solar radiation maintained glacier recession on kilimanjaro drawn from combined ice radiation geometry modeling 1 in the context of investigating modern glacier recession on kilimanjaro which began around 1880 this study addresses the glacier regime of the vertical ice walls that typically form the margins of kilimanjaro s summit glaciers these walls have suffered a continuous lateral retreat during the twentieth century to evaluate the role of solar radiation in maintaining glacier recession on kilimanjaro a radiation model is applied to an idealized representation of the 1880 ice cap the combined process based model calculates the spatial extent and geometry of the ice cap for various points in time after 1880 support for input data and fundamental assumptions are provided by an automatic weather station that has operated on the summit s northern icefield since february 2000 even in a simple climatic scenario only forced with an annual cycle of clouds the basic evolution in spatial distribution of ice bodies on the summit is modeled well the northern and southern icefields form in characteristic east west orientation which verifies the basic idea behind the model forcing the model with further climate related phenomena improves the results it then additionally reproduces the eastern icefield the third big ice entity on the summit this study qualitatively demonstrates that solar radiation is the main climatic parameter maintaining modern glacier recession on kilimanjaro summit but also suggests that retreat on the inner ice cap margin might have been supported by a secondary energy source the need for additional field measurements is emphasized in order to better understand the complex processes of glacier climate interaction on kilimanjaro index terms 1620 global change climate dynamics 3309 1827 hydrology glaciology 1863 3309 meteorology and atmospheric dynamics climatology 1620 3359 meteorology and atmospheric dynamics radiative processes 9305 information related to geographic region africa keywords tropical glaciers kilimanjaro climate change glacier retreat solar radiation modeling

the structure of the crust and upper mantle in the dead sea rift abstract the previously published results of a deep seismic refraction study of the dead sea gulf of elat rift show crustal thinning underneath the rift and the presence of a 5 km thick velocity transition zone in the lower crust along the rift the structural interpretation of the first arrival data was revised using the detailed velocity depth distribution the revised crustal thicknesses are 35 km near elat and 27 km 160 km south of elat the crustal thinning and the presence of the velocity transition zone are interpreted as being the result of intrusion of upper mantle material into the lower crust possibly representing the initial shape of the processes which have been active further south in the red sea since earlier times

tropical climate at the last glacial maximum inferred from glacier mass balance modeling model derived equilibrium line altitudes elas of former tropical glaciers support arguments based on other paleoclimate data for both the magnitude and spatial pattern of terrestrial cooling in the tropics at the last glacial maximum lgm relative to the present lgm elas were maintained by air temperatures that were 3 5 to 6 6 c lower and precipitation that ranged from 63 wetter in hawaii to 25 drier on mt kenya africa our results imply the need for a 3 c cooling of lgm sea surface temperatures in the western pacific warm pool sensitivity tests suggest that lgm elas could have persisted until 16 000 years before the present in the peruvian andes and on papua new guinea

recent evolution 1981 2005 of the maladeta glaciers pyrenees spain extent and volume losses and their relation with climatic and topographic factors analysis of aerial photographs gps mapping and comparison of digital elevation models have been used to quantify the losses in extent and volume observed 1981 2005 in the glaciers of the maladeta massif spanish pyrenees the data are examined in relation to different climatic temperature precipitation and topographic factors that control glacial retreat both at the general and local scales the evolution observed in the massif is characterized by the remarkable surface and volumetric shrinkage registered in all the glaciers 1 glacial ice decreased in extent 35 7 reducing from 240 9 ha to 155 0 ha 2 losses in total ice volume reached 0 0137 km 3 75 6mw e 3 mean altitude of the studied glaciers increased 43 5 m these changes seem to have been forced by climatic change reduction in the snowfall contributions and increase in the maximum temperatures during the past few decades in this pyrenean region in addition local variables such as the orientation of each glacier their altitude and their initial size seem to have induced significant spatial differences in the magnitude of the losses

