@article{ReschkeKroenerLaepple2020,
  author    = {Reschke, Maria and Kr{\"o}ner, Igor and Laepple, Thomas},
  title     = {Testing the consistency of Holocene and Last Glacial Maximum spatial correlations in temperature proxy records},
  series = {Journal of quaternary science : JQS},
  volume    = {36},
  journal   = {Journal of quaternary science : JQS},
  number    = {1},
  publisher = {Wiley},
  address   = {New York},
  issn      = {0267-8179},
  doi       = {10.1002/jqs.3245},
  pages     = {20 -- 28},
  year      = {2020},
  abstract  = {Holocene temperature proxy records are commonly used in quantitative synthesis and model-data comparisons. However, comparing correlations between time series from records collected in proximity to one another with the expected correlations based on climate model simulations indicates either regional or noisy climate signals in Holocene temperature proxy records. In this study, we evaluate the consistency of spatial correlations present in Holocene proxy records with those found in data from the Last Glacial Maximum (LGM). Specifically, we predict correlations expected in LGM proxy records if the only difference to Holocene correlations would be due to more time uncertainty and more climate variability in the LGM. We compare this simple prediction to the actual correlation structure in the LGM proxy records. We found that time series data of ice-core stable isotope records and planktonic foraminifera Mg/Ca ratios were consistent between the Holocene and LGM periods, while time series of Uk'37 proxy records were not as we found no correlation between nearby LGM records. Our results support the finding of highly regional or noisy marine proxy records in the compilation analysed here and suggest the need for further studies on the role of climate proxies and the processes of climate signal recording and preservation.},
  language  = {en}
}
@article{TianCaoDallmeyeretal.2017,
  author    = {Tian, Fang and Cao, Xianyong and Dallmeyer, Anne and Zhao, Yan and Ni, Jian and Herzschuh, Ulrike},
  title     = {Pollen-climate relationships in time (9 ka, 6 ka, 0 ka) and space (upland vs. lowland) in eastern continental Asia},
  series = {Quaternary science reviews : the international multidisciplinary research and review journal},
  volume    = {156},
  journal   = {Quaternary science reviews : the international multidisciplinary research and review journal},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0277-3791},
  doi       = {10.1016/j.quascirev.2016.11.027},
  pages     = {1 -- 11},
  year      = {2017},
  abstract  = {Temporal and spatial stability of the vegetation climate relationship is a basic ecological assumption for pollen-based quantitative inferences of past climate change and for predicting future vegetation. We explore this assumption for the Holocene in eastern continental Asia (China, Mongolia). Boosted regression trees (BRT) between fossil pollen taxa percentages (Abies, Artemisia, Betula, Chenopodiaceae, Cyperaceae, Ephedra, Picea, Pinus, Poaceae and Quercus) and climate model outputs of mean annual precipitation (P-ann) and mean temperature of the warmest month (Mt(wa)) for 9 and 6 ka (ka = thousand years before present) were set up and results compared to those obtained from relating modern pollen to modern climate. Overall, our results reveal only slight temporal differences in the pollen climate relationships. Our analyses suggest that the importance of P-ann compared with Mt(wa) for taxa distribution is higher today than it was at 6 ka and 9 ka. In particular, the relevance of P-ann for Picea and Pinus increases and has become the main determinant. This change in the climate tree pollen relationship parallels a widespread tree pollen decrease in north-central China and the eastern Tibetan Plateau. We assume that this is at least partly related to vegetation climate disequilibrium originating from human impact. Increased atmospheric CO2 concentration may have permitted the expansion of moisture-loving herb taxa (Cyperaceae and Poaceae) during the late Holocene into arid/semi-arid areas. We furthermore find that the pollen climate relationship between north-central China and the eastern Tibetan Plateau is generally similar, but that regional differences are larger than temporal differences. In summary, vegetation climate relationships in China are generally stable in space and time, and pollen-based climate reconstructions can be applied to the Holocene. Regional differences imply the calibration-set should be restricted spatially.},
