning rates and a bed stress model abstracta method is described to estimate the thickness of glacier ice using information derived from the measured ice extent surface topography surface mass balance and rate of thinning or thickening of the ice column shear stress beneath an ice column is assumed to be simply related to ice thickness and surface slope as for an inclined slab but this calculation is cast as a linear optimization problem so that a smoothness regularization can be applied assignment of bed stress is based on the flow law for ice and a mass balance calculation but must be preceded by delineation of the ice flow drainage basin validation of the method is accomplished by comparing thickness estimates to the known thickness generated by a numerical ice dynamics model once validated the method is used to estimate the subglacial topography for all glaciers in western canada that lie south of 60 n adding the present ice volume of each glacier gives the estimated total volume as 2320 km3 equivalent to 5 8 mm of sea leve

rapid disintegration of alpine glaciers observed with satellite data analyses of multispectral satellite data indicate accelerated glacier decline around the globe since the 1980s by using digitized glacier outlines inferred from the 1973 inventory and landsat thematic mapper tm satellite data from 1985 to 1999 we obtained area changes of about 930 alpine glaciers the 18 area reduction as observed for the period 1985 to 1999 1 3 a corresponds to a seven times higher loss rate compared to the 1850 1973 decadal mean extrapolation of area change rates and cumulative mass balances to all alpine glaciers yields a corresponding volume loss of about 25 km since 1973 highly individual and non uniform changes in glacier geometry disintegration indicate a massive down wasting rather than a dynamic response to a changed climate our results imply stronger ongoing glacier retreat than assumed so far and a probable further enhancement of glacier disintegration by positive feedbacks

recent changes in glacier area and volume within the southern canadian cordillera net changes in glacier area in the region 50 518 n 116 1258 w which includes the columbia and rocky mountains 1951 52 2001 and the coast mountains 1964 65 2002 were determined through a comparison of historic aerial photography and contemporary landsat 7 etm imagery the volumes of individual glaciers were estimated using an empirical volume area scaling relationship the area of glaciers in the coast mountains decreased by 120 10 km 2 or 5 of the initial ice covered area here the areas of glaciers in the columbia and rocky mountains decreased by 20 and 6k m 2 respectively corresponding to relative changes in total area of 5 and 15 the estimated total ice volume loss from the whole region was 13 3k m 3 in all parts of the study area the relative changes in area of individual glaciers showed considerable variability while the smallest glaciers remained essentially unchanged this suggests that local factors unique to individual glaciers largely determine their sensitivity to climatic change and that the very small glaciers are collectively less sensitive to such change

glacier recession and glacial lake outburst flood studies in zanskar basin western himalaya abstract glacier recession and formation of glacial lakes along with outburst flood hazards are increasing in response to changing climate in the himalayan region this study describes evolution of dalung and padam glaciers and their associated lakes employing multi temporal datasets of landsat mss tm etm indian remote sensing liss iii google earthtm aster gdem and survey of india topographic maps the dalung glacier dg and lake dl are present in suru river catchment whereas the padam glacier pg and lake pl are present in tsarap river catchment of zanskar basin western himalaya from 1962 to 2015 the dg and pg have shrunk at different rates the dg has shrunk by 2 6 0 56 km2 19 2 4 1 at a rate of 0 05 0 01 km2 a 1 whereas the pg has shrunk by 3 4 0 65 km2 12 7 2 4 at a rate of 0 06 0 01 km2 a 1 the frontal recession was recorded as 1 240 0 02 km 15 7 2 0 at a rate of 20 0 4 m a 1 for dg and 2 690 0 5 m 21 3 2 1 at a rate of 50 7 0 1 m a 1 for pg consequently the proglacial glacial lakes have formed indicating an expansion of 20 3 4 dl and 58 4 5 pl during 1990 2015 using integrated criteria of standard indices for the identification of potentially dangerous glacial lakes pdgls the lakes were found to be vulnerable and have a potential to cause breaching in the coming years in order to provide inputs for the emergency action plan one dimensional mike 11 model was used to generate the peak flood hydrographs at the lake and other vulnerable sites downstream highest peak discharge of 3361 7 m3 s 1 dl and 4210 3 m3 s 1 pl were estimated at the lake sites which has reduced to 1520 9 m3 s 1 and 1722 4 m3 s 1 respectively at the outlet sites the reduced discharge at downstream sites still bears the potential to create dangerous flood hazards

