@article{AtsawawaranuntComasBruMozhdehietal.2018, author = {Atsawawaranunt, Kamolphat and Comas-Bru, Laia and Mozhdehi, Sahar Amirnezhad and Deininger, Michael and Harrison, Sandy P. and Baker, Andy and Boyd, Meighan and Kaushal, Nikita and Ahmad, Syed Masood and Brahim, Yassine Ait and Arienzo, Monica and Bajo, Petra and Braun, Kerstin and Burstyn, Yuval and Chawchai, Sakonvan and Duan, Wuhui and Hatvani, Istvan Gabor and Hu, Jun and Kern, Zoltan and Labuhn, Inga and Lachniet, Matthew and Lechleitner, Franziska A. and Lorrey, Andrew and Perez-Mejias, Carlos and Pickering, Robyn and Scroxton, Nick and Atkinson, Tim and Ayalon, Avner and Baldini, James and Bar-Matthews, Miriam and Pablo Bernal, Juan and Breitenbach, Sebastian Franz Martin and Boch, Ronny and Borsato, Andrea and Cai, Yanjun and Carolin, Stacy and Cheng, Hai and Columbu, Andrea and Couchoud, Isabelle and Cruz, Francisco and Demeny, Attila and Dominguez-Villar, David and Dragusin, Virgil and Drysdale, Russell and Ersek, Vasile and Finne, Martin and Fleitmann, Dominik and Fohlmeister, Jens Bernd and Frappier, Amy and Genty, Dominique and Holzkamper, Steffen and Hopley, Philip and Kathayat, Gayatri and Keenan-Jones, Duncan and Koltai, Gabriella and Luetscher, Marc and Li, Ting-Yong and Lone, Mahjoor Ahmad and Markowska, Monika and Mattey, Dave and McDermott, Frank and Moreno, Ana and Moseley, Gina and Nehme, Carole and Novello, Valdir F. and Psomiadis, David and Rehfeld, Kira and Ruan, Jiaoyang and Sekhon, Natasha and Sha, Lijuan and Sholz, Denis and Shopov, Yavor and Smith, Andrew and Strikis, Nicolas and Treble, Pauline and Unal-Imer, Ezgi and Vaks, Anton and Vansteenberge, Stef and Veiga-Pires, Cristina and Voarintsoa, Ny Riavo and Wang, Xianfeng and Wong, Corinne and Wortham, Barbara and Wurtzel, Jennifer and Zong, Baoyun}, title = {The SISAL database}, series = {Earth System Science Data}, volume = {10}, journal = {Earth System Science Data}, number = {3}, publisher = {Copernicus}, address = {G{\"o}ttingen}, organization = {SISAL Working Grp Members}, issn = {1866-3508}, doi = {10.5194/essd-10-1687-2018}, pages = {1687 -- 1713}, year = {2018}, abstract = {Stable isotope records from speleothems provide information on past climate changes, most particularly information that can be used to reconstruct past changes in precipitation and atmospheric circulation. These records are increasingly being used to provide "out-of-sample" evaluations of isotope-enabled climate models. SISAL (Speleothem Isotope Synthesis and Analysis) is an international working group of the Past Global Changes (PAGES) project. The working group aims to provide a comprehensive compilation of speleothem isotope records for climate reconstruction and model evaluation. The SISAL database contains data for individual speleothems, grouped by cave system. Stable isotopes of oxygen and carbon (delta O-18, delta C-13) measurements are referenced by distance from the top or bottom of the speleothem. Additional tables provide information on dating, including information on the dates used to construct the original age model and sufficient information to assess the quality of each data set and to erect a standardized chronology across different speleothems. The metadata table provides location information, information on the full range of measurements carried out on each speleothem and information on the cave system that is relevant to the interpretation of the records, as well as citations for both publications and archived data.}, language = {en} } @article{ComasBruHarrisonWerneretal.2019, author = {Comas-Bru, Laia and Harrison, Sandy P. and Werner, Martin and Rehfeld, Kira and Scroxton, Nick and Veiga-Pires, Cristina and Ahmad, Syed Masood and Brahim, Yassine Ait and Mozhdehi, Sahar Amirnezhad and Arienzo, Monica and Atsawawaranunt, Kamolphat and Baker, Andy and Braun, Kerstin and Breitenbach, Sebastian Franz Martin and Burstyn, Yuval and Chawchai, Sakonvan and Columbu, Andrea and Deininger, Michael and Demeny, Attila and Dixon, Bronwyn and Hatvani, Istvan Gabor and Hu, Jun and Kaushal, Nikita and Kern, Zoltan and Labuhn, Inga and Lachniet, Matthew S. and Lechleitner, Franziska A. and