reading the climate record of the martian polar layered deposits abstract the martian polar regions have layered deposits of ice and dust the stratigraphy of these deposits is exposed within scarps and trough walls and is thought to have formed due to climate variations in the past insolation has varied significantly over time and caused dramatic changes in climate but it has remained unclear whether insolation variations could be linked to the stratigraphic record we present a model of layer formation based on physical processes that expresses polar deposition rates of ice and dust in terms of insolation in this model layer formation is controlled by the insolation record and dust rich layers form by two mechanisms 1 increased summer sublimation during high obliquity and 2 variations in the polar deposition of dust modulated by obliquity variations the model is simple yet physically plausible and allows for investigations of the climate control of the polar layered deposits pld we compare the model to a stratigraphic column obtained from the north polar layered deposits npld fishbaugh k e hvidberg c s byrne s russel p s herkenhoff k e winstrup m kirk r 2010a geophys res lett 37 l07201 and show that the model can be tuned to reproduce complex layer sequences the comparison with observations cannot uniquely constrain the pld chronology and it is limited by our interpretation of the observed stratigraphic column as a proxy for npld composition we identified however a set of parameters that provides a chronology of the npld tied to the insolation record and consistently explains layer formation in accordance with observations of npld stratigraphy this model dates the top 500 m of the npld back to 1 million years with an average net deposition rate of ice and dust of 0 55 mm a 1 the model stratigraphy contains a quasi periodic 30 m cycle similar to a previously suggested cycle in brightness profiles from the npld laskar j levrard b mustard f 2002 nature 419 375 377 milkovich s head j w 2005 j geophys res 110 but here related to half of the obliquity cycles of 120 and 99 kyr and resulting from a combination of the two layer formation mechanisms further investigations of the non linear insolation control of pld formation should consider data from other geographical locations and include radar data and other stratigraphic datasets that can constrain the composition and stratigraphy of the npld layers

deltaic deposits at aeolis dorsa sedimentary evidence for a standing body of water on the northern plains of mars a fundamental long standing question regarding mars history is whether the flat and low lying northern plains ever hosted an ocean the best opportunity to solve this problem is provided by stratigraphic observations of sedimentary deposits onlapping the crustal dichotomy here we use high resolution imagery and topography to analyze a branching network of inverted channel and channel lobe deposits in the aeolis dorsa region just north of the dichotomy boundary observations of stacked cross cutting channel bodies and stratal geometries indicate that these landforms represent exhumed distributary channel deposits observations of depositional trunk feeder channel bodies a lack of evidence for past topographic confinement channel avulsions at similar elevations and the presence of a strong break in dip slope between topset and foreset beds suggest that this distributary system was most likely a delta rather than an alluvial fan or submarine fan sediment transport calculations using both measured and derived channel geometries indicate a minimum delta deposition time on the order of 400 years the location of this delta within a thick and widespread clastic wedge abutting the crustal dichotomy boundary unconfined by any observable craters suggests a standing body of water potentially 105 km2 in extent or greater and is spatially consistent with hypotheses for a northern ocean

color imaging of mars by the high resolution imaging science experiment hirise hirise has been producing a large number of scientifically useful color products of mars and other planetary objects the three broad spectral bands coupled with the highly sensitive 14 bit detectors and time delay integration enable detection of subtle color differences the very high spatial resolution of hirise can augment the mineralogic interpretations based on multispectral themis and hyperspectral datasets tes omega and crism and thereby enable detailed geologic and stratigraphic interpretations at meter scales in addition to providing some examples of color images and their interpretation we describe the processing techniques used to produce them and note some of the minor artifacts in the output we also provide an example of how hirise color products can be effectively used to expand mineral and lithologic mapping provided by crism data products that are backed by other spectral datasets the utility of high quality color data for understanding geologic processes on mars has been one of the major successes of hirise

orbital forcing of the martian polar layered deposits since the first images of polar regions on mars revealed alternating bright and dark layers there has been speculation that their formation might be tied to the planet s orbital climate forcing1 2 3 4 but uncertainties in the deposition timescale exceed two orders of magnitude estimates based on assumptions of dust deposition ice formation and sublimation and their variations with orbital forcing suggest a deposition rate of 10 3 to 10 2 cm yr 1 refs 5 6 whereas estimates based on cratering rate result in values as high as 0 1 to 0 2 cm yr 1 ref 7 here we use a combination of high resolution images of the polar layered terrains8 high resolution topography9 and revised calculations of the orbital and rotational parameters of mars to show that a correlation exists between ice layer radiance as a function of depth obtained from photometric data of the images of the layered terrains and the insolation variations in summer at the martian north pole similar to what has been shown for palaeoclimate studies of the earth10 11 12 for the best fit between the radiance profile and the simulated insolation parameters we obtain an average deposition rate of 0 05 cm yr 1 for the top 250 m of deposits on the ice cap of the north pole of mars

new martian climate constraints from radar reflectivity within the north polar layered deposits the north polar layered deposits npld of mars represent a global climate record reaching back millions of years potentially recorded in visible layers and radar reflectors however little is known of the specific link between those layers reflectors and the global climate to test the hypothesis that reflectors are caused by thick and indurated layers known as marker beds the reflectivity of three reflectors was measured mapped and compared to a reflectivity model the measured reflectivities match the model and show a strong sensitivity to layer thickness implying that radar reflectivity may be used as a proxy for short term accumulation patterns and that regional climate plays a strong role in layer thickness variations comparisons to an orbitally forced npld accumulation model show a strong correlation with predicted marker bed formation but dust content is higher than expected implying a stronger role for dust in mars polar climate than previously thought

accelerated melting of himalayan snow and ice triggers pronounced changes in a valley peatland from northern india 1 the himalayan region of northern india depends on monsoon rains together with snow and glacial melt to supply life sustaining water to one of the world s most densely populated areas here we provide high resolution pollen and diatom evidence from a peat deposit in the pinder valley that shows a synchronous and abrupt ecosystem turnover toward a wetter state in the last two centuries that exceeded changes recorded over the last three millennia contrary to expectations there was no relationship between recent proxy changes and summer monsoon precipitation strong relationships however were found with winter climate data we link this recent unprecedented wetness to marked warming at higher elevations resulting in increased seasonal runoff and associated climatic feedbacks in this snow and ice melt dominated region in contrast to the expected desiccation and decomposition of most peat systems with warming this site has instead become the wettest in its ca 3500 year history

stratigraphy of the north polar layered deposits of mars from high resolution topography nasa earth and space science fellowship nnx13ao55h nasa s mars reconnaissance orbiter project hirise

earliest accumulation history of the north polar layered deposits mars from sharad abstract the approximately 2 km thick north polar layered deposits npld are often considered to contain the most complete and detailed stratigraphic records of recent climate of mars exposures of the dense layering within troughs and scarps allowed detailed reconstructions of the latest accumulation history of these water ice deposits but we lack knowledge of their initial emplacement the shallow radar sharad onboard mars reconnaissance orbiter mro penetrates the npld to their base and detects their internal layering overcoming the limitation of scarce and scattered visible outcrops of the lowermost sequences in this study we map reflectors in sharad data that result from discrete stratigraphic horizons in order to delineate the three dimensional stratigraphy of the lowermost 500 m npld sequence and reconstruct their accumulation history we confirm the large scale lateral continuity and thickness uniformity of the deposits previously detected within the lowermost npld however stratigraphic complexity in the form of pinch outs and significant thickness variations arises when we examine single radar units we find evidence of an initially limited geographic stability of water ice within two deposits that are centered at the north pole and present day gemina lingula a period of lateral ice sheet growth followed interrupted only once by a retreat episode lower net accumulation is observed on pre existing slopes suggesting a reduction of water ice stability due to increased solar radiation incidence and or transport by katabatic winds lateral transport of water ice by wind is also suggested by thickness undulations toward the top of the sequence resembling cyclic steps water ice accumulation models based on orbital forcing predict a sequence of deposition and retreat events that is generally compatible with our reconstructed accumulation history therefore we interpret the stratigraphic complexity that we observe as regional and possibly global climate change induced by orbital forcing we also find that at least two units are completely buried within the npld and do not outcrop and that npld deposition in some places was contemporaneous with deposition of the stratigraphically underlying cavi unit in other places both of these findings show that radar reflector mapping is a necessary complement to any stratigraphic reconstruction based on visible exposures

compact reconnaissance imaging spectrometer for mars observations of northern martian latitudes in summer 1 this paper brings together initial results obtained of the high northern latitudes in mars years 28 and 29 between october 2006 and october 2008 these measurements confirm many previous models and shed new light on the nature of polar surface materials particularly in intermediate albedo units of the polar layered deposits many of which are found to be ice rich we identify hydrated non ice materials present in many low albedo troughs as well as in the circumpolar erg that was previously associated with gypsum we identify icy outlier deposits that may be related to subsurface thermophysical properties and permafrost new observations of the gypsum rich dune material constrain models for its formation and distribution intrinsic properties of ice content and grain size are found to be independent of the albedo of fine layered units and may provide a novel method for stratigraphic identification and correlation

