simulation of historic glacier variations with a simple climate glacier model glacier variations during the last few centuries have shown a marked coherence over the globe characteristic features are the maximum stand somewhere in the middle of the nineteenth century and the steady retreat afterwards with some minor interrruptions depending on the particular region in many papers qualitative statements have been made about the causes of these fluctuations lower temperatures associated with solar variability and or volcanic activity are the most popular explanations in particular the statistical relation between glacier activity and major volcanic eruptions appears to be strong in this paper an attempt is made to simulate recent glacier fluctations with a physics based model a simple climate model calculating perturbations of surface radiation balance and air temperature not necessarily in phase is coupled to a schematic time dependent glacier model the climate model is forced by volcanic activity greenland acidity and or lamb s dust veil index and greenhouse warming solar variability was not considered because its effect on climate has still not been demonstrated in a convincing way the output is translated into variations in equilibrium line altitude driving the glacier model the simulated variations in glacier length show good agreement with the observed record but the amplitude is too small this is improved when mass balance gradients are assumed to be larger in warmer climates compared to recently published modelling studies of particular glaciers in which series of local parameters e g tree ring width and temperature were used as forcing the present simulation is better this suggests that the radiation balance is a decisive factor with regard to glacier variations on longer time scales the model experiments lend support to the results of porter 1986 who concluded from a more qualitative study that a strong relation exists between periods of increased volcanic activity and glacier advances a comparison of some selected runs shows that according to the present model the greenhouse warming would be responsible for about 50 of the glacier retreat observed over the last 100 years

quantifying global warming from the retreat of glaciers records of glacier fluctuations compiled by the world glacier monitoring service can be used to derive an independent estimate of global warming during the last 100 years records of different glaciers are made comparable by a two step scaling procedure one allowing for differences in glacier geometry the other for differences in climate sensitivity the retreat of glaciers during the last 100 years appears to be coherent over the globe on the basis of modeling of the climate sensitivity of glaciers the observed glacier retreat can be explained by a linear warming trend of 0 66 kelvin per century

application of a distributed degree day model of glaciers in the upper reaches of the beida river basin based on in situ data of qiyi glacier from 2010 to 2012 a daily distributed degree day model on a 90 90 m grid was developed to simulate the spatial and temporal variations of the glacier mass balance ela and meltwater run off depth in the beida river basin from 1957 to 2012 in the model different vertical lapse rates of temperature and precipitation gradients were used in different months and height belts and the influence of temperature jump was also considered the results indicated that the average annual mass balance and meltwater run off depth of the glaciers in the beida river basin were 93 3 mm w e and 443 mm respectively assuming a continuous linear trend the ela had risen by 505 m over 55 years the mass balance linearly increased with the altitude in the cold season oct apr and exponentially in the warm season may sep the most possible abrupt change points of the mass balance ela and meltwater run off depth time series were all in 1992 93 as determined through the m k test the mass balance turned increasingly negative since then but the ela and meltwater run off increased rapidly the climate sensitivity test showed that the air temperature was a dominant factor that affected the mass balance of the continental glaciers on the basin scale which was different from the response mechanism of maritime glaciers when the air temperature 1 c and precipitation 10 increased simultaneously the glacier mass loss and meltwater run off reached 1 66 108 m3 and 2 45 108 m3 respectively

climate sensitivity of the ice cap of king george island south shetland islands antarctica a two dimensiona l vertically integrated ice flow model has been used to simulate the current state of the ice cap of king george island south shetland islands antarctica as well as the sensitivity of this state to climate change the model was forced by an energy balance model that generates the specific mass balance from climatological input data of two research stations it proved difficult to simulate satisfactorily the entire geometry of the present day ice cap nevertheless it was possible to simulate a steady state ice cap whose volume and areal extent approximate the estimated current situation several experiments have indicated that this state is highly sensitive to climate change the model predicts that cooling by l k will increase the ice volume by 10 and warming by l k will decrease it by 36 a 10 change in precipitation will alter the ice volume by less than 8 application of the ipcc 90 business as usual scenario leads to a 55 reduction in the ice volume by the year ad 2100 compared to the present day situation the response of the ice cap to warming is therefore totally different from the response of the main antarctic ice sheet which is believed to gain mass by increasing temperatures

little ice age precipitation in jotunheimen southern norway recently published glaciological data from southern norway enable analysis of changes in glacier geometry since the little ice age lia and estimation of the magnitude of the lia precipitation anomaly glacier area extents in the jotunheimen region have been created for 2003 using glacier outlines derived from landsat and for the lia maximum about ad 1750 by using glacier outlines defined by moraines a 25 m digital terrain model from 1980 was used to derive inventory data for both times both inventories provide area and altitude range as well as length slope and aspect of the glaciers area altitude profiles a z for the lia maximum are calculated from the 1980 profiles by assuming that the area increase distribution a z was concentrated at low altitude and it integrates to the measured area difference between 1980 and the lia under this assumption the regionally averaged mean altitude change from 1980 to the lia z 68 m glacier mass balance measurements show that the mass balance gradie

climatic and morphometric controls on the altitudinal range of glaciers british columbia canada to examine the relation between climate and glacier extent we compared gridded monthly temperature and precipitation data to the altitudinal range of glaciers in british columbia canada we related glacier relief to ablation season temperature june august accumulation season precipitation september march and morphometric variables that included slope glacier order and a shape index for 523 alpine glaciers that ranged from 5 to 15 km2 in surface area a 1 c increase in mean june august temperature equates to a 109 to 182 m decrease in glacier relief and a 1 mm increase in mean monthly september march precipitation equates to a 0 78 to 2 20 m increase in glacier relief the most important morphometric controls on this glacier climate relation include average surface slope glacier order analogous to stream order and the ratio of upper accumulation area to lower ablation area width all of which are positively related to glacier relief we note strong relations between glacier relief and cli