characterizing the may 2015 karayaylak glacier surge in the eastern pamir plateau using remote sensing we investigate an internal surge of karayaylak glacier which was reported by the media in may 2015 to differentiate the may 2015 glacier surge from other glacier advances we surveyed changes in velocity crevasses and glacier area using landsat 8 oli l1t zy 1 02c and gaofen 1 images from october 2014 to july 2015 the velocity measured by automatic feature extraction and tracking during the active phase was 10 100 times the velocity during the quiescent phase with a maximum of 20 2 0 9 m d 1 mean standard error from 8 to 15 may 2015 in the west branch of the glacier the surge initiation and termination took place from 13 april to 16 june 2015 ice in the west branch length 7 km area 6 8 km 2 of karayaylak glacier accelerated down to the east branch leading to the development of crevasses and ice covering an additional 0 1 km 2 of summer pasture on the northwestern side however we detected no advance of the glacier s terminus

a new inventory of mountain glaciers and ice caps for the antarctic periphery although the glaciers in the antarctic periphery make up a large fraction of all mountain glaciers and ice caps on earth a detailed glacier inventory of the region is lacking we compile such an inventory recording areas area altitude distributions terminus characteristics and volume estimates glaciers on the mainland are excluded the inventory is derived from the antarctic digital database and some manual digitization we additionally rely on satellite imagery digital elevation models and a flowshed algorithm to classify ice bodies we find 1133 ice caps and 1619 mountain glaciers covering a total of 132 867 6643 km 2 estimated total volume corresponds to 0 121 0 010 m sea level equivalent of the total glacier area 99 drains either into ice shelves 63 or into the ocean 36 the inventory will provide a database for glacier mass balance assessments modelling and projections and help to reduce the uncertainties in previous studies

changes in area and geodetic mass balance of small glaciers polar urals russia 1950 2008 changes in area of 30 small glaciers mostly 1 km2 in the northern polar urals 67 5 68 25 n between 1953 and 2000 were assessed using historic aerial photography from 1953 and 1960 aster and panchromatic landsat etm imagery from 2000 and data from 1981 and 2008 terrestrial surveys changes in volume and geodetic mass balance of igan and obruchev glaciers were calculated using data from terrestrial surveys in 1963 and 2008 in total glacier area declined by 22 3 3 9 in the 1953 60 2000 period the areas of individual glaciers decreased by 4 46 surfaces of obruchev and igan glaciers lowered by 22 5 1 7 m and 14 9 2 1 m over 45 years geodetic mass balances of obruchev and igan glaciers were 20 66 2 91 and 13 54 2 57 m w e respectively glacier shrinkage in the polar urals is related to a summer warming of 1 c between 1953 81 and 1981 2008 and its rates are consistent with other regions of northern asia but are higher than in scandinavia while glacier shrinkage intensified in the 1981 2000 period relative to 1953 81 increasing winter precipitation and shading effects slowed glacier wastage in 2000 08

