cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.25921/b301-9054
title: NOAA/WDS Paleoclimatology - Vitas - Dotnuva - LADE - ITRDB LITH024

description: Tree ring data from the International Tree Ring Data Bank and World Data Center for Paleoclimatology archives.  Most data sets include raw treering measurements (most are annual ring width, with some collections of earlywood or latewood width or wood density), plus chronologies (standardized growth indices for a site compiled from multiple treering samples). Reconstructions of climate variables are included with some of these data sets.  Each data type is stored in a separate data file; the data type is coded into the file name. For details please see: http://www.ncdc.noaa.gov/paleo/treeinfo.htmll
description: NOAA Template Chronology file added 2018-12-19. NOAA Template Raw Measurements file added 2019-02-05.
DOI: 10.25921/bphf-kd79
title: NOAA/WDS Paleoclimatology - Central Equatorial Pacific Dust Flux Reconstruction 110-150 ka

description: The position of the Intertropical Convergence Zone (ITCZ) is sensitive to changes in the balance of heat between the hemispheres, which has fundamental implications for tropical hydrology and atmospheric circulation. Although the ITCZ is thought to experience the largest shifts in position during deglacial stadial events, the magnitude of shifts has proven difficult to reconstruct, in part because of a paucity of high-resolution records, particularly those including spatial components. Here, we track the position of the ITCZ from 150-110 ka at three sites in the central equatorial Pacific at sub-millennial time resolution. Our results provide the first evidence of large, abrupt changes in tropical climate during the penultimate deglaciation, coincident with North Atlantic Heinrich Stadial 11 (~136-129 ka). We identify this event both as a northern hemisphere increase in aeolian dust and as a shift in the mean position of the ITCZ a minimum of four degrees southwards at 160°W.
description: 230Thxs,0-normalized 232Th fluxes converted to dust fluxes; Note: Age-depth relationships for cores ML1208-37BB, 31BB and 17PC were developed on the basis of planktonic oxygen isotope stratigraphies (dataset: noaa-ocean-1001374), which were tied to the LR04 benthic stack with the assistance of a modified Monte-Carlo-enabled cross-correlation maximization scheme and random walk algorithm (MonteXCM). 
     Provided Keywords: Younger Dryas, glacial,thorium, dust
DOI: 10.25921/bxvb-3m37
title: NOAA/WDS Paleoclimatology - Gulf of Alaska, Northeast Pacific Geochemistry and Radiogenic Isotope Data from Leaching Experiments

description: The isotopic composition of neodymium (eNd) extracted from sedimentary Fe–Mn oxyhydroxide offers potential for reconstructing paleo-circulation, but its application depends on extraction methodology and the mechanisms that relate authigenic eNd to bottom water. Here we test methods to extract authigenic eNd from Gulf of Alaska (GOA) sediments and assess sources of leachate Nd, including potential contamination from trace dispersed volcanic ash. We show that one dominant phase is extracted via leaching of core-top sediments. Major and trace element geochemistry demonstrate that this phase is authigenic Fe–Mn oxyhydroxide. Contamination of leachate (authigenic) Nd from detrital sources is insignificant (<1%); our empirical results are consistent with established kinetic mineral dissolution rates and theory. Contamination of extracted eNd from leaching of volcanic ash is below analytical uncertainty. However, the eNd of core-top leachates in the GOA is consistently more radiogenic than bottom water. We infer that authigenic phases record pore water eNd, and the relationships of eNd among bottom waters, pore waters, authigenic phases and detrital sediments are primarily governed by the exposure time of bottom water to sea-floor sediments, rate of exchange across the sediment-water interface and the reactivity and composition of detrital sediments. We show that this conceptual model is applicable on the Pacific basin scale and provide a new framework to understand the role of authigenic phases in both modern and paleo-applications, including the use of authigenic eNd as a paleo-circulation tracer.
description: In this study we teste various leaching methods to extract authigenic iron manganese oxyhydroxides for neodymium isotope analysis from sediments in the Gulf of Alaska while avoiding contamination from lithogenic sedimenet components during chemical extractions. Method HH4 as described in the "Data" section is the final method of choice. This method was tested on a suite of core-top, down-core and marine ash layer samples from the Gulf of Alaska, as well as land fall volcanic ash samples from Mt St. Helens. We analyzed neodymium and strontium isotopes, major and trace elements, including the Rare Earth Elements, in the leachates and these data are reported here. Measurement precision- epsilon Nd: 0.37; 87Sr/86Sr: .000049; Aluminum,Barium,Calcium,Strontium,Iron,Manganese,Cobalt,Copper,Nickel,Zinc,Potassium,Magnesium,Vanadium,Chromium,Scandium, and Uranium: 5-10%; Yttrium,Lanthanum,Cerium,Praseodym,Neodymium,Samarium,Europium,Gadolinium,Terbium,Dysprosium,Holmium,Erbium,Thulium,Ytterbium,Lutetium: 5%
     Provided Keywords: neodymium isotopes, authigenic phase, Gulf of Alaska, North Pacific, core-top
DOI: 10.25921/b3ak-et30
title: NOAA/WDS Paleoclimatology - Hessl - Uurgat Lava - PISI - ITRDB MONG042

