early eocene asian climate dominated by desert and steppe with limited monsoons abstract paleoenvironmental reconstructions illustrated that asia was dominated by a zonal climate pattern in the eocene epoch with an almost latitudinal arid semiarid band extending from the eastern coast of china to central asia however the mechanism behind the formation of the broad zonal arid semiarid region and the possible occurrence of a monsoonal system remains unclear for that period here using a reconstructed land sea distribution and topography of 50 ma we employed a global climate model to simulate the early eocene climate in china a set of experiments with consideration to different topography orbital parameters vegetation sea surface temperature and atmospheric co2 concentration demonstrated that a large extent of arid semi arid region with annual precipitation less than 800 mm was distributed latitudinally between 20 n and 40 n paleolatitude in china this arid region was controlled by desert bwh and steppe bsh climates according to the koppen climate classification systems on the north of the zonal desert steppe region a mediterranean like climate occurred in central asia these simulations agree well with the geological reconstructions of a zonal desert steppe region and indicate that this pattern was primarily caused by subtropical high pressures associated with strong descending air however it is likely that the aridity in the zonal desert steppe was reduced occasionally by intensification of monsoon circulations over east asia the change in orbital parameters causing enhanced insolation in summer was the most likely factor that could enlarge the land sea thermal contrast and further intensify the monsoon circulations in the eocene epoch though its effect was reversible and impermanent in addition simulations show that east asian monsoon did not play a leading role in chinese paleogene climate although it may have affected eastern china occasionally

oligocene storm induced lacustrine deposits in the yaxi area of the jiuxi basin northeastern margin of the tibetan plateau abstract storm induced deposits in the sedimentary record can now be easily identified on account of a better understanding of processes of unidirectional and oscillatory flow thin bedded sandstone siltstone and interlayered mudstone deposits of the oligocene jianquanzi member in the yaxi area of the jiuxi basin along the northeastern margin of the tibetan plateau were formed by shallow lacustrine storm generated flows petrologic analysis reveals that the sandstones exhibit moderate to high compositional maturity but are texturally sub mature to immature based on investigation of drill cores six storm deposit lithofacies are identified including massive or graded sandstone parallel and trough cross bedded sandstones hummocky cross stratified sandstone wave rippled sandstone and siltstone massive or horizontal bedded mudstone and structurally deformed sandstone and mudstone in a vertical succession these lithofacies occur as three fining upward lithofacies associations each of which represents different architectural elements and depositional processes of proximal to distal storm deposits the relatively coarse proximal architectural element is formed by strong density flows and unidirectional dominated combined flows the transitional architectural element is dominated by unidirectional and oscillatory dominated combined flows to pure oscillatory flows resembling tb e divisions of the classic bouma sequence the relatively fine distal architectural element is dominated by unidirectional dominated combined flows with a very weak oscillatory flow component the origin of storms responsible for these deposits is attributed to asian winter monsoons associated with the paleoclimatic and paleogeographic setting

a new paleoclimate classification for deep time in deep time climates are mainly classified by climatically sensitive deposits paleontological evidences and modeling however they only have limited applicability in deep time studies here we propose a new paleoclimate classification based on the widely used koppen climate classification the proposed new classification is simple and quantitative but bridges the gap between modern and deep time climate studies the new classification is closely related to but differs from that of koppen by changing some limits a world map using the new classification shows the same patterns as the world map of the koppen climate classification using the new classification we are able to solve a long standing problem about the climates of east asia during the eocene we found that east asia shared the same climate type ca subtropical at all studied locations supporting the hypothesis of monsoon or monsoon like climate that prevailed there during the eocene

whiting events and the formation of aragonite in mediterranean karstic marine lakes new evidence on its biologically induced inorganic origin this paper discusses the formation of whiting events drifting milky clouds of water and their role in the formation of recent aragonite sediments in a semi enclosed karstic marine lake on the island of mljet adriatic sea this study is based on detailed structural morphological and sedimentological characterization of and strontium distribution in particles originating from suspended matter and sediments the particles were examined by x ray diffraction and electron diffraction analyses scanning and transmission electron microscopy as well as electron microprobe energy dispersive x ray analyses and atomic absorption spectroscopy morphological features granulometric characteristics strontium enrichment and characteristic details of the aragonite structure in the needle like particles were identical in both the suspended matter collected during whiting events and in the bottom sediments the whiting events which occasionally occurred in surface waters were found to be sites of short term active authigenic aragonite precipitation and the main source of fine grained aragonite mud this study exemplifies the role of biologically induced inorganic precipitation processes in the formation of recent aragonite mud in a restricted mediterranean environment

the coexistence approach a method for quantitative reconstructions of tertiary terrestrial palaeoclimate data using plant fossils abstract the coexistence approach is introduced as a method for quantitative terrestrial palaeoclimate reconstructions in the tertiary it is based on the assumption that tertiary plant taxa have similar climatic requirements to their nearest living relatives the aim of the coexistence approach is to find for a given fossil flora and a given climate parameter the climatic interval in which all nearest living relatives of the fossil flora can coexist for this purpose we have developed a data base climbot containing for over 800 tertiary plant taxa the nearest living relatives and their climatic requirements and an algorithm for analysis climst for all types of fossil floras the coexistence approach thus allows the rapid quantitative reconstruction of 10 different climate parameters including the mean annual temperature temperature of the warmest month temperature of the coldest month mean annual precipitation maximum monthly precipitation minimum monthly precipitation precipitation of the warmest month relative humidity potential evaporation as well as the ratio of mean annual precipitation over potential evaporation the reliability and resolution of the coexistence approach are tested with various techniques and proved to be reasonably good for instance the resolution with respect to the mean annual temperature can be up to 1 c applications to various modern and fossil floras are illustrated and the advantages and disadvantages of the coexistence approach are discussed

stable warm tropical climate through the eocene epoch earth s climate cooled from a period of extreme warmth in the early eocene epoch ca 50 ma to the early oligocene ca 33 ma when a large ice cap first appeared on antarctica evidence from the planktonic foraminifer oxygen isotope record in deep sea cores has suggested that tropical sea surface temperatures declined by 5 10 degrees over this interval eventually becoming much cooler than modern temperatures here we present paleotemperature estimates from foraminifer isotopes and the membrane lipids of marine crenarcheota from new drill cores in tanzania that indicate a warm and generally stable tropical climate over this period we reinterpret the previously published isotope records in the light of comparative textural analysis of the deep sea foraminifer shells which shows that in contrast to the tanzanian material they have been diagenetically recrystallized we suggest that increasingly severe alteration of the deep sea plankton shells through the eocene produced a diagenetic overprint on their oxygen isotope ratios that imparts the false appearance of a tropical sea surface cooling trend this implies that the long term eocene climatic cooling trend occurred mainly at the poles and had little effect at lower latitudes

