climate and vegetation history of the midcontinent from 75 to 25 ka a speleothem record from crevice cave missouri usa four missouri stalagmites yield consistent overlapping records of oxygen and carbon isotopic changes and provide a climate and vegetation history with submillennial resolution from 75 to 25 thousand years ago ka the thorium 230 dated records reveal that between 75 and 55 ka the midcontinental climate oscillated on millennial time scales between cold and warm and vegetation alternated among forest savanna and prairie temperatures were highest and prairie vegetation peaked between 59 and 55 ka climate cooled and forest replaced grassland at 55 ka when global ice sheets began to build during the early part of marine oxygen isotope stage 3

the indian monsoon and its variability for over 300 years the monsoon has been viewed as a gigantic land sea breeze it is shown in this paper that satellite and conventional observations support an alternative hypothesis which considers the monsoon as a manifestation of seasonal migration of the intertropical convergence zone itcz with the focus on the indian monsoon the mean seasonal pattern is described and why it is difficult to simulate it is discussed some facets of the intraseasonal variation such as active weak cycles break monsoon and a special feature of intraseasonal variation over the region namely poleward propagations of the itcz at intervals of 2 6 weeks are considered vertical moist stability is shown to be a key parameter in the variation of monthly convection over ocean and land as well as poleward propagations special features of the bay of bengal and the monsoon brought out by observations during a national observational experiment in 1999 are briefly described

strong coherence between solar variability and the monsoon in oman between 9 and 6 kyr ago variations in the amount of solar radiation reaching the earth are thought to influence climate but the extent of this influence on timescales of millennia to decades is unclear a number of climate records show correlations between solar cycles and climate1 but the absolute changes in solar intensity over the range of decades to millennia are small2 and the influence of solar flux on climate is not well established the formation of stalagmites in northern oman has recorded past northward shifts of the intertropical convergence zone3 whose northward migration stops near the southern shoreline of arabia in the present climate4 here we present a high resolution record of oxygen isotope variations for the period from 9 6 to 6 1 kyr before present in a th u dated stalagmite from oman the 18o record from the stalagmite which serves as a proxy for variations in the tropical circulation and monsoon rainfall allows us to make a direct comparison of the 18o record with the 14c record from tree rings5 which largely reflects changes in solar activity6 7 the excellent correlation between the two records suggests that one of the primary controls on centennial to decadal scale changes in tropical rainfall and monsoon intensity during this time are variations in solar radiation

strong influence of water vapor source dynamics on stable isotopes in precipitation observed in southern meghalaya ne india to calibrate 18o time series from speleothems in the eastern indian summer monsoon ism region of india and to understand the moisture regime over the northern bay of bengal bob we analyze the 18o and d of rainwater collected in 2007 and 2008 near cherrapunji india d values range from 18 5 to 144 4 while 18o varies between 0 8 and 18 8 the local meteoric water line lmwl is found to be indistinguishable from the global meteoric water line gmwl late ism september october rainfall exhibits lowest 18o and d values with little relationship to the local precipitation amount there is a trend to lighter isotope values over the course of the ism but it does not correlate with the patterns of temperature and rainfall amount 18o and d time series have to be interpreted with caution in terms of the amount effect in this subtropical region we find that the temporal trend in 18o reflects increasing transport distance during the ism isotopic changes in the northern bob surface waters during late ism and vapor re equilibration with rain droplets using an isotope box model for surface ocean waters we quantify the potential influence of river runoff on the isotopic composition of the seasonal freshwater plume in the northern bob temporal variations in this source can contribute up to 25 of the observed changes in stable isotopes of precipitation in ne india to delineate other moisture sources we use backward trajectory computations and find a strong correlation between source region and isotopic composition palaeoclimatic stable isotope time series from northeast indian speleothems likely reflect changes in moisture source and transport pathway as well as the isotopic composition of the bob surface water all of which in turn reflect ism strength stalagmite records from the region can therefore be interpreted as integrated measures of the ism strength