annual climate variability in the holocene interpreting the message of ancient trees abstract over vast areas of the world s landmasses where climate beats out a strong seasonal rhythm tree growth keeps unerring time in their rings trees record many climate melodies played in different places and different eras recent years have seen a consolidation and expansion of tree ring sample collections across the traditional research areas of north america and europe and the start of major developments in many new areas of eurasia south america and australasia from such collections are produced networks of precisely dated chronologies records of various aspects of tree growth registered continuously year by year across many centuries their sensitivities to different climate parameters are now translated into ever more detailed histories of temperature and moisture variability across expanding dimensions of time and space with their extensive coverage high temporal resolution and rigid dating control dendroclimatic reconstructions contribute significantly to our knowledge of late holocene climates most importantly on timescales ranging from 1 to 100 years in special areas of the world where trees live for thousands of years or where subfossil remnants of long dead specimens are preserved work building chronologies covering many millennia continues apace very recently trees have provided important new information about major modes of general circulation dynamics linked to the el nino southern oscillation and the north atlantic oscillation and about the effect of large volcanic eruptions as for assessing the significance of 20th century global warming the evidence from dendroclimatology in general supports the notion that the last 100 years have been unusually warm at least within a context of the last two millennia however this evidence should not be considered equivocal the activities of humans may well be impacting on the natural growth of trees in different ways making the task of isolating a clear climate message subtly difficult

the transitional depositional environment and sequence stratigraphy of chasma boreale abstract the depositional system within chasma boreale is unique in that it contains active aeolian environments expressed as dune fields and active cryosphere environments present as layered ice deposits as well as environments that transition between these this work presents a new analysis of the chasma boreale sediment system that creates an interpretative framework addressing a controls on the balance between aeolian and cryospheric processes in the modern depositional system b the stratigraphic architecture of related sedimentary deposits and c processes of sediment accumulation and preservation images from context camera ctx 6 m pixel are used to classify and map sedimentary environments surfaces and deposits on the reentrant floor to refine the established geologic map of the reentrant and to infer the stratigraphic record of the accumulation from chasma boreale s depositional system a spectrum of sedimentary environments occurring between those dominated by aeolian and by cryospheric processes are identified through time the boundaries of these sedimentary environments have shifted resulting in complex lateral changes in the configuration of sedimentary environments on the reentrant s floor vertically the stratigraphic record is characterized by the punctuation of sandy aeolian deposits by icy surfaces that indicate episodes of ice growth that preserve underlying deposits resulting in accumulation stabilized icy surfaces occur at multiple vertical temporal scales and lateral extents suggesting the influence of both regional climate change due to allogenic forcing as well as autogenic dynamics within the transitional system these observations demonstrate that the chasma boreale accumulation can be interpreted in an aeolian sequence stratigraphic framework this work contributes the first detailed description of the processes forming polar aeolian sequences with an emphasis on the competing and complementary dynamics between aeolian and cryospheric systems

a 4 kyr stalagmite oxygen isotopic record of the past indian summer monsoon in the andaman islands 1 in order to reconstruct the activity of the indian summer monsoon ism during the last 4 kyr two stalagmites from baratang cave in andaman islands have been investigated for their temporal variations in 18o the chronology is provided by radiocarbon ages on the stalagmites during 1800 2100 cal yr bp we observed a significant increase in stalagmite 18o that we infer is caused by the amount effect this increase implies a strong reduction in the strength of the ism that is correlated with the roman warm period other proxy records in the region confirm a reduction in ism activity during this time reduction in the ism is also observed around 1500 and 400 800 cal yr bp the latter period is the transition from the medieval warm period to the little ice age the strongest monsoon in the last 4 kyr is observed during 800 1200 cal yr bp the medieval warm period

models of climate cycles recorded in martian polar layered deposits abstract layered strata observed in orbital images of polar sedimentary terrains on mars have been hypothesized to contain information about recent variations in the martian climate celestial mechanicians have determined that mars has experienced large amplitude quasi periodic variations in obliquity and eccentricity planetary meteorologists have inferred that the resulting changing patterns of solar heating must have had dramatic effects on martian climate accordingly it might be possible to link the known recent history of orbit axial variations with the physical characteristics of the most recently deposited strate determined from orbital imagery our paper explores that possibility quantitatively for various models of the formation of the polar layered deposits and the layering developed within them we modeled the formation of polar layered deposits during the past 10 my for two general classes of model uniform deposition rate udr models assume that the major constituent of the layered deposits is deposited at a uniform rate and that layering is established by climate induced variations in the concentration of a minor constituent climate modulated deposition rate cmdr models assume that the deposition rate of the major constituent is controlled by climate and that layer boundaries correspond to intervals of nondeposition in both models abrupt changes in deposition regime occur when a function of the orbit axial parameters crosses a threshold value detailed physical mechanisms for the control of sedimentation by orbit axial variations were developed for two specific models of the cmdr type in one model the deposits are assumed to be primarily composed of dust in the other they are assumed to be predominantly water ice we calculated the times at which abrupt changes in deposition regime occur and determined the relative thicknesses of successive layers which can be compared against layer thicknesses made from orbital imagery in all these models obliquity variations exert the dominant influence on the sequential variations in layer thickness although eccentricity and precession index longitude of perihelion may take recognizable contributions as well the layer patterns for the north and south polar deposits are identical for the dust model and only slightly different for the ice model but this is at least partly a consequence of simplifying assumptions the sequential variation in layer thickness is also very sensitive to those model parameters which control the fraction of time for which deposition occurs when the climate threshold for deposition is low deposition occurs a large fraction of the total time and characteristic patterns form with one thick layer and a number of much thinner ones such patterns would be easily recognized in photogeological measurements of layer thickness when the threshold for deposition lies in the mid range with respect to excursions of the climate function deposition occurs approximately half of the time and there is only slight modulation of layer thickness when the threshold for deposition is high deposition occurs only a small fraction of the total time and groups of layers form which are separated form other groups by long periods of nondeposition the stratigraphic unconformities that separate groupings of five to ten layers in the polar deposits may indicate that the martian polar region has experienced such a depositional history the feasibility of using these model results to verify the theory of climate control of polar stratigraphy on mars and to gain additional insights into the significant processes is considered the stratigraphy issues raised here are also explored in the context of recent work on the interpretation of stratigraphy of ocean margins from this comparison there emerge some valuable insights into the stratigraphic effects of periods of nondeposition and the uncertaintiesin interpreting images of exposed polar strata on mars

reconstruction of potential evapotranspiration over western himalaya in india based on tree ring width records abstract tree ring chronologies from different sites of western himalaya have been used in this study to examine the climate variability change over the region the 1st principal component pc1 which has been computed by multi species tree ring chronologies of western himalaya is negatively correlated with heat index ht temperature tm and potential evapotranspiration pet but positively with the rainfall of the region during spring season however ht and pet showed the stronger influence on tree growth than temperature which has been used to reconstruct the spring season pet back to a d 1779 the extended periods of low pet have been found at ending phase of little ice age lia during 1827 1845 the reconstructed pet showed that the advance of the glaciers over the western himalaya might have influence on reduction of downward shortwave radiation on the earth s surface which may in turn cause low temperature and low pet over the region the result indicates that longer tree ring chronologies from the western himalaya are very useful to get valuable information on pet and glacier fluctuation during the last few centuries the highest pet in the entire reconstruction was noticed during the year 1921 in the 20th century which has been associated with lowest trees growth in the entire western himalaya

bed thickness distributions on mars an orbital perspective studies on earth show that sedimentary bed thickness and bed thickness distributions record information about the processes controlling sediment deposition high resolution digital terrain models dtms such as those derived from the high resolution imaging science experiment hirise now provide the opportunity to quantify bed thickness properties on mars over several orders of magnitude down to the submeter scale this study uses hirise dtms and visible images to measure bed thickness distributions at 10 deposits on mars with the aim of determining whether statistical techniques can provide useful criteria for distinguishing sedimentary depositional processes basic statistics including mean thickness and range are examined as are histograms cumulative frequency plots and log log plots statistical tests interrogate these deposits for thinning or thickening upward trends and the presence of normal lognormal and exponential distributions although there are challenges associated with these methods the statistical analysis of bed thickness coupled with morphological and mineralogical interpretations has the potential to be a powerful tool for characterizing and classifying sedimentary rocks on mars in particular bed thickness statistics are particularly well suited for examining changes in sediment supply and accommodation within martian sedimentary sequences

stratigraphic relationships within martian polar cap deposits abstract deposits of layered ice and dust accumulate on the smooth and banded terrains of the north and south polar cap deposits while erosion of equator facing slopes of layered terrain expose these layers banded terrain occurs at exposures of irregular layers resulting from slight erosion of the feather edges of layers deposited on pole facing trough walls these deposits unconformably overlap onto adjacent layered terrain stripping of layers occurs in areas of strong multidirectional wind forming striped terrain local wind scour has also produced steep scarps with crescentic planform often associated with dune fields positioned immediately downwind unconformities are common within layered deposits in areas of complex topography at the north pole these indicate that episodes of deposition of 5 10 layers alternate with slight erosion of pole facing trough walls troughs that strike north south alternate between erosional widening and deepening and depositional infilling creating multiple unconformities troughs near the equatorward limit of polar deposits increase in relief by deposition on adjacent smooth terrain and locally by erosional deepening troughs may migrate poleward replacing the relief increase by depositional infilling when they near the poles