cenozoic environmental evolution of the qaidam basin and its implications for the uplift of the tibetan plateau and the drying of central asia abstract a complete cenozoic pollen sequence of the qaidam basin has been constructed with absolute age control the cenozoic environmental evolution of the qaidam basin and its implications for the uplift of the tibetan plateau and the drying of central asia during the cenozoic era is discussed based on the interpretation of the pollen sequence the commencement of eolian deposition in central china and the change of climatic distribution pattern of china the results suggest that in the qaidam basin relatively dry climates prevailed in the eocene oligocene and pliocene pleistocene these dry periods resulted from the effects of a subtropical high pressure zone and the uplift of the surrounding mountains and the tibetan plateau respectively about a 600 km northward drift of western china has probably occurred during the late cenozoic resulting in the eocene oligocene arid climate belt twisting about six degrees of latitude the tibetan plateau reached probably 1500 m elevation by the latest miocene 8 5 ma not as high as it was thought previously the cenozoic environmental evolution of northwest china does not support the idea that the retreat of the paratethys sea played an important role in the late cenozoic drying of central asia at least not in northwest china

how wet was the arctic eocene rain forest estimates of precipitation from paleogene arctic macrofloras the eocene was the warmest part of the cenozoic when warm climates extended into the arctic and substantive paleobotanical evidence indicates broadleaf and coniferous polar forests paleontological temperature proxies provide a basis for understanding arctic early paleogene climates however there is a lack of corresponding proxy data on precipitation both leaf physiognomic analysis and quantitative analysis of nearest living relatives of an arctic macroflora indicate upper microthermal to lower mesothermal moist climates mean annual temperature 13 15 c cold month mean temperature 4 c mean annual precipitation 120 cm yr for axel heiberg island in the middle eocene leaf size analysis of paleocene and eocene arctic floras demonstrates high precipitation for the paleogene western and eastern arctic the predicted enormous volume of freshwater entering the arctic ocean as a result of northward drainage of a significant region of the northern hemisphere under a high precipitation regime would have strongly affected arctic ocean salinity potentially supporting arctic ocean azolla blooms high paleogene precipitation around the arctic basin is consistent with high atmospheric humidity which would have contributed significantly to polar and global eocene warming

how old is the asian monsoon system palaeobotanical records from china the recent discovery of monsoon records in early miocene raised a question of the time when the east asian monsoon system initiated a distinguishing feature of the modern monsoon system is its geographic distribution which disturbs the zonal pattern indigenous to the planetary climate system and the appearance of the monsoonal climate pattern in the geological records should signify the onset of the monsoon system here we present the results of a compilation of palaeobotanical and lithological data from 125 sites over china that has revealed two completely different patterns of climate zones the palaeogene pattern with a broad belt of aridity stretched across china from west to east and the neogene pattern with the arid zone restricted to northwest of china which has persisted until today the reorganization of the climate system around the oligocene miocene boundary provides evidence for the establishment of the modern east asian monsoon since then the neogene has witnessed significant variations of the monsoon system including enhancement of aridity and monsoon intensity at about 15 13 my around 8 my and 3 my the new data do not support the onset of the asian monsoon system around 8 my rather the new data led to a hypothesis that the transition to the monsoon climate system in east asia occurred in the latest oligocene

asian monsoons and aridification response to paleogene sea retreat and neogene westerly shielding indicated by seasonality in paratethys oysters asian climate patterns characterised by highly seasonal monsoons and continentality are thought to originate in the eocene epoch 56 to 34 million years ago ma in response to global climate tibetan plateau uplift and the disappearance of the giant proto paratethys sea formerly extending over eurasia the influence of this sea on asian climate has hitherto not been constrained by proxy records despite being recognised as a major driver by climate models we report here strongly seasonal records preserved in annual lamina of eocene oysters from the proto paratethys with sedimentological and numerical data showing that monsoons were not dampened by the sea and that aridification was modulated by westerly moisture sourced from the sea hot and arid summers despite the presence of the sea suggest a strong anticyclonic zone at central asian latitudes and an orographic effect from the emerging tibetan plateau westerly moisture precipitating during cold and wetter winters appear to have decreased in two steps first in response to the late eocene 34 37 ma sea retreat second by the orogeny of the tian shan and pamir ranges shielding the westerlies after 25 ma paleogene sea retreat and neogene westerly shielding thus provide two successive mechanisms forcing coeval asian desertification and biotic crises

a high resolution study of trace elements and stable isotopes in oyster shells to estimate central asian middle eocene seasonality modern asian climate is characterized by strong seasonality caused by the duality between monsoon dominated conditions in southeastern asia and semi arid to arid conditions in central asia eocene high resolution proxy records which enable the reconstruction of the onset and magnitude of changes in seasonality are lacking to understand in details how and when this climatic turnover pattern occurred here we propose an original method to estimate inter and intra annual variabilities in seawater temperature and salinity recorded by carbonate shell growth increments of the fossil oyster sokolowia buhsii grewingk collected from late lutetian marine strata of the proto paratethys in the southwestern tarim basin western china elemental ratio mg ca mn ca and carbonate stable isotope composition 18o were determined perpendicular to the growth lines of foliated calcite accumulated in the ligamental area during the oyster s lifetime we use temperature dependant mg incorporation to estimate seasonal temperature contrast in the past results suggest a warm annual average temperature 27 28 c with large offset between summer and winter temperatures until t 19 c combining these temperature estimates with stable oxygen isotope analyses from the same growth increments we deconvolve seawater 18osw as a proxy for salinity this suggests an average annual salinity about 34 35 increasing strongly during summer months and decreasing in winter based on these data we conclude that during the middle eocene central asian climate was characterized by a strong intra seasonal variability in both temperature and salinity although the subtidal setting might have contributed to the strong seasonal offsets this still suggests that semi arid to arid conditions prevailed during summer whereas winter was characterized by enhanced rainfall these results are consistent with previous regional palaeoenvironmental data and climate modelling experiments they thus attest for the reliability of the method developed here as a seasonal palaeoclimatic indicator

