regionally differentiated contribution of mountain glaciers and ice caps to future sea level rise the contribution to sea level rise from mountain glaciers and ice caps has grown over the past decades a projection of their melting during the twenty first century based on temperature and precipitation projections from ten climate models suggests that by 2100 these glaciers will lose about 21 of their total global volume

iceberg calving flux and mass balance of the austfonna ice cap on nordaustlandet svalbard 1 satellite radar interferometry 60 mhz airborne ice penetrating radar data and visible band satellite imagery were used to calculate the velocity structure ice thickness and the changing ice marginal extent of austfonna 8000 km2 and 2500 km3 the largest ice cap in the eurasian arctic ice cap motion is generally less than about 10 m a 1 except where faster flowing curvilinear features with velocities of several tens to over 200 m a 1 are present most drainage basins of austfonna have undergone ice marginal retreat over the past few decades at an average of a few tens of meters per year integrating margin change around the whole ice cap gives a total area loss of about 10 km2 a 1 iceberg flux from the marine margins of austfonna is about 2 5 0 5 km3 a 1 water equivalent about 45 of the total calving flux from the whole svalbard archipelago when mass loss by iceberg production is taken into account the total mass balance of austfonna is negative by between about 2 5 and 4 5 km3 a 1 this iceberg flux represents about 33 5 of total annual mass loss from austfonna with the remainder lost through surface ablation iceberg flux should be included in calculations of the total mass balance of the many large arctic ice caps including those located in the russian and canadian arctic that end in tidewater the neglect of this term has led to underestimates of mass loss from these ice caps and thus to underestimates of the contribution of arctic ice caps to global sea level rise

contribution of icelandic ice caps to sea level rise trends and variability since the little ice age 1 in total icelandic ice caps contain 3600 km3 of ice which if melted would raise sea level by 1 cm here we present an overview of mass changes of icelandic ice masses since the end of the 19th century they have both gained and lost mass during this period changes in ice volume have been estimated both through surface mass balance measurements performed annually since 1990 and differencing of digital elevation models derived from various satellite and airborne observations while the glaciers showed little mass loss as the 20th century began losses increased rapidly after 1925 peaked in the 1930s and 1940s and remained significant until the 1960s after being near zero or even positive during the 1980s and early 1990s glacier mass budgets declined considerably and have since the mid 1990s shown an average annual loss of 9 5 1 5 gt a 1 contributing 0 03 mm a 1 to sea level rise since 1995 interannual variability in mass loss is high ranging from 2 7 to 25 3 1 5 gt a 1 corresponding to surface mass balances of 0 2 to 2 2 0 15 m we a 1 this variability is driven by climate fluctuations and also by transient reduction of albedo due to volcanic eruptions

the δ15n of nitrate in the southern ocean nitrogen cycling and circulation in the ocean interior we report analyses of the nitrogen isotopic composition of nitrate in the eastern indian and pacific sectors of the southern ocean in this paper we focus on the subsurface data as well as data from the deep waters of other ocean basins nitrate 15n is relatively invariant in much of the abyssal ocean i e below 2 5 km with a value of 4 8 0 2 observed in lower circumpolar deep water north atlantic deep water and central pacific deep water the isotopic invariance of deep ocean nitrate stems fundamentally from the completeness of nitrate utilization in most of the global surface ocean the southern ocean surface being an important exception in the subantarctic zone north of the polar frontal zone the nitrate 15n of upper circumpolar deep water is 0 7 greater than that of lower circumpolar deep water this isotopic enrichment appears to result from denitrification in the low latitude water masses with which upper circumpolar deep water communicates the isotopic enrichment of upper circumpolar deep water is diminished in the antarctic probably because of the remineralization of sinking organic n which has a low 15n in the antarctic relative to the other water masses of the southern ocean the subantarctic thermocline has a very low nitrate 15n for its nitrate concentration because of exchange with the low latitude thermocline where this isotopic signature appears to originate this signature of the low latitude thermocline has two probable causes 1 mixing with low nitrate surface water and 2 the oxidation of newly fixed n