dendroclimatic reconstruction of april may temperature fluctuations in the western himalaya of india since a d 1698 abstract ring width chronologies of himalayan cedar cedrus deodara d don g don himalayan pine pinus wallichianaa b jackson and himalayan spruce picea smithiana wall boiss from the western himalayan region india have been used to reconstruct mean april may temperature back to a d 1698 the reconstruction correlates significantly with the average april may instrumental temperature record r 0 62 1876 1988 and is characterized by annual to multiyear fluctuations the most striking feature of the present reconstruction is the absence of any warming trend in the 20th century relationships between the mean april may temperature for the western himalayan region indian summer monsoon rainfall and southern oscillation index indicate that the tree ring chronologies as surrogate temperature records will provide valuable data for climate change studies with regional and global perspectives

first high resolution stratigraphic column of the martian north polar layered deposits 1 this study achieves the first high spatial resolution layer scale measured stratigraphic column of the martian north polar layered deposits using a 1m posting dem the marker beds found throughout the upper north polar layered deposits range in thickness from 1 6 m 16 0 m 1 4 m and 6 of 13 marker beds are separated by 25 35 m thin layer sets have average layer separations of 1 6 m these layer separations may account for the spectral power peaks found in previous brightness profile analyses marker bed layer thicknesses show a weak trend of decreasing thickness with depth that we interpret to potentially be the result of a decreased accumulation rate in the past for those layers however the stratigraphic column reveals that a simple rhythmic or bundled layer sequence is not immediately apparent throughout the column implying that the relationship between polar layer formation and cyclic climate forcing is quite complex

north polar cap of mars polar layered deposit characterization and identification of a fundamental climate signal of the cap 6 10 5 km 2 in the 13 images analyzed to date 3 assessment of geometric relationships shows that layers are not horizontal but rather have an apparent dip of approximately 0 5 degrees we interpret these results as follows 1 the fundamental 30 m signal is interpreted as a climate signal that may correspond to a 51 kyr insolation cycle 2 the lateral correlation and broad distribution of these layer sequences strongly imply that layer accumulation processes are widespread across the cap rather than confined within a single trough or region 3 local to regional variability in individual layer thicknesses and thus accumulation and sublimation rates is typically less than a factor of 2 5 providing the ability to study regional trends but often making it difficult to correlate visually the vertical sequences in individual cores finally initial examination of layers located deeper in the stratigraphic sequence within the north polar cap than the 300 m thick zone 1 provides evidence for a unit less than 100 m thick zone 2 in which the fundamental 30 m sequence is not detected we interpret this as a deposit having formed during a recent high obliquity phase of mars during which time polar volatiles underwent mobilization and were transport equatorward leaving a polar lag of dust rich material the most recent ice age 0 5 2 ma offers a plausible candidate for this period of ice cap removal and lag deposit formation an underlying zone 3 200 m contains a dominant 35 m signal and a lowermost zone 4 200 m contains multiple signals but no dominant one together these four zones represent 800 m of vertical stratigraphic section about one fourth of the total thickness of the cap these findings support earlier interpretations that orbital parameter variations could cause significant erosion and possibly complete removal of the polar caps the interpreted crater retention ages of the layered terrain are consistent with the correlations and vertical sequences described here suggesting that the polar caps wax and wane throughout geological history depending on the evolution of orbital parameters definition of the 30 m unit signal holds promise for determining 1 the detailed origin of individual layer types 2 the nature of deposition and sublimation processes and their relation to insolation geometry across the polar cap and 3 correlation with and comparison to the south polar layered terrain record

meter scale morphology of the north polar region of mars mars north pole is covered by a dome of layered ice deposits detailed 30 centimeters per pixel images of this region were obtained with the high resolution imaging science experiment on board the mars reconnaissance orbiter mro planum boreum basal unit scarps reveal cross bedding and show evidence for recent mass wasting flow and debris accumulation the north polar layers themselves are as thin as 10 centimeters but appear to be covered by a dusty veneer in places which may obscure thinner layers repetition of particular layer types implies that quasi periodic climate changes influenced the stratigraphic sequence in the polar layered deposits informing models for recent climate variations on mars

ephemeral liquid water at the surface of the martian north polar residual cap results of numerical modelling abstract gypsum a mineral that requires water to form is common on the surface of mars most of it originated before 3 5 gyr when the red planet was more humid than now however occurrences of gypsum dune deposits around the north polar residual cap nprc seem to be surprisingly young late amazonian in age this shows that liquid water was present on mars even at times when surface conditions were as cold and dry as the present day a recently proposed mechanism for gypsum formation involves weathering of dust within ice e g niles p b michalski j 2009 nat geosci 2 215 220 however none of the previous studies have determined if this process is possible under current martian conditions here we use numerical modelling of heat transfer to show that during the warmest days of the summer solar irradiation may be sufficient to melt pure water ice located below a layer of dark dust particles albedo 0 13 lying on the steepest sections of the equator facing slopes of the spiral troughs within martian nprc during the times of high irradiance at the north pole every 51 ka caused by variation of orbital and rotational parameters of mars e g laskar j et al 2002 nature 419 375 377 this process could have taken place over larger parts of the spiral troughs the existence of small amounts of liquid water close to the surface even under current martian conditions fulfils one of the main requirements necessary to explain the formation of the extensive gypsum deposits around the nprc it also changes our understanding of the degree of current geological activity on mars and has important implications for estimating the astrobiological potential of mars

recent warming in a 500 year palaeotemperature record from varved sediments upper soper lake baffin island canada laminated sediments from upper soper lake on southern baffin island provide a new 500 year record of temperature change in the arctic radiometric dating using 210pb and pu shows that the light and dark coloured laminae couplets are annually deposited varves dark laminae thickness is strongly correlated to average june temperature from kimmirut r 0 82 reflecting the influence of temperature on snowmelt and fluxes of runoff and suspended sediment this relationship allowed the construction of a palaeotemperature record that documents large amplitude interannual to decadal variability superimposed on distinct century scale trends including 2 c average warming and maximum temperatures during the 1900s similar patterns of change are seen in individual and regionally averaged palaeotemperature records from around the circum arctic upper soper lake records temperatures rates of change and variance during the twentieth century that are all anomal ously high within the context of the last 500 years and outside the observed range of natural variability comparisons of upper soper lake and arctic average palaeotemperature to proxy records of hypothesized forcing mechanisms suggest that the recent warming trend is mostly due to anthropogenic emissions of atmos pheric greenhouse gases the magnitude of the warming and decade scale variability throughout the records however indicate that natural forcing mechanisms such as changing solar irradiance and volcanic activity as well as positive feedbacks within the arctic environment also play an important role

geology and insolation driven climatic history of amazonian north polar materials on mars a wealth of image and topographic data from the mars global surveyor and mars odyssey missions has been combined in a detailed geological map of the north polar region of mars one intriguing finding is a cycle of ice deposition similar in duration to a 1 470 year climate cycle of unknown origin on earth if both are externally driven a mechanism that affects both planets such as variation in solar luminosity must be involved mariner 9 and viking spacecraft images revealed that the polar regions of mars like those of earth record the planet s climate history however fundamental uncertainties regarding the materials features ages and processes constituting the geologic record remained1 2 3 4 5 6 recently acquired mars orbiter laser altimeter data7 and mars orbiter camera high resolution images8 from the mars global surveyor spacecraft and moderately high resolution thermal emission imaging system visible images9 from the mars odyssey spacecraft permit more comprehensive geologic and climatic analyses10 11 12 13 14 15 16 17 here i map and show the history of geologic materials and features in the north polar region that span the amazonian period 3 0 gyr ago to present 18 19 erosion and redeposition of putative circumpolar mud volcano deposits15 formed by eruption of liquefied fine grained material led to the formation of an early amazonian polar plateau consisting of dark layered materials crater ejecta superposed on pedestals indicate that a thin mantle was present during most of the amazonian suggesting generally higher obliquity and insolation conditions at the poles than at present brighter polar layered deposits rest unconformably on the dark layers and formed mainly during lower obliquity over the past 4 5 myr ref 20 finally the uppermost layers post date the latest downtrend in obliquity 20 000 years ago20

mars north polar deposits stratigraphy age and geodynamical response the shallow radar sharad on the mars reconnaissance orbiter has imaged the internal stratigraphy of the north polar layered deposits of mars radar reflections within the deposits reveal a laterally continuous deposition of layers which typically consist of four packets of finely spaced reflectors separated by homogeneous interpacket regions of nearly pure ice the packet interpacket structure can be explained by approximately million year periodicities in mars obliquity or orbital eccentricity the observed 100 meter maximum deflection of the underlying substrate in response to the ice load implies that the present day thickness of an equilibrium elastic lithosphere is greater than 300 kilometers alternatively the response to the load may be in a transient state controlled by mantle viscosity both scenarios probably require that mars has a subchondritic abundance of heat producing elements

detailed stratigraphy and bed thickness of the mars north and south polar layered deposits the mars polar layered deposits pld likely hold an extensive record of recent climate during a period of high amplitude orbit and obliquity cycles previous work has detected limited evidence for orbital signatures within pld stratigraphy but data from the high resolution imaging science experiment hirise permit renewed analysis of pld stratigraphy at sub meter scale topography derived from hirise images using stereogrammetry resolves beds previously detectable only as alternating light and dark bands in visible images we utilize these data to measure the thickness of individual beds within the pld corrected for non horizontal bed orientation stratigraphic columns and bed thickness profiles are presented for two sites within the npld and show several sets of finely bedded units 1 2 m thick isolated marker beds 3 4 m thick and undifferentiated sections bed thickness measurements for three sites within the spld exhibit only one bed type based on albedo and morphology and bed thicknesses have a larger mean and variance compared to measurements for the npld power spectra of brightness and slope derived along the measured stratigraphic sections confirm the regularity of npld fine bed thickness and the lack of a dominant spld bed thickness the regularity of fine bed thickness of the npld is consistent with quasiperiodic bed formation albeit with unknown temporal period the spld thickness measurements show no such regularity