volume loss from lower peyto glacier alberta canada between 1966 and 2010 mass loss from mountain glaciers contributes to sea level rise and reduces freshwater availability in glacier fed river basins with negative effects on hydropower generation agriculture and the health of aquatic ecosystems in this study we determine the volume of lower peyto glacier alberta canada from ground penetrating radar surveys in 2008 10 and compare our volume estimate with previous estimates from 1966 and 1984 the long term record of mass balance estimates on peyto glacier highlights peyto s importance as an index glacier for the region we calculate a mean volume of 3 39 0 30 107 m3 for the glacier snout for the period 2008 10 glacier volume decreased linearly from 1966 to 2010 if this trend persists the glacier snout will disappear by 2019 and peyto glacier will have retreated by 1 km our results agree with modelling studies which suggest that peyto glacier and other nearby glaciers along the eastern slopes of the canadian rocky mountains will likely lose 80 90 of their present day volume by 2100

combining satellite multispectral image data and a digital elevation model for mapping debris covered glaciers automated glacier mapping from satellite multispectral image data is hampered by debris cover on glacier surfaces supraglacial debris exhibits the same spectral properties as lateral and terminal moraines fluvioglacial deposits and bedrock outside the glacier margin and is thus not detectable by means of multispectral classification alone based on the observation of low slope angles for debris covered glacier tongues we developed a multisource method for mapping supraglacial debris the method combines the advantages of automated multispectral classification for clean glacier ice and vegetation with slope information derived from a digital elevation model dem neighbourhood analysis and change detection is applied for further improvement of the resulting glacier debris map a significant percentage of the processing can be done automatically in order to test the sensitivity of our method against different dem qualities it was also applied to a dem obtained from aster stereo data additionally we compared our multisource approach to an artificial neural network ann classification of debris using only multispectral data while the combination with an aster derived dem revealed promising results the ann classification without dem data does not

the new remote sensing derived swiss glacier inventory i methods a new swiss glacier inventory is to be compiled from satellite data for the year 2000 the study presented here describes two major tasks 1 an accuracy assessment of different methods for glacier classification with landsat thematic mapper tm data and a digital elevation model dem 2 the geographical information system gis based methods for automatic extraction of individual glaciers from classified satellite data and the computation of three dimensional glacier parameters such as minimum maximum and median elevation or slope and orientation by fusion with a dem first results obtained by these methods are presented in part ii of this paper kaab and others 2002 thresholding of a ratio image from tm4 and tm5 reveals the best suited glacier map the computation of glacier parameters in a gis environment is efficient and suitable for worldwide application the methods developed contribute to the u s geological survey led global land ice measurements from space glims project which is currently compiling a global inventory of land ice masses within the framework of global glacier monitoring haeberli and others 2000

analysis of sub pixel snow and ice extent over the extratropical andes using spectral unmixing of historical landsat imagery abstract with more than 30 years of imagery the landsat database offers potential insights into changes in the global cryosphere in this study a landsat based sub pixel fractional snow covered area retrieval model based on spectral unmixing is applied and validated over a southern andes study region an application analyzing minimum annual snow ice covered areas is presented as an example of the utility of the existence of such a model and the landsat database the model was validated using high resolution imagery aggregated to the nominal landsat resolution showing good correlation for both fresh snow and ice old snow presence using annual minimum snow ice retrievals from landsat 5 and 7 the presence of trends in each snow ice covered pixel area was assessed for the 1986 2013 historical period and three metrics were examined pixels with significant negative trends total area loss and areas with any absolute negative change significant negative area reduction trends in most of the glacier fronts were found with a loss of approximately 15 of the original 241 km2 glacierized snow area between 1986 and 2011 trends in fractional values were compared with those derived from traditional binary classification of snow and significant discrepancies were observed even though the binary classification identified a greater total areal loss 33 vs 23 km2 when comparing scenes from the beginning and the end of the study period the fractional algorithm identified a larger number of pixels with significant negative trends between 1986 and 2013 42 3 vs 10 5 km2 the binary algorithm resulted in consistent overestimations of ice and snow area and does not offer the ability for identifying subpixel changes the method could enable future monitoring of andean and other glaciers and snow cover at a sub pixel scale over large scales and with landsat 8 in orbit a continuous stream of more than 30 years of data is already available