response of debris covered glaciers in the mount everest region to recent warming and implications for outburst flood hazards abstract in areas of high relief many glaciers have extensive covers of supraglacial debris in their ablation zones which alters both rates and spatial patterns of melting with important consequences for glacier response to climate change wastage of debris covered glaciers can be associated with the formation of large moraine dammed lakes posing risk of glacier lake outburst floods glofs in this paper we use observations of glaciers in the mount everest region to present an integrated view of debris covered glacier response to climate change which helps provide a long term perspective on evolving glof risks in recent decades debris covered glaciers in the everest region have been losing mass at a mean rate of 0 32 m yr 1 although in most cases there has been little or no change in terminus position mass loss occurs by 4 main processes 1 melting of clean ice close to glacier elas 2 melting beneath surface debris 3 melting of ice cliffs and calving around the margins of supraglacial ponds and 4 calving into deep proglacial lakes modelling of processes 1 and 2 shows that everest region glaciers typically have an inverted ablation gradient in their lower reaches due to the effects of a down glacier increase in debris thickness mass loss is therefore focused in the mid parts of glacier ablation zones causing localised surface lowering and a reduction in downglacier surface gradient which in turn reduce driving stress and glacier velocity so the lower ablation zones of many glaciers are now stagnant model results also indicate that increased summer temperatures have raised the altitude of the rain snow transition during the summer monsoon period reducing snow accumulation and ice flux to lower elevations as downwasting proceeds formerly efficient supraglacial and englacial drainage networks are broken up and supraglacial lakes form in hollows on the glacier surface ablation rates around supraglacial lakes are typically one or two orders of magnitude greater than sub debris melt rates so extensive lake formation accelerates overall rates of ice loss most supraglacial lakes are perched above hydrological base level and are susceptible to drainage if they become connected to the englacial drainage system speleological surveys of conduits show that large englacial voids can be created by drainage of warm lake waters along pre existing weaknesses in the ice roof collapses can open these voids up to the surface and commonly provide the nuclei of new lakes thus by influencing both lake drainage and formation englacial conduits exert a strong control on surface ablation rates an important threshold is crossed when downwasting glacier surfaces intersect the hydrological base level of the glacier base level lakes formed behind intact moraine dams can grow monotonically and in some cases can pose serious glof hazards glacier termini can evolve in different ways in response to the same climatic forcing so that potentially hazardous lakes will form in some situations but not others additionally the probability of a flood is not simply a function of lake volume but depends on the geometry and structure of the dam and possible trigger mechanisms such as ice or rockfalls into the lake satellite based measurements of glacier surface gradient and ice velocities allow probable future locations of base level lakes to be identified a base level lake has begun to grow rapidly on ngozumpa glacier west of mount everest and could attain a volume of 10 8 m 3 within the next 2 or 3 decades unless mitigation efforts are undertaken this lake could pose considerable glof hazard potential

exhumation of an active magmatic hydrothermal system in a resurgent caldera environment the example of ischia italy abstract ischia is a rare case of a well exposed caldera system that has experienced rapid recent resurgence which can be used to dissect the anatomy of an otherwise inaccessible active hydrothermal system developed in a caldera forming environment integrated analyses of melt and fluid inclusions mineralogy and stable isotopic compositions of pumices tuffs and syenitic xenoliths of the ischia volcanic system provide strong physico chemical constraints on the shallow magmatic reservoir and the hydrothermal system the hydrothermal system has been exposed by the rapid uplift of the mt epomeo resurgent block the engine of the hydrothermal system of ischia can be identified in the shallow magmatic system at around 2 km depth that hosts hot c 1000 c trachytic magma the hydrothermal system developed principally within thick intracaldera ignimbrite deposits and extended to a depth of at least 1 km defining a series of facies characterized by associations of alteration mineral assemblages typical of a seawater dominated high temperature geothermal system supplementary material sample descriptions and analytical methods are available at http www geolsoc org uk sup18371

divergent trajectories of antarctic surface melt under two twenty first century climate scenarios ice shelves modulate antarctica s contributions to sea level rise regional climate model simulations and observations suggest historical ice melt intensification before collapse of antarctic peninsula shelves and project future melt evolution

volume measurements of mittivakkat gletscher southeast greenland here we present ground penetrating radar measurements of mittivakkat gletscher southeast greenland to estimate an empirical volume area scaling relationship at an individual glacier between a previous direct volume survey in 1994 and one in 2012 the glacier volume has decreased from 2 02 km 3 to 1 44 km 3 while the study area has decreased from 17 6 km 2 to 15 8 km 2 these results are in accordance with the cumulative mass loss observed by long term mass balance measurements 1995 96 2011 12 at mittivakkat gletscher and confirm that the glacier is in severe climatic disequilibrium aar 0 17 the observed scaling exponent 3 14 and coefficient c 0 00025 km 3 2 are outside the range of global scaling parameters but sensitive to small uncertainties nevertheless existing global volume area scaling relationships estimate the volume of mittivakkat gletscher within 31 and 15 of the measured 1994 and 2011 volumes respectively