recent glacier retreat exceeds internal variability glacier fluctuations exclusively due to internal variations in the climate system are simulated using downscaled integrations of the echam4 opyc coupled general circulation model gcm a process based modeling approach using a mass balance model of intermediate complexity and a dynamic ice flow model considering simple shearing flow and sliding are applied multimillennia records of glacier length fluctuations for nigardsbreen norway and rhonegletscher switzerland are simulated using autoregressive processes determined by statistically downscaled gcm experiments return periods and probabilities of specific glacier length changes using gcm integrations excluding external forcings such as solar irradiation changes volcanic or anthropogenic effects are analyzed and compared to historical glacier length records preindustrial fluctuations of the glaciers as far as observed or reconstructed including their advance during the little ice age can be explained by internal variability in the climate system as represented by a gcm however fluctuations comparable to the present day glacier retreat exceed any variation simulated by the gcm control experiments and must be caused by external forcing with anthropogenic forcing being a likely candidate

influence of upper air conditions on glaciers in scandinavia a simple model using once daily us national centers for environmental prediction us national center for atmospheric research ncep ncar re analysis upper air values estimates winter balance summer balance and net balance at ten glaciers in norway and two in sweden with 0 37 r 2 0 90 the october may arctic oscillation ao an index of sea level pressure slp in the northern hemisphere correlates with winter balance and net balance with 0 09 r 2 0 82 lower than the model in all but 3 of the 24 cases the october may north atlantic oscillation nao an slp gradient in the north atlantic has lower correlations than the ao for all but 5 of the 24 cases at all ten glaciers with records beginning before 1987 net balance became more positive after 1988 owing mainly to increased winter balance with summer balance changing little although winter temperatures increased they were still well below freezing so the rain snow division of the precipitation was only slightly affected increase in winter balance was due to increased precipitation caused by a change in atmospheric circulation resulting in more frequent westerly flow concurrent with the warming at 850 hpa westerly flow is 2 5 c warmer than easterly flow westerly flow warmed by 0 3 c easterly by 0 7 c both the ao and nao with which winter balance is positively correlated at all 12 glaciers were more positive after 1988

glacier change in northern sweden from ad 500 a simple geometric model of storglaciaren a simple geometric model of glacier volume is derived the model is based on the assumption that the net mass balance averaged over the glacier surface is related to the summer temperature and winter accumulation at a representative height on the glacier this height varies with time as climate changes in ways that are determined by the geometry of the glacier surface expressions are derived for the equilibrium glacier volume v eq as a function of summer temperature and winter accumulation and for the glacier response time as a function of volume the model is used to reconstruct the volume of storglaciaren over the period ad 500 1992 measured net mass balance data for storglaciren 1946 92 are used to estimate the model parameters for the summer temperature forcing the long treering based temperature reconstruction for northern fennoscandia is used to extend a temperature record near the glacier back to ad 500 for the past accumulation forcing a range of assumptions is tested the results show that the prime cause of the decrease in volume of storglaciaren between 1946 and 1992 was relatively low accumulation over 1946 89 as opposed to warm temperatures as previously supposed reconstructed volume changes agree well with geomorphological evidence where differences occur deductions can be made about past accumulation for example the maximum reconstructed glacier volume is associated with the cold period from 1580 to 1740 but relatively low accumulation probably limited the volume to values not much larger than that achieved around 1916

a 2 d numerical model of snow ice energy balance and ice flow for paleoclimatic interpretation of glacial geomorphic features abstract standard methods of interpreting the paleoclimates recorded in alpine glacial geomorphic features rely on estimates of paleoglacier shape commonly assume that relationships between mass balance gradient and equilibrium line altitude of modern glaciers apply equally well to glaciers of in many cases dramatically different climates and do not account for the varying influence of topography on glacial extent while those methods may be adequate for many studies there are an increasing number of areas in which that level of analysis does not match the level of detail of the glacial chronologies being developed as an alternative we present a physically based 2 d glacier model that can be used to determine steady state glacier shapes and distributions for a wide range of climatic conditions the model requires only a modest amount of data beyond that which would be required for simpler methods and includes a relatively accurate representation of the effects of topography on the largest component of the surface energy balance shortwave radiation it calculates 2 d in the horizontal plane distribution of snow accumulation using a surface mass and energy balance approach and calculates the resultant glacier shapes with a 2 d flow model in addition to offering a potentially more accurate reconstruction of paleoclimatic conditions the model provides a means of performing detailed sensitivity analysis establishing relationships between similar deposits in basins of different shape and aspect and of predicting glacier shape terminus position in areas not yet explored

static mass balance sensitivity of arctic glaciers and ice caps using a degree day approach the purpose of this study is to enhance our understanding of the response of glaciers to climate change global sea level is affected by changes in glacier ice volume and melt water from glaciers is a principal water source in many regions this study applies glacier mass balance modelling with varying complexity and spatial resolution ranging from individual glaciers to regional and global assessments of glacier mass losses glaciers located in maritime environments generally show considerably higher mass balance sensitivities than those in continental settings on average an assumed increase in annual precipitation of 10 tends to offset the effect of an annual temperature change of 1 k by roughly 20 two case studies at storglaciaren sweden and hofsjokull iceland involve model results of future mass balance change and glacier melt induced changes in runoff applying a temperature and precipitation scenario for iceland in 2050 results in increased total runoff from hofsjokull by roughly one third and results emphasize the role of the firn layer in delaying water flow through glaciers yielding a redistribution of discharge within the year based on a global gridded data set of glacierized area the sea level equivalent from all mountain glaciers and ice caps outside the ice sheets in greenland and antarctica during 1961 2004 caused by changes in temperature and precipitation is estimated to be 0 58 0 34 mm a 1 the mountain glaciers and ice caps around antarctica alone contribute almost 40 of the global estimate and hence their contribution is considerably larger than previously assumed

