annual net balance of north cascade glaciers 1984 94 annual net balance on eight north cascade glaciers during the 1984 94 period has been determined by measurement of total mass loss from firn and ice melt and of residual snow depth at the end of the summer season overall spatial density of measurement points is 200 points km 2 mean annual balance of north cascade glaciers from 1984 to 1994 has been 0 38 m a 1 the resulting 4 2 m loss in water equivalent thickness is significant since north cascade glaciers have an average thickness of 30 50 m cross correlation of annual net babance for eight glaciers ranges from 0 83 to 0 97 this indicates the mass balances of the eight glaciers have been responding similarly to climate conditions despite their range of topographic and geographic characteristics annual net balance of individual glaciers was correlated with climate records the highest ablation season correlation coefficient is mean may august temperature ranging from 0 63 to 0 84 the highest accumulation season correlation coefficient is total accumulation season precipitation ranging from 0 35 to 0 59

tropical glaciers recorders and indicators of climate change are disappearing globally in this paper we review the interaction of el nino southern oscillation enso variability and warming trends recorded in ice core records from high altitude tropical glaciers discuss the implications of the warming trends for the glaciers and consider the societal implications of glacier retreat enso has strong impacts on meteorological phenomena that directly or indirectly affect most regions on the planet and their populations many tropical ice fields have provided continuous annually resolved proxy records of climatic and environmental variability preserved in measurable parameters especially oxygen and hydrogen isotopic ratios d 18 o dd and the net mass balance accumulation these records present an opportunity to examine the nature of tropical climate variability in greater detail and to extract new information on linkages between rising temperatures on tropical glaciers and equatorial pacific sea surface temperatures in critical enso indicator regions the long term climate records from a collection of high altitude tropical ice cores provide the longer term context essential for assessing the significance of the magnitude and rate of current climate changes that are in large measure driving glacier retreat the well documented ice loss on quelccaya in the peruvian andes naimona nyi in the himalaya kilimanjaro in eastern africa and the ice fields near puncak jaya in papua indonesia presents a grim future for low latitude glaciers the ongoing melting of these ice fields response is consistent with model predictions for a vertical amplification of temperature in the tropics driver and has serious implications for the people who live in these areas

antarctic ice sheet melting in the southeast pacific the first oceanographic measurements across a deep channel beneath the calving front of pine island glacier reveal a sub ice circulation driven by basal melting of 10 12 m yr 1 a salt box model described here gives a melt rate similar to that of ice balance and numerical models 5 50 times higher than averages for the george vi and ross ice shelves melting is fueled by relatively warm circumpolar deep water that floods the deep floor of the amundsen and bellingshausen sea continental shelves reaching the deep draft of this floating glacier a revised melt rate for ice shelves in the southeast pacific sector raises circumpolar ice shelf melting to 756 gt yr 1 given prior estimates of surface accumulation and iceberg calving this suggests that the antarctic ice sheet is currently losing mass to the ocean

after six decades of monitoring glacier mass balance we still need data but it should be richer data this paper reviews data on glacier mass balance together with extra metadata on topography and climate to put the data into context the 2007 intergovernmental panel on climate change ipcc estimates of global average glacier mass balance may not be much different from simple averages a more mathematically correct approach is to analyse long and continuous mass balance series measured in different regions but there are few long series and they do not cover the globe in any representative way however 30 year series from 30 glaciers confirm a recent 1996 2005 trend to very negative mass balance after two decades of nearly zero mass balance climate data from a global gridded climatology are applied to datasets for global glacier cover for 318 glaciers with mass balance data for at least 1 year and for 30 glaciers with 30 year series of measurements results show that mean precipitation is relatively low in the global glacier cover dataset and much higher for the observed glaciers this shows that current mass balance measurements are biased towards wetter conditions than are typical for global glacier cover we urgently need to find better ways of analysing sparse datasets with complex spatial and temporal patterns like the present mass balance dataset

changes in mass balance velocity and surface profile along a flow line on barnes ice cap 1970 1984 on a number of occasions between 1970 and 1984 measurements of mass balance surface velocity and surface elevation were made along a 10 2 km flow line extending from the divide to the margin on barnes ice cap baffin island canada the average mass balance rate on this arctic ice cap appears to be controlled principally by summer temperature years of negative mass balance dominated during the 14 year period of the study according to our measurements this should have resulted in a thinning of an average of 2 65 m along the flow line surface elevation measurements however suggest that the glacier thinned only 1 7 m during this time period the slightly compressive mean transverse strain can account for 0 20 m of the discrepancy between these two figures the rest is attributed to errors in mass balance in particular increases in density of old firn and freezing of water in crevasses could not be evaluated adequately from our measurements the thinning was not uniform near the margin the glacier thinned 5 m and near the divide 2 5 m but between 3 5 and 5 5 km from the divide there seems to have been no substantial change in thickness thus along the down glacier half of the flow line the decrease in thickness was accompanied by an increase in slope within 4 km of the margin the decrease in thickness resulted in a decrease in horizontal velocity of up to 15 despite the increase in slope higher on the glacier however the horizontal velocity increased 5 these changes are broadly consistent with those estimated from the changes in shear stress calculated using the hydrostatic approximation

glaciological applications with landsat 7 imagery early assessments enhanced thematic mapper plus etm data from landsat 7 are providing glaciologists with an ever expanding data set that makes a comprehensive monitoring of the global cryosphere feasible for the first time in history examples of etm data illustrate its ability to satisfy major scientific needs in the glaciological subdisciplines of sea ice glacier ice cap and ice sheet research with high resolution optical satellite imagery examples shown include use as proxy ground truth positioning glacier termini and snowlines and determining snow facies boundaries the additional etm panchromatic band at a higher spatial resolution of 15 m improves the spatial accuracy of these applications the glaciological aspects of the landsat 7 long term acquisition plan are discussed to show how the timing and location of the image acquisitions will generate a cryospheric data set of unprecedented utility for future research

a conceptual model for alpine proglacial river channel evolution under changing climatic conditions this paper integrates concepts derived from the literature to focus upon interactions between riparian vegetation and river channel dynamics in alpine glacier basins discussion of the nature and variability of discharge and sediment regimes of alpine glacier fed rivers downstream variations in the physical character of the river channel and corridor consequent downstream variations in lateral processes and regional variations in alpine glacier dynamics lead to the proposal of a conceptual model of proglacial river channel riparian vegetation interactions under changing climatic conditions