parameter uncertainty refreezing and surface energy balance modelling at austfonna ice cap svalbard 2004 08 we apply a physically based coupled surface energy balance and snowpack model to a site close to the equilibrium line on austfonna ice cap svalbard over the 2004 08 melt seasons to explain contributions to the energy available for melting and to quantify the significance of refreezing the model is forced using in situ meteorological measurements and precipitation downscaled from erainterim reanalysis applying a monte carlo approach to determine the tunable parameters of the model we estimate the uncertainty related to the choice of parameter values multiple criteria are evaluated to identify well performing parameter combinations evaluating the model performance with respect to longwave outgoing radiation snow and ice temperatures and surface displacement on average over the investigated melt seasons 1 june to 15 september net radiation and sensible heat contributed 90 2 and 10 2 respectively to the mean energy available for melting snow and ice the energy consumed by subsurface heat exchange reduced runoff by 15 2 in 2004 and 49 3 in 2008 refreezing of meltwater and rain was estimated to be 0 37 0 04mw e a 1on average over the five seasons which represents a considerable reduction of mass loss during summer our findings suggest that refreezing potentially exerts a decisive control on glacier mass balance in persistently snow or firncovered areas

changes in the glacier extent and surface elevation along the ningchan and shuiguan river source eastern qilian mountains china we investigate the changes at nine glaciers in the ningchan and shuiguan river source eastern qilian mountains between 1972 and 2010 according to analysis of topographic maps and multispectral satellite data all nine glaciers in the study area have retreated by a maximum of 250 57 4 m and a minimum of 91 57 4 m the total glacier area decreased by 1 20 km 2 corresponding to 9 9 of the glacierized area in 1972 comparing the two dems generated from the topographic maps and real time kinematic gps data the mean glacier thinning rate was 0 64 m yr 1 between 1972 and 2010 the most significant thinning generally occurred on the termini the ice volume loss was about 106 8 46 7 x 10 3 km 3 equal to 90 8 39 7 x 10 3 km 3 w e which suggested a mean water discharge of 0 1 0 05 m 3 s during 1972 2010 based on analysis of meteorological data the summer temperature june august tends to increase over a similar time period the consistency of temperature increase and glacier shrinkage allows us to suggest that air temperature plays an important role in glacier changes in this region c 2014 university of washington published by elsevier inc all rights reserved

changes in the velocity structure of the greenland ice sheet using satellite radar interferometry observations of greenland we detected widespread glacier acceleration below 66 north between 1996 and 2000 which rapidly expanded to 70 north in 2005 accelerated ice discharge in the west and particularly in the east doubled the ice sheet mass deficit in the last decade from 90 to 220 cubic kilometers per year as more glaciers accelerate farther north the contribution of greenland to sea level rise will continue to increase

regional and global volumes of glaciers derived from statistical upscaling of glacier inventory data 1 very few global scale ice volume estimates are available for mountain glaciers and ice caps although such estimates are crucial for any attempts to project their contribution to sea level rise in the future we present a statistical method for deriving regional and global ice volumes from regional glacier area distributions and volume area scaling using glacier area data from 123 000 glaciers from a recently extended world glacier inventory we compute glacier volumes and their sea level equivalent sle for 19 glacierized regions containing all mountain glaciers and ice caps on earth on the basis of total glacierized area of 741 103 68 103 km2 we estimate a total ice volume of 241 103 29 103 km3 corresponding to 0 60 0 07 m sle of which 32 is due to glaciers in greenland and antarctica apart from the ice sheets however our estimate is sensitive to assumptions on volume area scaling coefficients and glacier area distributions in the regions that are poorly inventoried i e antarctica north america greenland and patagonia this emphasizes the need for more volume observations especially of large glaciers and a more complete world glacier inventory in order to reduce uncertainties and to arrive at firmer volume estimates for all mountain glaciers and ice caps