revisiting the paleogene climate pattern of east asia a synthetic review abstract east asian paleogene climates have long been regarded as controlled by the planetary wind system which might result in a climate pattern with three latitudinally distributed zones two humid zones located separately in the north and south were lithologically designated by coals and oil shales while an arid zone in the middle was represented by red beds and evaporites because the middle arid zone was located along 30 n paleolatitude its presence had been further linked with a then subtropical high however this long standing model has recently been challenged by growing evidence from petrology sedimentology paleontology paleobiogeography paleoclimatology and climate modeling here we review the primary data from these disciplines and reinterpret their climate significances to revisit the east asian climate pattern during the paleogene petrologically while the occurrence of coals and or oil shales is accepted as an indicator for overall humid climates that of red beds and or evaporites is highly equivocal to exclusively indicate perennial arid climates unless their origins are carefully investigated in reality generic red beds merely represent an oxidizing environment not essentially associated with a single specific climate type meanwhile evaporites although typically precipitated in arid environments may be deposited in either perennial dry or seasonal monsoonal climates there is no solid evidence so far to convincingly support that the landscape of the so called middle arid zone was dominated by desert and or steppe under a then subtropical high during most of the paleogene the plant function type study additionally suggests that the middle arid zone appears to be lack of xerophytic vegetation even though some xerophytic or sclerophyllous plant taxa did sporadically occur interestingly paleozoological data show that the paleogene mammalian faunas were somewhat equably distributed over east asia strongly suggesting the evident absence of a critical biogeographical or climatic barrier stretched across the middle arid zone as the planetary wind model implied in contrast to the planetary wind model monsoonal or monsoon like paleogene climates have been broadly reported from the northern middle and southern east asia as well as adjacent regions of russia and kazakhstan if only the indicators for humid climates are considered simply due to the uncertainty of those for perennial arid climates east asia must have had a relatively dry region in the continental interior during the late eocene to oligocene transition likely caused by the continentality and or the rain shadow effect along with the global cooling the monsoonal interpretation is highly in agreement with the evidence from floras faunas basin analyses and modeling experiments and well explicates the paleogene climate distribution and seasonal dynamics of east asia however further studies will be largely needed to verify whether uniformly according to the modern criteria the paleogene climates of the east asia interior can be accurately attributed to the arid category

eocene monsoon prevalence over china a paleobotanical perspective abstract proxy based quantitative estimates of eocene climates can be made from marine isotope records for ocean conditions or fossil plants for terrestrial environment however our understanding about eocene terrestrial climates is derived mainly from north america and europe and little is known about east asia previous qualitative paleoclimate studies briefly revealed three climatic regimes across china during the eocene with a planetary wind dominated subtropical to tropical arid zone in the central part i e the subtropical highs which was flanked by the subtropical climate zone in the north and tropical climate zone in the south but such a pattern of paleoclimatic zonation still requires a test from quantitative study based on analyses of 66 plant assemblages carefully selected from 37 fossil sites throughout china we here report the first large scale quantitative climatic results and discuss the eocene climatic patterns in china our results demonstrate that the eocene monsoonal climate must have been more or less developed over china judging from the presence of apparent seasonality of both temperature and precipitation revealed by our quantitative estimation this appears not to support the previously claimed eocene planetary wind dominated climate system at least in the region of eastern china in addition the research indicates that with a slight declining trend of mat during the eocene the winter temperature substantially dropped in tropical southern china during the middle to late eocene interval this might be related to the development of a weak eocene kuroshio current in the southwestern pacific and or a significantly enhanced paleo winter monsoon from siberia

climatic change during the palaeocene to eocene based on fossil plants from fushun china abstract by applying the coexistence approach ca to palynological data from the laohutai lizigou guchengzi jijuntun and xilutian formations in fushun northeastern china a quantitative reconstruction of the palaeocene to eocene climate is made during that time mean annual temperature changed from 11 3 to 21 c mean annual precipitation from 654 to 1540 mm mean temperature of the warmest month from 19 4 to 28 2 c mean temperature of the coldest month from 3 6 to 13 9 c mean annual range of temperature from 12 8 to 23 5 c mean maximum monthly precipitation from 175 to 354 mm and mean minimum monthly precipitation from 8 to 27 mm all the parameters in the five formations indicate a subtropical climate this situation is different from the current climate at the same site a mid temperate and continental monsoon climate with a mean annual temperature of 6 6 c and a mean annual precipitation of 804 mm in addition the climatic parameters obtained from megafossil data only found in the jijuntun formation were analyzed and approximate those from the palynological data the parameters from the palynological data support the view that the palaeogene climate of northeast asia and north america was similar but unlike that of europe

tibetan uplift prior to the eocene oligocene climate transition evidence from pollen analysis of the xining basin uplift of the tibetan plateau and the himalayas since the onset of the indo asia collision is held responsible for asian aridifi cation and monsoon intensifi cation but may also have gradually cooled global climate leading to the 34 ma eocene oligocene transition to unravel the interplay between tibetan uplift and global climate proxy records of asian paleoenvironments constrained by accurate age models are needed for the paleogene period here we report the 38 ma appearance of high altitude vegetation recovered from palynological assemblages in precisely dated lacustrine sediments from the xining basin of the northeastern tibetan plateau region this result confi rms previous evidence for important regional uplift in the central and northern tibetan plateau regions during the early stage of the indo asia collision this is consistent with the idea that the associated increase in rock weathering and erosion contributed to lowering of atmospheric co 2 leading to the eocene oligocene transition

geomorphology lithofacies and sedimentary environment of lacustrine carbonates in the eocene dongying depression bohai bay basin china abstract the eocene lacustrine carbonates in the western dongying depression bohai bay basin were examined based on integrated analysis of 3d seismic data cores thin sections and geochemical testing seismic profiles and geomorphological mapping revealed a landmass attached semi isolated carbonate platform restricted by marginal syn sedimentary faults and surrounded by three deep sags 3d topographic analysis of the platform revealed six districts characterized by variable buried depths topographic gradient and fault combinations including two flat topped areas pfw and sd topographic gradient