a new semi automatic approach for dividing glacier complexes into individual glaciers many glaciological and hydrological studies require outlines of individual glaciers rather than total ice cover here we develop a new semi automatic algorithm that uses a digital elevation model dem and outlines of glacier complexes to calculate the extents of individual glaciers the algorithm first applies hydrological modeling tools to a modified dem to calculate flowsheds it then merges flowsheds that belong to individual glaciers using a distance based approach whose required empirical parameters are derived from the juneau icefield area in alaska in this region 2 of similar to 1300 glaciers were misclassified the algorithm was validated on 25 000 km 2 of ice in other regions in alaska and on 40 000 km 2 of ice in arctic canada resulting in similar to 2 and similar to 3 misclassified glaciers respectively results indicate that the algorithm is robust provided the dem and the outlines are of good quality

recent glacier advances in the premier range british columbia aerial photography 1948 1985 and field investigations are used to reconstruct recent ice front fluctuations for 27 glaciers size range 0 63 17 9 km2 in the premier range british columbia rapid rates of frontal recession between ca 1930 and the mid fifties were followed by glacier readvance at many sites culminating in the 1973 1976 period when 90 of the monitored ice fronts were either advancing 68 or stable maximum downvalley advance was about 0 5 km median 90 m and 14 glaciers formed new terminal or lateral moraine ridges between 1970 and 1985 nine of these postdate 1976 one is dated to the 1980 1981 winter using tree rings the glacial advance is attributed to significant mass balance changes inferred from periods of increased winter precipitation ca 1951 1976 and low summer temperatures 1954 1968 measured at valemount warmer summers and reduced winter precipitation after 1976 account for the slight recession of ice fronts from maximum downvalley positions in the last few years

assessment of multispectral glacier mapping methods and derivation of glacier area changes 1978 2002 in the central southern alps new zealand from aster satellite data field survey and existing inventory data we have measured the glacier area changes in the central southern alps new zealand between 1978 and 2002 and have compiled the 2002 glacier outlines using an image scene from the advanced spaceborne thermal emission and reflection radiometer aster three automated classification methods were tested 1 band ratio 2 normalized difference snow index and 3 supervised classification the results were compared with the glacier outlines photo interpreted from the aster data and were further validated using gps aided field mapping of selected test glaciers the aster 3 4 band ratio provided the best results however all the classification methods failed to extract extensive debris covered parts of the glaciers therefore the photo interpreted 2002 outlines were used when comparing with the existing 1978 glacier inventory derived from aerial photographs our results show a 17 reduction of glacier area mainly driven by the retreat of the large valley glaciers despite the large climatic gradient from west to east glaciers on both sides of the main divide lost similar percentages of area except franz josef and fox glaciers which advanced smaller glaciers were found to have changed very little in the study period

the 2008 09 surge of central yulinchuan glacier northern tibetan plateau as monitored by remote sensing the 2008 09 surge of central yulinchuan glacier cyg on the northwestern slope of muztag mountain tibetan plateau is studied based on satellite remote sensing the widely used cross correlation feature tracking method was used to collect satellite image control points and validate their geometric accuracies as well as to derive glacier surface velocity changes in glacier length and area were also retrieved results show that the surge of cyg initiated in may 2008 and terminated in july 2009 two diffluent glacier termini advanced 590 26 m 5 1 0 2 of the 2004 length and 182 26 m 1 8 0 3 respectively and glacier area increased by similar to 1 41 0 11 km 2 4 6 0 4 of the 2004 area during this period the most significant surge period was october 2008 to march 2009 when most of the terminus advances and area increases occurred the glacier surface drastically crevassed during this time as much as 1657 297 m of horizontal surface displacements were produced by surge ice and maximum surface speed reached 13 1 5 m d 1 results of transverse and longitudinal velocity profiles revealed two surge waves during this surge of cyg