a more complete version of the world glacier inventory the world glacier inventory wgi was conceived half a century ago as an activity to be completed during the international geophysical year 1957 58 it consisted until very recently of nearly 70 000 glacier records covering slightly less than one quarter of the glacier ice outside the ice sheets a complete wgi must be a compromise if it is to be available and usable soon a more complete version called wgi xf is available and usable now and contains records for just over 131 000 glaciers and nearly half of the global extent of ice the additional glaciers come mainly from the assimilation of existing inventories but also from rescuing inventories that have been lost and from new inventories in canada and the subantarctic in wgi xf the xf stands for extended format flagging the fact that wgi xf conforms to a set of explicit specifications which enhance usefulness by eliminating low level inconsistencies two important features are nominal glaciers and glacier complexes a nominal glacier of which there are about 5000 in wgi xf is one about which little is known other than its existence and approximate location a glacier complex is one or more contiguous glaciers this term embodies the idea which is not new that inventories can be preliminary based upon vector outlines which await subdivision by trained glaciologists many regional studies have found that measurements of changes in single glaciers require accurate work and painstaking quality control wgi xf is not assuredly reliable as a source for such detailed work but there are several other subjects in which less detail would be a price worth paying for more complete coverage incomplete information about the dates of imagery and maps is a hindrance to analysis and the recovery of dates from metadata should have high priority

atmospheric patterns over the antarctic peninsula abstractusing clustering analysis for the sea level pressure field of the era interim reanalysis between 1979 and 2016 five synoptic pressure patterns have been obtained for the drake area and antarctic peninsula ap region 45 75 s 20 120 w and the resulting daily series has been made available to the scientific community the five patterns have been named according to their most important features as follows low over the weddell sea lws low over the amundsen and bellingshausen seas lab low over the drake passage ldp zonal flow over the drake passage zdp and ridge over the antarctic peninsula rap each atmospheric pattern is described after analyzing its development and evolution a frequency analysis shows that the five atmospheric patterns present a similar annual frequency but a large seasonal variability the transitions from one pattern to another tend to follow a cycle in which synoptic atmospheric waves are displaced eastward by a quarter wavelength four of the five atmosphe

low sea level rise projections from mountain glaciers and icecaps under global warming the mean sea level has been projected to rise in the 21st century as a result of global warming such projections of sea level change depend on estimated future greenhouse emissions and on differing models but model average results from a mid range scenario a1b suggests a 0 387 m rise by 2100 refs 1 2 the largest contributions to sea level rise are estimated to come from thermal expansion 0 288 m and the melting of mountain glaciers and icecaps 0 106 m with smaller inputs from greenland 0 024 m and antarctica 0 074 m here we apply a melt model and a geometric volume model to our lower estimate of ice volume and assess the contribution of glaciers to sea level rise excluding those in greenland and antarctica we provide the first separate assessment of melt contributions from mountain glaciers and icecaps as well as an improved treatment of volume shrinkage we find that icecaps melt more slowly than mountain glaciers whose area declines rapidly in the 21st century making glaciers a limiting source for ice melt using two climate models we project sea level rise due to melting of mountain glaciers and icecaps to be 0 046 and 0 051 m by 2100 about half that of previous projections

comparing three different methods to model scenarios of future glacier change in the swiss alps ongoing atmospheric warming causes rapid shrinking of glaciers in the european alps with a high chance of their near complete disappearance by the end of the 21st century here we present a comparison of three independent approaches to model the possible evolution of the glaciers in the swiss alps over the 21st century the models have different levels of complexity work at a regional scale and are forced with three scenarios of temperature increase low moderate high the moderate climate scenario gives an increase in air temperature of 28c and 48c for the two scenario periods 2021 50 and 2070 99 respectively resulting in an area loss of 60 80 by 2100 in reality the shrinkage could be even faster as the observed mean annual thickness loss is already stronger than the modelled one the three approaches lead to rather similar results with respect to the overall long term evolution the choice of climate scenarios produces the largest spread 40 in the final area loss while the uncertainty in present day ice thickness estimation causes about half this spread

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

radio echo sounding and ice volume estimates of western nordenskiold land glaciers svalbard as part of ongoing work to obtain a reliable estimate of the total ice volume of svalbard glaciers and their potential contribution to sea level rise we present here volume calculations with detailed error estimates for ten glaciers on western nordenskiold land central spitsbergen svalbard the volume estimates are based upon a dense net of gpr retrieved ice thickness data collected over several field campaigns spanning the period 1999 2012 the total area and volume of the ensemble are 116 06 4 53 km 2 and 10 439 0 373 km 3 respectively while the individual areas volumes and average ice thickness lie within 2 6 50 4 km 2 0 08 5 54 km 3 and 29 108 m respectively volume area scaling relationships overestimate the total volume of these glaciers by up to 35 with respect to our calculation on the basis of the pattern of scattering in the radargrams we also analyse the hydrothermal structure of these glaciers nine of the ten are polythermal while only one is entirely cold