impacts of tectonic changes on the reorganization of the cenozoic paleoclimatic patterns in china abstract geologic studies have illustrated that the planetary wind dominant climate in the paleogene is changed into the monsoon dominant one near the oligocene miocene boundary in china the evolution is marked by the changes of regional aridity humidity contrasts the contrasts occur between the south and the north part of china in the eocene and then between east china and central asia near the oligocene miocene boundary indicating the onset of monsoon dominant climate in china the impacts of the himalaya tibetan plateau uplift and or the paratethys sea retreat on the asian monsoon have been well demonstrated however whether or not other factors have affected the above reorganization of paleoclimatic patterns remains a question to be addressed additional factors that should be addressed at least include the indian peninsular drift the south china sea expansion and the east china sea transgression here we use the iap agcm to explore their roles in the above paleoclimatic evolution our experiments demonstrate that the south china sea expansion is another major forcing in addition to the important roles of the paratethys retreat and the himalaya tibetan plateau uplift on the contrary the impacts of the indian peninsular drift and the east china sea transgression are relatively subordinate the himalaya tibetan plateau uplift plays a crucial role in the magnification of the aridity humidity contrasts between the south and the north part of china the paratethys retreat the himalaya tibetan plateau uplift and the south china sea expansion coact to cause the formation of the aridity humidity contrasts between east china and central asia the retreat and the uplift favor the dynamic condition and the expansion provides the water vapor condition for the monsoon dominant climate in china

eocene continental climates and latitudinal temperature gradients global climate during the mesozoic and early cenozoic is thought to have been warmer than at present but there is debate about winter temperatures paleontological data indicate mild temperatures even at high latitudes and in mid latitude continental interiors whereas computer simulations of continental paleoclimates produce winter temperatures closer to modern levels foliar physiognomy and floristic composition of 23 eocene floras from the interior of north america and australia indicate cold month means generally 2 c even where the mean annual temperature mat was

the evolution of miocene climates in north china preliminary results of quantitative reconstructions from plant fossil records the miocene climate evolution in north china is preliminarily discussed by means of comparisons in seven climate parameters quantitatively reconstructed by the coexistence approach on 34 selected macro and microfloras over north china the miocene temperatures show no great difference in the western and eastern part of north china temperature fluctuations particularly in mean annual temperature are found within floras from several sites the fluctuation pattern from a climate optimum in the mid miocene to cooling decline in the late miocene is generally consistent with the global trend of miocene temperature change the reconstructed precipitation from all the sites studied shows much wetter conditions in north china during the miocene than at present which corroborates the results from paleoprecipitation proxy of fossil mammals like the situation in paleo temperature the miocene precipitation from north china shows no distinct difference between the western and eastern regions it is suggested that north china particularly in the western part was by no means under an arid or semi arid environment during the miocene north china is an ideal region for study of the impact of the east asian monsoon system however the pattern of precipitation change derived from the monsoon index msh and mean annual precipitation map shows contradictory results therefore there appears no definite conclusion on when the east asian summer monsoon intensified possible reasons for inconsistency in temperature and precipitation changes are discussed directions of future work to improve the resolution of climate evolution are also pointed out c 2010 elsevier b v all rights reserved

precipitation patterns in the miocene of central europe and the development of continentality abstract understanding climate patterns with their decisive influence on plant distribution and development is crucial to understanding the history of vegetation patterns in europe during the miocene this paper presents the detailed analyses of several precipitation parameters including monthly precipitation of the wettest driest and warmest months for five miocene stages in conjunction with seasonality of temperature those parameters provide a meaningful measure of continentality and can help to document miocene climate changes and patterns and their possible influence on vegetation climate reconstructions provided here are entirely based on palaeobotanical material in total 169 miocene floras were selected including 14 burdigalian 41 langhian 40 serravallian 36 tortonian and 38 messinian localities all floras were analysed using the coexistence approach the analysis of several precipitation parameters the statistical inter correlation of results and the comparison with modern patterns provides a comprehensive account on miocene precipitation miocene climatic changes after the mid miocene climatic optimum mmco are evidenced in our data set by three major factors i e 1 increasing seasonality of temperature 2 changes in the annual distribution of precipitation towards a precipitation peak in summer and 3 a late increase of longitudinal gradients of precipitation parameters evidence of continental climate in eastern europe first appears during the messinian in addition to changes in temperature shifts in the annual distribution of precipitation may have played a major role in post langhian climate changes however the most significant climatic transformations occurred later from the end of miocene through to the present several authors have described patterns of vegetation development in europe that are in good agreement with our finding of the first evidence for continental climate in eastern europe during the messinian our data do not support an onset of opening of vegetation during the tortonian or even earlier as has been described for some parts of eastern and southern europe possibly either non climatic parameters influenced such an early development or our data lack the required resolution and or spatial coverage to fully decipher the influence of continentality on vegetation and to correlate climate and vegetation statistically nevertheless climatic data that quantify continentality can provide a sound basis for explaining the expansion of grassland in eurasia

isotopic and hydrologic responses of small closed lakes to climate variability comparison of measured and modeled lake level and sediment core oxygen isotope records abstract simulations conducted using a coupled lake catchment isotope mass balance model forced with continuous precipitation temperature and relative humidity data successfully reproduce within uncertainty limits long term i e multidecadal trends in reconstructed lake surface elevations and sediment core oxygen isotope 18 o values at castor lake and scanlon lake north central washington error inherent in sediment core dating methods and uncertainty in climate data contribute to differences in model reconstructed and measured short term i e sub decadal sediment i e endogenic and or biogenic carbonate 18 o values suggesting that model isotopic performance over sub decadal time periods cannot be successfully investigated without better constrained climate data and sediment core chronologies model reconstructions of past lake surface elevations are consistent with estimates obtained from aerial photography simulation results suggest that precipitation is the strongest control on lake isotopic and hydrologic dynamics with secondary influence by temperature and relative humidity this model validation exercise demonstrates that lake catchment oxygen isotope mass balance models forced with instrumental climate data can reproduce lake hydrologic and isotopic variability over multidecadal or longer timescales and therefore that such models could potentially be used for quantitative investigations of paleo lake responses to hydroclimatic change

mg ca in fossil oyster shells as palaeotemperature proxy an example from the palaeogene of central asia fossil oyster shells are well suited to provide palaeotemperature proxies from geologic to seasonal timescales due to their ubiquitous occurrence from triassic to quaternary sediments the seasonal nature of their shell growth and their relative strong resistance to post mortem alteration however the common use to translate calcitic oxygen isotopes into palaeotemperatures is challenged by uncertainties in accounting for past seawater 18o especially in shallow coastal environment where oysters calcify in principle the mg ca ratio in oyster shells can provide an alternative palaeothermometer several studies provided temperature calibrations for this potential proxy based on modern species nevertheless their application to palaeo studies remains hitherto unexplored here we show that past temperature variability in seawater can be obtained from mg ca analyses from selected fossil oyster species and specimens high resolution mg ca profiles combined with 18o were obtained along 41 fossil oyster shells of seven different species from the palaeogene proto paratethys sea central asia found in similar as well as different depositional age and environments providing comparison suitable mg ca profiles defined by continuous cyclicity and reproducibility within one shell are found to be consistent for specimens of the same species but differ systematically between species implying a dominant species specific effect on the mg ca signal two species studied here ostrea turkostrea strictiplicata and sokolowia buhsii provide an excellent proxy for palaeoclimate reconstruction from china to europe in palaeogene marine sediments more generally the protocol developed here can be applied to identify other fossil oyster species suitable for palaeoclimate reconstructions