summer temperature patterns over europe a reconstruction from 1750 a d based on maximum latewood density indices of conifers abstract temperature variations over europe are reconstructed for a 6 month summer season from april to september for the period 1750 1850 using a network of maximum latewood density chronologies of coniferous trees around 44 of the variance of the whole temperature grid was explained in calibration independent verification indicates that over the reconstruction period the explained variance averaged over the whole grid should lie in the range 30 to 35 the reconstructions are better in the north of the region about 50 explained temperature variance based on comparison with independent climate data than in the south below 20 the temperature recontructions indicate cooler summers over europe from 1812 to 1816 and during the 1830s the summers of the 1820s were the warmest reconstructed decadal variations occur on a regional scale but no similar periods of anomalously cooler or warmer summers occurred between 1750 and 1810 throughout europe

north polar stratigraphy and the paleo erg of mars an accurate self consistent way of coregistering the imaging and topographic data sets of the mars global surveyor mission was developed and used to begin a stratigraphic analysis of the northern polar region a distinct change in the layering style exists at a definite stratigraphic horizon near the base of the north polar layered deposits occurrences of the contact between two distinct layered units can be mapped hundreds of kilometers apart at nearly the same mars orbiter laser altimeter mola elevation the lower layered unit has a consistent association with sand dunes leading to the conclusion that it is an eroding sand rich deposit that predates most of the overlying north polar layered deposits which exhibits the expected features of a dust ice mixture these results suggest that an areally extensive erg was in existence before the present ice cap and that the present circumpolar erg is likely composed of material reworked from this older deposit the volume of this lower unit is estimated to be on the order of 10 5 km 3 the presence of this deposit implies that there existed a period in mars history when there was no icy polar cap a dramatic climatic change leading to the deposition of the upper layered icy unit in the present day polar layered deposits represents a major event in mars history however owing to uncertainties in the mechanics of layered deposits formation such an event cannot be dated at this time

a six hundred year annual minimum temperature history for the central tibetan plateau derived from tree ring width series the recent unprecedented warming found in different regions has aroused much attention in the past years how temperature has really changed on the tibetan plateau tp remains unknown since very limited high resolution temperature series can be found over this region where large areas of snow and ice exist herein we develop two juniperus tibetica kom tree ring width chronologies from different elevations we found that the two tree ring series only share high frequency variability correlation response function and partial correlation analysis indicate that prior year annual january december minimum temperature is most responsible for the higher belt juniper radial growth while more or less precipitation signal is contained by the tree ring width chronology at the lower belt and is thus excluded from further analysis the tree growth climate model accounted for 40 of the total variance in actual temperature during the common period 1957 2010 the detected temperature signal is further robustly verified by other results consequently a six century long annual minimum temperature history was firstly recovered for the yushu region central tp interestingly the rapid warming trend during the past five decades is identified as a significant cold phase in the context of the past 600 years the recovered temperature series reflects low frequency variability consistent with other temperature reconstructions over the whole tp region furthermore the present recovered temperature series is associated with the asian monsoon strength on decadal to multidecadal scales over the past 600 years

atmospheric transport into polar regions on mars in different orbital epochs abstract the variation of the transport of air into martian polar regions with obliquity is examined using a series of marswrf general circulation model simulations which include idealized age of air and exponential decay tracers these show substantial changes in the circulation polar vortex structure and tracer transport with changes in obliquity these changes are non monotonic with respect to obliquity as well as differing between the summer and winter polar regions in particular there is an increase in the rate of vertically integrated transport of air to the winter pole as obliquity increases from 5 to 25 followed by a decrease from 25 to 55 with generally the reverse trends for transport to the summer pole this behavior suggests that the amount of dust transport into polar regions will vary with obliquity and could contribute to the apparent cyclical deposition of dust in polar regions as expressed in the polar layered deposits furthermore the non monotonic variation with obliquity suggests that visible changes in the appearance of polar layering may vary on a cycle with half the period of the cycle over the full obliquity variation range

rates of mineral dissolution under co2 storage conditions abstract evaluating the potential of a sedimentary basin reservoir to securely store co 2 benefits from a comprehensive understanding of the geochemical reactions that take place once co 2 is injected into a formation in particular models that predict the transport and reaction of co 2 within a reservoir require a definition of the types of reactions affected by enhanced levels of co 2 and how the kinetics of these reactions will affect a heterogeneous mineralogy and formation waters within a reservoir over time in this review we evaluate rate models used to describe mineral dissolution kinetics and compare the range in values reported for the kinetic parameters used to describe the reactivity of various minerals relevant to mainly siliciclastic reservoirs parameters that have a significant impact on model results include the reactive surface area of a mineral the apparent activation energies used to extrapolate reaction rates to the temperatures of potential storage reservoirs c 50 125 c and the in situ ph of formation waters with elevated concentrations of dissolved co 2 the variation in reported values for these parameters can lead to predicted rates that span many orders of magnitude for a given mineral despite these uncertainties recent success with geochemical models has been made by applying a monte carlo approach to optimise the kinetic parameters for minerals where robust thermodynamic and kinetic data do not exist

topography and stratigraphy of the northern martian polar layered deposits using photoclinometry stereogrammetry and mola altimetry we present two photoclinometric profiles across a trough in the martian northern polar layered terrain complications caused by albedo variations were avoided by using an early springtime viking image with a thin cover of seasonal co2 frost the topographic profiles were constrained with stereogrammetric elevations derived from summertime viking images of the same region we find that the photoclinometric profiles are consistent with a nearby mola mars orbiter laser altimeter track crossing the same polar trough the trough is asymmetric with higher relief and a steeper slope on the equatorward facing wall individual layers are subdued and difficult to observe in the profiles a decrease in both relief and elevation toward the eastern end of the trough suggests that layers become thinner to the east declining equatorward slopes in the eastern portion of the trough imply that erosion rates have varied along the trough the variation in erosion rate may be linked to the change in layer thickness along the trough layers have an average thickness of 19 8 m in the center of the trough and 59 32 m on the northern wall the northern wall is most likely composed of thinner layers that are obscured to first order we find that a 19 m layer requires 16 000 years of deposition to form although this timescale does not coincide with orbital variation periods of 10 5 and 10 6 years deposition rates may not be constant and thus the 16 000 year layer formation time does not preclude layer formation during part of each orbital oscillation c 2000 academic press

martian north polar layered deposits stratigraphy implications for accumulation rates and flow 1 we have used mars orbiter camera moc images and mars observer laser altimeter mola data to correlate specific layers within the upper 500 m of the martian north polar layered deposits in many troughs using these correlation results we derive relative accumulation rates across the polar layered deposits and through time we identify two major layer sequences one lying stratigraphically above the other each consistent with an overall curving downward layer structure with shallow slopes but with significant localized variations in layer height major disruptions of stratigraphy such as angular unconformities do not appear within the correlated layer sequences on local and broad scales each layer sequence exhibits a different relative accumulation rate pattern indicating that this rate has not remained constant through time and has been affected by localized processes the overall pattern of the lower layer sequence is similar to that of a classic terrestrial ice sheet with a decreasing relative accumulation rate away from the center of the polar layered deposits southward the upper layer sequence exhibits no obvious overall trends we also compare our correlation results to predictions of the effects of simple ice flow on layer structure finding that mass balance patterns have overprinted any effects of large scale ice flow flow has not been significant compared to mass balance in forming the overall structure of the correlated layers

visual stratigraphy of the north greenland ice core project northgrip ice core during the last glacial period 1 a continuous high resolution record of digital images has been obtained from the north greenland ice core project northgrip ice core 75 1 n 42 3 w in the depth interval from 1330 m to the bedrock at 3085 m the ice core stratigraphy is clearly visible throughout the glacial period with the most frequent and brightest visible layers appearing during the coldest events down to a depth of 2600 m the horizontal layering is very regular below this depth small irregularities in the layering start to appear and below 2800 m the visual stratigraphy becomes more uncertain perhaps because of penetration into climatically warmer ice comparison of the visual stratigraphy with high resolution continuous records of chemical impurities and dust reveals a high degree of correlation which indicates that the visible layers are caused by these impurities a new approach is used to automatically determine annual layer thicknesses from the visual stratigraphy record by carrying out a frequency analysis of the most prominent visible layers in the profile the result gives strong support for the northgrip timescale model

surface temperature patterns associated with the southern oscillation abstract the typical global and large scale regional temperature patterns associated with the low warm and high cold phases of the southern oscillation so are investigated a total of 12 separate regions were found to have consistent temperature patterns associated with low phase of the so while 11 areas were found to have temperature patterns associated with the high phase of these areas 9 have expected temperature patterns during both phases of the so in the tropics temperature anomalies are of the same sign as the so related sea surface temperature sst anomaly in all land regions except for one area in the west pacific three extratropical responses to the low phase of the so are found over north america and one is found in japan high so temperature patterns were found in the extratropies for japan western europe and northwestern north america the identified temperature responses are more consistent in tropical regions than in the extratropies the so can influence the estimation of

spring precipitation variations over the western himalaya india since a d 1731 as deduced from tree rings 1 spring precipitation representative of regional scale features was reconstructed since a d 1731 using 15 site ring width chronologies of himalayan cedar cedrus deodara roxb ex lambert g don prepared from distantly located moisture stressed sites in the western himalayan region this is so far the strongest tree ring based precipitation reconstruction in terms of variance explained in the calibration model a d 1897 1986 from the western himalayan region the twentieth century experienced the driest and wettest years in the whole reconstructed series the 10 and 20 year means also indicate extreme precipitation periods in the twentieth century the increasing precipitation trend noticed in the reconstructed data of the late twentieth century closely matches with instrumental data