the physical basis of glacier volume area scaling ice volumes are known for only a few of the roughly 160 000 glaciers worldwide but are important components of many climate and sea level studies which require water flux estimates a scaling analysis of the mass and momentum conservation equations shows that glacier volumes can be related by a power law to more easily observed glacier surface areas the relationship requires four closure choices for the scaling behavior of glacier widths slopes side drag and mass balance reasonable closures predict a volume area scaling exponent which is consistent with observations giving a physical and practical basis for estimating ice volumes glacier volume is insensitive to perturbations in the mass balance scaling but changes in average accumulation area ratios reflect significant changes in the scaling of both mass balance and ice volume

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

glaciermip a model intercomparison of global scale glacier mass balance models and projections global scale 21st century glacier mass change projections from six published global glacier models are systematically compared as part of the glacier model intercomparison project in total 214 pro

flow dynamics and iceberg calving rates of devon ice cap nunavut canada the surface velocity field of devon ice cap nunavut canada was mapped using interferometric synthetic aperture radar insar ascending european remote sensing satellite 1 and 2 ers 1 2 tandem mode data were used for the western and southeast sectors and 3 day repeat pass ers 1 imagery for the northeast sector speckle tracking procedures were used with radarsat 1 imagery to obtain surface velocities over the terminus of belcher glacier a major calving front where decorrelation between ers data occurred the insar data highlight a significant contrast in ice flow dynamics between the east and west sides of the ice cap ice movement west of the main north south divide is dominated by relatively uniform sheet flow but three fast flowing outlet glaciers that extend 14 23 km beyond the ice cap margin also drain this region several outlet glaciers that extend up to 60km inland from the eastern margin drain the eastern side of the ice cap the dominant ice flow regimes were classified based on the relationship between the driving stress averaged over a length scale often ice thicknesses and the ratio of surface velocity to ice thickness the mapped distribution of flow regimes appears to depict the spatial extent of basal sliding across the ice cap this is supported by a close relationship between the occurrence of flow stripes on the ice surface and flow regimes where basal sliding was found to be an important component of the glacier motion iceberg calving rates were computed using measured surface velocities and ice thicknesses derived from airborne radio echo sounding the volume of ice calved between 1960 and 1999 was estimated to be 20 5 4 7 km 3 or 0 57km 3 a 1 approximately 89 of this loss occurred along the eastern margin the largest single source is belcher glacier which accounts for 50 of the total amount of ice calved

rapid dynamic activation of a marine based arctic ice cap we use satellite observations to document rapid acceleration and ice loss from a formerly slow flowing marine based sector of austfonna the largest ice cap in the eurasian arctic during the past two decades the sector ice discharge has increased 45 fold the velocity regime has switched from predominantly slow 101 m yr to fast 103 m yr flow and rates of ice thinning have exceeded 25 m yr at the time of widespread dynamic activation parts of the terminus may have been near floatation subsequently the imbalance has propagated 50 km inland to within 8 km of the ice cap summit our observations demonstrate the ability of slow flowing ice to mobilize and quickly transmit the dynamic imbalance inland a process that we show has initiated rapid ice loss to the ocean and redistribution of ice mass to locations more susceptible to melt yet which remains poorly understood

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

analysis of scaling methods in deriving future volume evolutions of valley glaciers volume area scaling is a common tool for deriving future volume evolutions of valley glaciers and their contribution to sea level rise we analyze the performance of scaling relationships for deriving volume projections in comparison to projections from a one dimensional ice flow model the model is calibrated for six glaciers nigardsbreen rhonegletscher south cascade glacier sofiyskiy glacier midre lovenbreen and abramov glacier volume evolutions forced by different hypothetical mass balance perturbations are compared with those obtained from volume area v a volume length v l and volume area length v a l scaling results show that the scaling methods mostly underestimate the volume losses predicted by the ice flow model up to 47 for v a scaling and up to 18 for v l scaling by the end of the 100 year simulation period in general v l scaling produces closer simulations of volume evolutions derived from the ice flow model suggesting that v l scaling may be a better approach for deriving volume projections than v a scaling sensitivity experiments show that the initial volumes and volume evolutions are highly sensitive to the choice of the scaling constants yielding both over and underestimates however when normalized by initial volume volume evolutions are relatively insensitive to the choice of scaling constants especially in the v l scaling the 100 year volume projections differ within 10 of initial volume when the v a scaling exponent commonly assumed 1 375 is varied by 30 to 45 0 95 2 00 and the v l scaling exponent q 2 2 is varied by 30 to 45 q 1 52 3 20 this is encouraging for the use of scaling methods in glacier volume projections particularly since scaling exponents may vary between glaciers and the scaling constants are generally unknown