contribution of small glaciers to global sea level observed long term changes in glacier volume and hydrometeorological mass balance models yield data on the transfer of water from glaciers excluding those in greenland and antarctica to the oceans the average observed volume change for the period 1900 to 1961 is scaled to a global average by use of the seasonal amplitude of the mass balance these data are used to calibrate the models to estimate the changing contribution of glaciers to sea level for the period 1884 to 1975 although the error band is large these glaciers appear to account for a third to half of observed rise in sea level approximately that fraction not explained by thermal expansion of the ocean

relationships between interannual variability of glacier mass balance and climate the interannual variability of glacier mass balance is expressed by the standard deviation of net balance which varies from about 0 1 to 1 4 m a for a sample of 115 glaciers with at least 5 years of record the standard deviation of net balance is strongly correlated with the mass balance amplitude half the difference between winter and summer balances for 60 glaciers so the amplitude can be estimated from net balance standard deviation for the other 55 glaciers where winter and summer balances are unavailable the observed and calculated mass balance amplitudes for the 115 glaciers show contrasts between the arctic and lower latitudes and between maritime and continental regions the interannual variability of mass balance means that balances must be measured for at least a few years to determine a statistically reliable mean balance for any glacier the net balance of the greenland ice sheet is still not accurately known but its standard deviation is here estimated to be about 0 24 m a 1 in agreement with other arctic glaciers mass balance variability of this magnitude implies that the ice sheet can thicken or thin by several metres over 20 30 years without giving statistically significant evidence of non zero balance under present climate

six decades of glacier mass balance observations a review of the worldwide monitoring network glacier mass balance is the direct and undelayed response to atmospheric conditions and hence is among the essential variables required for climate system monitoring it has been recognized as the largest non steric contributor to the present rise in sea level six decades of annual mass balance data have been compiled and made easily available by the world glacier monitoring service and its predecessor organizations in total there have been 3480 annual mass balance measurements reported from 228 glaciers around the globe however the present dataset is strongly biased towards the northern hemisphere and europe and there are only 30 reference glaciers that have uninterrupted series going back to 1976 the available data from the six decades indicate a strong ice loss as early as the 1940s and 1950s followed by a moderate mass loss until the end of the 1970s and a subsequent acceleration that has lasted until now culminating in a mean overall ice loss of over 20 m w e for the period 1946 2006 in view of the discrepancy between the relevance of glacier mass balance data and the shortcomings of the available dataset it is strongly recommended to 1 continue the long term measurements 2 resume interrupted long term data series 3 replace vanishing glaciers by early starting replacement observations 4 extend the monitoring network to strategically important regions 5 validate calibrate and accordingly flag field measurements with geodetic methods and 6 make systematic use of remote sensing and geo informatics for assessment of the representativeness of the available data series for their entire mountain range and for the extrapolation to regions without in situ observations and 7 make all these data and related meta information available

volume and velocity changes at mittivakkat gletscher southeast greenland we document changes for mittivakkat gletscher the peripheral glacier in greenland with the longest field based observed mass balance and surface velocity time series between 1986 and 2011 this glacier changed by 15 in mean ice thickness and 30 in volume we attribute these changes to summer warming and lower winter snow accumulation vertical strain compensated for 60 of the elevation change due to surface mass balance smb in the lower part and 25 in the upper part the annual mean ice surface velocity changed by 30 which can be fully explained by the dynamic effect of ice thinning within uncertainty mittivakkat gletscher summer surface velocities were on average 50 60 above winter background values and up to 160 higher during peak velocity events peak velocity events were accompanied by uplift of a few centimeters

microtremors as a geophysical exploration tool applications and limitations the usefulness of microtremors as a geophysical exploration tool has been analyzed this application is possible due to the relationship between the main resonance frequency of a given soil obtained from the h v spectral ratios of microtremors its thickness and average shear velocity we first measured the ambient noise at 33 sites and determined their main resonance frequency detailed geotechnical information was available for 23 of the sites thereby allowing us to establish a quantitative relationship between the resonance frequency and the thickness of the soil and indirectly between either of them and the shear velocity of the soil the practical application of this relationship has revealed its usefulness in determining the surface structure of a valley with excellent accuracy with an error of only 15 in the depths calculated these errors are due to the simplification of the problem that this method implies it requires that the shear velocity vary constantly with depth throughout the study region which is evidently not always so and that the input data themselves intrinsically have a certain degree of uncertainty this method is therefore not valid when there is no mechanical contrast between the study soil and the underlying layer or when the shear velocity varies irregularly with depth in the study area

mass balance of white glacier axel heiberg island n w t canada 1960 91 white glacier is a valley glacier at 79 5 n with an area of 38 7 km 2 its mass balance has been measured over 32 years with a 3 year gap by standard techniques using the stratigraphic system with a stake density of the order of one stake per km 2 errors in stake mass balance are about 200 250 mm due largely to the local unrepresentativeness of measurements errors in the whole glacier mass balance b are of the same order as single slake errors however the lag 1 autocorrelation in the time series of b is effectively zero so it consists of independent random samples and the error in the long term balance normal b is noticeably less b is 100 48 mm the equilibrium line altitude ela averages 970 m with a range of 470 1400 m mass balance is well correlated with ela but detailed modelling shows that the equilibrium line is undetectable on visible band satellite images a reduced network of a few stakes could give acceptable but less accurate estimates of the mass balance as could estimates based on data from a weather station 120 km away there is no evidence of a trend in the mass balance of white glacier to detect a climatologically plausible trend will require a ten fold reduction of measurement error a conclusion which may well apply to most estimates of mass balance based on similar stake densities

instruments and methods glaciological and volumetric mass balance measurements error analysis over 51 years for glacier de sarennes french alps the mass balance of glacier de sarennes french alps has been measured since 1949 using the glaciological method based on core and ablation stake data and area extrapolations to find the overall glacier balance the cumulative balance obtained in this way is very dependent on systematic errors that can increase linearly with the number n of measurement years whereas random errors rise with the volumetric balance method based on aerial photogrammetry provides results whose errors do not depend on the number of years this method was used to test field measurements for the period 1952 2003 and gives a mass balance of 32 30 1 04 m w e compared to 34 89 1 15 m w e based on field data the discrepancy between the two methods is discussed on the basis of a careful error analysis moreover the possibility of using the volumetric method to detect biases in field measurements is evaluated in terms of two types of errors the number and locations of measurement sites required to account for all the spatial and temporal variabilities of the mass balance is discussed by variance analysis methodological implications and recommendations are presented to provide mass balance measurements of the best possible accuracy

