slip along the sultanhani fault in central anatolia from deformed pleistocene shorelines of palaeo lake konya and implications for seismic hazards in low strain regions

estimation of evaporation from the normally dry lake frome in south australia depth profiles of deuterium composition expressed as delta values have been used to make point estimates of evaporation from the floor of the normally dry lake frome a salt lake in northern south australia values from five sites varying between 90 and 230 mm yr 1 have been used to obtain a relatively crude approximation for mean evaporation rate from the lake of 170 mm yr 1 under the assumption that this represents discharge of water from the regional groundwater system the groundwater inflow into the lake is calculated as 5 108 m3 yr 1 two possible models which describe groundwater inflow into the lake are discussed

fluvial response to climate change during and after the last glacial maximum in central anatolia turkey abstract fluvial response to climate change during and after the last glacial maximum lgm included incision aggradation phases recorded in sediment cores from the valley floor of the kizilirmak in central anatolia a numerical chronology was established by ams dating of fluvial sediments and ar ar dating of a basalt sample capping the youngest terrace late pleistocene terrace indicating that the main incision phase was completed at the end of the lgm the succeeding aggradation phase in the valley took place from the end of the lgm onwards it appears that the major climatic transition from the lgm to the late glacial gave rise to aggradation in the fluvial system and this event seems to be consistent with the timing of the regression phase of pluvial lakes and the termination of paleoglacier advances in the high mountains of anatolia this study of fluvial systems in anatolia indicates that the coldest periods are not always characterized by fluvial aggradation

cold and wet last glacial maximum on mount sandiras sw turkey inferred from cosmogenic dating and glacier modeling abstract in situ cosmogenic 36 cl was measured in boulders from moraines on mount sandiras 37 1 n 28 8 e 2295 m the southwestern most previously glaciated mountain in turkey valleys on the north side of the mountain were filled with 1 5 km long glaciers that terminated at an altitude of 1900 m the glacial activity on mount sandiras correlates with the broadly defined last glacial maximum lgm the maximum glaciation occurred approximately 20 4 1 3 ka 1 1 ka 1000 calendar years ago when glaciers started retreating and the most extensive moraines were deposited the glaciers readvanced and retreated by 19 6 1 6 ka ago and then again by 16 2 0 5 ka using the glacier modeling and the paleoclimate proxies from the eastern mediterranean we estimated that if temperatures during lgm were 8 5 11 5 c lower than modern precipitation was up to 1 9 times more than that of today thus the local lgm climate was cold and wet which is at odds with the conventional view of the lgm as being cold and dry in the region

paleoglacial records from kavron valley ne turkey field and cosmogenic exposure dating evidence abstract kavron valley lies in the kackar mountain range of northeastern anatolia and is a north south oriented typically u shaped glacial valley consisting of a main and three tributary valleys the quaternary units that outcrop in this valley have been mapped and 22 samples have been processed for surface exposure dating using cosmogenic 10 be according to the 10 be ages the advance of the kavron paleoglacier began at least 26 0 1 2 kyr ago with the last glacial maximum lgm advance continuing until 18 3 0 9 kyr after this time the kavron paleoglacier receded although the magnitude of this recession is still unknown subsequent to this retreat the glacier most probably separated into three smaller glaciers that were restricted to the tributary valleys ifrit derebasi and mezovit paleoglaciers the main valley was definitely ice free by 15 5 0 7 kyr ago with the mezovit paleoglacier completing its recession around 15 5 0 6 kyr a late glacial advance took place around 13 0 0 8 to 11 5 0 8 kyr and little ice age moraines appear to be absent our results from the kavron valley system seem to be consistent with the lgm paleoclimate record of anatolia which has been delineated by data gathered from lowlands and lakes the deposition of red clay layers in the northwestern black sea and the deposition of heinrich 1 layers in the north atlantic

climatic reconstruction in europe for 18 000 yr b p from pollen data an improved concept of the best analogs method is used to reconstruct the climate of the last glacial maximum from pollen data in europe in order to deal with the lack of perfect analogs of fossil assemblages and therefore to obtain a more accurate climate reconstruction we used a combination of pollen types grouped according to plant phenology and present climate constraints rather than pollen percentages for each individual taxon the distribution of pollen taxa into plant functional types pfts is aimed to reflect the vegetation in terms of biomes which have a wider distribution than a species the climatic variables are then calibrated on these pfts using an artificial neural network technique the use of pfts allowed us to deal with situations where pollen assemblages have only partial modern analogs the method is applied to the glacial steppic vegetation in europe using 15 pollen records north of the pyrenees alps line the reconstructed temperatures were lower than today 30 10 degrees c for the temperature of the coldest month t c and 12 3 degrees c far the annual mean t ann south of that line t c and t ann anomalies were respectively 15 5 degrees c and 10 5 degrees c the available moisture index and annual precipitation were also lower than present 60 20 north of mediterranean sea 800 100 mm for precipitation in italy and greece the available moisture was 20 lower with a precipitation anomaly of ca 600 200 mm southward the moisture index was close to that at present 20 and precipitation was lower 300 300 mm c 1998 university of washington