palaeoclimate and vegetation change in serbia during the last 30 ma abstract in the present study 14 published megafloras from the serbian cenozoic are analyzed with respect to vegetation type palaeoclimate and palaeogeographic settings the floras cover a time span from the oligocene to the late miocene the results obtained are compared with continental climate records from other parts of europe and discussed in the context of global climate change to obtain a quantitative palaeoclimate record a total of seven different climate variables is calculated for each of the floras using the coexistence approach it is shown that basic patterns of vegetation change such as the immigration of arcto tertiary deciduous floristic elements during the early miocene and the decreasing diversity of laurophyllous taxa during the late miocene are ruled by climate change and a changing palaeogeography the serbian cenozoic climate record shows a steep cooling gradient during the oligocene that is most probably is connected to a northward movement of tectonic plates the globally observed middle miocene climate optimum and the late miocene cooling are well reflected according to the palaeotemperatures calculated a warm temperate climate existed in serbia throughout the time span examined the late miocene cooling is most pronounced in winter temperatures and is connected to increasing seasonality precipitation rates obtained for the serbian cenozoic especially those of the warmest and wettest months tend to be lower when compared to the central european cenozoic according to climate analysis and the interpretation of vegetational data there is evidence for regionally drier conditions and increased seasonality of precipitation in the time span from the late badenian to the early sarmatian

late cenozoic central asian drying inferred from a palynological record from the northern tian shan abstract sediments contained in basins adjacent to great mountains provide opportunities to reconstruct the aridification history of central asia here we use a palynological record from the fluviolucustrine jingou river section collected from the northern tian shan nw china to reconstruct aridification in central asia during the late cenozoic biogeomagnetic results show that the section was continuously deposited through the interval 28 4 2 ma the palynological record with the auxiliary of the principal component analysis and the diversity index indicates that a late oligocene wet condition existed in central asia and shifted to dry conditions at 23 8 23 3 ma the dry condition remained until 17 3 ma and subsequently ameliorated to a relatively wet stage to 16 2 ma but then began to increase once again and reached a peak at 13 5 ma that last throughout the late miocene and the early pliocene comparing the aridification process to the global temperature trend and history of tectonics we suggest that the long term drying trend in central asia is dominated by late cenozoic cooling while the dry events that occurred at 23 8 23 3 ma and 16 2 13 5 ma are more likely associated with regional mountain building the land sea redistribution further complicated the drying processes

formation and evolution of gobi desert in central and eastern asia abstract although the development of gobi desert in central and eastern asia has greatly affected the regional and even the global climate its precise origin and evolution have yet to be determined the three preconditions for the formation of gobi desert are i a dry climate ii basin landforms and iii abundant sediment production in this study we present a synthesis of both new and published data on the formation and evolution of gobi desert in central and eastern asia we conclude that the combined effects of mountain building the mid latitude westerly circulation and changes in the asian monsoon accompanied by global cooling were principally responsible for the formation of modern gobi desert landscapes in central and eastern asia during the late pliocene the arid climate in central and parts of eastern asia probably developed in the early cenozoic from 50 ma related events included the collision of the indian and asian plates the closure and complete retreat of the paratethys ocean from central asia and the growth of the himalayas and the tibetan plateau in the eocene through late miocene which blocked the water vapor supply and intensified the aridification of the asian interior superimposed on the topographic changes was the process of stepwise global cooling since the early oligocene and in particular since the late miocene which controlled the formation and evolution of the gobi desert landscape global cooling weakened the asian monsoon circulation strengthened the westerly circulation and enhanced physical weathering processes in mountain areas which together promoted both the aridification of the asian interior and sediment production these processes finally resulted in the establishment of the modern gobi desert landscape in the late pliocene we estimate that the modern gobi desert landscape was formed at 2 6 ma and was the result of the stepwise evolution of asian topography and climate during the cenozoic dominated by asian tectonic deformation and uplift and the evolution of asian monsoon climate and the westerly circulation forced by global temperature change

the evolution of latitudinal temperature gradients from the latest cretaceous through the present abstract latitudinal temperature gradients are a defining characteristic of the climate system using thermometric indicators including 18o plant and animal fossils glycerol dialkyl glycerol tetraether gdgt proxies and clumped isotope estimates we document marine and terrestrial temperature gradients for the latest cretaceous late paleocene early eocene early oligocene pliocene and recent the changes in gradients reflect the transition greenhouse to icehouse conditions the evolution of latitudinal temperature gradients in marine and terrestrial realms are similar but has some distinctive differences marine temperatures are generally warmer than those on land except for the late paleocene early eocene the marine records show distinct inflection points at 30 and 50 latitude indicating the existence of frontal systems in the ocean except for the late paleocene early eocene the marine records show an increasingly steeper trend from latest cretaceous through recent being most pronounced after the early oligocene greenhouse icehouse transition this trend reflects the increasing intensity of high latitude and polar cooling as the icehouse state developed during the late paleocene early eocene the oceans were characterized by slightly warmer tropics and much warmer higher latitudes than at present the continents have generally had tropical temperatures like those of today varying by