glacier recession on kilimanjaro east africa 1912 89 the varying ice extent on the kibo cone of kilimanjaro east africa this century was reconstructed from terrestrial photogrammetric mappings in 1912 and 1953 and satellite images in 1976 and 1989 these were all conformed to the official 1 50 000 topographic sheet the ice distribution on kibo is characterized by lower ice margins on the southern than on the northern flanks and deepest reaching glaciers to the west contrasting with least ice cover on the eastern crater rim the meridional contrast appears to be related to the more abundant precipitation on the southern side the even more striking zonal asymmetry in ice cover is favored by the vigorous diurnal circulations with enhanced afternoon cloudiness blocking insolation on the western slopes the total ice cover diminished from 12 058 to 6675 to 4171 to 3305 x 10 3 m 2 between the years 1912 1953 1976 and 1989 and the three large coherent ice bodies disintegrated into numerous smaller ice fragments

a method for monitoring glacier mass balance using satellite albedo measurements application to vatnajskull iceland we compare satellite albedo images of vatnajokull iceland with mass balance measurements for the years 1991 99 we find that the equilibrium line is mostly not visible when it is located above its position of the previous year s equilibrium line detection is further hindered by clouds and a gradual transition between ice and firn or snow consequently firn line elevation at the end of the melting season is not particularly useful for estimating the annual mass balance instead we propose to study the mean albedo of the entire ice cap throughout the melting season so that all available information about the surface albedo is taken into account the mean net potential global radiation which can be estimated from the mean surface albedo alone both depends on and influences summer melt it also depends on winter precipitation and integrated over the melting season is found to relate linearly to the specific mass balance b r 0 87 and 0 94 for different outlets of vatnajokull b can be estimated quantitatively when this relation is known and qualitatively when it is not the uncertainty in the satellite derived value of b is 0 5 0 8 m w e which for vatnajokull corresponds to about 27 of the interannual variability of b

mantle structure and rifting processes in the baikal mongolia region geophysical data and evidence from xenoliths in volcanic rocks abstract the origin of the baikal rift zone brz has been debated between the advocates of passive and active rifting since the 1970s a re assessment of the relevant geological and geophysical data from russian and international literature questions the concept of broad asthenospheric upwelling beneath the rift zone that has been the cornerstone of many active rifting models results of a large number of early and recent studies favour the role of far field forces in the opening and development of the brz this study emphasises the data obtained through studies of peridotite and pyroxenite xenoliths brought to the surface by alkali basaltic magmas in southern siberia and central mongolia these xenoliths are direct samples of the upper mantle in the vicinity of the brz of particular importance are suites of garnet bearing xenoliths that have been used to construct p t composition lithospheric cross sections in the region for the depth range of 35 80 km xenolith studies have shown fundamental differences in the composition and thermal regime between the lithospheric mantle beneath the ancient siberian platform sampled by kimberlites and beneath younger mobile belts south of the platform the uppermost mantle in southern siberia and central mongolia is much hotter at similar levels than the mantle in the siberian craton and also has significantly higher contents of basaltic major elements ca al na and iron higher fe si and fe mg the combination of the moderately high geothermal gradient and the fertile compositions in the off cratonic mantle appears to be a determining factor controlling differences in sub moho seismic velocities relative to the siberian craton chemical and isotopic compositions of the off cratonic xenoliths indicate small scale and regional mantle heterogeneities attributed to various partial melting and enrichment events consistent with long term evolution in the lithospheric mantle age estimates of mantle events based on os sr nd isotopic data can be correlated with major regional stages of crustal formation and may indicate long term crust mantle coupling the ratios of 143 144nd in many lree depleted xenoliths are higher than those in morb or oib source regions and are not consistent with a recent origin from asthenospheric mantle mantle xenoliths nearest to the rift basins 30 50 km south of southern lake baikal show no unequivocal evidence for strong heating unusual stress and deformation solid state flow magmatic activity or partial melting that could be indicative of an asthenospheric intrusion right below the moho comparisons between xenoliths from older and younger volcanic rocks east of lake baikal together with observations on phase transformations and mineral zoning in individual xenoliths have indicated recent heating in portions of the lithospheric mantle that may be related to localised magmatic activity or small scale ascent of deep mantle material overall the petrographic p t chemical and isotopic constraints from mantle xenoliths appear to be consistent with recent geophysical studies which found no evidence for a large scale asthenospheric upwarp beneath the rift and lend support to passive rifting mechanism for the brz