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

ejecta scaling laws for craters in dry alluvial sites the existing factor of 20 scatter in the ejecta thickness data for surface bursts chemical and nuclear in dry alluvium is reduced to a scatter a factor of 4 by a simple yield correction this correction accounts for the mismatch in the scaling laws that govern the formation of the ejecta blanket and of the apparent crater craters from surface bursts obey strength scaling in which linear crater dimensions scale as cube root of the yield their ejecta blankets on the other hand obey gravity scaling in which linear ejecta blanket dimensions scale as yield to a power of less than a third for this reason geometric scaling scaling the range and the ejecta thickness by the crater radius is appropriate for craters in the gravity regime however it is not the appropriate scaling rule for ejecta from surface bursts and is the reason for the observed factor of 20 scatter a simple correlation is proposed that agrees with the data to better than a factor of 2 in the continuous ejecta region and slightly more than a factor of 2 in the discrete ejecta region for buried bursts the craters obey 1 3 4 scaling a transition between the strength and gravity regimes while the ejecta blankets scale with gravity despite this slight mismatch in the scaling field data for buried bursts agree with a proposed geometric scaled correlation to approximately a factor of 2 in the continuous ejecta region and approximately a factor of 5 in the discrete ejecta region

contribution of glacier melt to sea level rise since ad 1865 a regionally differentiated calculation the contribution of glacier melt including the greenland ice sheet to sea level change since ad 1865 is estimated on the basis of modelled sensitivity of glacier mass balance to climate change and historical temperature data calculations are done in a regionally differentiated manner to overcome the inhomogeneity of the global distribution of glaciers a distinction is made between changes in summer temperature and in temperature over the rest of the year our best estimate of the ice melt in the period 1865 1990 in terms of sea level change equivalent is 5 7 cm 2 7 cm for glaciers and 3 0 cm for the greenland ice sheet additional calculations show that simpler methods like using annual or even global mean temperature anomaly give estimates that differ by up to 55 consequently a regionally differentiating approach is advised for making projections of glacier melt with gcm output

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

the mass balance of mccall glacier brooks range alaska u s a its regional relevance and implications for climate change in the arctic mccall glacier has the only long term mass balance record in arctic alaska average annual balances over the periods 1958 72 and 1972 93 were 15 and 33cm respectively recent annual balances 1993 96 are about 60 cm and the mass balance gradient has increased for an arctic glacier with its low mass exchange rate this marks a significant negative trend recently acquired elevation profiles of mccall glacier and ten other glaciers within a 30 km radius were compared with topographic maps made in 1956 or 1973 most of these glaciers had average annual mass balances between 25 and 33 cm while mccall glacier averaged 28 cm for 1956 93 indicating that it is representative of the region in contrast changes in terminus position for the different glaciers vary markedly thus mass balance trends in this region cannot be estimated from fractional length changes at time scales of a few decades we developed a simple degree day accumulation mass balance model for mccall glacier the model was tested using precipitation and radiosonde temperatures from weather stations at inuvik canada and barrow kaktovik and fairbanks alaska and was calibrated with the measured balances the inuvik data reproduce all measured mass balances of mccall glacier well and also reproduce the long term trend towards more negative balances data from the other stations do not produce satisfactory model results we speculate that the arctic front oriented east west in this region causes the differences in model results

a flowline model for nigardsbreen norway projection of future glacier length based on dynamic calibration with the historic record historic glacier length variations are used to constrain a computer model for nigardsbreen norway a mass balance history is derived that when imposed on the flow model gives an almost perfect match between observed and simulated glacier length since ad 1748 being calibrated with past changes the model predicts an 800 in advance of the glacier snout if mass balance conditions remain as they were for the period 1962 93 several greenhouse warming scenarios are imposed to project the glacier s behaviour into the next century for a uniform heating rate of 0 02 k a nigardsbreen would advance slightly until ad 2020 but then a very rapid retreat would start in ad 2100 glacier volume would be only 10 of the 1950 volume

pedostratigraphy of chinese loess deposits and climatic cycles in the last 2 5 myr summary the pedostratigraphy and magnetostratigraphy of several sections in the loess plateau of north central china have been investigated and correlated the most complete and distinct loess paleosol sequence occurs in the baoji section of the southern part of the plateau thirty seven pedostratigraphic units are identifiable in the baoji section and correlated with those in other parts of the plateau the sequence represents thirty seven major cold to warm climatic cycles in the last 2 5 myr at about the time of the matuyama gauss magnetic reversal an abrupt climatic event occurred in north china represented by the shift of the well weathered red clay formation below the m g boundary to the alternating loess and paleosol units above marking the beginning of a new epoch in the course of climatic evolution in addition there are two other major shifts of dominant periods of climatic cycles recorded in the loess paleosol sequences one occurring at about 1 5 myr and another at about 0 8 myr the pedostratigraphy of loess deposits in north central china provides an independent measure of the world wide climatic fluctuations and is now the most complete and reliable record of the major climatic cycles in the last 2 5 myr