wetland evolution in the qinghai lake area china in response to hydrodynamic and eolian processes during the past 1100 years abstract the daotanghe riverine wetland in close proximity to the qinghai lake was investigated to demonstrate the interrelationships between qinghai lake hydrodynamic processes eolian mobility and ecological conditions during the past 1100 years in response to climate change we used ostracod assemblages from various sites east of qinghai lake and from the sediment core qw15 of daotanghe pond and combined them with grain size and geochemical data from the same core the statistical extraction of grain size endmembers em revealed three different transportation processes responsible for pond related fluvio lacustrine pure fluvial and eolian deposits identified seasonal effects eolian mobility phase and timing of ice cover are possible tracers for the competing influence between the asian summer monsoon and the westerlies in the daotanghe wetland and surrounding area our results show that ostracod associations and sediment properties are evidence of a fluvio lacustrine fresh water environment without ingression of qinghai lake into the wetland hydrodynamic variations coupled with phases of eolian input indicate highly variable water budgets in response to climate induced effective moisture supply the medieval warm period mwp until about 1270 ce displays generally moist and warm climate conditions with minor fluctuations likely in response to variations in summer monsoon intensity the three partite period of the little ice age lia shows hydrologically unstable conditions between 1350 and 1530 ce with remarkably colder periods assigned to a prolonged seasonal ice cover pond desiccation and replacement by fluvial deposits occurred between 1530 and 1750 ce superimposed by eolian deposits the phase 1730 1900 ce is recorded by the re occurrence of a pond environment with reduced eolian input principal component analysis pca on ostracod abundances shows similar trends all three phases of the lia developed during a weak summer monsoon influence favoring westerly derived climate conditions until ca 1850 ce in accordance with records from the adjacent regions seasonal freezing periods in excess of the average time of frozen water bodies also occurred in periods of the well known grand solar minima and indicate stronger seasonality possibly independent from variations in summer monsoon strength but with links to global northern hemispheric climate

persistent multidecadal power of the indian summer monsoon article i nfo the instrumental record of indian summer monsoon ism precipitation displays two complete manifesta tions of an inferred multidecadal cycle hitherto no precipitation sensitive proxy record from the indian subcontinent has had the necessary resolution and length to adequately assess whether this observed feature is an inherent aspect of the ism system on longer timescales here we present compelling evidence for persistence of this cycle using a millennial length ad 600 1550 and sub annually resolved speleothem oxygen isotope record 18 o from dandak cave in east central india the record displays a high degree of correlation with a speleothem based asian monsoon reconstruction from wanxiang cave in north central china on annual to decadal timescales showing theregional significanceof these findings theobserved period inourmonsoonreconstructionissimilartothatassociatedwiththegleissbergsolarcycleandmultidecadalsea surface temperature variability in the north atlantic amo both of which are often cited as the prominent pacemakers of ism variability on multidecadal timescales we document transient coherence between ism precipitation amount and solar variability that persists exclusively in the century prior to and during the medieval climate anomaly nominally ad 950 1300 the non stationary nature of the sfv monsoon relationship presented here may be evidence of the time varying influence of tropical ocean atmosphere dynamics on the solar monsoon link however it is not possible to show with significance that this period of coherenceisanythingmorethananartifactoftwotimeserieswithsimilarspectra wetherefore areinclinedto interpret our record as evidence of a minimal role of solar variability in driving persistent multidecadal variability of the ism multidecadal sst variability in the north atlantic remains as the likely alternative driver for persistence of this cycle regardless of the causative mechanism s the amplitude and regional signature of the observed cycle in ism precipitation highlight its societal importance with respect to forecasting ism precipitation on multidecadal timescales

climatic variability in central indian himalaya during the last 1800 years evidence from a high resolution speleothem record stable isotopes from a u th dated aragonite stalagmite from the central kumaun himalaya provide evidence of variation in climatic conditions in the last similar to 1800 years the delta o 18 and delta c 13 values vary from 4 3 parts per thousand to 7 6 parts per thousand and 3 4 parts per thousand to 9 1 parts per thousand respectively although the stalagmite was not grown in isotopic equilibrium with cave drip water a clear palaeoclimatic signal in stalagmite delta o 18 values is evident based on the regional climate data the stalagmite showed a rapid growth rate during 830 910 ad most likely the lower part of medieval warm period mwp and 1600 1640 ad the middle part of little ice age lia two distinct phases of reduced precipitation are marked by a 2 parts per thousand shift in 8180 values towards the end of mwp similar to 1080 1160 ad and after its termination from similar to 1210 to 1440 ad the lia similar to 1440 1880 ad is represented by sub tropical climate similar to modern conditions whereas the post lia was comparatively drier the inter tropical convergence zone itcz was located over the cave location during wetter warmer conditions when it shifted southward precipitation over the study area decreased a prominent drop in delta o 18 and delta c 13 values during the post lia period may also have been additionally influenced by anthropogenic activity in the area c 2013 elsevier ltd and inqua all rights reserved