why do foliar physiognomic climate estimates sometimes differ from those observed insights from taphonomic information loss and a clamp case study from the ganges delta abstract palaeoclimate estimates derived from plant based proxies are potentially subject to uncertainties arising from taphonomic filtering in any given fossil assemblage it is possible to identify the kinds of likely taphonomic influences but virtually impossible to quantify the uncertainties they introduce because filtering removes information because that information is missing it cannot be measured an alternative approach is to measure the maximum uncertainty possible due to specific information loss within recognised analytical protocols in respect of the multivariate foliar physiognomic technique known as clamp climate leaf analysis multivariate program we have attempted to do this by experimentally degrading both the character state scores and the number and composition of taxa as subsets of the full range of character states and taxonomic diversity in the source vegetation in this study a stand of protected vegetation on green island 23 08 58 n 88 26 59 19 e within the ganges delta was sampled following standard clamp protocols the island is subject to annual flooding during the monsoon season and is typical of the kinds of naturally disturbed vegetation likely to be represented in ancient delta floodplain assemblages a total of 56 woody dicot taxa were scored in the living vegetation from this complete sample leaf character states for lobing margin size apex base length to width ratio and shape were removed in turn from all 56 taxa to give 7 analyses simulating worst case taphonomic loss of physiognomic data ten subsets of 20 randomly selected taxa were also analysed to simulate taphonomic diversity loss of almost two thirds of the potentially available taxa in the source vegetation in all cases the completeness statistic remained above the clamp recommended minimum of 0 66 the results show that in all cases the uncertainties arising from taphonomic processes either through taphonomic diversity or character state filtering were not significantly different from the statistical clamp uncertainties associated with the most commonly used calibration dataset physg3brc and gave similar climatic estimates as the source vegetation in its entirety this suggests that stratigraphically well constrained museum collections lacking detailed sedimentary or taphonomic context can still be used with confidence for clamp analyses leaf margin analysis displayed a greater sensitivity to diversity loss the green island estimates suggested a cooler moister climate than that indicated by the observed regional climate as derived from a 0 5 0 5 gridded data set used in climate modelling evaluation the likely cause for this disparity is the prevalence of a sub canopy microclimate signal developed by the vegetation itself and this is strongly dependant on the temperature and humidity characteristics of the regional climate as well as the proximity to water bodies within the sample size limitations of this study this disparity is larger than that introduced by taphonomic processes but potentially can be corrected for

cenozoic continental climatic evolution of central europe continental climate evolution of central europe has been reconstructed quantitatively for the last 45 million years providing inferred data on mean annual temperature and precipitation and winter and summer temperatures although some regional effects occur the european cenozoic continental climate record correlates well with the global oxygen isotope record from marine environments during the last 45 million years continental cooling is especially pronounced for inferred winter temperatures but hardly observable from summer temperatures correspondingly cenozoic cooling in central europe is directly associated with an increase of seasonality in contrast inferred cenozoic mean annual precipitation remained relatively stable indicating the importance of latent heat transport throughout the cenozoic moreover our data support the concept that changes in atmospheric co2 concentrations although linked to climate changes were not the major driving force of cenozoic cooling

changes in tibetan plateau latitude as an important factor for understanding east asian climate since the eocene a modeling study abstract previous climate modeling studies suggest that the surface uplift of the himalaya tibetan plateau tp is a crucial parameter for the onset and intensification of the east asian monsoon during the cenozoic most of these studies have only considered the himalaya tp in its present location between 26 n and 40 n despite numerous recent geophysical studies that reconstruct the himalaya tp 10 or more of latitude to the south during the early paleogene we have designed a series of climate simulations to explore the sensitivity of east asian climate to the latitude of the himalaya tp our simulations suggest that the east asian climate strongly depends on the latitude of the himalaya tp surface uplift of a proto himalaya tp in the subtropics intensifies aridity throughout inland asia north of 40 n and enhances precipitation over east asia in contrast the rise of a proto himalaya tp in the tropics only slightly intensifies aridity in inland asia north of 40 n and slightly increases precipitation in east asia importantly this climate sensitivity to the latitudinal position of the himalaya tp is non linear particularly for precipitation across east asia the simulated precipitation patterns across east asia are significantly different between our scenarios in which a proto plateau is situated between 11 n and 25 n and between 20 n and 33 n but they are similar when the plateau translates northward from between 20 n and 33 n to its modern position our simulations when interpreted in the context of climate proxy data from central asia support geophysically based paleogeographic reconstructions in which the southern margin of a modern elevation proto himalaya tp was located at 20 n or further north in the eocene

cenozoic climate gradients in eurasia a palaeo perspective on future climate change abstract recent studies in the frame of the neclime neogene climate evolution in eurasia network provide a comprehensive inventory of continental palaeoclimate data for various time slices reconstructed from the palaeobotanical record the integrative analysis of spatial gradients and patterns observed from the proxy data together with data obtained from numeric modelling studies considerably improved our knowledge about the functioning of the climate system in the cenozoic when compared to the present an overall warmer more humid climate existed cenozoic climates are characterized by warm high latitudes shallow latitudinal and longitudinal gradients and wet continental interiors while concentration of greenhouse gases was about at the present day level or considerably higher thus these past climates potentially are valuable to better understand future climate change because they allow empirical access to climate situations that do not or not yet exist today in the present study continental climate data calculated from micro and macrofloras using the coexistence approach are analysed in order to compare past gradients and patterns and their anomalies relative to present day conditions with future climate change scenarios for the case study three time intervals are selected the mid eocene represents a very warm period of the cenozoic exemplifying greenhouse conditions with high atmospheric co 2 of over 1 100 ppmv the mid miocene is known as outstanding warm time interval as well the concentration of greenhouse gases is still controversially discussed but was certainly below the eocene level a third interval selected the tortonian represents a time span of subsequent cooling with the beginning of arctic glaciation for this period a pre industrial co 2 level is assumed it is shown that the study of past climate patterns provides important clues when evaluating modelling results for future scenarios anomalies predicted under global warming partly coincide with the palaeoclimate data sets as an example for greenhouse conditions the mid eocene data also show a strong warming of the high latitudes and a significant positive anomaly of winter temperatures in the continental interior as in the model study for the future scenario however for the tortonian where a pre industrial co 2 can be assumed data show the best agreement with predicted patterns

increased seasonality through the eocene to oligocene transition in northern high latitudes a profound global climate shift took place at the eocene oligocene transition approximately 33 5 million years ago when cretaceous early palaeogene greenhouse conditions gave way to icehouse conditions during this interval changes in the earth s orbit and a long term drop in atmospheric carbon dioxide concentrations resulted in both the growth of antarctic ice sheets to approximately their modern size and the appearance of northern hemisphere glacial ice however palaeoclimatic studies of this interval are contradictory although some analyses indicate no major climatic changes others imply cooler temperatures increased seasonality and or aridity climatic conditions in high northern latitudes over this interval are particularly poorly known here we present northern high latitude terrestrial climate estimates for the eocene to oligocene interval based on bioclimatic analysis of terrestrially derived spore and pollen assemblages preserved in marine sediments from the norwegian greenland sea our data indicate a cooling of approximately 5 degrees c in cold month winter mean temperatures to 0 2 degrees c and a concomitant increased seasonality before the oi 1 glaciation event these data indicate that a cooling component is indeed incorporated in the delta 18 o isotope shift across the eocene oligocene transition however the relatively warm summer temperatures at that time mean that continental ice on east greenland was probably restricted to alpine outlet glaciers