shallow shelf approximation as a sliding law in a thermomechanically coupled ice sheet model 1 the shallow shelf approximation a balance of membrane stresses for ice flow is an effective sliding law for ice sheet modeling our use of it as a sliding law becomes a standard model for ice stream flow when the sliding velocity is large 100 m a 1 and faster following schoof 2006a we describe the basal resistance as plastic till for which the yield stress is given by a mohr coulomb formula pore water pressure is related to basal melt rate the velocity field used in the mass continuity and conservation of energy equations is an average of velocities from the shallow shelf approximation and the nonsliding shallow ice approximation using this scheme our model has realistic time dependent ice streams which exhibit the range of surface velocities seen in actual ice streams we demonstrate the model at high spatial resolution 5 km grid over multiple millenia using its implementation in the parallel ice sheet model numerical experiments show that the entire scheme is stable with respect to many parameter changes some experiments reveal significant ice stream variability in a hypothetical steady climate with characteristic cycles on the order of 1000 years we believe this is the first practical whole ice sheet model with a unified treatment of vertical shear stresses and membrane stresses it is capable of high resolution thermomechanically coupled multimillenia simulations of ice sheets containing ice streams

positive degree day factors for ablation on the greenland ice sheet studied by energy balance modelling ice ablation is related to air temperature by the positive degree day factor variations of the positive degree day factor in west greenland are studied using an energy balance model to simulate ablation under different conditions degree day factors for simulated and measured ice ablation at nordbogletscher and qaman rssup sermia agree well with values around 8 mm d 1 c 1 degree day factors for snow are less than half those for ice energy balance modelling shows that degree day factors vary with summer mean temperature surface albedo and turbulence but there is only evidence of large positive degree day factors at lower temperatures and with low albedo 0 3 the greatest effect of albedo variations 0 3 0 7 is at lower temperatures while variations in turbulence have greater effect at higher temperatures current models may underestimate runoff from the greenland ice sheet by several tenths because they use a degree day factor for melting ice that is too small for the colder parts of the ice sheet i e the upper ablation area and the northerly margin

recession of the ice cap on mount agri ararat turkey from 1976 to 2011 and its climatic significance abstract glacier recession reports in response to sustained climatic warming are widespread however little information exists on glacier behaviors from the middle east where a few ice bodies still exist here an ice cap retreat from mount agri also known as ararat 39 70 n 44 30 e 5137 m turkey based on satellite measurements since 1976 were given the results show that the ice cap has lost 29 of its surface area at a rate of 0 07 km 2 a 1 the long term atmospheric warming trend observed at the nearby meteorological stations is consistent with this shrinking trend

surface exposure dating of late pleistocene glaciations at the dedegol mountains lake beysehir sw turkey situated on the interior side of the western central taurus mountains of sw anatolia the muslu valley in the dedegol mountains mt dipoyraz 37 37 07 n 31 19 42 e 2992 m above sea level a s l represents the lower part of a formerly glaciated valley system of 7 5 km in length surface exposure ages with cosmogenic 10be and 26al date a glacier expansion out of the muslu valley 24 3 1 8 ka ago 1 confidence interval and give evidence for pronounced glacier advances prior to the global last glacial maximum lgm 21 2 ka deglaciation commenced no later than 17 7 1 4 ka ago superimposed climatic oscillations are indicated by glacier fluctuations dated around 19 8 1 6 ka and again 13 9 2 3 ka prior to the first major amelioration of climate the late pleistocene glacier chronology from the western central taurus mountains published lake level fluctuation data of palaeolake konya and lake beysehir and nearby pollen data on the central anatolian plateau reveal a conspicuous time correlation of palaeoenvironmental change copyright 2009 john wiley sons ltd

remarkably extensive glaciation and fast deglaciation and climate change in turkey near the pleistocene holocene boundary moraines in the taurus mountains of south central turkey dated to latest pleistocene or earliest holocene show that glaciers were extraordinarily large typical of the last glacial maximum 21 ka and that rates of glacier retreat and temperature rise exceeded those of the past century surface exposure ages of 7 moraines in a valley at altitudes between 1100 m and 3100 m above sea level range from 10 2 0 2 ka to 8 6 0 3 ka computed using our own production rates and spatiotemporal scaling factors hitherto unresolved differences in cosmogenic 36 cl production rate estimates can make these ages signifi cantly older and therefore the analysis presented here focuses on the rate of change and not on the absolute chronology during deglaciation the equilibrium line altitude ascended 1430 m and the air temperature rose by 9 c deglaciation occurred in two phases during the second faster phase which lasted 500 yr the glacier length decreased at an average rate of 1700 m 100 yr implying a warming rate of 1 44 c 100 yr indicating a rapid climate shift marking the onset of the holocene in turkey