abrupt changes in indian summer monsoon strength during 33 800 to 5500 years b p speleothem proxy records from northeastern ne india reflect seasonal changes in indian summer monsoon strength as well as moisture source and transport paths we have analyzed a new speleothem record from mawmluh cave meghalaya india in order to better understand these processes the data show a strong wet phase 33 500 32 500 years b p followed by a weak dry phase from 26 000 to 23 500 years b p and a very weak phase from 17 000 to 15 000 years b p the record suggests abrupt increase in strength during the bolling allerod and early holocene periods and pronounced weakening during the heinrich and younger dryas cold events we infer that these changes in monsoon strength are driven by changes in temperature gradients which drive changes in winds and moisture transport into northeast india

abrupt changes in the asian southwest monsoon during the holocene and their links to the north atlantic ocean during the last ice age the indian ocean southwest monsoon exhibited abrupt changes that were closely correlated with millennial scale climate events in the north atlantic region1 2 3 suggesting a mechanistic link in the holocene epoch which had a more stable climate the amplitude of abrupt changes in north atlantic climate was much smaller and it has been unclear whether these changes are related to monsoon variability here we present a continuous record of centennial scale monsoon variability throughout the holocene from rapidly accumulating and minimally bioturbated sediments in the anoxic arabian sea our monsoon proxy record reveals several intervals of weak summer monsoon that coincide with cold periods documented in the north atlantic region4 including the most recent climate changes from the medieval warm period to the little ice age and then to the present we therefore suggest that the link between north atlantic climate and the asian monsoon is a persistent aspect of global climate

a numerical simulation of magma motion crustal deformation and seismic radiation associated with volcanic eruptions summary the finite difference method is used to calculate the magma dynamics seismic radiation and crustal deformation associated with a volcanic eruption the model geometry consists of a cylindrical reservoir and narrow cylindrical conduit embedded in a homogeneous crust we consider two models of eruption in the first model a lid caps the vent and the magma is overpressurized prior to the eruption the eruption is triggered by the instantaneous removal of the lid at which point the exit pressure becomes equal to the atmospheric pressure in the second model a plug at the reservoir outlet allows pressurization of only the magmatic fluid in the reservoir before the eruption magma transfer between the reservoir and conduit is triggered by the instantaneous removal of the plug and the eruption occurs when the pressure at the conduit orifice exceeds the material strength of the lid capping the vent in both models magma dynamics are expressed by the equations of mass and momentum conservation in a compressible fluid in which fluid expansion associated with depressurization is accounted for by a constitutive law relating pressure and density crustal motions are calculated from the equations of elastodynamics the fluid and solid are dynamically coupled by applying the continuity of wall velocities and normal stresses across the conduit and reservoir boundaries free slip is allowed at the fluid solid boundary both models predict the gradual depletion of the magma reservoir which causes crustal deformation observed as a long duration dilatational signal superimposed on this very long period vlp signal generated by mass transport are long period lp oscillations of the magma reservoir and conduit excited by the acoustic resonance of the reservoir conduit system during the eruption the volume of the reservoir vent size and magma properties control the duration of vlp waves and dominant periods of lp oscillations the second model predicts that when the magmatic fluid reaches the vent a high pressure pulse occurs at this location in accordance with the basic theory of compressible fluid dynamics this abrupt pressure increase just beneath the vent is consistent with observed seismograms in which pulse like rayleigh waves excited by a shallow source are dominant the strength of the lid plays an important role in the character of the seismograms and in defining the type of eruption observed