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

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

twentieth century warming preserved in a geladaindong mountain ice core central tibetan plateau high resolution 18 o records from a geladaindong mountain ice core spanning the period 1477 1982 were used to investigate past temperature variations in the yangtze river source region of the central tibetan plateau tp annual ice core 18 o records were positively correlated with temperature data from nearby meteorological stations suggesting that the 18 o record represented the air temperature in the region a generally increasing temperature trend over the past 500 years was identified with amplified warming during the 20th century a colder stage spanning before the 1850s was found to represent the little ice age with colder periods occurring during the 1470s 1500s 1580s 1660s 1700s 20s and 1770s 1840s compared with other temperature records from the tp and the northern hemisphere the geladaindong ice core record suggested that the regional climate of the central tp experienced a stronger warming trend during the 20th century than other regions in addition a positive relationship between the geladaindong 18 o values and the north atlantic oscillation index combined with a wavelet analysis of 18 o records indicated that there was a potential atmospheric teleconnection between the north atlantic and the central tp

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

mountain glaciers and ice caps around antarctica make a large sea level rise contribution the intergovernmental panel on climate change ipcc estimates that the sum of all contributions to sea level rise for the period 1961 2004 was 1 1 0 5 mm a 1 leaving 0 7

potential for bias in 21st century semiempirical sea level projections we examine the limitations of a semiempirical model characterized by a sea level projection of 73 cm with rcp4 5 scenario by 2100 calibrating the model with data to 1990 and then simulating the period 1993 2009 produces sea level in close agreement with acceleration in sea level rise observed by satellite altimetry nonradiative forcing contributors such as long term adjustment of greenland and antarctica ice sheets since last glacial maximum abyssal ocean warming and terrestrial water storage may bias model calibration which if corrected for tend to reduce median sea level projections at 2100 by 2 10 cm though this is within the confidence interval we apply the semiempirical approach to simulate individual contributions from thermal expansion and small glacier melting steric sea level projections agree within 3 cm of output from process based climate models in contrast semiempirical simulation of melting from glaciers is 26 cm which is twice large as estimates from some process based models however all process models lack simulation of calving which likely accounts for 50 of small glacier mass loss worldwide furthermore we suggest that changes in surface mass balance and dynamics of greenland ice sheet made contributions to the sea level rise in the early 20th century and therefore are included within the semiempirical model calibration period and hence are included in semiempirical sea level projections by 2100 antarctic response is probably absent from semiempirical models which will lead to a underestimate in sea level rise if as is probable antarctica loses mass by 2100

sharply increased mass loss from glaciers and ice caps in the canadian arctic archipelago the canadian arctic archipelago contains one third of the global volume of land ice outside the ice sheets but its contribution to sea level change is largely unknown gardner et al use three independent techniques to reveal that mass loss from the archipelago was 92 12 gigatonnes per year in 2007 09 about three times greater than in 2004 06 and coincident with warmer summer temperatures the record is too short to allow a firm conclusion on longer term trends but it is clear that the canadian arctic archipelago is a significant contributor to sea level rise mountain glaciers and ice caps are contributing significantly to present rates of sea level rise and will continue to do so over the next century and beyond1 2 3 4 5 the canadian arctic archipelago located off the northwestern shore of greenland contains one third of the global volume of land ice outside the ice sheets6 but its contribution to sea level change remains largely unknown here we show that the canadian arctic archipelago has recently lost 61 7 gigatonnes per year gt yr 1 of ice contributing 0 17 0 02 mm yr 1 to sea level rise our estimates are of regional mass changes for the ice caps and glaciers of the canadian arctic archipelago referring to the years 2004 to 2009 and are based on three independent approaches surface mass budget modelling plus an estimate of ice discharge smb d repeat satellite laser altimetry icesat and repeat satellite gravimetry grace all three approaches show consistent and large mass loss estimates between the periods 2004 2006 and 2007 2009 the rate of mass loss sharply increased from 31 8 gt yr 1 to 92 12 gt yr 1 in direct response to warmer summer temperatures to which rates of ice loss are highly sensitive 64 14 gt yr 1 per 1 k increase the duration of the study is too short to establish a long term trend but for 2007 2009 the increase in the rate of mass loss makes the canadian arctic archipelago the single largest contributor to eustatic sea level rise outside greenland and antarctica