timing of glaciation during the last glacial cycle evaluating the concept of a global last glacial maximum lgm abstract it has long been known that mountain glaciers and continental ice sheets around the globe reached their respective maximum extent at different times during the last glacial cycle often well before the global last glacial maximum lgm c 23 19 ka which is formally defined by peaks in global sea level and marine oxygen isotope records however there is increasing evidence from around the world that it was not only mountain glaciers which were asynchronous with the global lgm but also some regions of the large continental glaciers the barents kara ice sheet in northern eurasia together with a majority of ice masses throughout asia and australasia reached their maximum early in the last glacial cycle a few thousand years before the global lgm period the east antarctic ice sheet also reached its maximum extent several millennia before the global lgm in numerous mountainous regions at high mid and low latitudes across the world glaciers reached their maximum extent before marine isotope stage mis 2 in mis 5 4 and 3 this is in contrast to most sectors of the laurentide ice sheet the cordilleran ice sheet the se sector of the fennoscandinavian ice sheet and the alpine ice sheet in central europe which appear to have reached their maximum close to the global lgm in mis 2 the diachronous maximum extents of both mountain glaciers and continental ice sheets during the last glacial cycle means that the term and acronym last glacial maximum lgm has limited chronostratigraphical meaning when correlating glacial deposits and landforms

stable isotope characteristics of eclogites from the ultra high pressure metamorphic terrain east central china abstract a stable isotope study was made for the ultra high pressure uhp metamorphic rocks in the dabie and sulu terrains east central china 18 o values of minerals in eclogites cover a wide range from 4 to 6 the o isotope fractionations between minerals i e omphacite phengite and or amphibole and garnet in eclogites are mostly not in isotopic equilibrium the large range of o isotope composition of garnet may approximate the 18 o variations of eclogites during uhp metamorphism and must have been largely inherited from their pre subduction basaltic precursors which might have interacted with meteoric waters under variable temperature conditions and water rock ratios before uhp metamorphism the o isotope disequilibrium between minerals and garnet in eclogites was caused by retrograde hydration reactions the fluids required for these hydration reactions must have low or even negative o isotope compositions it is postulated that such fluids were either originated from meteoric deep infiltration or were derived from low 18 o para gneisses

glacier advances in northeastern turkey before and during the global last glacial maximum abstract our study in the basyayla valley in northeastern anatolia showed evidence of four glacier advances that built terminal and lateral moraines surface exposure dating of boulders on these moraines showed that the maximum ice extent mie was asynchronous with the global last glacial maximum lgm 22 1 4 3 thousand years ka the local mie took place at least 57 0 3 5 ka ago the extent of the basyayla glacier during this advance is not known exactly because the boulders are only preserved on a lateral moraine the next advance was prior to 41 5 2 5 ka and it descended down the valley to approximately 2320 m above sea level m a s l with a glacier length of 5 3 km during the early global lgm the basyayla glacier extended for a distance of 4 9 km down to approx 2430 m a s l the last recorded advance occurred during the global lgm this extension was 0 7 km smaller than the local mie and its terminus reached 2490 m a s l only the exposure ages of boulders in a retreat position at an altitude of approx 3045 m a s l indicate that the valley has remained ice free since the lateglacial period therefore the lateglacial extent was limited to the cirque system in the uppermost part of the catchment furthermore holocene glacier oscillations seem to be either absent or restricted to solifluction in the whole catchment and to rock glacier movements in the southern tributary of the basyayla valley system

a review of palaeoclimates and palaeoenvironments in the levant and eastern mediterranean from 25 000 to 5000 years bp setting the environmental background for the evolution of human civilisation abstract the southern levant has a long history of human habitation and it has been previously suggested that climatic changes during the late pleistocene holocene stimulated changes in human behaviour and society in order to evaluate such linkages it is necessary to have a detailed understanding of the climate record we have conducted an extensive and up to date review of terrestrial and marine climatic conditions in the levant and eastern mediterranean during the last 25 000 years we firstly present data from general circulation models gcms simulating the climate for the last glacial maximum lgm and evaluate the output of the model by reference to geological climate proxy data we consider the types of climate data available from different environments and proxies and then present the spatial climatic picture for key climatic events this exercise suggests that the major northern hemisphere climatic fluctuations of the last 25 000 years are recorded in the eastern mediterranean and levantine region however this review also highlights problems and inadequacies with the existing data