  language  = {en}
}
@article{PalagushkinaWetterichSchirrmeisteretal.2017,
  author    = {Palagushkina, Olga V. and Wetterich, Sebastian and Schirrmeister, Lutz and Nazarova, Larisa B.},
  title     = {Modern and fossil diatom assemblages from Bol'shoy Lyakhovsky Island (New Siberian Archipelago, Arctic Siberia)},
  series = {Contemporary Problems of Ecology},
  volume    = {10},
  journal   = {Contemporary Problems of Ecology},
  publisher = {Pleiades Publ.},
  address   = {New York},
  issn      = {1995-4255},
  doi       = {10.1134/S1995425517040060},
  pages     = {380 -- 394},
  year      = {2017},
  abstract  = {This article discusses the results of a taxonomic and ecological investigation of diatoms from polygonal ponds and Quaternary permafrost deposits of Bol'shoy Lyakhovsky Island (New Siberian Archipelago) and the reconstruction of climatic changes on the Island during late Pleistocene/Holocene transition using fossil diatom assemblages from the permafrost deposits. The taxonomic list of diatoms includes 159 diatom species. The main ecological factors that determine the distribution of diatoms in the investigated data set are mean July air temperature, рН, electrical conductivity, water depth, and concentrations of Si4+ and Al3+. An increase in water depth and stable lacustrine conditions in the Lateglacial-Holocene in the ancient thermokarst lake relate to Lateglacial warming before 11860 ± 160 years BP and during the early Holocene between 11210 ± 160 and 7095 ± 60 years BP.},
  language  = {en}
}
@article{SyrykhNazarovaHerzschuhetal.2017,
  author    = {Syrykh, Lydmila S. and Nazarova, Larisa B. and Herzschuh, Ulrike and Subetto, D. A. and Grekov, I. M.},
  title     = {Reconstruction of palaeoecological and palaeoclimatic conditions of the Holocene in the south of the Taimyr according to an analysis of lake sediments},
  series = {Contemporary Problems of Ecology},
  volume    = {10},
  journal   = {Contemporary Problems of Ecology},
  publisher = {Pleiades Publ.},
  address   = {New York},
  issn      = {1995-4255},
  doi       = {10.1134/S1995425517040114},
  pages     = {363 -- 369},
  year      = {2017},
  abstract  = {A sediment core from Khatanga-12 Lake (Taimyr Peninsula, Krasnoyarsk krai) has been studied. The 131.5-cm-long core covers ca. 7100 years of sedimentation. Chironomid analysis, a qualitative reconstruction of the paleoenvironment in the region, and a quantitative reconstruction of variations of the mean July air temperature and in the water depth of the lake have been performed using Northern Russia chironomid-inferred mean July temperature models (Nazarova et al., 2008, 2011, 2015). Khatanga-12 Lake was formed during the Middle Holocene warming as a result of thermokarst processes. The development of the lake ecosystem at different stages of its development was influenced by climatic and cryolithogenic factors. The Middle Holocene warming, which occurred around 7100-6250 cal. years BP, activated thermokarst processes and resulted in the formation of the lake basin. Later, between 6250 and 4500 cal. years BP, a period of cooling took place, as is proved by chironomid analysis. The bottom sediments of the lake during this period were formed by erosion processes on the lake shores. The reconstructed conditions were close to the modern after 2500 cal. years BP.},
  language  = {en}
}
@article{TrauthFoersterJungingeretal.2018,
  author    = {Trauth, Martin H. and Foerster, Verena and Junginger, Annett and Asrat, Asfawossen and Lamb, Henry F. and Sch{\"a}bitz, Frank},
  title     = {Abrupt or gradual?},
  series = {Quaternary research : an interdisciplinary journal},
  volume    = {90},
  journal   = {Quaternary research : an interdisciplinary journal},
  number    = {2},
  publisher = {Cambridge Univ. Press},
  address   = {New York},
  issn      = {0033-5894},
  doi       = {10.1017/qua.2018.30},
  pages     = {321 -- 330},
  year      = {2018},