description: The severity of recent droughts in semiarid regions is increasingly attributed to anthropogenic climate change, but it is unclear whether these moisture anomalies exceed those of the past and how past variability compares to future projections. On the Mongolian Plateau, a recent decade-long drought that exceeded the variability in the instrumental record was associated with economic, social, and environmental change. We evaluate this drought using an annual reconstruction of the Palmer Drought Severity Index (PDSI) spanning the last 2060 years in concert with simulations of past and future drought through the year 2100 CE. We show that although the most recent drought and pluvial were highly unusual in the last 2000 years, exceeding the 900-year return interval in both cases, these events were not unprecedented in the 2060-year reconstruction, and events of similar duration and severity occur in paleoclimate, historical, and future climate simulations. The Community Earth System Model (CESM) ensemble suggests a drying trend until at least the middle of the 21st century, when this trend reverses as a consequence of elevated precipitation. Although the potential direct effects of elevated CO2 on plant water use efficiency exacerbate uncertainties about future hydroclimate trends, these results suggest that future drought projections for Mongolia are unlikely to exceed those of the last two millennia, despite projected warming.
description: NOAA Template Raw Measurements file added 2019-04-08.
DOI: 10.25921/bcb0-gw86
title: NOAA/WDS Paleoclimatology - Asia 1200 Year Gridded Summer Temperature Reconstructions

description: We develop a summer temperature reconstruction for temperate East Asia based on a network of annual tree-ring chronologies covering the period 800-1989 C.E. The East Asia reconstruction is the regional average of 585 individual grid point summer temperature reconstructions produced using an ensemble version of point-by-point regression. Statistical calibration and validation tests indicate that the regional average possesses sufficient overall skill to allow it to be used to study the causes of temperature variability and change over the region. The reconstruction suggests a moderately warm early medieval epoch (ca. 850-1050 C.E.), followed by generally cooler 'Little Ice Age' conditions (ca. 1350-1880 C.E.) and 20th century warming up to the present time. Since 1990, average temperature has exceeded past warm epochs of comparable duration, but it is not statistically unprecedented. Superposed epoch analysis reveals a volcanic forcing signal in the East Asia summer temperature reconstruction, resulting in pulses of cooler summer conditions that may persist for several years. Substantial uncertainties remain, however, particularly at lower frequencies, thus requiring caution and scientific prudence in the interpretation of this record.
description: Tree-ring based 1200-year gridded (2x2 degree) reconstructions of summer (June through August, JJA) temperature 	for temperate East Asia, produced for the IGBP-PAGES Asia2k project. PAGES Asia 2k Members are Moinuddin Ahmed, Hemant Borgaonkar, Xu Chenxi, Guoqiang Chu, Zexin Fan, Narayan Gaire, Quansheng Ge, Katsuhiko Kimura, Jonathan Palmer, Tatyana Papina, Margit Schwikowski, Xuemei Shao, Feng Shi, Olga Solomina, Zafer Usama, Chenzi Xu, Koh Yasue, Masumi Zaiki, Kan Zhao, and Jingyun Zheng.
DOI: 10.25921/bts4-rg83
title: NOAA/WDS Paleoclimatology - Last Glacial Maximum and Preindustrial Iron Flux Global Ocean Model Results