Lorrey, Andrew and Markowska, Monika and Nehme, Carole and Novello, Valdir F. and Oster, Jessica and Perez-Mejias, Carlos and Pickering, Robyn and Sekhon, Natasha and Wang, Xianfeng and Warken, Sophie and Atkinson, Tim and Ayalon, Avner and Baldini, James and Bar-Matthews, Miryam and Bernal, Juan Pablo and Boch, Ronny and Borsato, Andrea and Boyd, Meighan and Brierley, Chris and Cai, Yanjun and Carolin, Stacy and Cheng, Hai and Constantin, Silviu and Couchoud, Isabelle and Cruz, Francisco and Denniston, Rhawn and Dragusin, Virgil and Duan, Wuhui and Ersek, Vasile and Finne, Martin and Fleitmann, Dominik and Fohlmeister, Jens Bernd and Frappier, Amy and Genty, Dominique and Holzkamper, Steffen and Hopley, Philip and Johnston, Vanessa and Kathayat, Gayatri and Keenan-Jones, Duncan and Koltai, Gabriella and Li, Ting-Yong and Lone, Mahjoor Ahmad and Luetscher, Marc and Mattey, Dave and Moreno, Ana and Moseley, Gina and Psomiadis, David and Ruan, Jiaoyang and Scholz, Denis and Sha, Lijuan and Smith, Andrew Christopher and Strikis, Nicolas and Treble, Pauline and Unal-Imer, Ezgi and Vaks, Anton and Vansteenberge, Stef and Voarintsoa, Ny Riavo G. and Wong, Corinne and Wortham, Barbara and Wurtzel, Jennifer and Zhang, Haiwei}, title = {Evaluating model outputs using integrated global speleothem records of climate change since the last glacial}, series = {Climate of the past : an interactive open access journal of the European Geosciences Union}, volume = {15}, journal = {Climate of the past : an interactive open access journal of the European Geosciences Union}, number = {4}, publisher = {Copernicus}, address = {G{\"o}ttingen}, organization = {SISAL Working Grp}, issn = {1814-9324}, doi = {10.5194/cp-15-1557-2019}, pages = {1557 -- 1579}, year = {2019}, abstract = {Although quantitative isotope data from speleothems has been used to evaluate isotope-enabled model simulations, currently no consensus exists regarding the most appropriate methodology through which to achieve this. A number of modelling groups will be running isotope-enabled palaeoclimate simulations in the framework of the Coupled Model Intercomparison Project Phase 6, so it is timely to evaluate different approaches to using the speleothem data for data-model comparisons. Here, we illustrate this using 456 globally distributed speleothem δ18O records from an updated version of the Speleothem Isotopes Synthesis and Analysis (SISAL) database and palaeoclimate simulations generated using the ECHAM5-wiso isotope-enabled atmospheric circulation model. We show that the SISAL records reproduce the first-order spatial patterns of isotopic variability in the modern day, strongly supporting the application of this dataset for evaluating model-derived isotope variability into the past. However, the discontinuous nature of many speleothem records complicates the process of procuring large numbers of records if data-model comparisons are made using the traditional approach of comparing anomalies between a control period and a given palaeoclimate experiment. To circumvent this issue, we illustrate techniques through which the absolute isotope values during any time period could be used for model evaluation. Specifically, we show that speleothem isotope records allow an assessment of a model's ability to simulate spatial isotopic trends. Our analyses provide a protocol for using speleothem isotope data for model evaluation, including screening the observations to take into account the impact of speleothem mineralogy on δ18O values, the optimum period for the modern observational baseline and the selection of an appropriate time window for creating means of the isotope data for palaeo-time-slices.}, language = {en} } @article{FohlmeisterLechleitner2019, author = {Fohlmeister, Jens Bernd and Lechleitner, Franziska A.