model study of the spatial distribution of the energy and mass balance of morteratschgletscher switzerland to investigate the spatial distribution of the energy and mass balance fluxes of a glacier a two dimensional mass balance model was developed and applied to morteratschgletscher switzerland the model is driven by meteorological input from four synoptic weather stations located in the vicinity of morteratschgletscher the model results were compared to observations made on the glacier the calculated mean specific mass balance is 0 47 m w e for 1999 and 0 23 m w e for 2000 net shortwave radiation shows a minimum at around 3350 m a s l due to the effects of shading slope aspect reflection from the slopes and obstruction of the sky ignoring these effects results in a 37 increase in the annual incoming shortwave radiation on the glacier causing 0 34 m w e more ablation a 1 c change in the air temperature results in a shift of 0 67 m w e in the mean specific mass balance while altering the precipitation by 10 causes a change of 0 17 m w e

sporteggbreen western norway in the past present and future simulations with a two dimensional dynamical glacier model a two dimensional shallow ice flow model yielding the glacier geometry at selected time intervals is used to simulate the development of sporteggbreen 1 from 8000 cal yr bp to the present 2 from ad 2011 to 2050 and 3 extending forward in time to ad 2100 and 2200 glacier surface geometry subglacial topography mass balance data internal deformation and subglacial sliding are used as input data for the model runs to force the model from 8000 cal yr bp to the present a mass balance series based on the equilibrium line altitude ela variations on jostedalsbreen to the west of sporteggbreen is applied a 50 reduction of the ela amplitude at jostedalsbreen is used to construct a new mass balance series and it was found that this gives a reasonably good coherence between the modelled and the real glacier the modelled time series for ela and length changes indicate that the glacier melted away c 7300 cal yr bp and was absent for c 1700 years it reformed c 5400 cal yr bp because of a mo

reconstructing climate from glaciers glaciers offer the potential to reconstruct past climate over timescales from decades to millennia they are found on nearly every continent and at the last glacial maximum glaciers were larger in all regions on earth the physics of glacier climate interaction are relatively well understood and glacier models can be used to reconstruct past climate from geological evidence of past glacier extent this can lead to significant insights regarding past present and future climate for example glacier modeling has demonstrated that the near ubiquitous global pattern of glacier retreat during the last few centuries resulted from a global scale climate warming of 1 c consistent with instrumental data and climate proxy records climate reconstructions from glaciers have also demonstrated that the tropics were colder at the last glacial maximum than was originally inferred from sea surface temperature reconstructions future efforts to reconstruct climate from glaciers may provide new constraints on climat

spatial and temporal variations of the surface albedo and other factors influencing urumqi glacier no 1 in tien shan china glacier albedo controls the surface energy budget the variability of which affects the glacier surface melt rate and in turn impacts the mass balance of the glacier during 2013 and 2014 spatial and temporal variations of albedo were investigated using 18 landsat images of urumqi glacier no 1 factors influencing these spatiotemporal profiles were analyzed an established retrieval process including geolocation radiometric calibration atmospheric topographic and anisotropic correction and narrow to broadband conversion was applied for the first time to landsat 8 images differences between landsat image derived albedo values and albedo values measured using a handheld spectroradiometer ranged from 0 024 to 0 049 spatial and temporal variations of surface albedo were significant especially in the ablation area the variability of the values of ice albedo ranged from 0 06 to 0 44 due to topographic effects and light absorbing impurities the results suggest that this retrieval method can be used to investigate the spatial and temporal variability of surface albedo from landsat 8 images on mountain glaciers moreover as constant albedo values for ice and snow cannot be assumed the distribution of albedo was not completely dependent on altitude under conditions of more intense ablation and by reason of light absorbing impurities during the melt season

comparison of mass balances for vernagtferner oetzal alps as obtained from direct measurements and distributed modeling the direct comparison of modeled glacier mass balance distribution with field measure ments could be problematic as the methodology of determination and the processes considered at the point or catchment scale could differ strongly moreover direct measurements cover only small parts of a glacier and model performance is thus difficult to assess outside these regions remaining opportunities for model validation include comparison of snowlines as derived from remote sensing data and maps of the mass balance distribution as interpreted by observers with local knowledge this study compares such hand drawn maps of the vernagtferner oetzal alps mass balance with the modeled pattern as obtained from a distributed energy mass balance model of intermediate complexity the model is driven by measured daily values of temperature global radiation and precipitation from a nearby climate station and grids of mean daily potential global radiation and climatologic annual precipitation sums compared with the direct measurements the calculated mean mass balance and equilibrium line altitude agreed very well in both balance years although the spatial pattern of the mass balance distribution displayed larger deviations in regions influenced by snowdrift or local topographic undulations however compared with the remaining snow as visible on a satellite image from 1999 the modeled snowline pattern for a larger sample of glaciers is in very good agreement

glacier mass variation and its effect on surface runoff in the beida river catchment during 1957 2013 using in situ measured data from qiyi glacier in combination with meteorological and runoff data from stations a distributed degree day model was developed for 631 investigated glaciers in the beida river catchment to explore glacier mass change and its effect on streamflow the results showed that the average mass balance was 272 67 mm w e a 1 with an ice loss of 3 99 gt during 1957 2013 assuming a continuous linear trend equilibrium line altitude rose by 242 m compared with morpho topographic variables climatic control is a more important factor affecting glacier change mass balance sensitivity to air temperature was 239 mm w e degrees c 1 a 1 while to precipitation it was 1 1 mm w e mm 1 a 1 that is a 210 mm increase in precipitation would be needed to compensate for the net mass loss induced by an air temperature increase of 1 degrees c average annual glacier meltwater runoff was 1 51 x 10 8 m 3 from 1957 to 2013 accounting for 15 2 of surface runoff the time series of meltwater runoff changed abruptly in 2000 and its contribution to surface runoff increased from 13 9 to 20 4