reanalysis of the us geological survey benchmark glaciers long term insight into climate forcing of glacier mass balance mountain glaciers integrate climate processes to provide an unmatched signal of regional climate forcing however extracting the climate signal via intercomparison of regional glacier mass balance records can be problematic when methods for extrapolating and calibrating direct glaciological measurements are mixed or inconsistent to address this problem we reanalyzed and compared long term mass balance records from the us geological survey benchmark glaciers these five glaciers span maritime and continental climate regimes of the western united states and alaska each glacier exhibits cumulative mass loss since the mid 20th century with average rates ranging from 0 58 to 0 30 m w e a 1 we produced a set of solutions using different extrapolation and calibration methods to inform uncertainty estimates which range from 0 22 to 0 44 m w e a 1 mass losses are primarily driven by increasing summer warming continentality exerts a stronger control on mass loss than latitude similar to elevation topographic shading snow redistribution and glacier surface features often exert important mass balance controls the reanalysis underscores the value of geodetic calibration to resolve mass balance magnitude as well as the irreplaceable value of direct measurements in contributing to the process based understanding of glacier mass balance

effect of melting glaciers on the earth s rotation and gravitational field 1965 1984 summary yearly mass balance data for 85 glaciers in 13 of the 31 mountain glacier systems designated in meier s 1984 paper are averaged for the years 1965 1984 average rates of volume change for the 13 regions are compared to meier s 1984 estimates of glacial melting these data cover regions that account for about 74 per cent of the volume change estimated to have occurred in all the 31 mountain glacier systems from 1900 to 1984 the volume changes in the 13 regions tend to be less than those calculated by using changes in the volume of glaciers between 1900 and 1961 meier 1984 although the reason for this difference is not well known it could result from melting during the first half of the 20th century of ice accumulated during earlier periods or a decrease in the rise in atmospheric temperatures from 1945 to 1980 spatial and temporal empirical orthogonal functional analysis is used to bring out the similarities and differences among the 13 regions and identify those regions contributing most to the variance of the data set these regions are not necessarily those with the greatest average rates of volume change enough spatial variability is present to support the hypothesis that satellites may eventually be able to discern changes in the earth s glaciers through the gravitational field even though the signal from the mass change is small and changes in the gravitational field of the earth are contaminated with gravity signals from other mass changes on the earth s surface and interior zonal coefficients of the spherical harmonic expansion of the gravitational potential are calculated for yearly mass changes for these 13 regions up to i 8 there is little similarity at decadal periods between the polar motion excitation from mountain glacier systems and the observed excitation the majority of observed polar motion excitation could be due to other surface mass changes including continental water storage see for example chao 1988 the amplitude of the interannual excitation due to the glacial signal computed here is less than 10 per cent of the observed excitation and the secular trend of the excitation from melting glaciers in the 13 regions is about one quarter of that of the observed excitation yearly changes in the length of day lod are calculated from the glacial signals and compared to the observed yearly alod excess lod signal the contribution of glaciers to the total excess lod signal is less than one part in 150 of the observed signal as alod is caused mainly by core mantle coupling at decadal periods and atmospheric coupling at shorter periods the contributions to displacement of the centre of mass of the solid earth as seen by a satellite tracked from the earth s surface are calculated for the mountain glaciers and an 80 year record of global sea level for the glaciers the average displacements are as much as 1 mm over 20 years and for sea level the z coordinate of the average displacement is 5mm over its 80 year record interannual signals

effect of precipitation seasonality on climatic sensitivity of glacier mass balance abstract numerical calculations are described aimed at evaluating the influence of precipitation seasonality and seasonality concentration on climatic sensitivity of glacier mass balance equilibrium line altitudes elas are modeled using idealized meteorological variables and then a warming test 1 c is performed which revealed that the effects of latitude and the annual precipitation amount are less than those of precipitation seasonality and its concentration calculation shows higher sensitivities for the glaciers located in a summer precipitation climate than for those located within a winter precipitation climate difference due to seasonality is enhanced with the seasonality concentration the present study suggests that the earlier parameterization of glacier mass balance with annual precipitation amount is insufficient to describe the response of glaciers to climate change distribution of precipitation seasonality and its concentration suggest that many parts of the world have a summer precipitation climate but their seasonality concentration is not significant worldwide on the other hand an extensive region of asia and part of the andes are located in the highly concentrated summer precipitation climate this suggests the high sensitivity of glacier mass balance in these regions to climate change

a method to reconstruct past accumulation rates in alpine firn regions a study on fiescherhorn swiss alps annual snow layers in the accumulation zone of glaciers become thinner by viscous deformation while moving to greater depth the reconstruction of the accumulation rate history requires the correction of the thickness of annual layers we apply a novel method to determine the vertical velocity by repeated survey with a caliper probe of grooves scratched into the wall of a borehole with this information and the assumptions of steady state velocity and density fields the correction of layer thicknesses can be determined without knowledge of the ice density profile and thus can be applied to boreholes without ice cores the method is applied to a borehole on fiescherhorn swiss alps resulting in a substantially larger correction than with the simpler method of nye 1963 copyright 2006 by the american geophysical union

homogenization of long term mass balance time series the re analysis of long term mass balance time series is important to provide bias corrected mass balance data for climate change impact studies a method to homogenize time series of compre hensive mass balance monitoring programmes is presented and applied to the nearly 50 year mass balance records of griesgletscher and silvrettagletscher switzerland using a distributed mass balance model in daily resolution we correct the mass balance data for varying observation dates direct point measurements are combined with independent geodetic mass changes a prerequisite for a thorough homogenization of mass balance records differences between mass balance evaluated in the hydro logical year or according to the measurement period and the stratigraphic system are analyzed and may be up to 0 5 m w e a 1 cumulative mass balance of both glaciers based on the glaciological method generally agrees well with geodetic mass change on the investigated glaciers however for silvretta gletscher a significant bias of 0 37 m w e a 1 has been detected and corrected for since 1994

glacier changes in alaska can mass balance models explain grace mascon trends temperature and precipitation data from three weather stations in the st elias mountains of alaska and northwestern canada were used to drive one dimensional 1 d elevation dependent and 0 d degree day mass balance models model outputs were optimized against a 10 day resolution time series of mass variability during 2003 07 obtained from gravity recovery and climate experiment grace mass concentration mascon solutions the models explained 52 60 of the variance in the grace time series modelled mass variations matched the phase of the grace observations and all optimized model parameters were within the range of values determined from conventional mass balance and meteorological observations we describe a framework for selecting appropriate weather stations and mass balance models to represent glacier variations of large regions there is potential for extending these calibrated mass balance models forwards or backwards in time to construct mass balance time series outside of the grace measurement window