description: Changes in the ocean iron cycle during the Last Glacial Maximum (LGM) have been proposed to help explain the low atmospheric CO2 from this period. Previous global modeling studies, however, have only considered changes in aeolian iron fluxes, although it is known that sedimentary and hydrothermal fluxes are important iron sources for today's ocean. Here we evaluate the effect of preindustrial-to-LGM changes in atmospheric dust, sedimentary, and hydrothermal fluxes on the ocean's iron and carbon cycles in a global coupled biogeochemical circulation model. Considering variable iron solubility we find that higher dust fluxes into the ocean in the LGM increase productivity and enhance the biological pump, sequestering carbon in deep waters and lowering CO2 by 4 ppm. The effect is countered by a decrease in sedimentary release of iron due to lower sea level, which increases CO2 by 15 ppm. In an upper-limit estimation of Southern Ocean surface iron fertilization, assuming a 10 times higher solubility for this region, combined with changes in sedimentary release we find an increase in deep dissolved inorganic carbon concentrations, that could potentially reduce atmospheric CO2 by 13 ppm. A five-fold increase in hydrothermal sources of iron during the LGM may have decreased atmospheric CO2 by an additional 6 ppm. We conclude that when addressing LGM-preindustrial changes in the ocean iron cycle, not only surface but also sedimentary and hydrothermal fluxes have to be taken into account.
description: Study contains data from LGM and Preindustrial model runs. The data folders contain output files, which are tavg and tsi netcdf files. The rest of the files are necessary to run the model, if more experiments are going to be carried out.
DOI: 10.25921/b7qb-zv30
title: NOAA/WDS Paleoclimatology - Zhuye Lake, China Holocene Grain Size and Pollen Data

description: This article examines Holocene environmental change in Zhuye Lake in the marginal area of the Asian monsoon, NW China. Holocene environment records were obtained for the QTH01 and QTH02 sections in Zhuye Lake. The fluctuations in grain size, pollen, total organic carbon content and C/N ratios record notable environmental variation. The early Holocene (11.0 to 7.4 cal. kyr BP) was relatively arid, while vegetation coverage was sparse and primary productivity low. The optimal environment prevailed during the mid-Holocene (7.4 to 4.7 cal. kyr BP). Vegetation coverage was the densest and primary productivity the highest during the mid-Holocene. During the late Holocene (4.7 to 0 cal. kyr BP), the environment became arid, as shown by low lake level and sparse vegetation coverage. After 1.6 cal. kyr BP another strong aridification occurred. In this area, the environment was likely to have been influenced by both the Westerlies and the East Asian monsoon during the Holocene. During the early Holocene, the relatively arid environment lay in the background of the increasing East Asian monsoon and dry westerly wind. During the mid-Holocene, central Asia was controlled by the humid Westerlies, while a strong East Asian monsoon prevailed in Central China. The mid-Holocene optimum in this area benefited from an expanded East Asian monsoon and the humid Westerlies. Weakening of the East Asian monsoon caused aridification of the environment during the late Holocene. Intensification of this aridification after 1.6 cal. kyr BP might be correlated with appearance of the arid environments in the Westerly domain after ~1.5 cal. kyr BP. These arid conditions might be affected by the decreased moisture content of the Westerlies.
description: Pollen assemblages and grain-size data from two Holocene sections collected in Zhuye Lake, north-west China.
DOI: 10.25921/bdec-g116
title: NOAA/WDS Paleoclimatology - Wilson - Meadow Mountain - PCEN - ITRDB CANA225

description: Maximum latewood density (MXD) is a strong proxy of summer temperatures. Despite this, there is a paucity of long MXD chronologies in the Northern Hemisphere, which limits large-scale tree-ring-based reconstructions of past temperature which are dominated by ring-width (RW) data - a weaker temperature proxy at inter-annual time-scales. This paucity likely results from the relative expense of measuring MXD and the lack of laboratories with the facilities to measure it. Herein, we test the ability of a relatively new, less expensive, tree-ring parameter, Blue Intensity (BI), to act as a surrogate parameter for MXD. BI was measured on Engelmann spruce samples from British Columbia where MXD had previously been measured to allow direct comparison between the two parameters. Signal strength analyses indicate that 8 MXD series were needed to acquire a robust mean chronology while BI needed 14. Utilising different detrending methods and parameter choices (RW + MXD vs RW + BI), a suite of reconstruction variants was developed. The explained variance from the regression modelling (1901-1995) of May-August maximum temperatures ranged from 52% to 55%. Validation tests over the earlier 1870-1900 period could not statistically distinguish between the different variants, although spectral analysis identified more lower frequency information extant in the MXD-based reconstructions - although this result was sensitive to the detrending method used. Ultimately, despite the MXD-based reconstruction explaining slightly more of the climatic variance, statistically robust reconstructions of past summer temperatures were also derived using BI. These results suggest that there is great potential in utilising BI for dendroclimatology in place of MXD data. However, more experimentation is needed to understand (1) how well BI can capture centennial and lower frequency information and (2) what biases may result from wood discolouration, either from species showing a distinct heartwood/sapwood boundary or from partly decayed sub-fossil samples. 
description: NOAA Template Raw Measurements file added 2019-02-04.
DOI: 10.25921/bc4h-t540
title: NOAA/WDS Paleoclimatology - Hoffsummer - Liege Archaeological - QUSP - ITRDB BELG002