modelling seasonal and spatial variations in the surface energy balance of haut glacier d arolla switzerland the impact of spatial and temporal variations in the surface albedo and aerodynamic roughness length on the surface energy balance of haut glacier d arolla switzerland was examined using a semi distributed surface energy balance model arnold and others 1996 the model was updated to incorporate the glacier wide effects of albedo and aerodynamic roughness length variations using parameterizations following brock 1997 after the model s performance was validated the glacier wide patterns of the net shortwave turbulent and melt energy fluxes were examined on four days representative of surface conditions in late may june july and august in the model meteorological conditions were held constant on each day in order that the impact of albedo and aerodynamic roughness length variations could be assessed independently a late summer snowfall event was also simulated albedo and aerodynamic roughness length variations particularly those associated with the migration of the transient snowline and the decay of the winter snowpack were found to exert a strong influence on the magnitude of the surface energy fluxes the importance of meteorological conditions in suppressing the surface energy fluxes and melt rate following a fresh snowfall was highlighted

climate sensitivity of glaciers in southern norway application of an energy balance model to nigardsbreen hellstugubreen and alfotbreen three glaciers in southern norway with very different massbalance characteristics are studied with an energy balance model of the ice snow surface the model simulates the observed mass balance profiles in a satisfactory way and can thus be used with some confidence in a study of climate sensitivity calculated changes in equilibrium line altitude for a 1 k temperature increase are 110 108 and 135 in for nigardsbreen hellstugubreen and alfotbreen respectively the corresponding changes in mass balance averaged over the entire glacier area are 0 88 0 715 and 1 11 in year water equivalent runs with an ice flow model for nigardsbreen to which calculated mass balance profiles are imposed predict that the front will advance by 3 km for a 1 k cooling and will retreat by as much as 6 5 km for a 1 k warming the response to a 10 increase in precipitation would be a 2 km advance of the snout whereas a 4 km retreat is predicted for a 10 decrease this large sensitivity as compared to many other glaciers is to a large extent due to the geometry of nigardsbreen

holocene climatic changes in iceland evidence from modelling glacier length fluctuations at solheimajokull abstract we use a coupled energy balance glacier flow model to reconstruct holocene climate from a 5000 yr record of glacier length fluctuations at solheimajokull an outlet glacier in southern iceland the climatic reconstruction is presented in terms of equilibrium line altitude and is translated to envelopes of possible temperature and precipitation changes the reconstruction is highly resolved between ad 1700 and 1990 the 20th century retreat of the glacier resulted from a warming between ad 1920 and 1940 while the advance since ad 1970 was in response to both a cooling and a precipitation increase after ad 1940 the early 18th century climate of iceland was warm comparable to that of the early 20th century while the coldest period in recent history occurred during the 1780s earlier holocene glacier advances at about 5000 3100 and 1400 yr bp and in the 10th and 14th centuries ad resulted from cooling of 1 2 c and correlate with worldwide glacier expansion atmospheric changes in greenland and changes in ocean circulation north of iceland glacier expansions follow periods when sea ice is extensive in the greenland and barents sea resulting temperature changes mean that natural climatic variability has a large signature in iceland making it difficult to isolate any longer term trends such as an enhanced anthropogenic signal

estimating south cascade glacier washington u s a mass balance from a distant radiosonde and comparison with blue glacier a simple flux model using twice daily measurements of wind humid ity and temperature from standard upper air levels in a distant radiosonde estimated winter balance of south cascade glacier over 1959 98 with error 0 24 m w e correla tion between net and winter balance is strong the model estimates net balance with error 0 53 m w e over the past 40 years average net balance of south cascade glacier has been strongly negative 0 46 m w e and it has been shrinking steadily in com parison 200 km wsw at blue glacier the average balance has been less negative 0 13 m w e that glacier has undergone little change over the 40 years balance histories of the two glaciers are positively correlated r 0 54 and south cascade has been more out of balance than blue presumably because it is still adjusting to climate change since the little ice age recent warming and drying has made the net balance of both glaciers strongly negative since 1976 0 84 m w e at south cascade 0 56 m w e at blue if south cascade glacier were in balance with the 1986 1998 climate it would be about 1 4 of its present area if conditions persist retreat of both glaciers is inevitable

aerodynamic stability and turbulent sensible heat flux over a melting ice surface the greenland ice sheet the turbulent sensible heat flux to a melting ice surface is calculated from wind speed and air temperature at 2 m over the ice surface assuming a certain wind profile with the appropriate surface roughness the aerodynamic stability of the boundary layer over melting ice is examined by comparing sensible heat fluxes for logarithmic and log linear wind profiles where the logarithmic profile is strictly valid only for neutral conditions increasing stability reduces the sensible heat flux to the glacier surface and introduces a non linear relation between heat flux and air temperature the stability effect is greatest at low wind speeds and fairly small at the high wind speeds that are common over the ice sheet earlier estimates of ablation by energy balance modelling may be too large due to neglect of stability but this was almost offset by using a surface roughness that was too small the log linear wind profile should be used in future energy balance models to take account of stability but more research is needed on the parameters of the profile as well as on the surface roughness

seasonal mass balance gradients in norway previously discovered regularity in vertical profiles of net balance b n z on ten glaciers in norway also exists in profiles of both winter bw z and summer b s z seasonal balances all three profiles unlike those of many glaciers elsewhere in the world are remarkably linear variations of gradients db w dz and db s dz from year to year are small and correlate poorly with glacier total balances b w and b s glacier to glacier correlation is weak for both gradients but is strongly positive for b w and b s there are two direct consequences of these properties of the gradients that apply to both seasonal balances b w and b s first because db dz varies so little from year to year the difference in balance ab from year to year is nearly the same over the entire glacier except near the top and bottom of its altitude range therefore balance at a site near the middle of the altitude range of the glacier correlates very well with glacier total balance second this correlation combined with the strong positive correlation of balance from glacier to glacier is the reason balance at one altitude on one glacier correlates well with glacier total balance at other nearby glaciers