10be surface exposure ages on the late pleistocene and holocene history of linnebreen on svalbard abstract arctic glaciers were sensitive to past changes in high latitude winter precipitation and summer temperature here we develop a late pleistocene to holocene history for linnebreen linne glacier in western svalbard using 10 be surface exposure ages on isolated erratic and moraine boulders we show that linnebreen had separated from the larger ice sheet over svalbard and was retreating up valley around the start of the younger dryas cold period we attribute this retreat during a cold period on svalbard to moisture starvation of linnebreen from advanced sea ice and or elevated shortwave boreal summer insolation that overwhelmed any reduction in sensible heat after an ice free period during the early to middle holocene linnebreen reformed sometime after 4 6 0 2 ka and was at a position roughly equivalent to its little ice age lia maximum extent before it began to retreat at 1 6 0 2 ka comparison with calibrated 14 c dates from three other glaciers could suggest that this period of ice retreat at 1 6 ka could be regional in extent linnebreen occupied the pre lia moraine when there was an increased ratio of cold arctic sourced relative to warm atlantic sourced waters around svalbard and advanced sea ice the retreat of linnebreen at 1 6 ka was concurrent with the increased presence of warm atlantic waters around svalbard and attendant sea ice retreat these coincident changes in ocean temperatures sea ice extent and linnebreen moraine age could imply a climatic forcing of the pre lia advance and retreat of linnebreen summer temperatures rather than changes in precipitation would then be dominant in driving ice retreat although the possibility of stochastic glacier margin variability cannot be excluded our data therefore suggest that linnebreen may have responded differently to past changes in sea ice extent that could depend on the background climate state deglacial climate vs late holocene climate which highlights the complexity in climatic controls on arctic glaciers

glacier velocity and water input variability in a maritime environment franz josef glacier new zealand short term glacier velocity variations typically occur when a water input is accommodated by an increase in the subglacial water pressure although these velocity variations have been well documented on many glaciers few studies have considered them on glaciers where heavy rain and glacier melt occur year round this study investigates the relationship between water inputs and glacier velocity on franz josef glacier new zealand we installed six gnss stations across the lower glacier during austral summer 2010 11 and one station during summer 2012 13 glacier velocity remained elevated at all stations for 7 days following large rain events during diurnal melt events we find velocity variations in the early afternoon 12 00 16 00 at 600 m a s l and in the late evening 20 00 01 00 at 400 m a s l we hypothesize that the late evening velocity variations occurred as an upstream region of high subglacial water pressures and accelerated ice motion propagated downstream this mechanism may also explain the increased longitudinal compression and transverse extension across the lower glacier during speed up events our results indicate that the subglacial drainage system likely decreases in efficiency upstream and that the water input variability can still cause short term velocity variations despite the large year round water inputs

first in situ record of decadal glacier mass balance 2003 2014 from the bhutan himalaya this study presents the first decadal mass balance record of a small debris free glacier in the bhutan himalaya where few in situ measurements have been reported to date since 2003 we have measured the mass balance of gangju la glacier which covers an area of 0 3km 2 and extends from 4900 to 5200ma s l using both differential gps surveys geodetic method and stake measurements direct method the observed mass balance ranged from 1 12 to 2 04mw e a 1 between 2003 and 2014 the glacier exhibited much greater mass loss than neighbouring glaciers in the eastern himalaya and southeastern tibet which are expected to be sensitive to climate change due to the monsooninfluenced humid climate observed mass balance profiles suggest that the equilibrium line altitude has been higher than gangju la glacier since 2003 implying that the entire glacier has experienced net ablation for at least the past decade