response of karakoram himalayan glaciers to climate variability and climatic change a regional climate model assessment the karakoram and the himalayan mountain range accommodate a large number of glaciers and are the major source of several perennial rivers downstream to interactively describe to response of glaciers to climate change a glacier parameterization scheme has been developed and implemented into the regional climate model remo the scheme simulates the mass balance as well as changes of the areal extent of glaciers on a subgrid scale the parameterization scheme is for the first time applied to the region a regional glacier inventory is compiled and is used to initialize glacier area and volume over the highly complex and data sparse region the simulated mass balance largely agrees with observations including the positive karakoram anomaly the simulated equilibrium line altitude is well captured although a systematic underestimation is apparent remo simulates the glacier climate interaction reasonably well it has clear potential to be used for future climate assessments

mass balance of himalayan glaciers using aar and ela methods the accumulation area ratio aar for himalayan glaciers representing zero mass balance is substantially lower than for north america and europe regression analysis suggests 0 44 for the aar representing zero mass balance in the western himalaya a good correlation was observed when this method was applied to individual glaciers such as gara and gor garang in himachal pradesh india the correlation coefficients r using 6 and 7 years of data respectively were 0 88 and 0 96 for gara and gor garang glaciers respectively however when data from six western himalayan glaciers were correlated the correlation was 0 74 the aar was also estimated by using landsat images which can be useful in obtaining a trend in mass balance for a large number of himalayan glaciers for which very little information exists a higher correlation was observed between equilibrium line altitude ela and mass balance the field data from gara and gor garang glaciers shows a high correlation coefficient i e 0 92 and 0 94 respectively the ela values obtained from the landsat satellite images combined with topographic maps suggest positive mass balance for the year 1986 87 and negative for 1987 88

distributed mass balance modelling on two neighbouring glaciers in ortles cevedale italy from 2004 to 2009 a 6 year application of an enhanced temperature index mass balance model to careser and la mare glaciers eastern italian alps is presented the two glaciers exhibit very different characteristics and a comprehensive dataset of distributed mass balance measurements was used to test the model performance the model was run using meteorological data acquired outside the glaciers the work was focused on two main aspects 1 the development of a morphological redistribution procedure for snow and 2 the comparison of three different melt algorithms proposed in the literature the results show that the simple method proposed for snow redistribution can greatly improve simulation of winter balance and further improvements would be achievable by collecting data on inaccessible and high altitude areas all three melt formulations displayed a good skill level and very similar results in modelling the mass balance distribution over glacier areas with slightly better results from a multiplicative algorithm in capturing the vertical balance gradient the simulation errors are related to aspect and elevation and tend to be spatially aggregated some assumptions concerning the spatial and temporal distribution of air temperature and incoming solar radiation although reasonable and widely used in the literature may be responsible for this aggregation hence there is a need to further investigate the processes that regulate the distribution of melt energy and that appear to control the current deglaciation phase in this area

melting of ice shelves and the mass balance of antarctica we calculate the present ice budget for antarctica from measurements of accumulation minus iceberg calving run off and in situ melting beneath the floating ice shelves the resulting negative mass balance of 469 gt year 1 differs substantially from other recent estimates but some components are subject to high temporal variability and budget uncertainties of 20 50 annual accumulation from an earlier review is adjusted to include the antarctic peninsula for a total of 2144 gt year 1 an iceberg production rate of 2016 gt year 1 is obtained from the volume of large icebergs calculated from satellite images since 1978 and from the results of an international iceberg census project ice shelf melting of 544 gt year 1 is derived from physical and geochemical observations of meltwater outflow glaciological field studies and modeling of the sub ice ocean circulation the highest melt rates occur near ice fronts and deep within sub ice cavities run off from the ice sheet surface and from beneath the grounded ice is taken to be 53 gt year 1 less than half of the negative mass balance need come from the grounded ice to account for the unattributed 0 45 mm year 1 in the ipcc best estimate of the recent global sea level rise

manaslu leucogranite a collision signature of the himalaya a model for its genesis and emplacement the manaslu pluton is one of 10 leucogranites that formed in the overthrusted higher himalaya after the indo eurasian collision field and analytical data indicate that the underlying migmatites of the tibetan slab may be where the leucogranitic melts were generated the himalayan crustal thrusting of a hot slab over a rather cold volcano sedimentary pile le fort 1975a provides the necessary release of fluids these fluids cross the main central thrust mct induce the partial anatexis of the overheated tibetan slab and produce a leucogranitic magma the emplacement of the magma at first is located along the main disharmonic plane above the mct between the infrastructure and the superstructure there it generates a convective hydrothermal system extending very far laterally according to the stratification of permeabilities progressive emplacement of the granite proceeds as the convected fluids including the fluids released by the saturated magma dissolve the mainly calcareous host rocks of tibetan sedimentaries a frozen image of this caving out progression is given by the extensive network of granitic dikes outside the pluton the two quite independant fluid cycles of the generation and of the emplacement were triggered or guided by the tectonics due to collision this two fold model dominated by fluid activity may be of importance for other leucogranites and granites

influence of precipitation seasonality on glacier mass balance and its sensitivity to climate change numerical calculations are described aimed at evaluating the influence of precipitation seasonality summer and winter on glacier mass balance first equilibrium line altitudes elas are modeled using idealized meteorological variables modeled climatic conditions summer mean temperature and annual precipitation at the ela of glaciers located within a winter accumulation pattern confirm the observational results of earlier studies however the ela of glaciers located within a summer accumulation climate pattern locates in a colder environment than that of glaciers located within a winter accumulation climate pattern this difference is mainly due to the annual snow accumulation and the surface albedo a warming test 1k reveals higher sensitivities for the glaciers located within a summer accumulation pattern than for the glaciers located within a winter accumulation pattern in a humid environment a significant decrease in snow accumulation on the glaciers located within a summer accumulation pattern directly causes higher sensitivities in an arid environment on the other hand the decreased summer snow induces accelerated melting by lowering the surface albedo and thus increasing absorption of solar radiation on the glaciers located within a summer accumulation pattern both influences are due to significant differences in summer precipitation this study shows the importance of precipitation seasonality on the climatic sensitivity of glacier mass balance which in previous studies has been linked only with annual precipitation