description: Tree ring data from the International Tree Ring Data Bank and World Data Center for Paleoclimatology archives.  Most data sets include raw treering measurements (most are annual ring width, with some collections of earlywood or latewood width or wood density), plus chronologies (standardized growth indices for a site compiled from multiple treering samples). Reconstructions of climate variables are included with some of these data sets.  Each data type is stored in a separate data file; the data type is coded into the file name. For details please see: http://www.ncdc.noaa.gov/paleo/treeinfo.htmll
description: NOAA Template Chronology file added 2018-12-19.
DOI: 10.25921/bhy5-7093
title: NOAA/WDS Paleoclimatology - Dongsha Atoll Coral Bimonthly Stable Isotope Data from 1968-2012 CE

description: With the rapid rise in pollution-associated nitrogen inputs to the western Pacific, it has been suggested that even the open ocean has been affected. In a coral core from Dongsha Atoll, a remote coral reef ecosystem, we observe a decline in the 15N/14N of coral skeleton_bound organic matter, which signals increased deposition of anthropogenic atmospheric N on the open ocean and its incorporation into plankton and, in turn, the atoll corals. The first clear change occurred just before 2000 CE, decades later than predicted by other work. The amplitude of change suggests that, by 2010, anthropogenic atmospheric N deposition represented 20 ± 5% of the annual N input to the surface ocean in this region, which appears to be at the lower end of other estimates.
description: Nitrogen isotope change in a South China Sea coral core records increased deposition of anthropogenic atmospheric N beginning just before the 2000 CE.
DOI: 10.25921/b42j-b787
title: NOAA/WDS Paleoclimatology - Northwest Atlantic Slope Holocene Alkenone SST Data

description: Climate of the last 11,000 years, the Holocene, is usually described as warm and stable. Benchmark temperature records from central Greenland ice cores show none of the large, abrupt variations that characterized the prior 100,000 years of glacial climate. Nor do they show any substantial trend, indicating at most 1°-3°C of cooling. Here we show that the slope waters east of the United States and Canada cooled 4°-10°C during the Holocene. Declining insolation, increasing convection in the Labrador Sea, and equatorward shifting of the Gulf Stream path may have caused the cooling.
description: Alkenone data and SST reconstructions for 3 sediment cores from continental slope waters east of the United States and Canada. Core locations: Laurentian Fan Core OCE326-GGC26: 43ºN, 55ºW, 3975 m; Scotian Margin (Emerald Basin) Core OCE326-GGC30: 44ºN, 63ºW, 250 m; Virginia Slope core CH07-98-GGC19: 36º52'N, 74º34'W, 1049 m
DOI: 10.25921/bea4-sh69
title: NOAA/WDS Paleoclimatology - Lake Qinghai, China 16,000 Year Alkenone Summer Temperature Reconstruction

description: Summer temperatures on the Tibetan Plateau (TP) significantly affect stability of glaciers that provide steady water resources to nearly half of the world population. However, lack of reliable, long-term proxy records greatly impedes understanding of regional temperature sensitivity to climate forcings. Here we present a 16 ka long, alkenone-based summer temperature record from Lake Qinghai, northeastern TP that demonstrates major regional temperature response to changes in summer insolation and Atlantic Meridional Overturning Circulation during the Holocene and late glacial. Importantly, we find a period of sustained summer temperature decline (>4C) between 5 and 3.5 ka, which coincides with expansion of Barents Sea ice coverage and is likely driven by intensification of the Westerlies. This unusually long and pronounced regional cooling event likely delayed permanent human settlements on the high-altitude regions (>3000 m) of the TP by at least 500 years.
description: Sediment alkenone concentration data and summer temperature reconstruction for the past 16,000 years from Lake Qinghai, China
DOI: 10.25921/bcc3-5r43
title: NOAA/WDS Paleoclimatology - Kairaitis - Aukstadvaris - QURO - ITRDB LITH035