the randolph glacier inventory a globally complete inventory of glaciers the randolph glacier inventory rgi is a globally complete collection of digital outlines of glaciers excluding the ice sheets developed to meet the needs of the fifth assessment of the intergovernmental panel on climate change for estimates of past and future mass balance the rgi was created with limited resources in a short period priority was given to completeness of coverage but a limited uniform set of attributes is attached to each of the 198 000 glaciers in its latest version 3 2 satellite imagery from 1999 2010 provided most of the outlines their total extent is estimated as 726 800 34 000 km 2 the uncertainty about 5 is derived from careful single glacier and basin scale uncertainty estimates and comparisons with inventories that were not sources for the rgi the main contributors to uncertainty are probably misinterpretation of seasonal snow cover and debris cover these errors appear not to be normally distributed and quantifying them reliably is an unsolved problem combined with digital elevation models the rgi glacier outlines yield hypsometries that can be com bined with atmospheric data or model outputs for analysis of the impacts of climatic change on glaciers the rgi has already proved its value in the generation of significantly improved aggregate estimates of glacier mass changes and total volume and thus actual and potential contributions to sea level rise

changes in glaciation of the balkhash alakol basin central asia over recent decades we describe changes in glaciers of the balkhash alakol basin central asia and analyse unified glacier inventories of the zailiyskiy kungei and jungar glacier systems and the chinese part of the ili river basin as well as mass balance monitoring data from tsentralniy tuyuksu glacier for the period 1957 2014 in spite of significant inter basin differences glaciation of the three glacial systems in the ili river basin within kazakhstan as well as within chinese territory is changing simultaneously and similarly differences in the rates of glacier degradation are small and are affected primarily by the orientation of the flanks of the mountain ridges since the mid 1950s glaciation of the region has remained degraded and on average over the period examined glaciers shrank at a rate of about 0 8 a 1 in area and about 1 a 1 in ice volume glacial systems in large basins such as balkhash alakol change simultaneously linearly and at similar rates the average rates of glacier reduction of the zailiyskiy kungei jungar and upper ili glacier systems for the period 1955 56 2008 amounted to 0 76 0 75 and 0 73 a 1 respectively

decadal changes in glacier parameters in the cordillera blanca peru derived from remote sensing we present spatial patterns of glacier fluctuations from the cordillera blanca peru glacier area terminus elevations median elevations and hypsography at decadal timescales derived from 1970 aerial photography 2003 spot5 satellite data geographic information systems gis and statistical analyses we derived new glacier outlines from the 2003 spot images and ingested them in the global land and ice measurements from space glims glacier database we examined changes in glacier area on the eastern and western side of the cordillera in relation to topographic and climate variables temperature and precipitation results include 1 an estimated glacierized area of 569 6 21 km 2 in 2003 2 an overall loss in glacierized area of 22 4 from 1970 to 2003 3 an average rise in glacier terminus elevations by 113 m and an average rise in the median elevation of glaciers by 66 m showing a shift of ice to higher elevations especially on the eastern side of the cordillera and 4 an increase in the number of glaciers which indicates disintegration of ice bodies annual air temperature showed a significant upward trend in the last 30 years with larger temperature increases at lower elevations there was a slight but not significant decrease in precipitation our results are consistent with glacier retreat and warming trends noted in the last three decades in the tropics

the second chinese glacier inventory data methods and results the second chinese glacier inventory was compiled based on 218 landsat tm etm scenes acquired mainly during 2006 10 the widely used band ratio segmentation method was applied as the first step in delineating glacier outlines and then intensive manual improvements were performed the shuttle radar topography mission digital elevation model was used to derive altitudinal attributes of glaciers the boundaries of some glaciers measured by real time kinematic differential gps or digitized from high resolution images were used as references to validate the accuracy of the methods used to delineate glaciers which resulted in positioning errors of 10 m for manually improved clean ice outlines and 30 m for manually digitized outlines of debris covered parts the glacier area error of the compiled inventory evaluated using these two positioning accuracies was 3 2 the compiled parts of the new inventory have a total area of 43 087 km 2 in which 1723 glaciers were covered by debris with a total debris covered area of 1494 km 2 the area of uncompiled glaciers from the digitized first chinese glacier inventory is similar to 8753 km 2 mainly distributed in the southeastern tibetan plateau where no images of acceptable quality for glacier outline delineation can be found during 2006 10