global glacier mass changes and their contributions to sea level rise from 1961 to 2016 glaciers distinct from the greenland and antarctic ice sheets cover an area of approximately 706 000 square kilometres globally1 with an estimated total volume of 170 000 cubic kilometres or 0 4 metres of potential sea level rise equivalent2 retreating and thinning glaciers are icons of climate change3 and affect regional runoff4 as well as global sea level5 6 in past reports from the intergovernmental panel on climate change estimates of changes in glacier mass were based on the multiplication of averaged or interpolated results from available observations of a few hundred glaciers by defined regional glacier areas7 10 for data scarce regions these results had to be complemented with estimates based on satellite altimetry and gravimetry11 these past approaches were challenged by the small number and heterogeneous spatiotemporal distribution of in situ measurement series and their often unknown ability to represent their respective mountain ranges as well as by the spatial limitations of satellite altimetry for which only point data are available and gravimetry with its coarse resolution here we use an extrapolation of glaciological and geodetic observations to show that glaciers contributed 27 22 millimetres to global mean sea level rise from 1961 to 2016 regional specific mass change rates for 2006 2016 range from 0 1 metres to 1 2 metres of water equivalent per year resulting in a global sea level contribution of 335 144 gigatonnes or 0 92 0 39 millimetres per year although statistical uncertainty ranges overlap our conclusions suggest that glacier mass loss may be larger than previously reported11 the present glacier mass loss is equivalent to the sea level contribution of the greenland ice sheet12 clearly exceeds the loss from the antarctic ice sheet13 and accounts for 25 to 30 per cent of the total observed sea level rise14 present mass loss rates indicate that glaciers could almost disappear in some mountain ranges in this century while heavily glacierized regions will continue to contribute to sea level rise beyond 2100 the largest collection so far of glaciological and geodetic observations suggests that glaciers contributed about 27 millimetres to sea level rise from 1961 to 2016 at rates of ice loss that could see the disappearance of many glaciers this century

zanskar shear zone northeast southwest extension within the higher himalayas ladakh india a complete geologic section through the northwestern himalayas is well exposed in ladakh india the collision between the indian shield and the tibetan platform caused large scale intracrustal thrusting and piling up of the himalayan nappes this compressional event was accompanied by prograde regional metamorphism the metamorphism ranges from low grade anchimetamorphism in the indus suture zone in the northeast to upper amphibolite grade in the higher himalaya tectonic unit in the southwest in the zanskar area a well exposed and morphologically prominent shear zone 2 25 to 6 75 km wide can be followed from the northwest to the southeast for at least 80 km in contrast to the main compressional tectonics this shear zone indicates an extensional event within the higher himalaya tectonic unit the zanskar shear zone involves granitic rocks leucogranites of miocene age and various metasediments and in general separates the late precambrian early cambrian sedimentary sequence phe formation from the underlying crystalline basement zanskar crystalline unit a normal sense of shear has been determined by using asymmetric macroscopic and microscopic structures such as pegmatite boudins feldspar augen and crystallographic fabrics the metamorphic isograds are very close within this shear zone as a result of shear deformation a gradual transition from upper amphibolite to lower greenschist facies occurs within 200 m movement in this zone occurred late in the metamorphic history under greenschist or lower metamorphic conditions the minimum horizontal extension and vertical displacement are on the order of 16 and 19 km respectively

geodetic and direct mass balance measurements comparison and joint analysis this paper describes a new compilation of both direct and geodetic mass balance measurements develops a procedure to reduce diverse balance measurements over different time spans to common time spans and presents updated estimates of global average balance of small glaciers based on the enlarged compilation although geodetic measurements are fewer than direct measurements they cover four times as many balance years direct and geodetic measurements are unbiased with respect to one another but differences are often substantial the statistical procedure can be understood by imagining that an n year balance measurement is an average of a series of 1 year measurements the series is hypothetical but we can calculate the uncertainty of each of its elements if in addition to its measured average we can also estimate its standard deviation for this claim to be valid the annual series must be stationary and normally distributed with independent roughly uncorrelated elements for which there is reasonable evidence the need to know the standard deviation means that annual direct measurements from a nearby glacier or equally reliable information about variability are indispensable given this information the new methodology results in moderately more negative balances this is probably because tidewater glaciers are better represented in the geodetic data in any case the most recent published estimate of global average balance 0 8 1 0 mm a 1 of sea level equivalent for 2001 04 is now increased substantially to 1 1 1 4 mm a 1 for 2001 05

the new remote sensing derived swiss glacier inventory ii first results complete swiss glacier inventories are available for 1850 reconstructed and 1973 from aerial photography connected to the global land ice measurements from space project a new swiss glacier inventory for approximately the year 2000 sgi 2000 is compiled mainly based on satellite imagery the developed and applied remotesensing and geographical information system gis methods are described in part i of the contribution in part ii the inventory design first result analyses and comparisons with former glacial conditions are presented as basic entries sgi 2000 contains the individual glacier identification planimetric glacier boundaries as derived from image analysis digitized central flowlines and polygonal glacier basin maps all other parameters are automatically deduced from the above entries and a digital elevation model within a gis here we analyze a set of small bernese and valais glaciers of area 2 these glaciers lost about 21 of area from 1973 to 1998 in addition to about 80 during 1850 1973 both with respect to the 1973 area in order to track the latest trend in more detail anintermediate glacier condition has been compiled from satellite imagery of 1985 this analysis gave an increasing speed of area loss 19 for 1985 98

radiometric chronology of neh nar glacier kashmir surface and core samples of neh nar glacier in the kashmir valley have been analysed for the radionuclides 32si 2lopb 40k and 137cs the lateral and vertical profiles at an altitude of about 4 140 m reveal i 32si activity decreasing slowly from the accumulation zone to 4 050 m altitude and then abruptly towards the snout 2 five zones of alternating high and low 2lopb activity in the surface samples 3 an horizon at between 2 and 3 m depth containing 210pb activity above natural levels this horizon is also associated with 1l7cs and a maximum in total activity the ice sam les have been dated on the basis of a simplified two component model the fresh contribution determined by 21opb and the old component by 32si the following conclusions can be drawn from these observations i the model age of the snout ice is c 850 years 2 the average rate of ice movement in the lower glacier is about 2 m year which compares well with the annual movement rate of 2 65 m year observed since 1974

influence of the arctic circumpolar vortex on the mass balance of canadian high arctic glaciers abstract variability in july mean surface air temperatures from 1963 to 2003 accounted for 62 of the variance in the regional annual glacier mass balance signal for the canadian high arctic a regime shift to more negative regional glacier mass balance occurred between 1986 and 1987 and is linked to a coincident shift from lower to higher mean july air temperatures both the interannual changes and the regime shifts in regional glacier mass balance and july air temperatures are related to variations in the position and strength of the july circumpolar vortex in years when the july vortex is strong and its center is located in the western hemisphere positive mass balance anomalies prevail in contrast highly negative mass balance anomalies occur when the july circumpolar vortex is either weak or strong without elongation over the canadian high arctic and its center is located in the eastern hemisphere the occurrence of westerly positioned july vortices has decreased by 40 since 1987 the associat