stalagmite based high resolution precipitation variability for past four centuries in the indian central himalaya chulerasim cave re visited and data re interpretation abstract although the variations in 18 o and 13 c and the u th dating in the speleothems are considered as key proxies improved dating with better quality resolution as well as composition of stalagmites and growth rate along with the cave monitoring are equally important for understanding the high resolution precipitation variability in the past with a total of six dates on a 11 5 cm long stalagmite we re interpret the decadal to century scale climatic changes with multi year droughts from the indian central himalaya between ca 1622 and 1950 ad the sample is composed of aragonite both compact sub layers and porous sub layers although the age model of this young speleothem may be within age uncertainty owing to the high 230 th 23 2 th isotope ratios yet the distinction of this study lies in recording various historical drought events which are otherwise never reported from the himalayan foothills additionally the sample consists of reasonable amount of u 2 ppm thus the age correction requirement may be minimum the higher growth rate and comparatively lower values of 18 o and 13 c are observed during the little ice age lia until ca 1820 ad indicating its being wet in the himalayan foothills in contrast to the peninsular india and other regions which are solely influenced by the indian summer monsoon ism this is mainly because the monsoon trough moves from the plains to the himalayan foothills during break monsoon conditions and provides more orographic precipitation in form of the westerlies in the south facing himalayan slopes the post lia period from ca 1820 ad onwards is interpreted as comparatively drier than the lia

indian summer monsoon variability during the last millennium as recorded in stalagmite from baratang mahadev cave andaman islands abstract this study presents a stable oxygen isotope record of indian summer monsoon ism variability using cave speleothem carbonate from baratang island andaman islands encompassing the last millennium from 10th to 19th century ce the studied interval encompasses two major climatic events the medieval climate anomaly mca and the little ice age lia as well as the current warm period cwp our data suggest generally higher precipitation during the warm mca when the ism was relatively strong and low precipitation during the cold lia with a few exceptions when wet conditions prevailed the baratang cave record shows greater similarity with the records from the sahiya and klang caves and opposite trends relative to those from the northeastern himalaya owing to the dipolar nature of ism precipitation high frequency sub decadal to centennial scale pulses of weakened summer monsoons are observed during 16th to 19th century ce these phases of weak ism are correlated with severe droughts and famines in the indian subcontinent owing to deficient monsoon rainfall which had pronounced effect on south asian societies spectral analysis suggests a strong periodicity of 190 yr de vries cycle indicating strong influence of solar insolation

climatic and in cave influences on δ18o and δ13c in a stalagmite from northeastern india through the last deglaciation northeastern ne india experiences extraordinarily pronounced seasonal climate governed by the indian summer monsoon ism the vulnerability of this region to floods and droughts calls for detailed and highly resolved paleoclimate reconstructions to assess the recurrence rate and driving factors of ism changes we use stable oxygen and carbon isotope ratios 18o and 13c from stalagmite maw 6 from mawmluh cave to infer climate and environmental conditions in ne india over the last deglaciation 16 6ka we interpret stalagmite 18o as reflecting ism strength whereas 13c appears to be driven by local hydroclimate conditions pronounced shifts in ism strength over the deglaciation are apparent from the 18o record similarly to other records from monsoonal asia the ism is weaker during the late glacial lg period and the younger dryas and stronger during the bolling allerod and holocene local conditions inferred from the 13c record appear to have changed less substantially over time possibly related to the masking effect of changing precipitation seasonality time series analysis of the 18o record reveals more chaotic conditions during the late glacial and higher predictability during the holocene likely related to the strengthening of the seasonal recurrence of the ism with the onset of the holocene

investigation of the stable isotope fractionation in speleothems with laboratory experiments many speleothems show evidence for calcite precipitation under disequilibrium conditions to improve the understanding of these kinetic processes several laboratory experiments were performed to study the fractionation of stable oxygen and carbon isotopes during the precipitation of calcite carbonate was precipitated under controlled conditions from both a body of standing water beaker experiments and a solution flowing along a channel channel experiments at a relative humidity of 100 slow degassing of co2 simulated by the beaker experiments results in 18o values in equilibrium with the solution in contrast the 13c values show a significant enrichment inversely proportional to the height of the solution in the beakers fast degassing of co2 simulated by the channel experiments showed an enrichment of both 13c and 18o and a slope of 13c 18o of 1 4 0 6 these results represent experimental evidence for the hendy effect which is manifested in i a progressive increase in 18o and 13c away from the growth axis and ii a positive correlation between 18o and 13c along a single growth layer of a stalagmite