}, title = {STAlagmite dating by radiocarbon (star)}, series = {Quaternary geochronology : the international research and review journal on advances in quaternary dating techniques}, volume = {51}, journal = {Quaternary geochronology : the international research and review journal on advances in quaternary dating techniques}, publisher = {Elsevier}, address = {Oxford}, issn = {1871-1014}, doi = {10.1016/j.quageo.2019.02.008}, pages = {120 -- 129}, year = {2019}, abstract = {Speleothems, secondary cave carbonates, are important tools for climate reconstruction, especially as they often can be very precisely dated with the UTh method. If the U-Th method fails, dating becomes difficult, and often results in abandonment of samples and study sites. Radiocarbon dating is the only other radiometric dating technique applicable to the last similar to 50 ka, but presents complexities related to temporal variability of the reservoir effect in speleothems. Thus, radiocarbon dating of speleothems is not straightforward, and there are currently no publicly available tools to define proper age-depth relationships with this method. Here, we present an improved version of a previously published radiocarbon based age-depth modelling approach (star, Lechleitner et al., 2016b), which is now made freely available. The software is easy to use and provides the possibility to obtain reliable age-depth relationships, without prior knowledge of reservoir effects and their variability. In addition, star is able to detect and handle growth stops and phases with different growth rates. We test star on artificially constructed data sets and illustrate steps to improve the model performance. Furthermore, we apply the new approach to published radiocarbon data of U-Th dated stalagmites. This offers the possibility to investigate the strengths and weaknesses of the new approach with respect to potentially significant long term trends in the radiocarbon reservoir effect, which might otherwise remain undetected. In summary, we have produced a valuable software, which easily enables to construct age-depth relationships on the basis of reservoir effect disturbed radiocarbon measurements.}, language = {en} } @article{LechleitnerBaldiniBreitenbachetal.2016, author = {Lechleitner, Franziska A. and Baldini, James U. L. and Breitenbach, Sebastian Franz Martin and Fohlmeister, Jens Bernd and McIntyre, Cameron and Goswami, Bedartha and Jamieson, Robert A. and van der Voort, Tessa S. and Prufer, Keith and Marwan, Norbert and Culleton, Brendan J. and Kennett, Douglas J. and Asmerom, Yemane and Polyak, Victor and Eglinton, Timothy I.}, title = {Hydrological and climatological controls on radiocarbon concentrations in a tropical stalagmite}, series = {Geochimica et cosmochimica acta : journal of the Geochemical Society and the Meteoritical Society}, volume = {194}, journal = {Geochimica et cosmochimica acta : journal of the Geochemical Society and the Meteoritical Society}, publisher = {Elsevier}, address = {Oxford}, issn = {0016-7037}, doi = {10.1016/j.gca.2016.08.039}, pages = {233 -- 252}, year = {2016}, abstract = {Precisely-dated stalagmites are increasingly important archives for the reconstruction of terrestrial paleoclimate at very high temporal resolution. In-depth understanding of local conditions at the cave site and of the processes driving stalagmite deposition is of paramount importance for interpreting proxy signals incorporated in stalagmite carbonate. Here we present a sub-decadally resolved dead carbon fraction (DCF) record for a stalagmite from Yok Balum Cave (southern Belize). The record is coupled to parallel stable carbon isotope (delta C-13) and U/Ca measurements, as well as radiocarbon (C-14) measurements from soils overlying the cave system. Using a karst carbon cycle model we disentangle the importance of soil and karst processes on stalagmite DCF incorporation, revealing a dominant host rock dissolution control on total DCF. Covariation between DCF, delta C-13, and U/Ca indicates that karst processes are a common driver of all three parameters, suggesting possible use of delta C-13 and trace element ratios to independently quantify DCF variability. A statistically significant multi-decadal lag of variable length exists between DCF and reconstructed solar activity, suggesting that solar activity influenced regional precipitation in Mesoamerica over the past 1500 years, but that the relationship was non-static. Although the precise nature of the observed lag is unclear, solar-induced changes in North Atlantic oceanic and atmospheric dynamics may play a role. (C) 2016 Elsevier Ltd. All rights reserved.