  abstract  = {We used a change point analysis on a late Pleistocene-Holocene lake-sediment record from the Chew Bahir basin in the southern Ethiopian Rift to determine the amplitude and duration of past climate transitions. The most dramatic changes occurred over 240 yr (from similar to 15,700 to 15,460 yr) during the onset of the African Humid Period (AHP), and over 990 yr (from similar to 4875 to 3885 yr) during its protracted termination. The AHP was interrupted by a distinct dry period coinciding with the high-latitude Younger Dryas stadial, which had an abrupt onset (less than similar to 100 yr) at similar to 13,260 yr and lasted until similar to 11,730 yr. Wet-dry-wet transitions prior to the AHP may reflect the high-latitude Dansgaard-Oeschger cycles, as indicated by cross-correlation of the potassium record with the NorthGRIP ice core record between similar to 45-20 ka. These findings may contribute to the debates regarding the amplitude, and duration and mechanisms of past climate transitions, and their possible influence on the development of early modern human cultures.},
  language  = {en}
}
@article{Herzschuh2019,
  author    = {Herzschuh, Ulrike},
  title     = {Legacy of the Last Glacial on the present-day distribution of deciduous versus evergreen boreal forests},
  series = {Global ecology and biogeography : a journal of macroecology},
  volume    = {29},
  journal   = {Global ecology and biogeography : a journal of macroecology},
  number    = {2},
  publisher = {John Wiley \& Sons, Inc.},
  address   = {Hoboken},
  issn      = {1466-822X},
  doi       = {10.1111/geb.13018},
  pages     = {198 -- 206},
  year      = {2019},
  abstract  = {Issue Despite their rather similar climatic conditions, eastern Eurasia and northern North America are largely covered by different plant functional types (deciduous or evergreen boreal forest) composed of larch or pine, spruce and fir, respectively. I propose that these deciduous and evergreen boreal forests represent alternative quasi-stable states, triggered by their different northern tree refugia that reflect the different environmental conditions experienced during the Last Glacial. Evidence This view is supported by palaeoecological and environmental evidence. Once established, Asian larch forests are likely to have stabilized through a complex vegetation-fire-permafrost soil-climate feedback system. Conclusion With respect to future forest developments, this implies that Asian larch forests are likely to be governed by long-term trajectories and are therefore largely resistant to natural climate variability on time-scales shorter than millennia. The effects of regional human impact and anthropogenic global warming might, however, cause certain stability thresholds to be crossed, meaning that irreversible transitions occur and resulting in marked consequences for ecosystem services on these human-relevant time-scales.},
  language  = {en}
}
@article{TrauthAsratDuesingetal.2019,
  author    = {Trauth, Martin H. and Asrat, Asfawossen and D{\"u}sing, Walter and Foerster, Verena and Kr{\"a}mer, K. Hauke and Marwan, Norbert and Maslin, Mark A. and Sch{\"a}bitz, Frank},
  title     = {Classifying past climate change in the Chew Bahir basin, southern Ethiopia, using recurrence quantification analysis},
  series = {Climate dynamics : observational, theoretical and computational research on the climate system},
  volume    = {53},
  journal   = {Climate dynamics : observational, theoretical and computational research on the climate system},
  number    = {5-6},
  publisher = {Springer},
  address   = {New York},
  issn      = {0930-7575},
  doi       = {10.1007/s00382-019-04641-3},
  pages     = {2557 -- 2572},
  year      = {2019},
  abstract  = {The Chew Bahir Drilling Project (CBDP) aims to test possible linkages between climate and evolution in Africa through the analysis of sediment cores that have recorded environmental changes in the Chew Bahir basin. In this statistical project we consider the Chew Bahir palaeolake to be a dynamical system consisting of interactions between its different components, such as the waterbody, the sediment beneath lake, and the organisms living within and around the lake. Recurrence is a common feature of such dynamical systems, with recurring patterns in the state of the system reflecting typical influences. Identifying and defining these influences contributes significantly to our understanding of the dynamics of the system. Different recurring changes in precipitation, evaporation, and wind speed in the Chew