planimetric and volumetric glacier changes in the khumbu himal nepal since 1962 using corona landsat tm and aster data multitemporal space imagery from 1962 corona kh 4 1992 landsat tm 2001 and 2005 terra aster was used to investigate the glacier changes in the khumbu himal nepal the ice coverage in the investigation area decreased by about 5 between 1962 and 2005 with the highest retreat rates occurring between 1992 and 2001 the debris coverage increased concomitantly with the decrease in total glacier area the clean ice area decreased by 10 digital terrain model dtm generation from the early corona kh 4 stereo data in this high relief terrain is time consuming and the results still contain some elevation errors however these are minor in the snow free areas with gentle slopes thus comparison of the surfaces of the debris covered glacier tongues based on the corona dtm and an aster dtm is feasible and shows the downwasting of the debris covered glaciers the highest downwasting rates more than 20 m 0 5 m a 1 can be found near the transition zone between the active and the stagnant glacier parts of the debris covered glacier tongues the downwasting is lower but still evident in the active ice areas and at the snout with thick debris cover all investigated debris covered glaciers in the study area show similar behaviour the estimated volume loss for the investigated debris covered glacier tongues is 0 19 km 3

glacial changes of five southwest british columbia icefields canada mid 1980s to 1999 this study adjusts and compares digital elevation models dems created from photogrammetric and interferometric synthetic aperture radar techniques to determine volume and surface elevation changes of five icefields in a remote region of southwest british columbia canada between the mid 1980s and 1999 preliminary differences between the dems in ice free and vegetation free areas indicated variable elevation offsets with increasing altitude 11 m km 1 and with increasing slope 2 7 m 108 1 results indicate a surface elevation change of 6 0 2 7 m 0 5 0 2 m a 1 and a total volume loss of 19 4 8 8 km 3 1 5 0 7 km 3 a 1 which represents a potential sea level rise contribution of 0 004 0 002 mm a 1 temperature and snowfall data from four nearby meteorological stations indicate that increased temperatures and decreased snowfall throughout the late 1980s and 1990s are a likely cause of the thinning glacier terminus positions were compared between a historical map 1927 and satellite images 1974 1990 91 and 2000 01 all observed glaciers were in retreat between 1927 and 1974 as well as between 1990 91 and 2000 01 but many glaciers advanced or significantly slowed in their retreat between 1974 and 1990 91

rapid wastage of alaska glaciers and their contribution to rising sea level we have used airborne laser altimetry to estimate volume changes of 67 glaciers in alaska from the mid 1950s to the mid 1990s the average rate of thickness change of these glaciers was 0 52 m year extrapolation to all glaciers in alaska yields an estimated total annual volume change of 52 15 km 3 year water equivalent equivalent to a rise in sea level sle of 0 14 0 04 mm year repeat measurements of 28 glaciers from the mid 1990s to 2000 2001 suggest an increased average rate of thinning 1 8 m year this leads to an extrapolated annual volume loss from alaska glaciers equal to 96 35 km 3 year or 0 27 0 10 mm year sle during the past decade these recent losses are nearly double the estimated annual loss from the entire greenland ice sheet during the same time period and are much higher than previously published loss estimates for alaska glaciers they form the largest glaciological contribution to rising sea level yet measured