the mechanism of continental splitting abstract continental splitting is the response of the continental lithosphere under favourable conditions to deviatoric tension and a hot partially fused upper mantle beneath it has commonly been suggested that rift systems such as that of east africa may possibly represent splitting in the process of occurring here the hot upper mantle has probably formed by convective upwelling from deep in the mantle allowing the escape of heat from the earth s interior by hotspot activity this causes volcanism and isostatic uplift of the heated and thinned lithosphere and the crustal tension subsequently develops in response to the surface load caused by the uplift and the upthrust of the isostatic compensation at depth it is suggested here that the crustal tension causing continental splitting does not normally originate as in east africa but rather by the suction force acting on the overriding plates at trenches at periods in earth history when subduction occurs on the opposite sides of a large continental mass such as pangaea the critical evidence on the splitting mechanism is mostly deeply buried at passive margins and inaccessible to study some margins such as the north biscay one were apparently formed under much quieter volcanic and tectonic conditions than continental rift zones whereas others such as those of the icelandic region underwent extensive continental volcanism indicating a hot upper mantle beneath the icelandic types of margin probably acted as foci for continental splitting by dyke emplacement with dykes propagating laterally from them through the more quietly developed parts of the margin to link with existing plate boundaries normal plate motions occur in response to the steady escape of heat from the deep interior through formation and cooling of the oceanic lithosphere which can be recycled whereas continental splitting is seen as the result of the spasmodic escape of heat from the deep interior through the continental lithosphere

solar radiation cloudiness and longwave radiation over low latitude glaciers implications for mass balance modelling broadband radiation schemes parameterizations are commonly used tools in glacier mass balance modelling but their performance at high altitude in the tropics has not been evaluated in detail here we take advantage of a high quality 2 year record of global radiation g and incoming longwave radiation l measured on kersten glacier kilimanjaro east africa at 5873 m a s l to optimize parameterizations of g and l we show that the two radiation terms can be related by an effective cloud cover fraction neff s og or l can be modelled based on neff derived from measured l or g respectively at neff 1 g is reduced to 35 of clear sky g and l increases by 45 65 depending on altitude relative to clear sky l validation for a 1 year dataset of g and l obtained at 4850 m on glaciar artesonraju peruvian andes yields a satisfactory performance of the radiation scheme whether this performance is acceptable for mass balance studies of tropical glaciers is explored by applying the data from glaciar artesonraju to a physically based mass balance model which requires among others g and l as forcing variables uncertainties in modelled mass balance introduced by the radiation parameterizations do not exceed those that can be caused by errors in the radiation measurements hence this paper provides a tool for inclusion in spatially distributed mass balance modelling of tropical glaciers and or extension of radiation data when only g or l is measured

ice core palaeoclimate records in tropical south america since the last glacial maximum ice core records spanning the last 25 000 yr from the tropical andes of south america are reviewed these records from quelccaya huascaran and sajama present a high temporal resolution picture of both the late glacial stage lgs and the holocene climatic and environmental conditions in the south american andes late glacial stage conditions at high elevations appear to have been cooler than today although the magnitude of the inferred cooling differs with the particular proxy used e g snowline depression pollen ice cores insoluble dust and anion concentrations in the ice cores reveal that lgs hydrological conditions in the tropics 9 s were much drier than today whereas in the subtropics 18 s lgs conditions were much wetter this probably reflects the migration of the tropical hadley cell in response to a different meridional temperature gradient low nitrate concentrations in the lgs ice from both huascaran and sajama suggest that the amazon basin forest cover may have been much less extensive discussed is the conundrum surrounding the use of d 18 o as a palaeothermometer in the tropics where temperatures exhibit little seasonal variation yet the ice core records suggest that d 18 o records temperature variations on decadal to millennial time scales finally evidence is presented for a strong twentieth century warming copyright 2000 john wiley sons ltd

comparison of different retrieval techniques for melt ponds on arctic sea ice from landsat and modis satellite data melt ponds are regularly observed on the surface of arctic sea ice in late spring and summer they strongly reduce the surface albedo and accelerate the decay of actic sea ice until now only a few studies have looked at the spatial extent of melt ponds on arctic sea ice knowledge of the melt pond distribution on the entire arctic sea ice would provide a solid basis for the parameterization of melt ponds in existing sea ice models due to the different spectral properties of snow ice and water a multispectral sensor such as landsat 7 etm is generally applicable for the analysis of distribution an additional advantage of the etm sensor is the very high spatial resolution 30 m an algorithm based on a principal component analysis pca of two spectral channels has been developed in order to determine the melt pond fraction pca allows differentiation of melt ponds and other surface types such as snow ice or water spectral bands 1 and 4 with central wavelengths at 480 and 770 nm respectively are used as they represent the differences in the spectral albedo of melt ponds a landsat 7 etm scene from 19 july 2001 was analysed using pca the melt pond fraction determined by the pca method yields a different spatial distribution of the ponded areas from that developed by others a modis subset from the same date and area is also analysed the classification of modis data results in a higher melt pond fraction than both landsat classifications