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

decadal multi decadal temperature discrepancies along the eastern margin of the tibetan plateau abstract knowledge of the synchronicity and discrepancy of temperature variations along the eastern margin of the tibetan plateau etp is critical in understanding the driving forcing of regional temperature variations in this study we established 15 n timeseries in organic matter and 13 c timeseries in ostracod shells from sediments of lake lugu and attributed their variations to decadal multi decadal temperature variations we compared temperature variations along the etp transect during the past four centuries based on our presently developed and previously developed temperature proxy indices as well as temperature variations reconstructed by other researchers we found that 1 over the north etp area n etp the decadal multi decadal variations in temperature correlate well with each other 2 over the south etp area s etp temperature variations correlate not so well with each other while those at south to west portion of the tibetan plateau are rather local 3 the decadal variations in temperature are generally synchronous with those in precipitation over the n etp area and they are broadly anti phase out of phase with the corresponding ones over the s etp area 4 the long term temperature and precipitation trends are coupling over the n etp but decoupling over the s etp we speculate that because the n etp is located at the frontier of the asian summer monsoon asm region temperature variations there are not as strongly influenced by the asm they are most likely dominated by changes in solar activities and show general similarity to the average of the northern hemisphere over the s etp area decadal temperature variations are obviously influenced by precipitation because the decadal multi decadal precipitation variations are anti phase and or out of phase between the n etp and s etp the decadal multi decadal temperature variations between these two regions are also anti phase and or out of phase

integrating radar stratigraphy with high resolution visible stratigraphy of the north polar layered deposits mars abstract shallow radar sharad on board nasa s mars reconnaissance orbiter has successfully detected tens of reflectors in the subsurface of the north polar layered deposits npld of mars radar reflections are hypothesized to originate from the same material interfaces that result in visible layering as a first step towards verifying this assumption this study uses signal analyses and geometric comparisons to quantitatively examine the relationship between reflectors and visible layers exposed in an npld outcrop to understand subsurface structures and reflector geometry reflector surfaces have been gridded in three dimensions taking into account the influence of surface slopes to obtain accurate subsurface geometries these geometries reveal reflector dips that are consistent with optical layer slopes distance elevation profiling of subsurface reflectors and visible layer boundaries reveals that reflectors and layers demonstrate similar topography verifying that reflectors represent paleosurfaces of the deposit statistical and frequency domain analyses of the separation distances between successive layers and successive reflectors confirms the agreement of radar reflector spacing with characteristic spacing of certain visible layers direct elevation comparisons between individual reflectors and discrete optical layers while necessary for a one to one correlation are complicated by variations in subsurface structure that exist between the outcrop and the sharad observations as inferred from subsurface mapping although these complications have prevented a unique correlation a genetic link between radar reflectors and visible layers has been confirmed validating the assumption that radar reflectors can be used as geometric proxies for visible stratigraphy furthermore the techniques for conducting a stratigraphic integration have been generalized and improved so that the integration can be undertaken at additional locations

paleoclimatic investigations using isotopic signatures of the late pleistocene holocene groundwater of the stratified aquifers in kuwait abstract the study attempts to determine paleo recharge sources for two major aquifer units of kuwait namely kuwait group aquifer kga and dammam formation dfm were collected and analyzed for major ions and isotopes the obtained results of 14c ages indicated that the groundwater samples ranged from 31 9 ky to 3 9 ky in dfm and 23 3 ky to 0 8 ky in kga the variations in 18o signatures with respect to age reflected that there were two major sources of rainwater such as enriched southern indian ocean monsoon and the depleted northwesterly mediterranean vapor source the samples found to show variations during the three marine isotopic stages mis 1 3 heinrich events bolling allerod and dryas time periods in both aquifers a shift in the intertropical convergence zone itcz was witnessed in the groundwater of both aquifers from 7 8 ky to 4 9 ky the variation in the holocene climate is mainly due to the influence of tropospheric easterly jet governed by the swing in itcz as a result of holocene volcanism the mean 18o values of dfm samples 3 81 reflect depletion than kga samples 2 31 and the d excess values were 0 95 and 2 05 respectively thus it could be inferred that the dfm was predominantly recharged during late pleistocene period and it was in a relatively cooler climate than recharge environment of kga the study infers that kga was recharged between 26on and 26 8on latitudes and that of the dfm was noted to be recharged south west of kuwait in two different patches between 25 8on and 26 2on and 26 7on 27 4on latitudes during late pleistocene the kga was concluded to be recharged between 25 5on and 27 5on latitudes south of kuwait during holocene

origin and characteristics of the mars north polar basal unit and implications for polar geologic history building upon previous studies we have used mars orbiter camera and mars orbiter laser altimeter data to characterize in detail the newly discovered north polar basal unit lying stratigraphically between the polar layered deposits from which it is likely separated by an unconformity and the vastitas borealis formation this unit has introduced new complexity into north polar stratigraphy and has important implications for polar history exposures of the basal unit in olympia planitia and chasma boreale reveal relatively dark layers which exhibit differential erosion eroded primarily by wind the basal unit may be the major if not sole source for the north polar dunes and ergs and has contributed material to the lower polar cap layers we investigate four possible origins for the basal unit outflow channel oceanic deposits basal ice paleopolar deposits and eolian deposits the patchy layering within the unit its likely sandy grain size and presence only in the north polar basin suggest that it is primarily an eolian deposit supporting byrne and murray s 2002 earlier conclusion this implies that at some time during the early to late amazonian migrating sand was mixed with water ice forming a relatively dark sandy deposit during this time either no classic polar layered deposits were forming or smaller caps were growing and shrinking possibly adding material to the basal unit

high resolution topography and albedo of the south polar layered deposits on mars using a new photoclinometric technique with high resolution mariner 9 images maximum slopes of 10 20 are found to occur on an exposure of layered deposits within the south polar residual cap of mars stereophotogrammetry is used to constrain the photoclinometric solutions which resolve layer thicknesses of 100 300 m albedo variations are correlated with slope indicating that frost is present on level areas there is evidence for temporal changes in frost distribution in the 7 days 4 of l s between the two images used in this study the magnitude of the slopes derived here and consideration of the stability of water ice at the surface of the layered deposits strongly suggest the presence of a competent weathering rind the weathered surface may be composed of dark filamentary sublimation residue particles that protect the underlying ice from solar heating this hypothesis is consistent with previous studies of the regional color and albedo of the layered deposits which indicate that the deposits are slightly darker and less red than the bright dust that mantles much of the south polar region furthermore the proposed weathering mechanism provides a plausible source of dark saltating material for the martian polar dune fields

color and albedo of the south polar layered deposits on mars five color albedo units including polar frost have been recognized and mapped in the southern layered deposits on mars atmospheric dust scattering was measured in shadows and modeled in order to remove the component of brightness in mars images due to the atmosphere and quantify the albedo and color of the surface the layered deposits appear to be mantled by red dust except where eolian stripping has exposed the underlying bedrock frost and bare ground are mixed below the resolution of the images in many areas adjacent to the polar cap some of which appear to be younger than the surrounding layered terrain dark material has been deposited in topographic depressions in much of the south polar region including the layered deposits the available observational data suggest that the layered deposits are composed of bright dust ice and a small amount of dark material if the dark material is sand a periodic change in polar winds seems required in order to transport the sand poleward into the layered terrain in any case the observations are not consistent with the layered deposits being composed only of bright dust and ice the mars observer camera and infrared instruments should be particularly useful in this investigation

evaluating the meaning of layer in the martian north polar layered deposits and the impact on the climate connection abstract using data from the high resolution imaging science experiment hirise aboard the mars reconnaissance orbiter we reassess the methods by which layers within the north polar layered deposits npld can be delineated and their thicknesses measured apparent brightness and morphology alone are insufficient for this task high resolution topographic data are necessary from these analyses we find that the visible appearance of layers depends to a large degree on the distribution of younger mantling deposits which in turn is partially influenced by inherent layer properties and on the shape and location of the particular outcrop this younger mantle partially obscures layer morphology and brightness and is likely a cause of the gradational contacts between individual layers at this scale high resolution images reveal that there are several layers similar in appearance to the well known marker bed discovered by malin m edgett k 2001 j geophys res 106 23429 23570 the morphology thicknesses 4 8 2 m and separation distances 5 32 2 m of these marker beds as gleaned from a high resolution stereo digital elevation model lend insight into the connection between stratigraphy and climate