spatial and temporal variations in albedo on storglaciaren sweden extensive albedo data from storglaciaren sweden during nine summers are analyzed focusing on the effect of surface slope on measurements and on the influence of clouds on albedo of both snow and ice surfaces on clear sky days albedo continuously dropped throughout the day by 0 3 when derived from measurements in a horizontal plane over the slightly sloping surface when we correct for the tilt effect over frozen surfaces the apparent decrease in albedo largely disappeared while over melting surfaces it became significantly less pronounced this emphasizes the need to correct horizontally measured data for slope when they are used for example as ground truth for satellite derived albedo or in high resolution glacier melt runoff models albedo varied by 0 1 due to cloud fluctuations to quantify cloud effects albedo changes between successive half hourly and daily data were regressed against corresponding changes in cloudiness expressed by the ratio of global radiation to top of atmosphere solar radiation the resulting relationship over snow explains 66 of oberved albedo changes using hourly and 4 using daily time steps over ice the corresponding values arc 28 and 0 hence cloudiness is a dominating factor in determining short term variability of albedo over snow whereas over ice the observed large day to day variability 20 is mainly attributed to changes in the physical characteristics of the weathering crust results suggest that cloud effects should be incorporated into models treating snow and ice surfaces separately

evaluation of lateglacial temperatures in the southern alps of new zealand based on glacier modelling at irishman stream ben ohau range abstract climate proxy records from the middle to high latitude southern hemisphere indicate that a lateglacial 15 000 11 500 years ago climate reversal approximately coeval with the antarctic cold reversal acr interrupted a warming trend during deglaciation in new zealand some palaeoclimate proxy records indicate a cool episode during the acr ca 14 500 12 500 years ago while others do not express a significant change in climate recently published moraine maps and ages present an opportunity to improve the palaeoclimate interpretation through numerical modelling of glaciers we use a coupled energy balance and ice flow model to quantify palaeoclimate from past glacier extent constrained by mapped and dated moraines in the headwaters of irishman stream a high elevation catchment in the southern alps first a suite of steady state model runs is used to identify the temperature and precipitation forcing required to fit the modelled glacier to well dated lateglacial moraine crests second time dependent glacier simulations forced by a nearby proxy temperature record derived from chironomids are used to assess the fit with the glacial geomorphic record steady state experiments using an optimal parameter set demonstrate that the conditions under which the 13 000 year old moraine formed were 2 3 3 2 c colder than present with the range in temperature corresponding to a 20 variance in precipitation relative to the present day this reconstructed climate change relative to the present day corresponds to an equilibrium line altitude of ca 2000 40 m above sea level asl which is ca 400 m lower than present time dependent simulations of glacier length produce ice advance to within 100 m of the 13 000 year old terminal moraine indicating that the chironomid based temperature forcing and moraine record provide consistent information about past climate our results together with other climate proxy reconstructions from pollen records and marine sediment cores support the notion that temperatures during the acr in new zealand were 2 3 c cooler than today

climate sensitivity of a high precipitation glacier in new zealand the sensitivity of glaciers to climatic change is key information in assessing the response and sea level implications of projected future warming new zealand glaciers are important globally as an example of how maritime glaciers will contribute to sea level rise a spatially distributed energy balance model is applied to brewster glacier new zealand in order to calculate glacier mass balance run off and sensitivity to climate change the model successfully simulates four annual mass balance cycles close to half 52 of the energy available for melt on the glacier is supplied by turbulent heat fluxes with radiation less important except during the winter model sensitivity to temperature change is one of the largest reported on earth at 2 0 m w e a 1 8c 1 in contrast a 50 change in precipitation is required to offset the mass balance change resulting from a 18c temperature change meltwater run off sensitivity is also very high increasing 60 with a 18c warming the extreme sensitivity of mass balance to temperature change suggests that significant ice loss will occur with even moderate climate warming

mass balance gradients and climatic change it is generally assumed that the mass balance gradient on glaciers is more or less conserved under climatic change in studies of the dynamic response of glaciers to climatic change one of the following assumptions is normally made i the mass balance perturbation is independent of altitude or ii the mass balance profile does not change it simply shifts up and down observational evidence for such an approach is not convincing on some glaciers the inter annual changes in mass balance seem to be independent of altitude on others not at all moreover it is questionable whether inter annual variation can be projected on different climatic states to see what a physical approach might contribute we developed an altitude dependent mass balance model it is based on the energy balance of the ice snow surface where precipitation is included in a parameterized form and numerical integrations are done through an entire balance year with a 30 min time step atmospheric temperature snowfall and atmospheric transmissivity for solar radiation are all dependent on altitude so a mass balance profile can be calculated slope and exposure of the ice snow surface are taken into account and the effects of these parameters studied in general the calculations were done for 100 m elevation intervals climatological data from the sonnblick observatory austria 3106 m a s l and from vent 2000 m a s l oetztal alps austria served as input for a number of runs simulation of the mass balance profiles for hinterseisferner north easterly exposure and kesselwandferner southeasterly exposure yields reasonable results the larger balance gradient on kesselwandferner is produced by the model so exposure appears to be an important factor here sensitivity of mass balance profiles to shading effects different slope and exposure are systematically studied another section deals with the sensitivity to climatic change perturbations of air temperature cloudiness albedo and precipitation are imposed to see their effects on the mass balance profiles the results clearly show that in general mass balance perturbations depend strongly on altitude they generally increase down glacier and are not always symmetric about the reference state for typical climatic conditions in the alps we found that a 1 k temperature change leads to a change in equilibrium line altitude of 130 m three factors contribute to this large value turbulent heat flux longwave radiation from the atmosphere and fraction of precipitation falling as snow here the albedo feed back increases the sensitivity in a significant way