diagnosing the 2005 drought in equatorial east africa abstract equatorial east africa suffered severe drought during its 2005 short rains centered on october november the circulation mechanisms of such precipitation anomalies are examined using long term upper air and surface datasets and based on diagnostic findings from earlier empirical investigations the steep eastward pressure gradient is conducive to fast westerlies over the central equatorial indian ocean surface manifestation of a powerful zonal circulation cell with subsidence over east africa and ascending motion over indonesia with fast westerlies rainfall in east africa is deficient and they tend to be accompanied by anomalously cold waters in the northwestern and warm anomalies in the southeastern extremity of the equatorial indian ocean basin without any seesaw between these domains in october november 2005 pressure in the west was anomalously high entailing a steep eastward pressure gradient along the equator conducive to fast westerlies and further symptomatic of the zonal ci

on the evolution of rifted continental margins comparison of models and observations for the nova scotian margin summary a model for the formation and evolution of rifted continental margins based on lithospheric extension during rifting and its thermal and mechanical consequences is proposed model predictions are then compared with geological and geophysical observations from a transect of the 185 ma old rifted margin off nova scotia through the scotian basin three kinematic models of the rifting process are discussed these are 1 the uniform extension model in which the amount of extension is uniform with depth but varies with position across the margin 2 the uniform extension and melt segregation model which has similar properties but also provides an explanation for the properties of the extended continental crust and its transition to oceanic crust by postulating that basaltic melt segregates from the asthenosphere and migrates to the crust and 3 the depth dependent extension model in which the first order consequences of rapidly changing rheological properties with depth in the lithosphere are included by decoupling the lithosphere into two zones with depth each of which undergoes differing amounts of extension these rift models predict the form of crustal and lithospheric thinning subsidence and temperature change once the amount of extension has been determined this is estimated from seismic measurements of present crustal thickness on the assumption that the crust had a uniform thickness equal to that currently measured in the adjacent continental region before rifting occurred rifting is also considered to occur instantaneously a time stepping thermo mechanical model is used to predict the cooling of rifted margin additional thermal contraction subsidence and its amplification by water and sediment loading thermal aspects are calculated using a finite difference model of time dependent conductive heat transport whereas regional isostatic response to loading is calculated by a finite element model the models are coupled because the temperature distribution is used to define a rheological lithosphere an elastic region with thickness that varies in time and space as the model evolves for flexural calculations in the mechanical model secondary coupling occurs through perturbations to the temperature field by sedimentary thermal blanketing and advection of heat during isostatic adjustment the model predictions of 1 sedimentary basin stratigraphy 2 moho position 3 free air gravity anomaly 4 age depth relations for deep exploratory wells and 5 subsidence and temperature histories agree well with observations from the scotian basin additional effects due to sedimentary and crustal radiogenic heat production lateral heat transport and the possible existence of a near surface brittle listric faulted region created during rifting are also considered it is concluded that a model in which rifting occurred by depth dependent extension and which includes a finite thickness for the rheological lithosphere radiogenic heat production in the sediments and crust and a brittle listric faulted crustal layer affords an accurate description of the first order processes that occur during rifting and evolution of this margin