an early advance of glaciers on mount akdag sw turkey before the global last glacial maximum insights from cosmogenic nuclides and glacier modeling abstract for the first time in turkey we report an early advance of glaciers before the broadly defined global last glacial maximum lgm forty one moraine boulders from three glacial valleys on mount akdag 36 54 n 29 57 e 3016 m southwest coast of turkey were dated with cosmogenic 36 cl valleys on the north side of the mountain were filled with few km long glaciers that terminated at elevations of about 2000 m above sea level a s l the pre lgm glaciations reached their maximum positions 2150 m a s l by 35 1 2 5 ka ago 1 ka 1000 calendar years the glaciers readvanced during the global lgm and reached their farthest locations 2050 m a s l by around 21 7 1 2 ka ago later glaciers retreated and shortly stabilized during the lateglacial at around 15 1 0 9 ka ago using the glacier modeling and paleoclimate proxies from the eastern mediterranean we estimated that if temperatures during the lgm were 8 11 c colder than modern which is suggested by paleotemperature proxies from the region precipitation was up to two times more than that of today previous estimates on southwest coast of turkey indicate a similar precipitation value while central turkey requires drier conditions implying regional heterogeneity on lgm climates in turkey

basal mechanics of ice stream b west antarctica 2 undrained plastic bed model based on the results of our studies of the physical conditions beneath ice stream b we formulate a new analytical ice stream model the undrained plastic bed model henceforth the upb model mathematically the upb model is represented by a non linear system of four coupled equations which express the relationships among ice sliding velocity till strength water storage in till and basal melt rate we examine this system of equations for conditions of ice stream stability over short timescales that permit holding ice stream geometry constant less than hundreds of years temporal variability is introduced into the upb model only by the direct dependence of till void ratio changes e t on the basal melting rate m r since till strength b e and ice stream velocity u b b change as long as till void ratio varies the first condition for ice stream stability is that of constant till water storage 0 the second condition for ice stream stability arises from the feedback between ice stream velocity till strength and the basal melting rate which depends on shear heating m r u b b this is the weak till condition which requires that in a steady state till strength is a small fraction of the gravitational driving stress b n 1 1 d the salient feature of the upb model is its ability to produce two thermo mechanically controlled equilibrium states one with a strong bed and slow ice velocities ice sheet mode and one with a weak bed and fast ice velocities ice stream mode this bimodality of basal conditions is consistent with the available observations of subglacial conditions beneath slow and fast moving ice in west antarctica basal conditions that do not correspond to these two steady states may occur transiently during switches between the two stable modes the upb model demonstrates that ice streams may be prone to thermally triggered instabilities during which small perturbations in the basal thermal energy balance grow leading to generation or elimination of the basal conditions which cause ice streaming

vegetation and climate of anatolia and adjacent regions during the last glacial period abstract reinterpretation of vegetation and climatic conditions of anatolia and neighboring regions during last glacial 30 15 cal ka bp have been done using a non quantitative biomization approach based on previously published plant functional types the results suggest that the climate was cold and humid before 25 cal ka bp and also during the period 23 19 cal ka bp except east anatolia forest vegetation was 80 90 of the land cover in the northwestern anatolia and black sea coast and 50 60 along the mediterranean coast at the same period during heinrich event 2 from 25 to 23 cal ka bp steppe vegetation dominated the anatolian region due to the sudden change to very cold and arid conditions approximately between 18 and 16 cal ka bp in the late glacial during heinrich event 1 a brief interval of cold and arid conditions resulted in weaker steppe vegetation over some part of anatolia around at 15 cal ka bp suitable climatic conditions for forest vegetation prevailed across a great part of anatolia except for eastern anatolia and western iran which are highlands

age palaeoenvironments and climatic significance of late pleistocene konya lake turkey abstract the konya basin a closed depression at the southern margin of the anatolian plateau contained a shallow but extensive lake during the late quaternary nearshore sands and gravels containing dreissena shells form prominent depositional terraces around the basin edges at elevations between 1005 and 1020 m and the highest has been dated at more than 30 000 yr b p the last major phase of limnic sedimentation occurred between 23 000 and 17 000 yr b p after which the lake fragmented into a number of subbasins or secondary depressions which evolved to become either marshes or playas a final expansion of these residual lakes has been dated to ca 11 000 yr b p in one secondary depression archaeological and other evidence indicate that only minor lake level fluctuations occurred during the holocene the dominant sedimentary process over the last 10 000 years has been alluviation at the basin margin the konya sequence confirms that the most recent period of high lake levels in the northern near east was of the last glacial age the palaeolakes of anatolia and iran were however more a product of reduced evaporation brought about by temperature depression than of changes in precipitation and thus belie their often used description as an indicator of pluvial climatic conditions