topographic influences on recent changes of very small glaciers in the monashee mountains british columbia canada an analysis of the local topographic setting of very small 0 4 km 2 glaciers within a small region of the monashee mountains british columbia was conducted to investigate its influence on recent changes in the extent of these glaciers net changes in glacier extent were determined from a detailed manual comparison of remotely sensed imagery acquired in 1951 2001 and 2004 most of the 86 glaciers included in the study showed no observable net change in area over the study period while six glaciers retreated four disappeared entirely and only one advanced indices derived to characterize elements of the local topographic setting that might affect the local mass balance suggest that most of the glaciers are situated in locations that favor ice preservation by enhancing mass input and or reducing ablation rates glaciers situated in less favorable settings generally either decreased in area or disappeared the results suggest that most of the glaciers studied have retreated as far as they are likely to under the climatic conditions of the late 20th century

an 825 year long varve record from lillooet lake british columbia and its potential as a flood proxy abstract lillooet river in southwest british columbia has produced damaging floods many times during the past century the floods are recorded in lillooet lake into which the river flows as anomalously thick clastic varves in order to determine whether an 825 year long varve record obtained from 12 percussion and vibracores can be used as flood proxy we compare river discharge records dating back to 1914 to the thickness of the varves deposited during the same time period correlations between varve thickness and a variety of historical discharge measures are low to moderate for the periods 1914 2004 r 2 0 37 and 1914 1945 r 2 0 40 but higher for the period 1946 2004 r 2 0 55 the best correlation r 2 0 55 is between maximum fall discharge and varve thickness during the most recent period 1946 2004 varve thickness for the earlier period of hydrometric data 1914 1946 which is a time of rapid glacier retreat and warmer temperatures in british columbia is best explained with a discharge proxy combining nival runoff glacier runoff and maximum fall discharge landslides glacier fluctuations river dyking artificial lowering of lillooet lake as well as lag effects of storms are responsible for the considerable unexplained variance in the relation between discharge measures and varve thickness over the historic period the cores contain many anomalously thick varves some of which we attribute to previously dated prehistoric landslides in the watershed or to local landslides into the lake we conclude that many historic and prehistoric floods are faithfully recorded as anomalously thick clastic varves but that other processes operating in the watershed preclude using this record as a reliable paleo flood proxy

glacier mass balance over the central nyainqentanglha range during recent decades derived from remote sensing data to obtain information on changes in glacier mass balance in the central nyainqentanglha range a comprehensive study was carried out based on digital elevation models derived from the 1968 topographic maps the shuttle radar topography mission dem 2000 and terrasar x tandem x 2013 glacier area changes between 1968 and 2016 were derived from topographic maps and landsat oli images this showed the area contained 715 glaciers with an area of 1713 42 51 82 km 2 in 2016 ice cover has been shrinking by 0 68 0 05 a 1 since 1968 the glacier area covered by debris accounted for 11 9 of the total and decreased in the se nw directions using digital elevation model differencing and differential synthetic aperture radar interferometry a significant mass loss of 0 46 0 10 m w e a 1 has been recorded since 1968 mass losses accelerated from 0 42 0 20 m w e a 1 to 0 60 0 20 m w e a 1 between 1968 2000 and 2000 2013 with thinning noticeably greater on the debris covered ice than the clean ice surface elevation changes can be influenced by ice cliffs as well as debris cover and land or lake terminating glaciers changes showed spatial and temporal heterogeneity and a substantial correlation with climate warming and decreased precipitation

recent changes of two selected glaciers in hami prefecture of eastern xinjiang and their impact on water resources abstract it is important to understand and quantify glacier changes and their impact on water resources in hami prefecture an extremely arid region in the eastern xinjiang of northwestern china yushugou glacier no 6 and miaoergou ice cap in hami prefecture were selected in this study results showed that the thickness of yushugou glacier no 6 decreased by 20 m with a rate of 0 51 m y 1 from 1972 to 2011 and the terminus retreated by 254 m or 6 5 m y 1 for the same period the thickness along the main axis of miaoergou ice cap decreased 0 20 m during 1981 2007 and the terminus retreat rate was less than 3 0 m y 1 in 2013 the melting rate of miaoergou ice cap was smaller than yushugou glacier no 6 which was directly related to the differences of glacier type and elevation the impact of glacier changes on water resources would be different in the various drainage basins of hami prefecture depending on the proportion of glacier coverage