history and features of trans oceanic tsunamis and implications for paleo tsunami studies abstract far field tsunamis and their features as well as methods to quantify trans oceanic tsunamis are reviewed with examples of instrumental and historical data tsunamis from the 1854 nankai earthquakes the 1946 aleutian tsunami earthquake the 1960 and 2010 chile earthquakes as well as the 2011 tohoku earthquake were recorded around the pacific ocean the 1883 krakatoa volcanic eruption caused volcanic tsunami in the indian ocean and meteotsunami in the pacific ocean the 2004 indian ocean tsunami was also recorded in the pacific ocean when a tsunami amplitude is larger than that of ocean tides which usually requires the parent earthquake to be gigantic mw 9 it can cause damage and may be historically documented the trans pacific tsunamis described in historical documents include those from the 1700 cascadia earthquake the 1730 1751 1837 and 1877 earthquakes off chile and the 1687 and 1868 earthquakes off peru the tsunami record in japan from the 1586 peru earthquakes was found to be incorrect and should be discounted the tsunami magnitude scale relates the tsunami heights to the earthquake size tsunami travel time can be computed from actual bathymetry and the tsunami ray tracing provides relative amplitudes due to focusing defocusing caused by irregular bathymetry numerical computations from fault models produce tsunami amplitudes and waveforms and indicate strong directivity due to strike of fault or orientation of subduction zones far field tsunamis are often long lasting due to multiple reflections across the basin or on continental shelf or due to resonance in bays harbors these features would provide important criteria to estimate tsunami sources from paleo tsunami data

abrupt changes in indian summer monsoon strength during the last 900 years and their linkages to socio economic conditions in the indian subcontinent abstract abrupt shifts in indian summer monsoon ism precipitation largely affected regional hydrometeorology accelerating socio economic and cultural adaptations of agrarian economies in south asia in the last millennium linking ism variability to human history in the indian subcontinent is still limited by the scarcity of high resolution paleoclimatic data for the period encompassing the last 1000 years or earlier we present a new high resolution oxygen isotope proxy record from the wah shikar cave northeastern india and identified abrupt shifts in the ism that had profound impact on human societies during the last 900 yrs the ism was strong during the medieval climate anomaly mca and the current warm period cwp and show multiple shifts during the little ice age lia the abrupt shifts in the ism were more frequent during warm intervals showing a secular trend with few exceptions during the cold periods intervals of prolonged summer monsoon weakening are correlated to the decline of major dynasties in india possibly due to decrease in agriculture productivity declining economy and societal crisis changes in atmospheric temperature due to volcanic eruptions and sun spot activity have played major role in the onset of the lia and other prolonged weak intervals of the ism during the last 900 yrs

holocene forcing of the indian monsoon recorded in a stalagmite from southern oman a high resolution oxygen isotope record from a thorium uranium dated stalagmite from southern oman reflects variations in the amount of monsoon precipitation for the periods from 10 3 to 2 7 and 1 4 to 0 4 thousand years before the present ky b p between 10 3 and 8 ky b p decadal to centennial variations in monsoon precipitation are in phase with temperature fluctuations recorded in greenland ice cores indicating that early holocene monsoon intensity is largely controlled by glacial boundary conditions after approximately 8 ky b p monsoon precipitation decreases gradually in response to changing northern hemisphere summer solar insolation with decadal to multidecadal variations in monsoon precipitation being linked to solar activity

abrupt onset of the little ice age triggered by volcanism and sustained by sea ice ocean feedbacks 1 northern hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes however the causes of superposed century scale cold summer anomalies of which the little ice age lia is the most extreme remain debated largely because the natural forcings are either weak or in the case of volcanism short lived here we present precisely dated records of ice cap growth from arctic canada and iceland showing that lia summer cold and ice growth began abruptly between 1275 and 1300 ad followed by a substantial intensification 1430 1455 ad intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium a transient climate model simulation shows that explosive volcanism produces abrupt summer cooling at these times and that cold summers can be maintained by sea ice ocean feedbacks long after volcanic aerosols are removed our results suggest that the onset of the lia can be linked to an unusual 50 year long episode with four large sulfur rich explosive eruptions each with global sulfate loading 60 tg the persistence of cold summers is best explained by consequent sea ice ocean feedbacks during a hemispheric summer insolation minimum large changes in solar irradiance are not required