assessment of current methods of positive degree day calculation using in situ observations from glaciated regions the continued use of the positive degree day pdd method to predict ice sheet melt is generally favoured over surface energy balance methods partly due to the computational efficiency of the algorithm and the requirement of only one input variable temperature in this paper we revisit some of the assumptions governing the application of the pdd method using hourly temperature data from the gc net network we test the assumption that monthly pdd total pddm can be represented by a gaussian distribution with fixed standard deviation of monthly temperature m the results presented here show that the common assumption of fixed m does not hold and that m may be represented more accurately as a quadratic function of average monthly temperature for greenland the mean absolute error in predicting pddm using our methodology is 3 9 c day representing a significant improvement on current methods 7 8 c day when m 4 5 c over a range of glaciated settings our method reproduces pddm on average to within 1 5 8 5 c day compared to 4 4 15 7 c day when m 4 5 the improvement arises because we capture the systematic reduction in temperature variance that is observed over melting snow and ice when surface temperatures cannot warm above o c

environmental processes of the ice age land oceans glaciers epilog knowledge of the state of the earth at the last glacial maximum lgm an interval around 21 000 years ago is an important benchmark for understanding the sensitivity of global environmental systems to change much progress in understanding climates of the lgm has occurred in the 20 years since the end of the climap project of the 1970s climate long range investigation mapping and prediction here we review this progress based on presentations and discussion at a rst open science meeting of the epilog project environmental processes of the ice age land oceans glaciers held in delmenhorst germany may 1999 we outline key controversies and document protocols for epilog contributions so that a new synthesis of the lgm earth can emerge as an open project of the world s community of scientists 2001 elsevier science ltd all rights reserved

an enthalpy formulation for glaciers and ice sheets polythermal conditions are ubiquitous among glaciers from small valley glaciers to ice sheets conventional temperature based cold ice models of such ice masses cannot account for that portion of the internal energy which is latent heat of liquid water within temperate ice so such schemes are not energy conserving when temperate ice is present temperature and liquid water fraction are however functions of a single enthalpy variable a small enthalpy change in cold ice is a change in temperature while a small enthalpy change in temperate ice is a change in liquid water fraction the unified enthalpy formulation described here models the mass and energy balance for the three dimensional ice fluid for the surface runoff layer and for the subglacial hydrology layer together in a single energy conserving theoretical framework it is implemented in the parallel ice sheet model results for the greenland ice sheet are compared with those from a cold ice scheme this paper is intended to be an accessible foundation for enthalpy formulations in glaciology

last glacial maximum climate in new zealand inferred from a modelled southern alps icefield abstract we present a simulation of the new zealand southern alps icefield at the last glacial maximum lgm c 30 000 20 000 calendar years ago ka in an attempt to constrain the climate of that period we use a 500 m resolution ice sheet model parameterised using empirical glaciological climatological and geological data specific to the model domain to simulate the entire southern alps icefield we find that an lgm cooling of at least 6 6 5 c is necessary to bring about valley glaciers that extend beyond the mountains however climate topography thresholds related to the elevation and hypsometry of individual catchments control the gradient of the rate of glacier expansion in the domain and in order to remain within geologically reconstructed lgm limits we find that the lgm cooling was most likely associated with a precipitation regime up to 25 drier than today wetter than present scenarios give rise to equilibrium line depressions and ice extents that are incompatible with empirical evidence these results perhaps indicate that either the westerly air masses affecting new zealand during the lgm were drier than today or that they were weaker or zonally displaced with respect to present

extensive retreat and re advance of the west antarctic ice sheet during the holocene to predict the future contributions of the antarctic ice sheets to sea level rise numerical models use reconstructions of past ice sheet retreat after the last glacial maximum to tune model parameters 1 reconstructions of the west antarctic ice sheet have assumed that it retreated progressively throughout the holocene epoch the past 11 500 years or so 2 4 here we show however that over this period the grounding line of the west antarctic ice sheet which marks the point at which it is no longer in contact with the ground and becomes a floating ice shelf retreated several hundred kilometres inland of today s grounding line before isostatic rebound caused it to re advance to its present position our evidence includes first radiocarbon dating of sediment cores recovered from beneath the ice streams of the ross sea sector indicating widespread holocene marine exposure and second ice penetrating radar observations of englacial structure in the weddell sea sector indicating ice shelf grounding we explore the implications of these findings with an ice sheet model modelled re advance of the grounding line in the holocene requires ice shelf grounding caused by isostatic rebound our findings overturn the assumption of progressive retreat of the grounding line during the holocene in west antarctica and corroborate previous suggestions of ice sheet re advance 5 rebound driven stabilizing processes were apparently able to halt and reverse climate initiated ice loss whether these processes can reverse present day ice loss 6 on millennial timescales will depend on bedrock topography and mantle viscosity parameters that are difficult to measure and to incorporate into ice sheet models