high resolution topomapping of candidate mer landing sites with mars orbiter camera narrow angle images 1 we analyzed narrow angle mars orbiter camera moc na images to produce high resolution digital elevation models dems in order to provide topographic and slope information needed to assess the safety of candidate landing sites for the mars exploration rovers mer and to assess the accuracy of our results by a variety of tests the mapping techniques developed also support geoscientific studies and can be used with all present and planned mars orbiting scanner cameras photogrammetric analysis of moc stereopairs yields dems with 3 pixel typically 10 m horizontal resolution vertical precision consistent with 0 22 pixel matching errors typically a few meters and slope errors of 1 3 these dems are controlled to the mars orbiter laser altimeter mola global data set and consistent with it at the limits of resolution photoclinometry yields dems with single pixel typically 3 m horizontal resolution and submeter vertical precision where the surface albedo is uniform the dominant error is 10 20 relative uncertainty in the amplitude of topography and slopes after calibrating photoclinometry against a stereo dem to account for the influence of atmospheric haze we mapped portions of seven candidate mer sites and the mars pathfinder site safety of the final four sites elysium gusev isidis and meridiani was assessed by mission engineers by simulating landings on our dems of hazard units mapped in the sites with results weighted by the probability of landing on those units summary slope statistics show that most hazard units are smooth with only small areas of etched terrain in gusev crater posing a slope hazard

the spiral troughs of mars as cyclic steps we combine observations of stratigraphy morphology and atmospheric processes to relate the spiral troughs on mars polar layered deposits to a class of features known as cyclic steps cyclic steps are quasi stable repeating and upstream migrating bed forms that have been studied in terrestrial and submarine environments the repeating pattern is bounded by hydraulic jumps which act to stabilize the form we use radar stratigraphy from the shallow radar instrument on mars reconnaissance orbiter to examine trough evolution and constrain lateral transport we examine visible images from the thermal emission imaging system and observe low altitude clouds that we interpret to be the result of katabatic jumps i e the aeolian counterpart of hydraulic jumps in open channel flow we then devise a theoretical framework for understanding the origin of the spiral troughs that agree with 10 criteria that should be explained for any scenario to satisfactorily model the spiral troughs finally we use froude and geometrical analysis to estimate the rate of upstream migration caused by katabatic winds for the spiral troughs

introduction to the 4th mars polar science and exploration conference special issue five top questions in mars polar science abstract as an introduction to this icarus special issue for the 4th mars polar science and exploration conference we discuss five key questions in mars polar science gleaned from plenary discussions and presentations held at the conference these questions highlight major unknowns in the field 1 what are the physical characteristics of the polar layered deposits pld and how are the different geologic units within beneath and surrounding the pld related 2 how old are the pld and what are their glacial fluvial depositional and erosional histories 3 what are the mass and energy budgets of the pld and what processes control these budgets on seasonal and longer timescales 4 what chronology compositional variability and record of climatic change is expressed in the stratigraphy of the pld 5 how have volatiles and dust been exchanged between polar and non polar reservoirs and how has this exchange affected the past and present distribution of surface and subsurface ice

signals of astronomical climate forcing in the exposure topography of the north polar layered deposits of mars nasa earth and space science fellowship nnx13ao55h nasa s mars reconnaissance orbiter project

panigarh cave stalagmite evidence of climate change in the indian central himalaya since ad 1256 monsoon breaks and winter southern jet depressions abstract variations in petrography stable isotopes reflectance and luminescence along the central growth axis of a 14 5 cm stalagmite from panigarh cave indicate cooler and slightly wetter conditions in the himalayan foothills of northern india during the little ice age lia which lasted from ad 1489 1889 based on deposition of calcite and ad 1450 1820 based on rapid changes in 18o values conditions were warmer and drier during the preceding medieval climate anomaly mca and also in the post lia periods as evidenced by deposition of aragonite a review of currently existing stalagmite and other proxy data from south and east asia reveals a broad spatial pattern in precipitation over south and east asia during the lia with northern areas showing generally increased precipitation and southern areas reduced precipitation during the mca and after the lia the records suggest this pattern was reversed weaker ism during the lia brought drought conditions to the core ism area but triggered more monsoon breaks that brought higher precipitation to the himalayas at the same time the weaker ism may also have pushed more depressions along the path of the southern winter jet which brought more winter precipitation to the himalayas and therefore a lia wetter in our study area

climatic fluctuations during the lia and post lia in the kumaun lesser himalaya india evidence from a 400 y old stalagmite record this paper presents the first stable isotope delta o 18 and delta c 13 data of a similar to 400 years 1590 2006 ad long annual to decadal resolution speleothem record collected from the indian lesser himalaya the data show a variation from 2 7 to 5 9 parts per thousand in delta o 18 and 5 3 to 8 8 parts per thousand in delta c 13 the isotopic analyses indicate that the climate during this period can be divided into two stages a wet phase during the little ice age lia 1590 1850 ad and comparatively dry phase during the post lia after 1850 ad however the record also documents the minor dry events during the lia and a wet episode after the lia within the age uncertainty the dry spells during the lia are linked with the historical drought events in the indian subcontinent and similar latitudes the isotopic record is consistent with a number of previous studies in the areas influenced by the westerlies but appears to be conflicting to the regions dominated by the indian summer monsoon ism this may be due to the possible changes in the strength of westerlies in the study area and added by negative anomaly of north atlantic oscillation nao during the lia c 2012 elsevier ltd and inqua all rights reserved

the holocene floods and their affinity to climatic variability in the western himalaya india abstract the present study in the middle satluj valley explores the sedimentary records of past floods with an objective to understand the climatic processes responsible for their genesis based on lithostratigraphy sedimentology and grain size variability 25 flood events are identified the geochemical data indicate that the flood sediments were mostly generated and transported from the higher himalayan crystalline and the trans himalaya our study suggests that the floods were generated by landslide lake outburst floods llofs during extreme precipitation events however the existing database does not allow us to negate the contribution from glacial lake outburst floods glofs field stratigraphy supported by optical chronology indicates four major flood phases that are dated to 13 4 10 4 8 3 3 6 2 2 1 4 and

glacial interglacial changes in mineral dust and sea salt records in polar ice cores sources transport and deposition 1 sea salt and mineral dust records as represented by na and ca2 concentrations respectively in greenland and antarctic ice cores show pronounced glacial interglacial variations for the last glacial maximum lgm mineral dust sea salt concentrations in greenland show an increase of a factor of approximately 80 15 compared to the holocene and significant shifts by a factor of 15 5 during dansgaard oeschger events in antarctica the dust sea salt flux is enhanced by a factor of 15 3 during the lgm compared to the holocene and variations by approximately a factor of 8 1 2 exist in parallel to antarctic warm events primary glacial dust sources are the asian deserts for greenland and patagonia for antarctica ice core evidence and model results show that both changes in source strength as well as atmospheric transport and lifetime contributed to the observed changes in greenland ice cores in antarctica changes in ice core fluxes are in large parts related to source variations both for sea salt and dust where the formation of sea salt aerosol from sea ice may play a pivotal role summarizing our latest estimates on changes in sources transport and deposition these processes are roughly able to explain the glacial increase in sea salt in both polar regions while they fall short by at least a factor of 4 7 for mineral dust future improvements in model resolution and in the formulation of source and transport processes together with new ice core records e g on dust size distributions will eventually allow convergence of models and observations

spiral trough diversity on the north pole of mars as seen by shallow radar sharad we combine observations from ground penetrating radar and optical instruments to conduct a comprehensive survey of spiral troughs on the north polar layered deposits of mars our survey reveals that all north polar troughs have common characteristics but there is strong regional diversity we divide the north polar layered deposits npld into eight regions based on observations of morphology and stratigraphy in order to classify the spiral troughs morphologic features that separate the regions include central promontories topographic undulations bedrock floors and trough asymmetry among others we demonstrate here that the troughs formed during two periods the first generation of troughs formed on the main lobe and in part of gemina lingula during accumulation of 600 m of ice and dust the second generation of troughs formed stratigraphically higher and immediately after large scale erosion in gemini scopuli which we conclude created the slopes necessary for troughs to form we test scenarios of trough evolution and find that only three concurrent processes are required for their formation wind transport insolation induced sublimation and atmospheric deposition our observations are inconsistent with other hypothesized processes to produce spiral troughs including incision after the formation of the npld fracturing due to flowing ice and sublimation driven patterns from insolation

tree ring based spring temperature patterns over the past four centuries in western himalaya a network of 12 tree ring width chronologies of himalayan cedar cedrus deodara from the western himalayan region india has been used to reconstruct mean spring march may temperature variations back to a d 1600 the most conspicuous feature of the temperature reconstruction is the long term cooling trend since the late 17th century that ended early in the 20th century the warmest 30 yr mean for the 20th century was recorded during 1945 1974 however this warming in the context of the past four centuries is well within the range of natural variability since warmer springs of greater magnitude occurred in the later part of the 17th century 1662 1691

regional stratigraphy of the south polar layered deposits promethei lingula mars discontinuity bounded units in images and radargrams abstract the mars south polar layered deposits spld are the result of depositional and erosional events which are marked by different stratigraphic sequences and erosional surfaces to unambiguously define the stratigraphic units at regional scale we mapped the spld on the basis of observed discontinuities i e unconformities correlative discontinuities and conformities as commonly done in terrestrial modern stratigraphy this methodology is defined as discontinuity bounded units or allostratigraphy and is complemented by geomorphological mapping our study focuses on promethei lingula pl and uses both high resolution images ctx hirise and radargrams sharad to combine surface and sub surface observations and obtain a 3d geological reconstruction of the spld one regional discontinuity named aur1 was defined within the studied stratigraphic succession and is exposed in several non contiguous outcrops around pl as well as observed at depth within the ice sheet this is the primary contact between two major depositional sequences showing a different texture at ctx resolution the lower sequence is characterized mainly by a ridge and trough morphology ridge and trough sequence rts and the upper sequence shows mainly by a stair stepped morphology stair stepped sequence sss on the basis of the observations we defined two regional discontinuity bounded units in pl respectively coinciding with rts and sss sequences our stratigraphic reconstruction provides new hints on the major scale events that shaped this region oscillations in martian axial obliquity could have controlled local climate conditions in the past affecting the pl geological record