paleogene temperature gradient seasonal variation and climate evolution of northeast china abstract continental paleogene climates have been well studied in europe and north america but very little is known from asia because paleoclimatic results have only been reported from particular geological intervals here based on 29 plant assemblages from 8 well age controlled fossiliferous sites we quantitatively reconstruct the climates through most of the paleogene of northeast china and discuss related seasonal variations our results demonstrate that the mean annual temperature mat gradient was fairly shallow 0 27 c 1 latitude during the paleocene throughout this region in the eocene seasonality was high in the region indicated by marked differences in both temperature and precipitation between winters and summers of the sites the paleo east asian monsoon must have had intensified at least in the late mid eocene shown by apparent differences in annual precipitation distribution at all the sites regarding the paleogene climatic evolution of northeast china our quantitative results suggest that mat overall declined from warm in the paleocene and eocene to moderate in the oligocene generally consistent with the trend of marine records but with some distinctions two significant cooling events are recognized in the early and mid eocene with mat 3 4 c and 3 8 c lower and winter temperature 5 8 c and 4 7 c lower respectively in similar magnitudes to corresponding variations in europe and north america furthermore the present results show that mat rebounded in the late mid eocene and then decreased until the oligocene a similar pattern demonstrated in europe during the mid eocene to oligocene interval

hydrogeologic processes in saline systems playas sabkhas and saline lakes abstract pans playas sabkhas salinas saline lakes and salt flats are hydrologically similar varying only in their boundary conditions thus in evaluating geochemical processes in these systems a generic water and solute mass balance approach can be utilized a conceptual model of a coastal sabkha near the arabian gulf is used as an example to illustrate the various water and solute fluxes analysis of this model suggests that upward flux of ground water from underlying formations could be a major source of solutes in the sabkha but contribute only a small volume of the water local rainfall is the main source of water in the modeled sabkha system with a surprisingly large recharge to rainfall ratio of more than 50 the contribution of seawater to the solute budget depends on the ratio of the width of the supratidal zone to the total width and is generally confined to a narrow zone near the shoreline of a typical coastal sabkha because of a short residence time of water steady state flow is expected within a short time 50 000 years the solute composition of the brine in a closed saline system depends largely on the original composition of the input water the high total ion content in the brine limits the efficiency of water rock interaction and absorption because most natural systems are hydrologically open the chemistry of the brines and the associated evaporite deposits may be significantly different than that predicted for hydrologically closed systems seasonal changes in temperature of the unsaturated zone cause precipitation of minerals in saline systems undergoing evaporation thus during the hot dry season months minerals exhibit retrograde solubility so that gypsum anhydrite and calcite precipitate evaporation near the surface is also a major process that causes mineral precipitation in the upper portion of the unsaturated zone e g halite and carnallite provided that the relative humidity of the atmosphere is less than the activity of water the slope of the fresh brine water interface in saline lake systems is shallower than in fresh seawater interface because of the greater density difference between the fresh brine water bodies the interface between sabkha brines and seawater slopes seaward unlike normal marine fresh water systems that slope landward moreover the brine seawater interface does not achieve steady state because it is pushed toward the sea by the sabkha s brine

radiocarbon geochemistry of modern and ancient arctic lake systems baffin island canada the accuracy of arctic lake chronologies has been assessed by measuring the14c activities of modern carbon sources and applying these isotopic mass balances to dating fossil lake materials small 1 km2 shallow 25 m arctic lakes with watersheds 12 km2have soil and peat stratigraphic sections with14c activities ranging from 98 to 51 modern the14c activity of particulate organic carbon dissolved organic carbon and dissolved inorganic carbon from lake and stream waters ranges from 121 to 95 modern the sediment water interface of the studied lakes shows consistent14c ages of 100014c yr although the14c activity of living aquatic vegetation is 115 modern radiocarbon measurements of components of the lacustrine carbon pool imply that the 100014c yr age of the sediment water interface results from deposition of14c depleted organic matter derived from the watershed

climate driven hydrologic transients in lake sediment records calibration of groundwater conditions using 20th century drought abstract the effect of 20th century drought on groundwater and lakes in a climatically sensitive area of the northern great plains grant county western minnesota was investigated by analysis of lake sediments and historical air photos in conjunction with groundwater flow simulations drought caused an observed 4 0 to 5 1 m lake head decline between 1923 and 1938 all but three either dried completely or declined to 210 pb dated sediment core was analyzed for ostracode species distribution and geochemistry of c rawsoni shells 18 o 13 c mg ca sr ca mg ca and 13 c increased during drought at the same time that salinity tolerant ostracodes thrived suggesting increasing salinity however 18 o decreased during drought anti correlative with mg ca a numerical model for transient response of groundwater flow to drought modeled after that of 1923 38 was constrained by drought end recessional strand lines observed on air photos of one lake with strand line elevations inferred from bathymetry simulated lake water level declines in the first 15 drought years were consistent with strand line elevations the rate of decline was exponential at drought onset slowing as water in lakes and wetlands receded to below land surface and lake evaporation declined a near steady state was attained between 40 and 50 simulation years after onset of drought with the water table from 1 5 m below the level of dry lakebeds and only the two deepest lakes still holding water they were however greatly constricted in area and depth simulated evaporation fluxes were reduced by over 50 within 15 years despite increased et rates due to lake area constriction and water table declines both relate to land surface morphology beneath and around lakes model results suggest that lake bed elevations exert control on the rate and ultimate level to which groundwater is depressed by drought the deepest lakes in any region will tend to become the focus of groundwater flow during sustained drought once lakes around it dry out the unexpected finding of decreasing shell 18 o in response to drought is interpreted as some combination of source and or evaporation reduction effects such as seasonality of recharge precipitation or reduced et flux from wetlands that seep back into lakes