glacier specific elevation changes in parts of western alaska the meltwater from glaciers in alaska contributes strongly to global sea level rise but accurate determination is challenging as only two comparatively small glaciers have long term measurements of annual mass balance gulkana and wolverine simple upscaling of their values to the entire region is error prone as their representativeness is unknown and might be biased alternatively differencing digital elevation models dems from two epochs provides overall volume changes for a longer period of time that can be converted to mass changes using appropriate density assumptions here we combine outlines from two glacier inventories to determine glacier specific elevation changes over a 50 year period for 3180 glaciers in western alaska using dem differencing this allows us to determine the representativeness of the land terminating gulkana and wolverine glaciers for the entire region and to exclude calving glaciers marine and lacustrine from the sample mean changes for all land terminating lake terminating and tidewater glaciers are 0 23 0 44 0 63 0 40 and 0 64 0 66 m a 1 respectively and 0 7 and 0 6 m a 1 for the two mass balance or benchmark glaciers thus fortuitously their changes better represent calving glaciers and the overall mean 0 63 1 14 m a 1 than the change of land terminating glaciers i e they are not representative for their own type different methods of considering potential dem artefacts provide variable mean changes but the same general result

an inventory and morphometric analysis of british columbia glaciers canada we describe an automated method to generate an inventory of glaciers and glacier morphometry from a digital topographic database containing glacier boundaries and a digital elevation model for british columbia canada the inventory contains over 12 000 glaciers with a total cumulative area that exceeds 25 000 km 2 based on mapping from aerial photographs circa the mid 1980s we use the inventory to examine dimensional characteristics among glaciers namely the scaling relations between glacier length width and area glacier length is a good predictor of glacier area and its predictive ability improves when glaciers are stratified by the number of up valley accumulation basins the spatial pattern of glacier mid range altitude parallels glaciation limits previously mapped for british columbia and similarly reflects large scale controls of orographic precipitation and continentality the inventory is also used to refine models that relate glacier mid range and terminus altitudes to regional position aspect and in the case of terminus altitudes an index of glacier shape relations between glacier altitude limits and controlling spatial and topographic factors are used to make further climatic and mass balance inferences from the glacier inventory

modelling the phanerozoic carbon cycle and climate constraints from the 87sr 86sr isotopic ratio of seawater a numerical model describing the coupled evolution of the biogeochemical cycles of carbon sulfur calcium magnesium phosphorus and strontium has been developed to describe the long term changes of atmospheric carbon dioxide and climate during the phanerozoic the emphasis is on the effects of coupling the cycles of carbon and strontium various interpretations of the observed phanerozoic history of the seawater 87sr 86sr ratio are investigated with the model more specifically the abilities of continental weathering volcanism and surface lithology in generating that signal are tested and compared it is suggested that the observed fluctuations are mostly due to a changing weatherability over time it is shown that such a conclusion is very important for the modelling of the carbon cycle indeed it implies that the conventional belief that the evolution of atmospheric carbon dioxide and climate on a long time scale is governed by the balance between the volcanic input of co2 and the rate of silicate weathering is not true rather carbon exchanges between the mantle and the exogenic system are likely to have played a key role too further the increase of the global weathering rates with increasing surface temperature and or atmospheric co2 pressure usually postulated in long term carbon cycle and climate modelling is also inconsistent with the new model other factors appear to have modulated the weatherability of the continents through time such as mountain building and the existence of glaciers and ice sheets based on these observations a history of atmospheric carbon dioxide and climate during phanerozoic time consistent with the strontium isotopic data is reconstructed with the model and is shown to be compatible with paleoclimatic indicators such as the timing of glaciation and the estimates of cretaceous paleotemperatures