climatic and environmental controls on speleothem oxygen isotope values variations in speleothem oxygen isotope values d 18 o result from a complicated interplay of environmental controls and processes in the ocean atmosphere soil zone epikarst and cave system as such the controls on speleothem d 18 o values are extremely complex an understanding of the processes that control equilibrium and kinetic fractionation of oxygen isotopes in water and carbonate species is essential for the proper interpretation of speleothem d 18 o as paleoclimate and paleoenvironmental proxies and is best complemented by study of site specific cave processes such as infiltration flow routing drip seasonality and saturation state and cave microclimate among others this review is a process based summary of the multiple controls on d 18 o in the atmosphere soil epikarst and speleothem calcite illustrated with case studies primary controls of d 18 o in the atmosphere include temperature and relative humidity through their role in the multiple isotope effects variability and modifications of water d 18 o values in the soil and epikarst zones are dominated by evaporation mixing and infiltration of source waters the isotopically effective recharge into a cave system consists of those waters that participate in precipitation of caco3 resulting in calcite deposition rates which may be biased to time periods with optimal dripwater saturation state recent modeling experimental and observational data yield insight into the significance of kinetic fractionation between dissolved carbonate phases and solid caco3 and have implications for the hendy test to assist interpretation of speleothem d 18 o time series quantitative and semi quantitative d 18 o climate calibrations are discussed with an emphasis on some of the difficulties inherent in using modern spatial and temporal isotope gradients to interpret speleothems as paleoclimate proxy records finally several case studies of globally significant speleothem paleoclimate records are discussed that show the utility of d 18 o to reconstruct past climate

northeast indian stalagmite records pacific decadal climate change implications for moisture transport and drought in india two types of el nino events are distinguished by sea surface temperature sst anomalies centered in the central or eastern equatorial pacific the central pacific el nino events cp el nino are more highly correlated with weakening of the central indian summer monsoon and linked to decadal pacific climate variability we present a 50 year subannually resolved speleothem 18o record from northeast india that exhibits a significant correlation with northern pacific decadal variability and central equatorial pacific ssts accordingly we suggest that 18o time series in similar northeast indian speleothems are effective tools for investigating preinstrumental changes in pacific climate including changes in el nino dynamics in contrast to central india rainfall amounts in northeast india are relatively unaffected by el nino however back trajectory analysis indicates that during cp el nino events moisture transport distance to northeast india is reduced suggesting that variations in moisture transport primarily control 18o in the region

the leading mode of indian summer monsoon precipitation variability during the last millennium 1 the internally generated intraseasonal variability of the indian summer monsoon is characterized by intermittent periods of enhanced active and deficient break precipitation which produce a quasi east west precipitation dipole over the indian subcontinent here we present multicentennial length and near annually resolved reconstructions of monsoon precipitation inferred from absolute dated and instrumentally calibrated speleothem oxygen isotope records from regions central and northeast india that have diametric responses to active break monsoon circulation patterns on centennial timescales ad 1400 2008 precipitation variability from these two regions exhibit opposing behavior oscillating between periods with a persistently active dominated ad 1700 to 2007 and a break dominated ad 1400 to 1700 regime the switch between these regimes occurs abruptly within decades at a time ad 1650 1700 when a proxy record of upwelling intensity from the arabian sea suggest an abrupt increase in the monsoon winds on the basis of these observations we hypothesize that the frequency distribution of active break periods varies on centennial timescales implying a leading role of internal dynamics in governing the ism response to slowly evolving changes in the external boundary conditions

chinese stalagmite δ 18 o controlled by changes in the indian monsoon during a simulated heinrich event carbonate cave deposits in india and china are assumed to record the intensity of monsoon precipitation because the 18 o of the carbonate tracks the isotopic signature of precipitation these records show spatially coherent variability throughout the last ice age and suggest that monsoon strength was altered during the millennial scale climate variations known as dansgaard oeschger events and during the heinrich cooling events here we use a numerical climate model with an embedded oxygen isotope model to assess what caused the shifts in the oxygen isotope signature of precipitation during a climate perturbation designed to mimic a heinrich event our simulations show that a sudden increase in north atlantic sea ice extent during the last glacial period leads to cooling in the northern hemisphere reduced precipitation over the indian basin and weakening of the indian monsoon the precipitation is isotopically heavier over india and the water vapour exported to china is isotopically enriched our model broadly reproduces the enrichment of 18 o over northern india and east asia evident in speleothem records during heinrich events we therefore conclude that changes in the 18 o of cave carbonates associated with heinrich events reflect changes in the intensity of indian rather than east asian monsoon precipitation