deglaciated areas of kilimanjaro as a source of volcanic trace elements deposited on the ice cap during the late holocene abstract ice fields on kilimanjaro 5895 m a s l tanzania are retreating and 85 of the ice cover has been lost since 1912 the degree to which this recession is exceptional during the holocene is uncertain as age control of the entire ice stratigraphy exists only for the very shallow and very bottom ice of the northern ice field this empirical evidence suggests that the kilimanjaro ice cover may be a persistent holocene feature while a model based on maximum possible extent and a constant shrinkage rate of the summit glaciers suggests a cyclic decay time on the order of one to two centuries today the mass balance of these ice fields is negative and no persistent ice accumulation zones are observed over multiannual scales the expanding deglaciated area within the kilimanjaro caldera should act as an increasingly larger and productive source of volcanic origin aeolian dust that is quickly deposited onto the surface of the adjacent ice fields particularly in the seasonal absence of caldera snow cover variations in the local dust influx may directly influence albedo and the energy balance of these ice fields investigating the characteristics of insoluble material entrapped in the ice remnants of kilimanjaro can thus provide insights into the extent of ice and or continuity of the summit snow cover through time here we report the trace element composition linked to the insoluble particles entrapped in holocene kilimanjaro ice in the context of the current understanding of the past ice accumulation processes including solid precipitations and ablation contributing to build the horizontal caldera ice fields for this purpose we analysed an ice core drilled to bedrock from the northern ice field thought to span the late holocene 2200 bc 1950 ad the ultra low trace element concentrations recorded in this kilimanjaro core are consistent with a generally low volcanic dust source availability i e limited exposure of the deglaciated area in the caldera and fairly continuous ice accumulation during the late holocene in contrast the maximum concentrations for most of the trace elements recorded in the surface ice section suggest that the current lack of ice accumulation on the kilimanjaro ice fields is unusual over the last 4 ka

changes of the equilibrium line altitude since the little ice age in the nepalese himalaya changes of the equilibrium line altitude ela since the end of the little ice age lia in eastern nepal have been studied using glacier inventory data the toe to headwall altitude ratios thars for individual glaciers were calculated for 1992 and used to estimate the ela in 1959 and at the end of the lia thar for debris free glaciers is found to be smaller than for debris covered glaciers the elas for debris covered glaciers are higher than those for debris free glaciers in eastern nepal there is considerable variation in the reconstructed change in ela ela between glaciers within specific regions and between regions this is not related to climate gradients but results from differences in glacier aspect southeast and south facing glaciers show larger elas in eastern nepal than north or west facing glaciers the data suggest that the rate of ela rise may have accelerated in the last few decades the limited number of climate records from nepal and analyses using a simple ela climate model suggest that the higher rate of the ela between 1959 and 1992 is a result of increased warming that occurred after the 1970s at higher altitudes in nepal

structure of the crust and upper mantle beneath the central european rift system the crustal structure of the central european rift system has been investigated by seismic methods with varying success only a few investigations deal with the upper mantle structure beneath the rhinegraben the moho is elevated with a minimum depth of 25 km below the flanks it is a first order discontinuity while within the graben it is replaced by a transition zone with the strongest velocity gradient at 20 22 km depth an anomalously high velocity of up to 8 6 km s seems to exist within the underlying upper mantle at 40 50 km depth a similar structure is also found beneath the limagnegraben and the young volcanic zones within the massif central of france but the velocity within the upper mantle at 40 50 km depth seems to be slightly lower here the total crustal thickness reaches only 25 km the crystalline crust becomes extremely thin beneath the southern rhonegraben where the sediments reach a thickness of about 10 km while the moho is found at 24 km depth the pronounced crustal thinning does not continue along the entire graben system north of the rhinegraben in particular the typical graben structure is interrupted by the rhenohercynian zone with a normal west european crust of 30 km thickness evident beneath the north trending hessische senke a single ended profile again indicates a graben like crustal structure west of the leinegraben north of the rhenohercynian zone no details are available for the north german plain where the central european rift system disappears beneath a sedimentary sequence of more than 10 km thickness

holocene and latest pleistocene alpine glacier fluctuations a global perspective abstract alpine glacier fluctuations provide important paleoclimate proxies where other records such as ice cores tree rings and speleothems are not available about 20 years have passed since a special issue of quaternary science reviews was published to review the worldwide evidence for holocene glacier fluctuations since that time numerous sites have been discovered new dating techniques have been developed and refined climatic hypotheses have been proposed that contribute to a better understanding of earth s climate system this special volume includes 12 papers on holocene and latest pleistocene alpine glacier fluctuations that update the seven review papers from 1988 major findings of these 12 papers include the following many but certainly not all alpine areas record glacier advances during the younger dryas cold interval most areas in the northern hemisphere witnessed maximum glacier recession during the early holocene with some glaciers disappearing although a few sites yield possible evidence for advances during the 8 2 ka cooling event in contrast some alpine areas in the southern hemisphere saw glaciers reach their maximum post glacial extents during the early to middle holocene in many parts of the globe glaciers reformed and or advanced during neoglaciation beginning as early as 6 5 ka neoglacial advances commonly occurred with millennial scale oscillations with many alpine glaciers reaching their maximum holocene extents during the little ice age of the last few centuries although the pattern and rhythm of these glacier fluctuations remain uncertain improved spatial coverage coupled with tighter age control for many events will provide a means to assess forcing mechanisms for holocene and latest pleistocene glacial activity and perhaps predict glacier response to future impacts from human induced climate change