impact of two conceptual precipitation downscaling schemes on mass balance modeling of gran campo nevado ice cap patagonia precipitation downscaling in mountainous regions with sparse station data is challenging but needed to link global climate datasets with high resolution glacier models in this study we apply a linear orographic precipitation model opm to generate orographic precipitation fields for mass balance studies at gran campo nevado gcn southern patagonia the opm is driven by large scale atmospheric input variables taken from the reanalysis data of the us national centers for environmental prediction and the us national center for atmospheric research the orographic precipitation fields are compared to precipitation fields assessed by a linear precipitation gradient widely used in earlier mass balance studies of gcn and elsewhere both downscaling methods are implemented into a degree day model to analyze the sensitivity of mass balance modeling to different precipitation inputs significant spatio temporal differences are found particularly in the summit region the mass balance modeling shows high sensitivity to the different precipitation distribution methods leading to differences in the mass balance gradients on the east side of gcn

rapid quantification of cryoconite granule geometry and in situ supraglacial extents using examples from svalbard and greenland supraglacial dust cryoconite is an important but poorly understood component of the glacial system there is a lack of primary data on cryoconite form extent and dynamics here we present a suite of rapid low cost methodologies for quantification of granule geometry and supraglacial cryoconite coverage using image data captured by commercially available digital cameras we develop robust transferable protocols for analysis of 1 cryoconite granule geometry major axis feret diameter circularity 2 centimetre metre scale supraglacial extent m2 cryoconite m 2 surface and 3 temporal change in supraglacial extent at hourly intervals over several days image processing methodologies were developed using the public domain software imagej manual supervised controls were used to estimate sources of error and measurements then automated using simple scripting tools macros fully automated processing successfully identified 90 of a sample of isolated granules ranging between 2 5 and 39 2 mm with uncertainties of 20 particle sphericity inferred from circularity decreased as particle size increased supraglacial cryoconite extent was obtained with a mean uncertainty of 37 and 22 for data from field sites in greenland and svalbard respectively these methods will facilitate acquisition and analysis of datasets for cryoconite across a range of spatial scales supporting research into cryoconite impacts on supraglacial hydrological connections nutrient and carbon cycling and initiation of primary succession in deglaciating environments

antarctic ice volume and deep sea temperature during the last 50 myr a model study a simple quasi analytical model is used to study the sensitivity of the antarctic ice sheet to climate change the model is axisymmetrical and has a profile that only depends on the ice sheet radius the climatic conditions are represented by three parameters the altitude of the runoff line the accumulation rate above the runoff line and the balance gradient below the runoff line the ice sheet may extend into the sea at the grounding line the ice velocity is assumed to be proportional to the water depth for this set up an explicit algebraic expression for the total mass budget of the ice sheet can be derived after calibration of the model with respect to the present day ice sheet equilibrium states are studied for a wide range of temperatures the model predicts a maximum ice volume 3 4 for a temperature that is 2 5 k above the present value for a temperature increase of 7 k mass loss by runoff and calving are about the same in this case the ice volume is about 82 of the current value the ice sheet model is used to correct the cenozoic deep sea temperature record 18o record from benthic foraminifera in ocean sediments for antarctic ice volume the model is forced with the oxygen isotope record which is then corrected for the calculated ice volume therefore the resulting deep sea temperature and antarctic ice volume curves are mutually consistent it is concluded that for the last 35 106 years the 18o record truly is a mixed temperature ice volume record in which the contributions from these parameters have the same order of magnitude

late quaternary glacial advances in the eastern qilianshan north eastern tibet as inferred from luminescence dating of fluvioglacial sediments

mapping of a hydrological ice sheet drainage basin on the west greenland ice sheet margin from ers 1 2 sar interferometry ice radar measurement and modelling

the impact of climate change on future frontal variations of briksdalsbreen western norway a flowline model coupled with a surface mass balance model forced by climate data from bergen was used to simulate future frontal changes of briksdalsbreen a western outlet glacier from jostedalsbreen western norway under various future climate scenarios the model was used to calculate the time lag of frontal response to a sudden and short change in the mass balance according to the model the front has a time lag for maximum advance rate of 4 5 years in close agreement with previous studies the response time for briksdalsbreen was calculated by running the model for 200 years with different mass balance perturbations for mass balance perturbations of 0 3 and 0 6 m w e the model yields response times of 52 and 60 years respectively we ran the model from 1963 to 2007 with measured mass balance data and from 2007 to 2085 using calculated mass balances from 12 different climate scenarios the model predicts retreat up the steep valley from the lake inlet with a total frontal retreat of 2 5 5 0 km by 2085 a spectacular icefall one of the main tourist attractions in western norway may thus disappear and the glacier may become a plateau glacier that will gradually melt down

exceptional ablation arising from rainfall induced slushflows brewster glacier new zealand an exceptional ablation event resulted in the destruction of a network of glacier survey stakes on the brewster glacier new zealand up to 5 m of surface lowering occurred over 26 days releasing at least 1 6 106 m3 of water the episode is attributed to saturation of the snowpack by rainfall and consequent slushflows slushflows permit surface lowering at rates greater than expected from the surface energy balance on snow resulting slushflow events may significantly influence glacier mass balance and may constitute a hazard little is known of their physical characteristics but some descriptive background is provided copyright 2000 john wiley sons ltd