possible role of oceanic heat transport in early eocene climate increased oceanic heat transport has often been cited as a means of maintaining warm high latitude surface temperatures in many intervals of the geologic past including the early eocene although the excess amount of oceanic heat transport required by warm high latitude sea surface temperatures can be calculated empirically determining how additional oceanic heat transport would take place has yet to be accomplished that the mechanisms of enhanced poleward oceanic heat transport remain undefined in paleoclimate reconstructions is an important point that is often overlooked using early eocene climate as an example we consider various ways to produce enhanced poleward heat transport and latitudinal energy redistribution of the sign and magnitude required by interpreted early eocene conditions our interpolation of early eocene paleotemperature data indicate that an approximately 30 increase in poleward heat transport would be required to maintain eocene high latitude temperatures this increased heat transport appears difficult to accomplish by any means of ocean circulation if we use present ocean circulation characteristics to evaluate early eocene rates either oceanic processes were very different from those of the present to produce the early eocene climate conditions or oceanic heat transport was not the primary cause of that climate we believe that atmospheric processes with contributions from other factors such as clouds were the most likely primary cause of early eocene climate

asian monsoons in a late eocene greenhouse world the strong present day asian monsoons are thought to have originated between 25 and 22 million years myr ago driven by tibetan himalayan uplift however the existence of older asian monsoons and their response to enhanced greenhouse conditions such as those in theeocene period 55 34myrago are unknownbecause of the paucity of well dated records here we show late eocene climate records revealing marked monsoon like patterns in rainfall and wind south and north of the tibetan himalayan orogen this is indicated by low oxygen isotope values with strong seasonality in gastropod shells and mammal teeth from myanmar and by aeolian dust deposition in northwest china our climate simulations support modern like eocene monsoonal rainfall and show that a reinforced hydrological cycle responding to enhancedgreenhouse conditions counterbalanced the negative effect of lowertibetanrelief onprecipitation these strong monsoons later weakened with the global shift to icehouse conditions 34myr ago

eocene prevalence of monsoon like climate over eastern china reflected by hydrological dynamics abstract hydrological dynamics of sedimentary basins are essential for understanding regional climatic pattern in the geological past in previous qualitative studies lithologically depending on the occurrence of featured sedimentary rocks the eocene climate of china had been subdivided into three latitudinal zones with one subtropical high controlled arid zone throughout middle china and two humid zones respectively in the north and south however recent advances on mammalian fauna distribution plant fossil based quantitative paleoclimatic reconstruction and modeling experiment jointly suggest that the relatively humid monsoonal climate might have prevailed over the territory here we examine and compare sedimentary sequences of 10 eocene sections across eastern china and hence the lake level fluctuations to discuss the nature of climate type our results show that instead of the categorically zonal pattern the hydroclimate dynamics is intensified landward this is demonstrated by the fact that in contrast to the wide developed coal layers around the periphery evaporites are growingly occurred endocentrically to the central part of middle china however although we have had assumed that all evaporites are indicator of extreme aridity the highly oscillated climate in the central part of middle china was humid in the majority of the eocene distinct from permanent arid as seen in deserts or steppe along modern horse latitude from the upcountry distribution pattern of the eocene hydrological dynamics it appears that the relatively dry climate in central china was caused by the impact of continentality or rain shadow effect under monsoonal or monsoon like climate

paleobiogeography of the lotus plant nelumbonaceae nelumbo and its bearing on the paleoclimatic changes the historical reconstruction of the origin and dispersal of plant taxa in space and time facilitates a better understanding of their modern distribution patterns however most studies of paleobiogeography have focused on terrestrial plants and the distribution changes of aquatic plants are less well understood here we study the lotus plant nelumbo nelumbonaceae an aquatic perennial herb with a disjunctive distribution across east south and southeast asia north australia and north america the reproductive organs of nelumbo changchangensis he et jin from the eocene of hainan china are supplementarily described analysis of the spatial and temporal distributions of nelumbo in the geologic past indicates that the genus first occurs in mid latitude area of laurasia in the early cretaceous then becomes widespread in north america and eurasia and expands into south america during the late cretaceous and reaches its maximum northern limit during the eocene the genus persists and thrives in north america and eurasia until the pliocene the pleistocene ice age causes the extinction of nelumbo in europe and central asia and its populations in north american and asia are also restricted to refuges of lower latitude like the terrestrial plants metasequoia cupressaceae and nordenskioeldia trochodendraceae the fluctuations of nelumbo distribution ranges are also linked to climatic changes in the cenozoic the cooling climate and increasing seasonality in the eocene of east asia may favor the origin of tubers and the differentiating of the ecotypes in lotus which allow the deciduous type to survive in cold winters

global warming and rainfall lessons from an analysis of mid miocene climate data abstract the mid miocene climatic optimum mmco has been regarded as an analog for future global warming due to its scale of warming being equivalent to the warming predicted for the next century by the international panel on climate change ipcc s fourth report however little is known about how the mmco influenced paleoprecipitation in central china in this study two pollen floras from the eastern longzhong basin northern central china were quantitatively analyzed to reconstruct the climatic conditions likely during the mmco the paleoclimatic parameters obtained by applying the coexistence approach coa to these two palynological assemblages showed that the mean annual temperature mat 16 6 c for the mmco was 5 7 c higher than the present day mat 10 9 c and that mean annual precipitation map 955 4 mm was 413 5 mm higher than at present 541 9 mm indicating a much warmer and wetter climate the higher mean temperature for the coldest month cmt and the minimum monthly precipitation mimp values also indicate a warmer and wetter coldest and driest month respectively and thus suggest the prevalence of a more balanced seasonal paleoclimate in northern central china these climatic conditions are equivalent to higher global temperatures of 5 6 c during the mmco this finding would imply that precipitation in northern central china will increase in the context of ongoing global warming

do climate simulations support the existence of east asian monsoon climate in the late eocene abstract early synthesis of geologic evidence demonstrated that a zonal climate pattern once dominated china in the paleogene the zonal climate pattern is very different from the non zonal modern monsoon climate pattern it has been hypothesized that the transition from a zonal to non zonal pattern is related to the initiation of the east asian monsoon the earliest timing of east asian monsoon initiation is suggested to be the late eocene although this is still the subject of hot debate here we use the low resolution norwegian earth system model noresm l and the high resolution community atmosphere model version 4 cam4 to simulate the climate in china for the early and late eocene and further evaluate the climate effect of topography and sea surface temperature sst on east asian regional climate our simulations supported a zonal zonal like arid desert steppe climate band appearance in china in the early eocene but the zonal band very likely disappeared in the late eocene due to increased precipitation over east china the increased precipitation is caused by intensified summer southerlies associated with the westward extension of the western pacific subtropical high wpsh in the late eocene however the disappearance of a zonal climate band does not sufficiently indicate formation of an east asian monsoon climate in the late eocene simulated wind and precipitation seasonality is still much weaker in the late eocene and should be distinguished from the modern monsoonal seasonality