geologic history of the polar regions of mars based on mars global surveyor data ii amazonian period based on mars orbiter laser altimeter mola and mars orbiter camera moc observations of amazonian polar layered deposits pld morphology composition and thickness we conclude that the plds are composed of porous unconsolidated layers that have not experienced significant basal melting or other glacial type processes morphologic features and associations within the pld chasmata including preserved craters and sinuous ridges indicate that the dominant process of chasmata formation is wind scouring our detailed analysis of south polar spiral trough topography in conjunction with the identification of similar layered stratigraphy within north polar spiral troughs suggests that trough migration due to preferential ablation of sun facing slopes cannot be demonstrated within the layered sequences we have not identified widespread unconformities discontinuities or pinch outs that would indicate an accublation origin of the plds we therefore postulate that the well defined plds at both poles eventually reached and maintained their present form following deposition without extensive deformation or redeposition large cuspate ridges in the ultimi lobe of planum australe appear to be layered and may be unusual erosional remnants of a once thicker pld in this area beneath the north polar layered deposits in planum boreum we have identified a platform of older highly degraded polar deposits as much as a kilometer thick that may have once covered an area larger than planum boreum

is there an orbital signal in the polar layered deposits on mars do the polar layered deposits on mars refl ect orbital control or stochastic variability it is fi useful to determine whether an orbital signal would be detected even if present an estimate of the uncertainty in the time depth relationship of the polar stratigraphy shows that nonlinearities in this relationship and noise in the signal will hamper or preclude detection of orbital forcing even if layer composition is directly proportional to insolation indeed stratigraphic sections of the north polar layered deposits reconstructed from spacecraft images yield no clear evidence of orbital control and are largely consistent with an autoregressive stochastic formation process there is however a broad rise in spectral power centered on a wavelength of roughly 1 6 m that appears in many of the stratigraphic sections this bedding may record a time scale associated with processes internal to mars climate system perhaps related to dust storms alternatively if formed in response to variations in mars obliquity or orbital precession the 1 6 m bedding implies that the 1 km thick upper north polar layered deposits formed over 30 70 myr

influence of the flow rate on dissolution and precipitation features during percolation of co2 rich sulfate solutions through fractured limestone samples abstract calcite dissolution and gypsum precipitation are expected to occur when injecting co2 in a limestone reservoir with sulfate rich resident brine if the reservoir is fractured these reactions will take place mainly in the fractures which serve as preferential paths for fluid flow as a consequence the geometry of the fractures will vary leading to changes in their hydraulic and transport properties in this study a set of percolation experiments which consisted of injecting co2 rich solutions through fractured limestone cores was performed under p 150 bar and t 60 c flow rates ranging from 0 2 to 60 ml h and sulfate rich and sulfate free solutions were used variation in fracture volume induced by calcite dissolution and gypsum precipitation was measured by x ray computed microtomography xcmt and aqueous chemistry an increase in flow rate led to an increase in volume of dissolved limestone per unit of time which indicated that the calcite dissolution rate in the fracture was transport controlled moreover the dissolution pattern varied from face dissolution to wormhole formation and uniform dissolution by increasing the flow rate i e pe from 1 to 346 fracture permeability always increased and depended on the type of dissolution pattern

quaternary glacial history of nw garhwal central himalayas a first account of the quaternary glacial history is presented for northwest garhwal central himalaya on the basis of sediments and landforms one glacial stage has been recognised this is called the bhagirathi glacial stage when extensive valley glaciers advanced down the bhagirathi valley to jhala 40 5 km from the snout of gangotri glacier the ela depression during this stage was ca 640 m the bhagirathi glacial stage is constrained by optically stimulated luminescence dates of ca 63 ka and 5 ka bp and this glaciation is considered equivalent to the last glaciation elsewhere in the world the maximum extent of ice occurred ca 63 ka bp this however does not correlate with the last glacial maximum for the northern hemisphere ice sheets 20 18 ka bp a series of sharp crested moraines are present between 1 to 3 km beyond the snouts of most of the present glaciers these moraines formed during the mid holocene 5 ka bp termed here the shivling glacial advance small moraines are inset into these and are dated at about 200 to 300 bp the bhujbas glacial advance ca 300 to 200 bp and considered equivalent to the little ice age in other parts of the world ela depressions of between 40 100 m and 20 60 m occurred during the shivling and bhujbas glacial advances respectively since the bhujbas glacial advance there has been progressive retreat of glaciers initially by downwasting and retreat and then by simple retreat this retreat has accelerated during the last few decades impressive paraglacial fans are associated with deglaciation representing very rapid resedimentation during and soon after ice retreat

ultrahigh resolution topographic mapping of mars with mro hirise stereo images meter scale slopes of candidate phoenix landing sites 1 the objectives of this paper are twofold first to report our estimates of the meter to decameter scale topography and slopes of candidate landing sites for the phoenix mission based on analysis of mars global surveyor mgs mars orbiter camera moc images with a typical pixel scale of 3 m and mars reconnaissance orbiter mro high resolution imaging science experiment hirise images at 0 3 m pixel 1 and second to document in detail the geometric calibration software and procedures on which the photogrammetric analysis of hirise data is based a combination of optical design modeling laboratory observations star images and mars images form the basis for software in the u s geological survey integrated software for imagers and spectrometers isis 3 system that corrects the images for a variety of distortions with single pixel or subpixel accuracy corrected images are analyzed in the commercial photogrammetric software socet set bae systems yielding digital topographic models dtms with a grid spacing of 1 m 3 4 pixels that require minimal interactive editing photoclinometry yields dtms with single pixel grid spacing slopes from moc and hirise are comparable throughout the latitude zone of interest and compare favorably with those where past missions have landed successfully only the mars exploration rover mer b site in meridiani planum is smoother moc results at multiple locations have root mean square rms bidirectional slopes of 0 8 4 5 at baselines of 3 10 m hirise stereopairs one per final candidate site and one in the former site yield 1 8 2 8 slopes at 1 m baseline slopes at 1 m from photoclinometry are also in the range 2 3 after correction for image blur slopes exceeding the 16 phoenix safety limit are extremely rare

the role of eolian processes in forming surface features of the martian polar layered deposits abstract the major topographic features of the martian polar layered deposits include the conspicuous spiral troughs subtle undulations broad reentrants chasma steep arcuate scarps and dune fields a prominent role for eolian processes in the formation of all of these features is proposed strong katabatic winds occur on the north polar cap producing widespread frost streaks these cold drainage winds are analogous to those on the terrestrial antarctic cap in the chasmae convergent katabatic winds create yardangs and erode arcuate scarps in the layered deposits that are also the source for local dune fields migrating outward from the polar cap the chasmae are postulated to originate by long term erosion by katabatic wind wind plays a role in formation of the troughs and scarps primarily through removal of dust freed from exposed layered deposits by ablation of ice on defrosted equator facing slopes the undulations are created by interaction between surface erosion or deposition of perennial ice and standing waves in the shallow katabatic windflow the south polar layered deposits exhibit topographic features similar to those at the north polar cap but erosion and depositional processes creating these features may be inactive during the current epoch because of the lack of an extensive perennial ice cover and associated katabatic wind

feasibility of limestone reservoirs as a carbon dioxide storage site an experimental study carbon capture and storage technology is a means to permanently store carbon dioxide co2 in suitable geologic formations such as depleted oil and gas reservoirs and saline aquifers the potential of depleted carbonates reservoirs for being a secure storage site has been assessed in several studies based on the key storage aspects however minor attention has been given to rock type and the potential compaction of carbonates at different injection rates when geochemical interactions posed by supercritical co2 reduces their elastic properties and strength in this study limestone samples were tested to investigate changes in their physical and mechanical characteristics once flooded by co2 at a very low injection rate the results obtained indicate that an excessive pressure drop might be experienced even under a very low injection rate because of continuous dissolution of carbonates in the presence of co2 and brine creation of wormholes and the dissolution of the matrix were also observed through scanning electron microscope computerized tomography scan and nuclear magnetic resonance tests it was also observed that the elastic parameters and the strength of the limestone samples may significantly decrease after co2 flooding which might be linked to calcite dissolution and weakening of the solid skeleton

sequence architecture of the cavi unit chasma boreale mars abstract the principles of terrestrial sequence stratigraphy provide a proven approach for evaluating the cavi unit where it transitions into the north polar layered deposits npld three cavi unit outcrops at the head of chasma boreale were examined using high resolution imagery and topography and interpreted in a sequence stratigraphic framework lithofacies present in the cavi unit were identified and consist of 1 dark lithic material 2 dark material with icy foresets 3 icy cavi 4 isolated dunes 5 dirty ice and 6 layered ice these lithofacies represent a progression in the dominance of aeolian to cryosphere processes and have analogs in the modern chasma boreale depositional environment parasequences were defined as aeolian units bounded by outcrop scale unconformities permafrost layers and layered ice deposits the northern outcrop is dominated by sandy lithofacies with large bodies of sand also dominating the northern parts of the central and southern outcrops in the central and southern outcrops sandy lithofacies yield southward to icier accumulations concurrently vertical trends in lithofacies distribution indicate an increasing prevalence of ice deposits through time considered across all three outcrops the parasequences form a set that expresses the northward retreat of the cavi aeolian system coincident with transgression of an ice sheet originating in gemini lingula this retrogradational stacking pattern of cavi aeolian parasequences with gradual transgression of the npld environment implies that the transitional cavi unit and npld form a single sequence that may correspond to allogenic forcing by orbital parameters the dynamics between aeolian and cryosphere processes revealed at the parasequence scale indicate that preservation of the stratigraphic record is driven by the ice transgression suggesting that during episodes of ice sheet collapse the north polar sedimentary environment reverts to one dominated by aeolian erosion and reworking as represented by the basal cavi unit