simulation of the historical variations in length of unterer grindelwaldgletscher switzerland the historical length variations in unterer grindelwaldgletscher have been simulated by coupling a numerical mass balance model to a dynamic ice flow model as forcing functions we used partly reconstructed local climatic records which were transformed by the mass balance model into a mass balance history the ice flow model then computes the length variations that have occurred over the course of time in a model run from ad 1530 to the present with both seasonal temperature and precipitation variations as forcing functions the observed maximum length of the glacier around ad 1860 and the subsequent retreat are simulated the observed ad 1600 maximum however does not show up in the simulation this is probably due to an incorrect reconstruction of the mass balance for this period as detailed climatic data are available only since 1865 the root mean square difference between the simulated and the observed front positions is 0 28 km the simulated glacier geometry for 1987 fits the observed geometry for that year reasonably well because of the success of the historical simulation an attempt is made to predict future glacier retreat on the basis of two different greenhouse gas scenarios for a business asusual scenario only 29 of the 1990 volume would remain in ad 2100

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

little ice age variations of outlet glaciers from the jostedalsbreen ice cap southern norway a regional lichenometric dating study of ice marginal moraine sequences and their climatic significance complex moraine ridge sequences in front of seven outlet glaciers of the jostedalsbreen ice cap austerdalsbreen bergsetbreen fabergstolsbreen lodalsbreen stegaholbreen tuftebreen bodalsbreen are dated using families of lichenometric dating curves established previously at an eighth outlet nigardsbreen applicability of the nigardsbreen curves at the regional level is tested using independent historical evidence moraines deposited during the present century are dated to an accuracy of 9 4 yr 16 0 and most of them are dated to an accuracy of 5 5 yr 9 4 results from the moraine sequences are combined to form a composite jostedalsbreen record median predicted dates for moraine ridges cluster around ad 1939 2 yr 1929 3 1908 3 1886 5 1875 2 1867 4 1855 3 1842 5 1822 5 1807 4 and 1785 5 at least four glaciers reached their little ice age maxima prior to ad 1780 two nigardsbreen and bodalsbreen at ca 1750 one fabergstolsbreen at ca 1705 stegaholbreen attained its maximum ca 1863 since the little ice age maximum and despite large differences in glacier size frontal variations of the various outlets have exhibited a high degree of synchroneity which suggests that the moraine sequences contain a sensitive record of high frequency climatic variations over the last ca 250 yr during the early twentieth century measured readvances of the order of 5 150 m over 1 10 yr led to moraine formation dendroclimatic evidence indicates that since the late eighteenth century moraine ridges formed about 5 yr after summer temperature minima and correlate with runs of cool summers temperature depression of 0 5 1 0 c below the ad 1700 1950 average almost simultaneous glacier advances appear to have been caused by reduced ablation this near immediate response to climatic variation by glacier tongues that descend to relative low altitudes is superimposed upon the longer term dynamic response of the ice cap to climate

initial results from a distributed physically based model of glacier hydrology this paper describes the development and testing of a distributed physically based model of glacier hydrology the model is used to investigate the behaviour of the hydrological system of haut glacier d arolla valais switzerland the model has an hourly time step and three main components a surface energy balance submodel a surface flow routing submodel and a subglacial hydrology submodel the energy balance submodel is used to calculate meltwater production over the entire glacier surface the surface routing submodel routes meltwater over the glacier surface from where it is produced to where it either enters the subglacial hydrological system via moulins or runs off the glacier surface the subglacial hydrology submodel calculates water flow in a network of conduits which can evolve over the course of a melt season simulation in response to changing meltwater inputs the main model inputs are a digital elevation model of the glacier surface and its surrounding topography start of season snow depth distribution data and meteorological data model performance is evaluated by comparing predictions with field measurements of proglacial stream discharge subglacial water pressure measured in a borehole drilled to the glacier bed and water velocities inferred from dye tracer tests the model performs best in comparison with the measured proglacial stream discharges but some of the substantial features of the other two records are also reproduced in particular the model results show the high amplitude water pressure cycles observed in the borehole in the mid melt season and the complex velocity discharge hysteresis cycles observed in dye tracer tests the results show that to model outflow hydrographs from glacierized catchments effectively it is necessary to simulate spatial and temporal variations in surface melt rates the delaying effect of the surface snowpack and the configuration of the subglacial drainage system itself the model s ability to predict detailed spatial and temporal patterns of subglacial water pressures and velocities should make it a valuable tool for aiding the understanding of glacier dynamics and hydrochemistry 1998 john wiley sons ltd

estimating the contribution of arctic glaciers to sea level change in the next 100 years in this paper we report on an approach to estimate the contribution of arctic glaciers to sea level change in our calculation we assume that a static approach is feasible we only calculate changes in the surface balance from modelled sensitivities these sensitivities summarized in the seasonal sensitivity characteristic can be used to calculate the change in the surface mass budget for given anomalies of monthly temperature and precipitation we have based our calculations on a subdivision of all arctic ice into 13 regions four sectors of the greenland ice sheet the canadian arctic 74 n the canadian arctic 60 n as forcing for the calculations we have used the output from five climate models for the period 2000 2100 these models were forced by the same greenhouse gas scenario ipcc b2 the calculated contributions to sea level rise in the year 2100 vary from almost zero to about 6 cm the differences among the models stem first of all from differences in the precipitation the largest contribution to sea level change comes from the greenland ice sheet the glaciers in alaska also make a large contribution not because of the area they cover but because they are more sensitive than other glaciers in the arctic the climate models do not agree on regional patterns the runoff from svalbard glaciers for instance increases for two models and decreases for the three other models we conclude that the uncertainty due to a simple representation of the glaciological processes is probably smaller than the uncertainty induced by the differences in the climate change scenarios produced by the models