common climatic signal from glaciers in the european alps over the last 50 years conventional glacier wide mass balances are commonly used to study the effect of climate forcing on glacier melt unfortunately the glacier wide mass balances are also influenced by the glacier s dynamic response investigations on the effects of climate forcing on glaciers can be largely improved by analyzing point mass balances using a statistical model we have found that 52 of the year to year deviations in the point mass balances of six glaciers distributed across the entire european alps can be attributed to a common variability point mass balance changes reveal remarkable regional consistencies reaching 80 for glaciers less than 10 km apart compared to the steady state conditions of the 1962 1982 period the surface mass balance changes are 0 85 m water equivalent w e a 1 for 1983 2002 and 1 63 m w e a 1 for 2003 2013 this indicates a clear and regionally consistent acceleration of mass loss over recent decades over the entire european alps

a reconciled estimate of glacier contributions to sea level rise 2003 to 2009 glaciers distinct from the greenland and antarctic ice sheets are losing large amounts of water to the world s oceans however estimates of their contribution to sea level rise disagree we provide a consensus estimate by standardizing existing and creating new mass budget estimates from satellite gravimetry and altimetry and from local glaciological records in many regions local measurements are more negative than satellite based estimates all regions lost mass during 2003 2009 with the largest losses from arctic canada alaska coastal greenland the southern andes and high mountain asia but there was little loss from glaciers in antarctica over this period the global mass budget was 259 28 gigatons per year equivalent to the combined loss from both ice sheets and accounting for 29 13 of the observed sea level rise

greenland ice sheet mass balance distribution a variance analysis of existing field data a large number of mass balance measurements have been carried out on the greenland ice sheet but few of the series obtained are well suited for statistical studies rather than looking at the global mass balance value this paper deals with the spatial and temporal mass balance variability on the ice sheet two sorts of analysis are possible direct comparisons of the series measured at a given site or a broader approach involving comparisons between different sites using variance analysis for glaciers in the southwest ablation area a significant interannual variability around 1 0 m w e is found this variability is spatially consistent in the accumulation area the results are more complex for example there is consistent evidence of year to year variations on the west east expeditions glaciologiques internationales au groenland egig profile but other closer sites are weakly correlated these results emphasize the need for a better coverage of measurements over the entire ice sheet as well as longer and more continuous measurement series

airborne surface profiling of glaciers a case study in alaska a relatively lightweight and simple airborne system for surface elevation profiling of glaciers in narrow mountain valleys has been developed and tested the aircraft position is determined by kinematic global positioning system gps methods the distance to the glacier surface is determined with a laser ranger the accuracy is about 0 3 m sufficient to permit future changes to be observed over short time intervals long term changes can be estimated by comparison of profiles with existing maps elevation profiles obtained in 1993 94 from three glaciers in central and south central alaska are compared with maps made about 1950 the resulting area averaged seasonally corrected thickness changes during the interval are gulkana glacier central alaska range 11 m worthington glacier central chugach mountains 7 m and bear lake glacier kenai mountains 12 m all three glaciers retreated during the interval of comparison the estimated uncertainty in the average thickness change is 5 m which is mainly due to errors in the existing maps constraints on the accuracy of the maps are obtained by profiling in proglacial areas

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

mass balance of glaciers other than the ice sheets small glaciers appear to have been at equilibrium or shrinking very slightly during 1961 90 according to analysis of an essentially compl ete set of published measurements simple calculations give an average annual mass balance of 195 59 mm a 1 water equivalent but this is too low because of systema tic errors eglect of internal accumulation is respon sible for some tens of millime ters of under esti mate uneven spatial coverage with fewer measurements where mass balances are less negative accounts for about 50 mm a 1 of underestimate this figure derives from spatial interpolati on based on global data on ice extent and on an analysis of correlations between balance time series the eorrelogram shows exponential decay the scale length being about 600 km the largest bias is due to a newly detec ted dependence of mass balance on glacier size among the 231 measured glaciers many arc small and belong to a restricted size range in which balance is negativ e but much of the small glacier extent is accounted for by larger glac iers in a size range where balance is indisti ngui shable from zero correct ing for this size bias increases the average balance to 35 89 mm a i inspection of time series for 1940 95 251 glaciers shows that mass balance was least negative during the 1960s and has varied in broad agreementvith northern hemisphere temperature anomalies smaller small glaciers a 16 km2 appear to be more sensitive than larger small glaciers to changes in thermal forci ng the small glaci er contribution to sea level rise implied by this asse ssment is only 0 06 0 32 mm a i consistent with glaciers in general mak i ng little or no contri bution to sea level change during 1961 90

mass balance of glaciers and ice caps consensus estimates for 1961 2004 1 working with comprehensive collections of directly measured data on the annual mass balance of glaciers other than the two ice sheets we combine independent analyses to show that there is broad agreement on the evolution of global mass balance since 1960 mass balance was slightly below zero around 1970 and has been growing more negative since then excluding peripheral ice bodies in greenland and antarctica global average specific balance for 1961 1990 was 219 112 kg m 2 a 1 representing 0 33 0 17 mm sle sea level equivalent a 1 for 2001 2004 the figures are 510 101 kg m 2 a 1 and 0 77 0 15 mm sle a 1 including the smaller greenland and antarctic glaciers global total balance becomes 0 38 0 19 mm sle a 1 for 1961 1990 and 0 98 0 19 mm sle a 1 for 2001 2004 for 1991 2004 the glacier contribution 0 77 0 26 mm sle a 1 is 20 30 of a recent estimate of 3 2 0 4 mm a 1 of total sea level rise for 1993 2005 while our error estimates are not rigorous we believe them to be liberal as far as they go but we also discuss several unquantified biases of which any may prove to be significant

on thermal expansion over the last hundred years estimates of sea level rise during the period 1856 1991 due to thermal expansion are presented the estimates are based on an ocean model that consists of three zonally averaged ocean basins representing the atlantic pacific and indian oceans these basins are connected by a circumpolar basin that represents the southern ocean the ocean circulation in the model was prescribed surface ocean forcing was calculated from observed sea surface temperatures global mean forcing and regionally varying forcing were distinguished different parameterizations of ocean heat mixing were incorporated according to the model presented global mean sea level rise caused by thermal expansion over the last hundred years ranged from 2 2 to 5 1 cm a best estimate being 3 5 cm 34 refs 5 figs

carbon isotopic thermometry calibrated by dolomite calcite solvus temperatures abstract the temperature dependence of carbon isotopic fractionations between calcite and graphite and between dolomite and graphite are calibrated by the calcite dolomite solvus geothermometry using marbles collected from the contact metamorphic aureole in the kasuga area central japan the carbon isotopic fractionations 13ccc gr and 13cdo gr systematically decrease with increasing metamorphic temperature the concordant relationships between the fractionations and solvus temperatures are approximately linear with t 2 over the temperature range 400 to 680 c 13ccc gr 5 6 106 t 2 k 2 4 13cdo gr 5 9 106 t 2 k 1 9 these systematic relationships between fractionation and temperature suggest that carbon isotopic equilibria between carbonates and graphite were attained in many cases the equation for the calcite graphite system has a slope steeper than bottinga s 1969 results it is however in good agreement with that of valley and o neil 1981 in the temperature range from 600 to 800 c because of the relatively high sensitivity to temperature these isotopic geothermometers are useful for determining the temperatures in moderate to high grade metamorphosed carbonate rocks