pollen stratigraphy of late quaternary cores from marmara sea land sea correlation and paleoclimatic history marine pollen analysis is an important tool for paleoclimatic reconstruction of regions like the eastern mediterranean and near east where few onshore sites provide long pollen records first a compilation was made of core top data from the eastern mediterranean to blackseas to map regional variations in modern marine pollenspore concentrations these data show a strong linkbetween pollen spore concentrations and sea surface salinity with minima of 5 grains g in the southern mediterranean and maxima of 160 000 grains g in the blacksea despite under representation of some forest and herbaceous vegetation indicators e g fagus and pistacia variations in species composition of the marine assemblages correspond closely with the distribution of regional vegetation zones and can be used as proxies for spatial differences in seasonal and total temperature and rainfall pollen spore assemblages in five cores from the marmara sea with multiple ages ranging from 33 550 to 1990 yr bp and one holocene core from southeastern blacksea were used to compile a late quaternary marine pollen stratigraphy these data were then compared with eastern mediterranean onshore reference sites in order to reconstruct a vegetation and paleoclimate history for the blacksea aegean corridor from the pleniglacial interval to present five marine pollen zones are recognized pz 5 v33 6 24 ka corresponds to the late wu rm pleniglacial pz 4 v24 13 ka spans the late glacial maximum lgm pz 3 v13 10 2 ka includes the allero d younger dryas glacial interglacial transition pz 2 10 2 4 ka marks the early holocene interglacial warm wet interval and pz 1 covers the latest holocene colonization phase which may also have been cooler and drier using the steppe forest index of traverse 1975 it is shown that the only intervals of severely dry conditions occurred briefly during the lgm and its transition during most of the pleniglacial and all of the postglacial time precipitation versus evaporation rates were sufficiently high to permit persistence of oro mediterranean forest vegetation furthermore there is no evidence for environmental conditions in the blacksea marmara region that would have encouraged pastoral or agricultural settlement in the littoral region prior to the bronze age commencing 4600 years ago crown copyright a 2002 elsevier science b v all rights reserved

seven ambiguities in the mediterranean palaeoenvironmental narrative abstract a review of seven outstanding issues on mediterranean palaeoenvironments is presented these are related to the dominant orbital pacing of climate variability the length of the interglacial vegetation succession the influence of the african summer monsoon the seasonality of precipitation during boreal insolation maxima the moisture balance during glacial maxima and the appearance of the mediterranean type climate rhythm and evolution of mediterranean sclerophyllous plants what emerges is that 1 marine 18oplanktonic and sst records show that precession has been a fundamental tempo of mediterranean climate change representing both a low latitude signal runoff from north africa and the direct influence of insolation at mediterranean latitudes but high latitude glacial effects 41 kyr and 100 kyr cycles became superimposed after 2 8 ma sapropel and dust deposition patterns in marine cores reveal that obliquity also has an effect on mediterranean climate through dry wet oscillations which are independent of glacial interglacial variability 2 the temperate part of interglacial vegetation succession has a duration of approximately half a precession cycle this persisted during the interval of obliquity dominated glacial cycles 2 8 1 ma with distinct forest successions following the precessional cycles however these are not always separated by an open vegetation phase because of minimal ice growth producing an impression of a prolonged interglacial forest interval 3 the effect of an enhanced african monsoon during summer insolation maxima has been mainly indirect in terms of nile discharge and runoff along the north african coast leading to increased freshwater input into the mediterranean sea reduced deep water ventilation and sapropel deposition 4 the notion of an accentuated summer rain regime in the northern mediterranean borderlands also contributing to a freshening of the mediterranean sea during boreal insolation maxima is not supported by the available evidence which suggests increased summer aridity 5 recent improvements in chronological precision and data resolution point to an increase in aridity and decreased temperatures during the last glacial maximum 21 2 ka but suggest an increase in effective moisture during the immediately preceding interval of 24 27 ka 6 the mediterranean type climate is not exclusively a post 3 6 ma phenomenon but may have appeared intermittently during the course of the tertiary or before 7 if that is the case then the paradigm that the sclerophyllous evergreen habit represents a pre adaptation to summer drought may need re evaluation