Bahir basin could result in similar (but not identical) conditions in the lake (e.g., depth and area of the lake, alkalinity and salinity of the lake water, species assemblages in the water body, and diagenesis in the sediments). Recurrence plots (RPs) are graphic displays of such recurring states within a system. Measures of complexity were subsequently introduced to complement the visual inspection of recurrence plots, and provide quantitative descriptions for use in recurrence quantification analysis (RQA). We present and discuss herein results from an RQA on the environmental record from six short (< 17 m) sediment cores collected during the CBDP, spanning the last 45 kyrs. The different types of variability and transitions in these records were classified to improve our understanding of the response of the biosphere to climate change, and especially the response of humans in the area.},
  language  = {en}
}
@article{SahaOwenOrretal.2019,
  author    = {Saha, Sourav and Owen, Lewis A. and Orr, Elizabeth N. and Caffee, Marc W.},
  title     = {High-frequency Holocene glacier fluctuations in the Himalayan-Tibetan orogen},
  series = {Quaternary science reviews : the international multidisciplinary research and review journal},
  volume    = {220},
  journal   = {Quaternary science reviews : the international multidisciplinary research and review journal},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0277-3791},
  doi       = {10.1016/j.quascirev.2019.07.021},
  pages     = {372 -- 400},
  year      = {2019},
  abstract  = {Holocene glacial chronostratigraphies in glaciated valleys spread throughout the Himalayan-Tibetan orogen, including the Himalaya, Tibet, Pamir, and Tian Shan, are developed using a landsystems approach, detailed geomorphic mapping, and new and published Be-10 surface exposure dating. New studies in the Kulti valley of Lahul and the Parkachik valley of the Nun Kun massif of the Himalaya of northern India define three glacier advances at similar to 14.7, 12.2, 0.5 ka, in addition to one historically dated late 19th Century advance in the Kulti valley, and one Late Holocene advance at similar to 0.2 ka in the Parkachik valley. Three major climatic groups (subdivided into five climatic zones) are defined across the orogen using Cluster Analysis (CA) and Principal Component Analysis (PCA) to identify glaciated regions with comparable climatic characteristics to evaluate the timing, and extent of Holocene glacier advances across these regions. Our regional analyses across the Himalayan-Tibetan orogen suggest at least one Lateglacial (similar to 15.3-11.8 ka) and five Himalayan-Tibetan Holocene glacial stages (HTHS) at similar to 11.5-9.5, similar to 8.8-7.7, similar to 7.0-3.2, similar to 2.3-1.0, and <1 ka. The extent (amplitude) of glacier advances in 77 glaciated valleys is reconstructed and defined using equilibrium-line altitudes (ELAs). Modern glacier hypsometries are also assessed to help explain the intra-regional variations in glacier amplitudes during each regional glacier advance. A linear inverse glacier flow model is used to decipher the net changes in temperature (Delta T) between periods of reconstructed regional glacier advances in 66 glaciated valleys across different climatic regions throughout the orogen. The Be-10, ELAs, and Delta T data suggest enhanced monsoonal and increased precipitation during the Early Holocene, followed by relative cooling and increased aridity during the Mid- and Late Holocene that influenced glaciation. The sublimation-dominated cold-based glaciers in the northern regions of Himalayan-Tibetan orogen are more affected during these shifts in climate than the temperate glaciers in the south. (C) 2019 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{CaoTianDallmeyeretal.2019,
  author    = {Cao, Xianyong and Tian, Fang and Dallmeyer, Anne and Herzschuh, Ulrike},
  title     = {Northern Hemisphere biome changes (> 30 degrees N) since 40 cal ka BP and their driving factors inferred from model-data comparisons},
  series = {Quaternary science reviews : the international multidisciplinary research and review journal},
  volume    = {220},
  journal   = {Quaternary science reviews : the international multidisciplinary research and review journal},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0277-3791},