description: Pedunculate oak (Quercus robur L.) is one of the widely used and dendrochronologically investigated species in Europe. Still, it is a problematical dating object if its outermost section is missing partly or totally. Thus, we need sapwood estimation of living trees. As sapwood amount varies geographically, numbers of sapwood rings have been published for different regions in Europe but no such estimation has been done for the Baltic States yet. Therefore, this paper deals with the estimation of pedunculate oak sapwood growing in the eastern Baltic region, i.e. in Finland, Estonia, Latvia, and Lithuania.

In total, 668 oak core samples of living trees from 43 stands were investigated. Ring widths were measured and the number of sapwood rings was determined according to two criteria: difference of colour and absence of tyloses in earlywood vessels. The samples were divided into two sets, according to the tH-values between site chronologies and the major geobotanical sub-provinces. Thus, the nine Finnish and western Estonian sites were attributed to the western region and the 34 eastern Estonian, Latvian and Lithuanian sites to the eastern region.

As the result of a statistical analysis, we explain that the number of oak sapwood rings ranges from 4.09 to 20.85 and 6.45 to 18.02 within 95% confidence limits in the western and eastern regions, respectively. For the three Baltic countries and southern Finland in general, we recommend to consider a sapwood estimate of 6.18-18.71 rings. Regarding earlier studies, the general European trend of decreasing sapwood ring number towards the east was confirmed. A geographical pattern of eastward decrease of the median sapwood ring number was noticed in the Baltics as well. The chronology based upon 668 samples of living oak trees from all sites covered the period of 1631-2008.
description: NOAA Template Raw Measurements file added 2019-02-05.
DOI: 10.25921/b5pg-qx61
title: NOAA/WDS Paleoclimatology - ITASE-2002-4 Antarctic Ice Core 400 Year Oxygen Isotope Data

description: Changes in atmospheric circulation over the past five decades have enhanced the wind-driven inflow of warm ocean water onto the Antarctic continental shelf, where it melts ice shelves from below. Atmospheric circulation changes have also caused rapid warming over the West Antarctic Ice Sheet, and contributed to declining sea-ice cover in the adjacent Amundsen-Bellingshausen seas. It is unknown whether these changes are part of a longer-term trend. Here, we use water-isotope (d18O) data from an array of ice-core records to place recent West Antarctic climate changes in the context of the past two millennia. We find that the d18O of West Antarctic precipitation has increased significantly in the past 50 years, in parallel with the trend in temperature, and was probably more elevated during the 1990s than at any other time during the past 200 years. However, d18O anomalies comparable to those of recent decades occur about 1% of the time over the past 2,000 years. General circulation model simulations suggest that recent trends in d18O and climate in West Antarctica cannot be distinguished from decadal variability that originates in the tropics. We conclude that the uncertain trajectory of tropical climate variability represents a significant source of uncertainty in projections of West Antarctic climate and ice-sheet change.
description: Antarctic ice core ITASE-2002-4 sub-annual oxygen isotope (d18O) data for the past 400 years.
DOI: 10.25921/b7pf-dm10
title: NOAA/WDS Paleoclimatology - Schweingruber - Balschaya Kamenka River - LAGM - ITRDB RUSS124

description: Tree ring data from the International Tree Ring Data Bank and World Data Center for Paleoclimatology archives.  Most data sets include raw treering measurements (most are annual ring width, with some collections of earlywood or latewood width or wood density), plus chronologies (standardized growth indices for a site compiled from multiple treering samples). Reconstructions of climate variables are included with some of these data sets.  Each data type is stored in a separate data file; the data type is coded into the file name. For details please see: http://www.ncdc.noaa.gov/paleo/treeinfo.htmll
description: NOAA Template Chronology file added 2019-01-09. NOAA Template Raw Measurements file added 2019-04-08.