from pleniglacial to holocene a 14c chronostratigraphy of environmental changes in the konya plain turkey abstract in the endoreic semi arid konya basin on the central anatolian plateaux long term hydrological evolution has left various landforms and lacustrine deposits reflecting the regional climatic evolution as well as human influence on the local environments this paper presents results from a cooperative programme grouping several institutes from turkey and france on lacustrine marshy and aeolian sediment sequences of upper pleistocene and holocene age the detailed study of environmental evolution is based on the reconstruction as well as on the characterization of the extension and contraction phases of wetlands occupying the lowest parts of the konya plain a soil and a marsh layer are 14c dated ca 28 000 25 000 yr bp three phases of pleniglacial from ca 22 000 to 17 000 yr bp high lake levels are distinguished complementary osl dates on aeolian dunes confirm the occurrence of two drought periods the first occurs around the start of the late glacial the second after the mid holocene climatic optimum the latter being in phase with a similar drought in other eastern mediterranean regions after 17 000 yr bp no lacustrine phase reached as high a level as the pleniglacial lake during the late glacial a shallow freshwater lacustrine phase is identified from 12 500 to 11 000 yr bp the late glacial to holocene transition corresponds to a general absence of deposits and dateable material thus suggesting a period of drought to which no aeolian features have so far been related the holocene environmental evolution shows a period of marsh and shallow lake extansion from 6000 to 5500 yr bp this wetter period is interrupted by the second drought ca 5500 yrs bp as indicated by aeolian dune activity during the late holocene a renewal of marshes as well as soil development on slopes can be interpreted either as climatic changes or as impacts of human use of water and soil resources during prehistoric and historic times

climatic changes in eurasia and africa at the last glacial maximum and mid holocene reconstruction from pollen data using inverse vegetation modelling in order to improve the reliability of climate reconstruction especially the climatologies outside the modern observed climate space an improved inverse vegetation model using a recent version of biome4 has been designed to quantitatively reconstruct past climates based on pollen biome scores from the biome6000 project the method has been validated with surface pollen spectra from eurasia and africa and applied to palaeoclimate reconstruction at 6 cal ka bp calendar years the climate was generally wetter than today in southern europe and northern africa especially in the summer winter temperatures were higher 1 5 c than present in southern scandinavia northeastern europe and southern africa but cooler in southern eurasia and in tropical africa especially in mediterranean regions summer temperatures were generally higher than today in most of eurasia and africa with a significant warming from 3 to 5 c over northwestern and southern europe southern africa and eastern africa in contrast summers were 1 3 c cooler than present in the mediterranean lowlands and in a band from the eastern black sea to siberia at 21 cal ka bp a marked hydrological change can be seen in the tropical zone where annual precipitation was 200 1 000 mm year lower than today in equatorial east africa compared to the present a robust inverse relationship is shown between precipitation change and elevation in africa this relationship indicates that precipitation likely had an important role in controlling equilibrium line altitudes ela changes in the tropics during the lgm period in eurasia hydrological decreases follow a longitudinal gradient from europe to siberia winter temperatures were 10 17 c lower than today in eurasia with a more significant decrease in northern regions in africa winter temperature was 10 15 c lower than present in the south while it was only reduced by 0 3 c in the tropical zone comparison of palaeoclimate reconstructions using lgm and modern co2 concentrations reveals that the effect of co2 on pollen based lgm reconstructions differs by vegetation type reconstructions for pollen sites in steppic vegetation in europe show warmer winter temperatures under lgm co2 concentrations than under modern concentrations and reconstructions for sites in xerophytic woods scrub in tropical high altitude regions of africa are wetter for lgm co2 concentrations than for modern concentrations because our reconstructions account for decreased plant water use efficiency

the effect of a holocene climatic optimum on the evolution of the greenland ice sheet during the last 10 kyr the holocene climatic optimum was a period 8 5 kyr ago when annual mean surface temperatures in greenland were 2 3 c warmer than present day values however this warming left little imprint on commonly used temperature proxies often used to derive the climate forcing for simulations of the past evolution of the greenland ice sheet in this study we investigate the evolution of the greenland ice sheet through the holocene when forced by different proxy derived temperature histories from ice core records focusing on the effect of sustained higher surface temperatures during the early holocene we find that the ice sheet retreats to a minimum volume of 0 15 1 2 m sea level equivalent smaller than present in the early or mid holocene when forcing an ice sheet model with temperature reconstructions that contain a climatic optimum and that the ice sheet has continued to recover from this minimum up to present day reconstructions without a warm climatic optimum in the early holocene result in smaller ice losses continuing throughout the last 10 kyr for all the simulated ice sheet histories the ice sheet is approaching a steady state at the end of the 20th century