tropical ice core records evidence for asynchronous glaciation on milankovitch timescales over the last 28 years ice core records have been systematically recovered from ten high elevation ice fields nine of which are located in the low latitudes each core has provided new information about the regional climate and environmental change and together their records challenge existing paradigms about the earth s climate system when viewed collectively these ice core histories provide compelling evidence that the growth glaciation and decay deglaciation of large ice fields in the lower latitudes are often asynchronous both between the hemispheres and with high latitude glaciation that occurs on milankovitch timescales although stable isotopic records suggest that global scale cooling occurred during the last glacial stage lgs we contend that precipitation is the primary driver of glaciation in the low latitudes this is consistent with the time transgressive nature of precession driven changes in insolation and hence precipitation such that glaciers advance retreat in the tropics north of the equator while glaciers retreat advance in the tropics south of the equator thus the coeval inter hemispheric retreat of glaciers in the 20th century and the beginning of the 21st century is atypical copyright 2005 john wiley sons ltd

the position of continental flood basalts in rift zones and its bearing on models of rifting abstract two models of rifting pure shear and simple shear are at present being widely discussed in this paper attention is drawn to the fact that continental flood basalts cfb associated with rifts usually display a strong asymmetry relative to the rift axis the karroo the parana and the deccan basalts as well as the ethiopian flood basalts and the basalts of the arabian shield are concentrated mainly on one side of the respective rifts structural data indicate that the eruptions occurred on the upper plates if the low angle simple shear model of wernicke 1985 is accepted it is suggested that the asymmetry of eruptions is caused by the asymmetric position of the asthenopheic rise predicted by this model the low angle detachment may serve as a conduit for magmatic fluid this fits well with data on the existence of large magmatic reservoirs of cfb at subcrustal or crustal levels and explains why eruptions are concentrated in the rift and on one of its shoulders while being restricted on the other this asymmetry of volcanism supports models of continental rifting associated with low angle simple shear detachment

the late quaternary glaciation of africa a regional synthesis abstract there are numerous mountain ranges in africa which carry evidence of quaternary glaciation though few have glaciers now and these are rapidly disappearing the best studied sites are in east africa and ethiopia in east africa the three highest mountains kilimanjaro kenya and the rwenzori each have evidence of 3 5 major glaciations dating back to an estimated 400 000 bp one of which is dated to the last glacial maximum lgm by radiocarbon or cosmogenic radionucleide crn methods two other mountains have similar large moraine systems inferred to date to the lgm in ethiopia three mountains have clear evidence of glaciation and on two of them radiocarbon dates give minimum ages which suggest that these are lgm features in north africa the atlas and other groups of mountains have evidence of glaciation but in the absence of any dating it is unclear whether these sites were glaciated at the lgm although geomorphic features resembling moraines and protalus ramparts have been described from the drakensberg mountains south africa it is still unclear whether these features indicate glaciation and can be attributed to the lgm thus although circumstances for fieldwork on african mountains are very difficult in many cases investigations for more than a century provide an extensive picture of quaternary glaciation in some cases there has been an increasingly detailed mapping of field evidence and the first crn dates were carried out recently thus improving the global picture considerably particularly in east africa and ethiopia there is sufficiently reliable field information to make useful estimates of equilibrium line altitude changes at the provisionally identified lgm but this age needs confirmation by further crn dating by making some hypothetical assumptions inferences can be drawn that indicate a temperature lowering of 5 6 c during the lgm elsewhere in africa further field surveys are required