iron and manganese speciation and cycling in glacially influenced high latitude fjord sediments west spitsbergen svalbard evidence for a benthic recycling transport mechanism abstract glacial environments may provide an important but poorly constrained source of potentially bioavailable iron and manganese phases to the coastal ocean in high latitude regions little is known about the fate and biogeochemical cycling of glacially derived iron and manganese in the coastal marine realm sediment and porewater samples were collected along transects from the fjord mouths to the tidewater glaciers at the fjord heads in smeerenburgfjorden kongsfjorden and van keulenfjorden along western svalbard solid phase iron and manganese speciation determined by sequential chemical extraction could be linked to the compositions of the local bedrock and hydrological weathering conditions below the local glaciers the concentration and sulfur isotope composition of chromium reducible sulfur crs in kongs and van keulenfjorden sediments largely reflect the delivery rate and isotope composition of detrital pyrite originating from adjacent glaciers the varying input of reducible iron and manganese oxide phases and the input of organic matter of varying reactivity control the pathways of organic carbon mineralization in the sediments of the three fjords high reducible iron and manganese oxide concentrations and elevated metal accumulation rates coupled to low input of fresh organic matter lead to a strong expression of dissimilatory metal oxide reduction evidenced in very high porewater iron up to 800 m and manganese up to 210 m concentrations in kongsfjorden and van keulenfjorden sediment reworking by the benthic macrofauna and physical sediment resuspension via iceberg calving may be additional factors that promote extensive benthic iron and manganese cycling in these fjords on going benthic recycling of glacially derived dissolved iron into overlying seawater where partial re oxidation and deposition occurs facilitates the transport of iron across the fjords and potentially into adjacent continental shelf waters such iron dominated fjord sediments are likely to provide significant fluxes of potentially bioavailable iron to coastal waters and beyond by contrast low delivery of reducible iron oxyhydr oxide phases and elevated organic carbon mineralization rates driven by elevated input of fresh marine organic matter allow organoclastic sulfate reduction to dominate carbon remineralization at the outer smeerenburgfjorden sites which may limit iron fluxes to the water column

variability of the climatic mass balance of vestfonna ice cap northeastern svalbard 1979 2011 vestfonna ice cap northeastern svalbard is one of the largest ice bodies in the european arctic but little is known about the evolution of its mass balance this study presents a reconstruction of the climatic mass balance of the ice cap for the period 1979 80 2010 11 the reconstruction is based on calculations using a mass balance model that combines a surface elevation dependent accumulation scheme with a spatially distributed temperature index ablation model that includes net shortwave radiation refreezing is included based on the basic p max approach the model accounts for cloud cover effects and surface albedo variations that are calculated by a statistical albedo model era interim derived air temperature precipitation and total cloud cover data are used as input results reveal a mean climatic mass balance rate of 0 09 0 15 m w e a 1 for the study period annual balances show a slight insignificant trend towards less positive values over the study period refreezing is estimated to contribute about one third to annual accumulation and a significant positive trend in refreezing is present over the study period the modelling results reveal a significant steepening of the climatic mass balance gradient and indicate a lengthening of the characteristic 3 month ablation period in recent years

glaciers dominate eustatic sea level rise in the 21st century ice loss to the sea currently accounts for virtually all of the sea level rise that is not attributable to ocean warming and about 60 of the ice loss is from glaciers and ice caps rather than from the two ice sheets the contribution of these smaller glaciers has accelerated over the past decade in part due to marked thinning and retreat of marine terminating glaciers associated with a dynamic instability that is generally not considered in mass balance and climate modeling this acceleration of glacier melt may cause 0 1 to 0 25 meter of additional sea level rise by 2100

computing the volume response of the antarctic peninsula ice sheet to warming scenarios to 2200 the contribution to sea level to 2200 from the grounded mainland antarctic peninsula ice sheet apis was calculated using an ice sheet model initialized with a new technique computing ice fluxes based on observed surface velocities altimetry and surface mass balance and computing volume response using a linearized method volume change estimates of the apis resulting from surface mass balance anomalies calculated by the regional model racmo2 forced by a1b and e1 scenarios of the global models echam5 and hadcm3 predicted net negative sea level contributions between 0 5 and 12mm sea level equivalent sle by 2200 increased glacier flow due to ice thickening returned 15 of the increased accumulation to the sea by 2100 and 30 by 2200 the likely change in volume of the apis by 2200 in response to imposed 10 and 20km retreats of the grounding line at individual large outlet glaciers in palmer land southern antarctic peninsula ranged between 0 5 and 3 5mm sle per drainage basin ensemble calculations of apis volume change resulting from imposed grounding line retreat due to ice shelf break up scenarios applied to all 20 of the largest drainage basins in palmer land covering 40 of the total area of apis resulted in net sea level contributions of 7 16mm sle by 2100 and 10 25mm sle by 2200 inclusion of basins in the northern peninsula and realistic simulation of grounding line movement for ap outlet glaciers will improve future projections