1738 years of mongolian temperature variability inferred from a tree ring width chronology of siberian pine 1738 years ad 262 1999 of temperature variability are inferred from tree ring widths of siberian pine at solongotyn davaa sol dav a timberline 2420 m site in mongolia this chronology can account for 33 of the temperature variance from 1882 1993 the warmest conditions over the past millennium are during the 20th century the 1999 ring width has the highest index value over the past millennium both warmer and colder intervals are inferred during the medieval warm epoch the most severe cold occurred in the 19th century unusual cold and frost in ad 536 545 coincide with extremes in other proxies and historical accounts confirming a widespread catastrophic event trends resemble those of other eurasian paleoseries and hemispheric scale reconstructions over the past millennium more chronologies such as sol dav are essential to improve coverage in the uncertain earlier centuries of these reconstructions and their estimates of natural variability relative to recent anthropogenic change

recent formation and evolution of northern martian polar layered deposits as inferred from a global climate model 1 we present a time marching model which simulates the exchange of water ice between the martian northern cap the tropics and a high latitude surface reservoir net annual exchange rates of water and their sensitivity to variations in orbital rotational parameters are examined using the martian water cycle modeled by the lmd three dimensional global climate model these rates are propagated over the last 10 myr to follow the thickness of the reservoirs the effect of a sublimation dust lag is taken account to test simple models of layer formation periods of high mean polar summer insolation 5 10 ma ago lead to a rapid exhaustion of a northern polar cap and a prolonged formation of tropical glaciers the formation of a northern cap and of a high latitude icy mantle may have started 4 ma ago with the average decrease of polar insolation tropical ice may have disappeared around 2 7 ma ago but small glaciers could have formed during the last peaks of polar summer insolation over the last 4 myr most of the present cap may have formed at the expense of tropical and high latitude reservoirs forming distinct layers at almost each 51 kyr 120 kyr insolation cycle layers thickness ranges from 10 to 80 m variations being produced by the modulation of the obliquity with 2 4 and 1 3 myr periods because only 30 insolation cycles have occurred since 4 ma ago we found an inconsistency between the recent astronomical forcing the observed number of layers and simple astronomically based scenarios of layers formation

long term temperature trends and tree growth in the taymir region of northern siberia abstract the northernmost conifers in the world are located well above the arctic circle in the taymir region of northern siberia and have been recording the thermal environment for centuries to millennia the trees respond to temperatures beyond the narrow season of actual cambial cell division by means of root growth photosynthesis lignification of cell walls and other biochemical processes data from annual tree ring widths are used to reconstruct may september mean temperatures for the past four centuries these warm season temperatures correlate with annual temperatures and indicate unusual warming in the 20th century however there is a loss of thermal response in ring widths since about 1970 previously the warmer temperatures induced wider rings most major warming and cooling trends are in agreement with other high latitude temperature reconstructions based on tree ring analyses with some regional differences in timing of cooling in the late 18th century and of warming in the late 19th century

early holocene to present palaeoenvironmental shifts and short climate events from the tropical wetland and lake sediments kukkal lake southern india geochemistry and palynology the kukkal basin tamil nadu india receives most of its rain from the southwest monsoon swm a sediment core from kukkal lake preserves a continuous sediment record from the early holocene to p

aeolian processes as drivers of landform evolution at the south pole of mars abstract we combine observations of surface morphology topography subsurface stratigraphy and near surface clouds with mesoscale simulations of south polar winds and temperature to investigate processes governing the evolution of spiral troughs on the south pole of mars in general we find that the south polar troughs are cyclic steps that all formed during an erosional period contrary to the troughs at the north pole which are constructional features the shallow radar instrument sharad onboard mars reconnaissance orbiter detects subsurface stratigraphy indicating relatively recent accumulation that occurred post trough formation in many locations using optical instruments especially the thermal emission imaging system themis we find low altitude trough clouds in over 500 images spanning 6 mars years the locations of detected clouds correspond to where recent accumulation is detected by sharad and offers clues about surface evolution the clouds migrate by season moving poleward from 71 s at l s 200 until l s 318 when the last cloud is detected our atmospheric simulations find that the fastest winds on the pole are found roughly near the external boundary of the seasonal co 2 ice cap thus we find that the migration of clouds and katabatic jumps corresponds spatially to the retreat of the co 2 seasonal ice as detected by titus 2005 and that trough morphology through recent accumulation is integrally related to this seasonal retreat

the high resolution imaging science experiment hirise during mro s primary science phase psp the high resolution imaging science experiment hirise on the mars reconnaissance orbiter mro acquired 8 terapixels of data in 9137 images of mars between october 2006 and december 2008 covering 0 55 of the surface images are typically 5 6 km wide with 3 color coverage over the central 20 of the swath and their scales usually range from 25 to 60 cm pixel nine hundred and sixty stereo pairs were acquired and more than 50 digital terrain models dtms completed these data have led to some of the most significant science results new methods to measure and correct distortions due to pointing jitter facilitate topographic and change detection studies at sub meter scales recent results address noachian bedrock stratigraphy fluvially deposited fans in craters and in or near valles marineris groundwater flow in fractures and porous media quasi periodic layering in polar and non polar deposits tectonic history of west candor chasma geometry of clay rich deposits near and within mawrth vallis dynamics of flood lavas in the cerberus palus region evidence for pyroclastic deposits columnar jointing in lava flows recent collapse pits evidence for water in well preserved impact craters newly discovered large rayed craters and glacial and periglacial processes of particular interest are ongoing processes such as those driven by the wind impact cratering avalanches of dust and or frost relatively bright deposits on steep gullied slopes and the dynamic seasonal processes over polar regions hirise has acquired hundreds of large images of past present and potential future landing sites and has contributed to scientific and engineering studies of those sites warming the focal plane electronics prior to imaging has mitigated an instrument anomaly that produces bad data under cold operating conditions

enhanced deformation of limestone and sandstone in the presence of high fluids 1 geological repositories subject to the injection of large amounts of anthropogenic carbon dioxide will undergo chemical and mechanical instabilities for which there are currently little experimental data this study reports on experiments where low and high 8 mpa aqueous fluids were injected into natural rock samples the experiments were performed in flow through triaxial cells where the vertical and confining stresses temperature and pressure and composition of the fluid were separately controlled and monitored the axial vertical strains of two limestones and one sandstone were continuously measured during separate experiments for several months with a strain rate resolution of 10 11 s 1 fluids exiting the triaxial cells were continuously collected and their compositions analyzed the high fluids induced an increase in strain rates of the limestones by up to a factor of 5 compared to the low fluids injection of high fluids into the sandstone resulted in deformation rates one order of magnitude smaller than the limestones the creep accelerating effect of high fluids with respect to the limestones was mainly due to the acidification of the injected fluids resulting in a significant increase in solubility and reaction kinetics of calcite compared to the limestones the much weaker response of the sandstone was due to the much lower solubility and reactivity of quartz in high fluids in general all samples showed a positive correlation between fluid flow rate and strain rate x ray tomography results revealed significant increases in porosity at the inlet portion of each core the porosity increases were dependent on the original lithological structure and composition the overall deformation of the samples is interpreted in terms of simultaneous dissolution reactions in pore spaces and intergranular pressure solution creep

two centuries temperature variations over subtropical southeast china inferred from pinus taiwanensis hayata tree ring width high resolution long term temperature reconstructions in subtropical southeast china ssc are very scarce yet indispensable for the comprehensive understanding of climate change in china even in east asia we reconstructed the first previous growth season temperature in the sanqingshan mountains sqs southeast china since 1806 based on tree ring width data the reconstruction accounts for 56 4 of the total variance in the instrumental record over 1954 2009 unlike the northern hemispheric warming during recent two centuries the reconstruction captured a slowly cooling trend from 1806 to 1980 followed by a rapid warming afterward 2003 2009 was the warmest period in the reconstruction 1970 2000 was colder than the last stage of the little ice age lia most of the warm and cold periods in this reconstruction could be found in the tree ring based temperature reconstructions of vicinity area indicating that the temperature variations in ssc were almost synchronous at least at decadal scale this regional coherence of temperature variation was further confirmed by the spatial correlation patterns with the cru ts3 22 grid dataset a strong positive relationship between the temperature over sqs region and sea surface temperature sst over the north pacific ocean np has been noted suggesting that sst variations over np and the related pacific decadal oscillation significantly influenced the temperature variability over ssc to better understand the climate variability during the lia and the regional differences in temperature variations over sqs and northern hemisphere long data sets from more diverse areas of southern china are needed