}, language = {en} } @article{LechleitnerBreitenbachChengetal.2017, author = {Lechleitner, Franziska A. and Breitenbach, Sebastian Franz Martin and Cheng, Hai and Plessen, Birgit and Rehfeld, Kira and Goswami, Bedartha and Marwan, Norbert and Eroglu, Deniz and Adkins, Jess F. and Haug, Gerald}, title = {Climatic and in-cave influences on delta O-18 and delta C-13 in a stalagmite from northeastern India through the last deglaciation}, series = {Quaternary research : an interdisciplinary journal}, volume = {88}, journal = {Quaternary research : an interdisciplinary journal}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {0033-5894}, doi = {10.1017/qua.2017.72}, pages = {458 -- 471}, year = {2017}, abstract = {Northeastern (NE) India experiences extraordinarily pronounced seasonal climate, governed by the Indian summer monsoon (ISM). The vulnerability of this region to floods and droughts calls for detailed and highly resolved paleoclimate reconstructions to assess the recurrence rate and driving factors of ISM changes. We use stable oxygen and carbon isotope ratios (delta O-18 and delta C-13) from stalagmite MAW-6 from Mawmluh Cave to infer climate and environmental conditions in NE India over the last deglaciation (16-6ka). We interpret stalagmite delta O-18 as reflecting ISM strength, whereas delta C-13 appears to be driven by local hydroclimate conditions. Pronounced shifts in ISM strength over the deglaciation are apparent from the delta O-18 record, similarly to other records from monsoonal Asia. The ISM is weaker during the late glacial (LG) period and the Younger Dryas, and stronger during the BOlling-Allerod and Holocene. Local conditions inferred from the delta C-13 record appear to have changed less substantially over time, possibly related to the masking effect of changing precipitation seasonality. Time series analysis of the delta O-18 record reveals more chaotic conditions during the late glacial and higher predictability during the Holocene, likely related to the strengthening of the seasonal recurrence of the ISM with the onset of the Holocene.}, language = {en} } @article{LechleitnerBreitenbachRehfeldetal.2017, author = {Lechleitner, Franziska A. and Breitenbach, Sebastian Franz Martin and Rehfeld, Kira and Ridley, Harriet E. and Asmerom, Yemane and Prufer, Keith M. and Marwan, Norbert and Goswami, Bedartha and Kennett, Douglas J. and Aquino, Valorie V. and Polyak, Victor and Haug, Gerald H. and Eglinton, Timothy I. and Baldini, James U. L.}, title = {Tropical rainfall over the last two millennia: evidence for a low-latitude hydrologic seesaw}, series = {Scientific reports}, volume = {7}, journal = {Scientific reports}, publisher = {Nature Publ. Group}, address = {London}, issn = {2045-2322}, doi = {10.1038/srep45809}, pages = {9}, year = {2017}, abstract = {The presence of a low-to mid-latitude interhemispheric hydrologic seesaw is apparent over orbital and glacial-interglacial timescales, but its existence over the most recent past remains unclear. Here we investigate, based on climate proxy reconstructions from both hemispheres, the inter-hemispherical phasing of the Intertropical Convergence Zone (ITCZ) and the low-to mid-latitude teleconnections in the Northern Hemisphere over the past 2000 years. A clear feature is a persistent southward shift of the ITCZ during the Little Ice Age until the beginning of the 19th Century. Strong covariation between our new composite ITCZ-stack and North Atlantic Oscillation (NAO) records reveals a tight coupling between these two synoptic weather and climate phenomena over decadal-to-centennial timescales. This relationship becomes most apparent when comparing two precisely dated, high-resolution paleorainfall records from Belize and Scotland, indicating that the low-to mid-latitude teleconnection was also active over annual-decadal timescales. It is likely a combination of external forcing, i.e., solar and volcanic, and internal feedbacks, that drives the synchronous ITCZ and NAO shifts via energy flux perturbations in the tropics.}, language = {en} }