nonparametric regression for estimation of spatiotemporal mountain glacier retreat from satellite images historical variations in the extent of mountain glaciers give insight into natural and forced changes of these bellwethers of the climate because of the limited number of ground observations relative to the number of glaciers it is useful to develop techniques that permit for the monitoring of glacier systems using satellite imagery here we propose a new approach for identifying the glacier terminus over time from landsat images the proposed method permits for detecting inflection points in multispectral satellite imagery taken along a glacier s flow path in order to identify candidate terminus locations a gated tracking algorithm is then applied to identify the best candidate for the glacier terminus location through time finally the long term trend of the terminus position is estimated with uncertainty bounds this is achieved by applying nonparametric regression to the temporal sequence of estimated terminus locations the method is shown to give results consistent with ground based observations for the franz josef and gorner glaciers and is further applied to estimate the retreat of viedma a glacier with no available ground measurements

ocean crustal dynamics the study of oceanic crust continues to be important because of the presence of economic resources in oceanic areas and because many fundamental problems of geologic evolution are best solved from studies of the ocean although modeling and syntheses of existing data remain important key breakthroughs in the future will come from the application of new technology such as multichannel towed seismic arrays deep towed side scan sonars improved thermal probes deep drilling and satellite altimeters

energy balance model validation on the top of kilimanjaro tanzania using eddy covariance data eddy covariance data collected over a horizontal surface on the largest ice body on kilimanjaro tanzania over 26 29 july 2005 were used to assess the uncertainty of calculating sublimation with a surface energy balance seb model data required for input to the seb model were obtained from an existing automatic weather station surface temperatures that were solved iteratively by the seb model were used to compute emitted longwave radiation turbulent heat fluxes using the aerodynamic bulk method and the subsurface heat flux roughness lengths for momentum and temperature which were found to be the most important input parameters controlling the magnitude of modelled bulk method turbulent heat fluxes were obtained using eddy covariance data the roughness length for momentum was estimated to be 1 7 10 3 m while the length for temperature was one order of magnitude smaller modelled sensible and latent heat fluxes bulk method compared well to eddy covariance data with root mean square differences between 3 1 and 4 8 w m 2 for both turbulent heat fluxes modelled sublimation accounted for about 90 of observed ablation confirming that mass loss by melting is much less important than sublimation on the horizontal surfaces of the remaining plateau glaciers on kilimanjaro

two types of rifting dependence on the condition of extension abstract rifting of continental lithosphere occurs in two ways 1 1 through continuous extension and subsequent sinking 2 2 in a series of pulses separated by quiet periods sometimes of considerable duration in the first case rifting is not accompanied by significant uplifts in the second uplifts of various sizes from 100 to 2000 km are typical rifting of the first type takes place when continental fragments are freely dispersed as was the case with pangea during its late triassic early jurassic break up in the cenozoic rifts developed in the course of continental collision when relative plate motion was restricted and occurred in short pulses uplift is caused by accumulation of anomalous mantle at the base of the crust during the intervals between phases of extension geological evidence is not consistent with the idea of rifting being directly related to a local source of energy in the mantle mantle plumes and diapirs it is produced by regional stresses in the lithosphere which in their turn may have different origins the lithospheric inhomogeneities observed below the present day rifts are not the cause but a consequence of extension

is the decline of ice on kilimanjaro unprecedented in the holocene glaciers on kilimanjaro s highest peak kibo are currently regarded as a persistent feature of the holocene here we synthesize all available measurements observations and our understanding of current processes on kibo gained from intensive research over the past decade to formulate an alternative hypothesis about the age of these ice fields this suggests a shorter discontinuous history of the tabular shaped glaciers on kibo s plateau where typical life cycles of the ice may last only a few hundred years if life cycles overlap they are likely the cause of the observed steps in the plateau glaciers thus it is likely that ice has come and gone repeatedly on kibo s summit plateau throughout the holocene such a cyclicity is supported by lake derived proxy records

kilimanjaro glaciers recent areal extent from satellite data and new interpretation of observed 20th century retreat rates 1 recent and long term variations in ice extent on kilimanjaro are investigated in the context of 20th century climate change in east africa quickbird satellite data show that the areal extent of glaciers on kilimanjaro is 2 51 km2 in february 2003 to assess glacier retreat on kilimanjaro two glacier systems are identified 1 plateau 5700 m and 2 slope 5700 m vertical wall retreat that governs the retreat of plateau glaciers is irreversible and changes in 20th century climate have not altered their continuous demise rapid retreat of slope glaciers at the beginning of the 20th century implies a strong departure from steady state conditions during this time this strong imbalance can only be explained by a sudden shift in climate which is not observed in the early 20th century results suggest glaciers on kilimanjaro are merely remnants of a past climate rather than sensitive indicators of 20th century climate change