metamorphic equilibria in the siliceous dolomite system 6 kbar experimental data and geologic implications hydrothermal experiments with h2o co2 fluids at pfluid 6 kbar yielded the following quilibrium conditions for reactions important in metamorphosed siliceous dolomites t c x xco2 3 dolomite 2 quartz diopside 2 co2t 620 8x 0 73 0 03 5 5 dolomite 8 quartz h2o tremolite 3 calcite 7 co2t 600 5 550 5 540 5 500 5x 0 66 0 03 0 21 0 03 0 21 0 04 0 06 0 02 7 3 dolomite 4 quartz h2o talc 3 calcite 3 co2t 550 5 500 5 450 5x 0 25 0 05 0 07 0 02 0 03 0 02 8 2 dolomite talc 4 quartz tremolite 4 co2t 550 5 540 5 500 5x 0 22 0 03 0 21 0 02 0 06 0 02 a thermodynamically self consistent 6 kbar t xco2 topology results by extrapolating equilibria from experimental brackets using a modified redlich kwong equation for activities in h2o co2 mixtures this topology restricts the assemblage talc calcite to a narrow stability band in t xco2 space at xco2 0 55 and t 590 c accordingly the occurrence of talc calcite in pure siliceous dolomites metamorphosed at pfluid 6 kbar implies correspondingly water rich fluids

glacial isostatic adjustment and the anomalous tide gauge record of eastern north america sea level variations as recorded by the global network of tide gauges represent a rich data set for studying a wide range of natural and anthropogenic phenomena such as the sea level rise induced by possible global warming for this purpose long term sea level trends must be corrected for the contaminating effects of continuing glacial isostatic adjustment1 5 gia the numerical correction procedure has for sites on the east coast of north america yielded a set of highly anomalous sea level rates characterized by systematic geographical trends2 4 5 we demonstrate that these trends are a consequence of inadequacies in the previous standard numerical prediction for gia in particular we find that the well known trends in the gia corrected tide gauge rates are eliminated if the lower mantle viscosity of the earth model used in the gia prediction is increased this result obviates the need to explain the anomalous trend as a manifestation of gulf stream ocean circulation4 or neotectonic processes2

representing glaciers in a regional climate model a glacier parameterization scheme has been developed and implemented into the regional climate model remo the new scheme interactively simulates the mass balance as well as changes of the areal extent of glaciers on a subgrid scale the temporal evolution and the general magnitude of the simulated glacier mass balance in the european alps are in good accordance with observations for the period 1958 1980 but the strong mass loss towards the end of the twentieth century is systematically underestimated the simulated decrease of glacier area in the alps between 1958 and 2003 ranges from 17 1 to 23 6 the results indicate that observed glacier mass balances can be approximately reproduced within a regional climate model based on simplified concepts of glacier climate interaction however realistic results can only be achieved by explicitly accounting for the subgrid variability of atmospheric parameters within a climate model grid box

monitoring of seasonal glacier mass balance over the european alps using low resolution optical satellite images we explore a new method to retrieve seasonal glacier mass balances mbs from low resolution optical remote sensing we derive annual winter and summer snow maps of the alps during 1998 2014 using spot vegetation 1 km resolution imagery we combine these seasonal snow maps with a dem to calculate a mean regional altitude of snow z in a region surrounding a glacier then we compare the interannual variation of z with the observed winter summer glacier mb for 55 alpine glaciers over 1998 2008 our calibration period we find strong linear relationships in winter mean r 2 0 84 and small errors for the reconstructed winter mb mean rmse 158 mm w e a 1 this is lower than errors generally assumed for the glaciological mb measurements 200 400 mm w e a 1 results for summer mb are also satisfying mean r 2 and rmse respectively 0 74 and 314 mm w e a 1 comparison with observed seasonal mb available over 2009 2014 our evaluation period for 19 glaciers in winter and 13 in summer shows good agreement in winter rmse 405 mm w e a 1 and slightly larger errors in summer rmse 561 mm w e a 1 these results indicate that our approach might be valuable for remotely determining the seasonal mb of glaciers over large regions

geothermobarometry in metasediments of the southern grossvenediger area tauern window austria metasediments in the southern grossvenediger area tauern window austria were studied along a cross section through rocks of increasing metamorphic grade from the margin of the tauern window in the south to the base of the upper schieferhulle including the eclogite zone in the north in the southern part of the cross section there is no evidence for a pre late alpine metamorphic history in the form of high pressure relics or pseudomorphs mineral assemblages are characterized by the stability of tremolite calcite biotite calcite and biotite chlorite calcite in the northern part a more complete alpine metamorphic evolution is preserved primary high pressure assemblages are dolomite quartz tremolite zoisite zoisite dolomite quartz phengite i and probably tremolite dolomite phengite i secondary post kinematic assemblages tremolite calcite talc calcite phengite ii chlorite calcite quartz biotite chlorite calcite biotite zoisite calcite formed as a result of the dominant late alpine metamorphic overprint the occurrence of biotite zoisite calcite is confined to the northernmost area and defines a biotite zoisite calcite isograd p t estimates based on standard thermobarometric techniques and on stability relationships of tremolite calcite dolomite quartz and zoisite give consistent results p t conditions of the main tertiary metamorphic overprint were 525 c p 7 5 1 kbar in the northern part of the cross section the southern part was metamorphosed at lower temperatures of 430 470 c the si content of phengites from this area is almost as high as that of phengites from the eclogite zone simax 3 4 pfu pressures 10 kbar at 420 c are suggested by phengite barometry according to massone schreyer 1987 in the absence of high pressure relics or pseudomorphs these phengites which lack late alpine re equilibration are the only record that rocks of the southern part probably also experienced an early non eclogitic high pressure metamorphism