synchronous last glacial maximum across the anatolian peninsula uludag is a prominent mountain in northwestern turkey where glacial deposits have been documented in the kovuk valley and the glacial history has been reconstructed based on 31 cosmogenic 10 be exposure ages from glacially transported boulders and bedrock the results suggest that the kovuk glacier began advancing before 26 5 1 6 ka it reached its maximum extent at 20 3 1 3 ka followed by a re advance at 19 3 1 2 ka both during the global last glacial maximum lgm within marine isotope stage 2 the timing of the lgm glaciations in the kovuk valley is consistent with the investigated lgm glaciations in other mountains of anatolia the mediterranean and the alps based on the geomorphological ice margin reconstruction and using the accumulation ablation area ratio aar approach the equilibrium line altitude ela of the kovuk lgm glacier was c 2000 m above sea level for an estimated aar of 0 67 this indicates a c 1000 m lowering of the ela for the lgm compared with the modern ela estimate these lines of evidence are consistent with the lgm glaciers that have been documented elsewhere in the anatolian mountains

application of a degree day model to reconstruct pleistocene glacial climates there is empirical evidence of a nonlinear relation between annual precipitation or accumulation and summer mean temperature at the equilibrium line altitude ela on glaciers around the world the degree day model gives a similar relation between accumulation and summer temperature although instead of a single universal curve there is a family of curves depending upon the annual temperature range furthermore the degree day model also gives nonlinear relations between accumulation and annual mean temperature thus estimations of accumulation can be made from both summer and annual temperatures at the ela of former reconstructed glaciers such as those in greece this is particularly useful since these climatic variables have major implications for biological proxies such as vegetation history indicated in the pollen record and for periglacial proxies such as permafrost distributions indicated in the geomorphological record the close relationship between glaciers and climate provides one of the most precise methods for reconstructing former climates and offers considerable potential for resolving our understanding of pleistocene cold stage climates

error sources in basal yield stress inversions for jakobshavn isbrae greenland derived from residual patterns of misfit to observations the basal interface of glaciers is generally not directly observable geophysical inverse methods are therefore used to infer basal parameters from surface observations such methods can also provide information about potential inadequacies of the forward model ideally an inverse problem can be regularized so that the differences between modeled and observed surface velocities reflect observational errors however deficiencies in the forward model usually result in additional errors here we use the spatial pattern of velocity residuals to discuss the main error sources for basal stress inversions for jakobshavn isbrae greenland synthetic tests with prescribed patterns of basal yield stress with varying length scales are then used to investigate different weighting functions for the data model misfit and for the ability of the inversion to resolve details in basal yield stress we also test real data inversions for their sensitivities to prior estimate forward model parameters data gaps and temperature fields we find that velocity errors are not sufficient to explain the residual patterns of real data inversions conversely ice geometry errors and especially simulated errors in model simplifications are capable of reproducing similar error patterns and magnitudes we suggest that residual patterns can provide useful guidance for forward model improvements

evaporation rate from a salt pan estimates from chemical profiles in near surface groundwaters evaporation of water from saturated saline soils or sediments induces gradients of the solutes in the remaining interstitial solution these gradients lead to a systematic and predictable solute distribution in the soil solution which may be used in some cases to estimate the rate of evaporation simple one dimensional transport models for the distribution of cl and br indicate net evaporation rates from the salt covered surface of lake eyre south australia of between 0 9 and 2 8 cm yr 1 the former is a minimum estimate averaged over 20 yrs which includes the major 1974 filling event while the latter reflects the most recent summer evaporation period

glaciations and paleoclimate of mount erciyes central turkey since the last glacial maximum inferred from 36cl cosmogenic dating and glacier modeling abstract forty four boulders from moraines in two glacial valleys of mount erciyes 38 53 n 35 45 e 3917 m central turkey dated with cosmogenic chlorine 36 36cl indicate four periods of glacial activity in the past 22 ka 1 ka 1000 calendar years last glacial maximum lgm glaciers were the most extensive reaching 6 km in length and descending to an altitude of 2150 m above sea level these glaciers started retreating 21 3 0 9 ka 1 ago they readvanced and retreated by 14 6 1 2 ka ago lateglacial and again by 9 3 0 5 ka ago early holocene the latest advance took place 3 8 0 4 ka ago late holocene using glacier modeling together with paleoclimate proxy data from the region we reconstructed the paleoclimate at these four discrete times the results show that lgm climate was 8 11 c colder than today and moisture levels were somewhat similar to modern values with a range between 20 more and 25 less than today the analysis of lateglacial advance suggests that the climate was colder by 4 5 6 4 c based on up to 1 5 times wetter conditions the early holocene was 2 1 4 9 c colder and up to twice as wet as today while the late holocene was 2 4 3 c colder and its precipitation amounts approached to similar conditions as today our paleoclimate reconstructions show a general trend of warming for the last 22 ka and an increase of moisture until early holocene and a decrease after that time the recent glacier terminates at 3450 m on the northwest side of the mountain it is a remnant from the last advance possibly during the little ice age repeated measurements of glacier length between 1902 and 2008 reveal a retreat rate of 4 2 m per year which corresponds to a warming rate of 0 9 1 2 c per century