evidence for late pleistocene climate changes from buried soils on the southern slopes of mt kilimanjaro tanzania abstract the distribution of the altitudinal vegetation zones on the slopes of mt kilimanjaro is well known but no reliable data are available about the vegetation shifts during the quaternary here i present palaeopedological results elemental biomarker stable isotope and radiocarbon analyses indicating that the frequently occurring buried black a horizons in the montane forest belt are developed under ericaceous vegetation since erica species are not abundant at this altitude nowadays but are characteristic for the sub alpine zone the palaeosols reflect palaeoclimatically driven fluctuations and changes of the vegetation zones on mt kilimanjaro the downhill descent of the ericaceous belt coincided with cold and dry periods like the late glacial and the last glacial maximum older palaeosols document that such events also took place during the marine isotope stages 3 and 4

response to molg et al glacier loss on kilimanjaro is consistent with widespread ice loss in low latitudes our paper 1 does not seek to review all potential controls on glacier mass balance mb but to i present ice volume change calculations revealing that glacier thinning now accounts for 50 of the ice volume loss for the summit ice fields ii update changes in the areal extent of the ice fields based on newer 2007 aerial photographs and iii highlight that ice loss on kilimanjaro is not exceptional we disagree with molg et al 2 that we inappropriately propose that kilimanjaro s shrinking ice fields are not unique 1 the reduction in areal extent and ice volume shrinking of kilimanjaro si cefields is not unique it isconsistentwiththewell documentedwidespread glacier retreat in lower latitudes molg et al 2 obfuscate the issue of kilimanjaro s glacier recession by not differentiating between processes responsible for decreasing ice area i e vertical wall retreat and more typical mb processes acting on horizontal surfaces where the balance is currently negative in fact since 2000 we have documented area weighted plateau thinning of 4 m a tremendous increase over the rate of 1 m per

modeling heterogeneous stretching during episodic or steady rifting of the continental lithosphere the geometry of brittle ductile extension and modes of normal faulting during steady or episodic rifting of the continental lithosphere are investigated by analogue modeling using the centrifuge technique we use a frictional material to simulate the brittle behavior and various nonlinear bouncing putties to represent the ductile rheology of the stratified lithosphere steady stretching of the continental lithosphere supports rapid differential subsidence and flexure of the brittle crust with formation of marginal grabens and a panel of domino style fault blocks in contrast episodic stretching of the lithosphere progressing in a series of pulses separated by longer periods of quiescence supports formation of spaced grabens and horsts with less subsidence this is due to a counterflow of ductile material from the margins to the central rift zone we show here that the isostatic adjustment in the lithosphere can be related to the steady or episodic mode of heterogeneous stretching we apply the model results to the southern red sea for which the inferred opening history involved continuous or stepwise extension

a new index of glacier area change a tool for glacier monitoring since the mid 19th century most glaciers have been losing area and volume this loss of area has not been homogeneous in time and space and direct observations are sparse making regional and global estimates of glacier change difficult this paper focuses on developing a single index for monitoring glacier change one that would be particularly useful for remote sensing applications we combine the results of direct glacier mass balance observations b total glacier area s and accumulation area sc derived from maps or remotely sensed images using the accumulation area ratio aar sc s we note the differences between observed aar time averaged aar hi and the equilibrium state aar0 as determined by its value at b 0 from a regression of b aar we suggest that d aar hi aar0 aar0 quantifies the difference between the currently observed state of glaciers and their equilibrium state and measures the delay in the dynamic response of s relative to the climatic response of sc using all available observations for the period 1961 2004 d 65 for tropical glaciers which implies their rapid shrinkage as s continues to decrease and catch up with sc during the same period mid latitude and polar glaciers show less negative values of d of 86 glaciers from all latitudes and regions only 11 show positive d at any time between 1961 and 2004 averaged over 1961 2004 d is 15 1 2 2 and b hi is 360 42 mm a 1 w e values for aar0 range between about 40 and 80 but the bulk of the equilibrium values are between 50 and 60 the average aar0 is 57 9 0 9 and has remained stable over time the equilibrium aar has not changed with climate overall the observed negative d suggests a committed retreat of glaciers and their continuing contribution to sea level even if global temperature is held constant