updated estimates of glacier volume changes in the western chugach mountains alaska and a comparison of regional extrapolation methods and 2001 2004 average net balance rates ranged between 3 1 to 0 16 m yr 1 for the tidewater and 1 5 to 0 02 m yr 1 for the nontidewater glaciers we tested several methods for extrapolating these measurements to all the glaciers of the western chugach mountains using a process similar to cross validation predictions of individual glacier changes appear to be difficult probably because of the effects of glacier dynamics which on long multidecadal timescales complicates the response of glaciers to climate in contrast estimates of regional contributions to rising sea level were similar for different methods mainly because the large glaciers whose changes dominated the regional total were among those measured for instance the above sea level net balance rate of columbia glacier 3 1 0 08 km 3 yr 1 water equivalent weq or an equivalent rise in sea level sle of 0 0090 0 0002 mm yr 1 was nearly half of the total regional net balance rate of the western chugach mountain glaciers 7 4 1 1 km 3 yr 1 weq or 0 020 0 003 mm yr 1 sle between 1950 1957 and 2001 2004 columbia glacier is a rapidly retreating tidewater glacier that has lost mass through processes largely independent of climate tidewater glaciers should therefore be treated separately when performing regional extrapolations

the metamorphism in the central himalaya all along the himalayan chain an axis of crystalline rocks has been preserved made of the higher himalaya crystalline and the crystalline nappes of the lesser himalaya the salient points of the metamorphism as deduced from data collected in central himalaya central nepal and kumaun are 1 the higher himalaya crystalline also called the tibetan slab displays a polymetamorphic history with a first stage of barrovian type overprinted by a lower pressure and or higher temperature type metamorphism the metamorphism is due to quick and quasi adiabatic uplift of the tibetan slab by transport along an mct ramp accompanied by thermal refraction effects in the contact zone between the gneisses and their sedimentary cover the resulting metamorphic pattern is an apparent diachronic inverse zonation with the sillimanite zone above the kyanite zone 2 conversely the famous inverted zonation of the lesser himalaya is basically a primary pattern acquired during a one stage prograde metamorphism its origin must be related to the thrusting along the mct with heat supplied from the overlying hot tibetan slab as shown by synmetamorphic microstructures and the close geometrical relationships between the metamorphic isograds and the thrust 3 thermal equilibrium is reached between units above and below the mct far behind the thrust tip there is good agreement between the maximum temperature attained in the hanging wall and the temperature of the tibetan slab during the second metamorphic stage but closer to the mct front the thermal accordance between both sides of the thrust is due to a retrogressive metamorphic episode in the basal part of the tibetan slab

integrated monitoring of mountain glaciers as key indicators of global climate change the european alps the internationally recommended multi level strategy for monitoring mountain glaciers is illustrated using the example of the european alps where especially dense information has been available through historical times this strategy combines in situ measurements mass balance length change with remote sensing inventories and numerical modelling it helps to bridge the gap between detailed local process oriented studies and global coverage since the 1980s mass balances have become increasingly negative with values close to 1 m w e a 1 during the first 5 years of the 21st century the hot dry summer of 2003 alone caused a record mean loss of 2 45 m w e roughly 50 above the previous record loss in 1998 more than three times the average between 1980 and 2000 and an order of magnitude more than characteristic long term averages since the end of the little ice age and other extended periods of glacier shrinkage during the past 2000 years it can be estimated that glaciers in the european alps lost about half their total volume roughly 0 5 a 1 between 1850 and around 1975 another 25 or 1 a 1 of the remaining amount between 1975 and 2000 and an additional 10 15 or 2 3 a 1 in the first 5 years of this century

historically unprecedented global glacier decline in the early 21st century observations show that glaciers around the world are in retreat and losing mass internationally coordinated for over a century glacier monitoring activities provide an unprecedented dataset of glacier observations from ground air and space glacier studies generally select specific parts of these datasets to obtain optimal assessments of the mass balance data relating to the impact that glaciers exercise on global sea level fluctuations or on regional runoff in this study we provide an overview and analysis of the main observational datasets compiled by the world glacier monitoring service wgms the dataset on glacier front variations 42000 since 1600 delivers clear evidence that centennial glacier retreat is a global phenomenon intermittent readvance periods at regional and decadal scale are normally restricted to a subsample of glaciers and have not come close to achieving the maximum positions of the little ice age or holocene glaciological and geodetic observations 5200since 1850 show that the rates of early 21st century mass loss are without precedent on a global scale at least for the time period observed and probably also for recorded history as indicated also in reconstructions from written and illustrated documents this strong imbalance implies that glaciers in many regions will very likely suffer further ice loss even if climate remains stable

time scale for adjustment of glaciers to changes in mass balance the length of time tm over which a glacier responds to a prior change in climate is investigated with reference to the linearized theory of kinematic waves and to results from numerical models we show the following tm may in general be estimated by a volume time scale describing the time required for a step change in mass balance to supply the volume difference between the initial and final steady states the factor f in the classical estimate of m l u where i is glacier length and u is terminus velocity has a simple geometrical interpretation ft is the ratio of thickness change averaged over the full length i to the change at the terminus although both u and f relate to dynamic processes local to the terminus zone the ratio f u and therefore tm are insensitive to details of the terminus dynamics in contrast to conclusions derived from some simplified kinematic wave models a more robust estimate of tm independent of terminus dynamics is given by tm h b where h is a thickness scale for the glacier and b is the mass balance rate negative at the terminus we suggest that tm for mountain glaciers can be substantially less than the 1o2 103 years commonly considered to be theoretically expected

global scale modeling of glacier mass balances for water resources assessments glacier mass changes between 1948 and 2006 abstract glaciers play an important role for freshwater resources but in global scale freshwater assessments their impact on river flows has not yet been taken into account as a first step we developed a global glacier model that can be coupled to global land surface and hydrological models with a spatial resolution of 0 5 by 0 5 the glacier model hyoga computes glacier mass balance by a simple degree day approach for 50 m sub grid elevation bands modeling all glaciers within a grid cell as one glacier the model is tuned individually for each grid cell against observed glacier mass balance data hyoga is able to compute glacier mass balances reasonably well even those of summer accumulation type glaciers still model uncertainty is high which is among other reasons due to the uncertainty of global data sets of temperature and precipitation which do not represent well the climatic situation at glacier sites we developed a 59 yr 1948 2006 time series of global glacier mass balance and glacier area by driving hyoga with daily near surface atmospheric data according to our computations most glaciers have lost mass during the study period compared to estimates derived from a rather small number of observed glacier mass balances hyoga computes larger glacier mass losses in asia europe canadian arctic islands and svalbard in accordance with the estimates average annual mass losses have increased strongly after 1990 as compared to the 30 yrs before the sea level equivalent of the melt water from glaciers is 0 76 mm yr water equivalent after 1990 as compared to only 0 34 mm yr water equivalent before we computed an acceleration of glacier mass losses after 1990 for all world regions except south america where the number of gauge observations of precipitation is very small after 1980

mass balance of rhonegletscher during 1882 83 1986 87 les bilans de masse effectues sur le glacier des sources du rhone alpes suisses pendant differentes periodes 1884 85 1908 09 1979 80 et 1981 82 sont presentes