  doi       = {10.1016/j.quascirev.2019.07.034},
  pages     = {291 -- 309},
  year      = {2019},
  abstract  = {Ongoing and past biome transitions are generally assigned to climate and atmospheric changes (e.g. temperature, precipitation, CO2), but the major regional factors or factor combinations that drive vegetation change often remain unknown. Modelling studies applying ensemble runs can help to partition the effects of the different drivers. Such studies require careful validation with observational data. In this study, fossil pollen records from 741 sites in Europe, 728 sites in North America, and 418 sites in Asia (extracted from terrestrial archives including lake sediments) are used to reconstruct biomes at selected time slices between 40 cal ka BP (calibrated thousand years before present) and today. These results are used to validate Northern Hemisphere biome distributions (>30 degrees N) simulated by the biome model BIOME4 that has been forced with climate data simulated by a General Circulation model. Quantitative comparisons between pollen- and model-based results show a generally good fit at a broad spatial scale. Mismatches occur in central-arid Asia with a broader extent of grassland throughout the last 40 ka (likely due to the over-representation of Artemisia and Chenopodiaceae pollen) and in Europe with over-estimation of tundra at 0 cal ka BP (likely due to human impacts to some extent). Sensitivity analysis reveals that broad-scale biome changes follow the global signal of major postglacial temperature change, although the climatic variables vary in their regional and temporal importance. Temperature is the dominant variable in Europe and other rather maritime areas for biome changes between 21 and 14 ka, while precipitation is highly important in the arid inland regions of Asia and North America. The ecophysiological effect of changes in the atmospheric CO2-concentration has the highest impact during this transition than in other intervals. With respect to modern vegetation in the course of global warming, our findings imply that vegetation change in the Northern Hemisphere may be strongly limited by effective moisture changes, i.e. the combined effect of temperature and precipitation, particularly in inland areas. (C) 2019 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{SahaOwenOrretal.2019,
  author    = {Saha, Sourav and Owen, Lewis A. and Orr, Elizabeth N. and Caffee, Marc W.},
  title     = {Cosmogenic Be-10 and equilibrium-line altitude dataset of Holocene glacier advances in the Himalayan-Tibetan orogen},
  series = {Data in brief},
  volume    = {26},
  journal   = {Data in brief},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {2352-3409},
  doi       = {10.1016/j.dib.2019.104412},
  pages     = {13},
  year      = {2019},
  abstract  = {A comprehensive analysis of the variable temporal and spatial responses of tropical-subtropical high-altitude glaciers to climate change is critical for successful model predictions and environmental risk assessment in the Himalayan-Tibetan orogen. High-frequency Holocene glacier chronostratigraphies are therefore reconstructed in 79 glaciated valleys across the orogen using 519 published and 16 new terrestrial cosmogenic 10Be exposure age dataset. Published 10Be ages are compiled only for moraine boulders (excluding bedrock ages). These ages are recalculated using the latest ICE-D production rate calibration database and the scaling scheme models. Outliers for the individual moraine are detected using the Chauvenet's criterion. In addition, past equilibrium-line altitudes (ELAs) are determined using the area-altitude (AA), area accumulation ratio (AAR), and toe-headwall accumulation ratio (THAR) methods for each glacier advance. The modern maximum elevations of lateral moraines (MELM) are also used to estimate modern ELAs and as an independent check on mean ELAs derived using the above three methods. These data may serve as an essential archive for future studies focusing on the cryospheric and environmental changes in the Himalayan-Tibetan orogen. A more comprehensive analysis of the published and new 10Be ages and ELA results and a list of references are presented in Saha et al. (2019, High-frequency Holocene glacier fluctuations in the Himalayan-Tibetan orogen. Quaternary Science Reviews, 220, 372-400).},
  language  = {en}
}