cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.25921/gw1z-5644
title: NOAA/WDS Paleoclimatology - Paleo-pCO2 Database Tianshui Basin Middle Miocene Paleosol d13C Data

description: Understanding the future trajectory of Earth's climate requires knowledge of shifts in atmospheric CO2 concentrations during past warm episodes. The Miocene Climatic Optimum (MCO, ~17-14 Ma) was likely the warmest episode of the past 25 Myr, and thus atmospheric CO2 concentrations during this interval are of particular interest. However, CO2 records across the middle Miocene are rather scattered and data are notably sparse for the latter part of the MCO. Here we present a paleosol-based CO2 record from the Tianshui Basin, northern China, spanning 17-7 Ma. Our results show elevated mean CO2 during the second half of the MCO corresponding with some of the lowest benthic d18O values and highest benthic d13C values, as part of the "Monterey excursion", published for the Neogene. This result supports the idea that the broader Monterey excursion was primarily associated with a CO2 maximum, not carbon burial and CO2 minima as previously interpreted. The new CO2 record, along with previous CO2 records based on paleosols, stomata and foraminiferal boron isotope compositions, also suggests that mean CO2 across the MCO was elevated compared with the immediately following (post-MCO, 14-11 Ma, >80% probability) and immediately preceding (pre-MCO, 20-17 Ma, 70% probability) time periods. The most probable magnitude of the MCO CO2 peak is 20% higher than post-MCO and 12.5% higher than pre-MCO levels. Larger factors, of perhaps 50% higher CO2, likely apply in narrower (<1 Myr) time slices. CO2 records from each proxy individually support the conclusion of modestly elevated MCO CO2, although large temporal gaps exist in records from any one proxy. Using all proxies together, we estimate average MCO CO2 of 375+150/-100 (84th and 16th percentile) ppm. Although mean MCO CO2 was elevated, the MCO was also characterized by highly variable CO2. In addition, determinations from all three proxies suggest that at times during the MCO, CO2 levels were as low as they were following the ice sheet expansion of the Miocene Climate Transition. Furthermore, pre-MCO CO2 levels are indistinguishable from post-MCO CO2 levels (60% probability of pre-MCO CO2 > post-MCO CO2), despite significantly lower benthic d18O values during the former. We conclude that 1) the MCO was a period of slightly elevated and highly variable CO2 compared with the immediately preceding and following intervals, and 2) neither CO2 decrease, orbitally-controlled seasonality over Antarctica nor the confluence of these factors was sufficient to cause Miocene Climate Transition ice sheet expansion. Rather strengthening of the Antarctic Circumpolar Current and Southern Ocean cooling related to closure of the eastern Tethys was a necessary first step.
description: Carbon isotope (d13C) data and CO2 estimates from Miocene paleosols of the Yanwan section, Tianshui Basin, Gansu, China, contributed to the Paleo-pCO2 Database
DOI: 10.25921/gt90-j909
title: NOAA/WDS Paleoclimatology - North Pacific Holocene Alkenone Sea Surface Temperature Reconstruction

description: Suborbital climate variability during the last glacial period is suggested to have involved a 1500-year pacing cycle, but the expression and spatial distribution of the ~1500-year oscillation during interglacials remains unclear. We generated a multidecade resolution record of alkenone sea surface temperature (SST) in the northwestern Pacific off central Japan during the Holocene. The SST record showed centennial and millennial variability with an amplitude of ~1C throughout the entire Holocene. Spectral analysis for SST variation revealed a statistically significant peak with 1470-year periodicity. The SST variation partly correlated with the variations of ice-rafted hematite-stained grain content in North Atlantic sediments. These findings indicate that the mean latitude of the Kuroshio Extension has varied on a 1500-year cycle, and suggest that a climatic link exists between the North Pacific gyre system and the high-latitude North Atlantic thermohaline circulation. The regular pacing at 1500-year intervals seen throughout both the Holocene and the last glacial period suggests that the oscillation was a response to external forcing.
description: Alkenone unsaturation index and sea surface temperature reconstruction for 3 co-located North Pacific sediment cores over the Holocene. Cores MD01-2421, KR02-06 St. A GC, and KR02-06 St. A MC, were collected at 36 deg 02'N, 141 deg 47'E, water depth of 2224m, off the coast of central Japan.
DOI: 10.25921/gz33-r403
title: NOAA/WDS Paleoclimatology - Génova - Sierra de las Nieves 1 - ABPN - ITRDB SPAI075

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 Raw Measurements file added 2019-02-05.
DOI: 10.25921/gbbh-qd51
title: NOAA/WDS Paleoclimatology - Génova - Sierra de las Nieves 2 - ABPN - ITRDB SPAI076

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 Raw Measurements file added 2019-02-05.
DOI: 10.25921/gqct-0c60
title: NOAA/WDS Paleoclimatology - Lomonosovfonna, Svalbard 800 Year Ice Core Black Carbon Data

description: Produced by the incomplete combustion of fossil fuel and biomass, black carbon (BC) contributes to Arctic warming by reducing snow albedo and thus triggering a snow-albedo feedback leading to increased snowmelt. Therefore, it is of high importance to assess past BC emissions to better understand and constrain their role. However, only a few long-term BC records are available from the Arctic, mainly originating from Greenland ice cores. Here, we present the first long-term and high-resolution refractory black carbon (rBC) record from Svalbard, derived from the analysis of two ice cores drilled at the Lomonosovfonna ice field in 2009 (LF-09) and 2011 (LF-11) and covering 800 years of atmospheric emissions. Our results show that rBC concentrations strongly increased from 1860 on due to anthropogenic emissions and reached two maxima, at the end of the 19th century and in the middle of the 20th century. No increase in rBC concentrations during the last decades was observed, which is corroborated by atmospheric measurements elsewhere in the Arctic but contradicts a previous study from another ice core from Svalbard. While melting may affect BC concentrations during periods of high temperatures, rBC concentrations remain well preserved prior to the 20th century due to lower temperatures inducing little melt. Therefore, the preindustrial rBC record (before 1800), along with ammonium (NH4+), formate (HCOO-) and specific organic markers (vanillic acid, VA, and p-hydroxybenzoic acid, p-HBA), was used as a proxy for biomass burning. Despite numerous single events, no long-term trend was observed over the time period 1222-1800 for rBC and NH4+. In contrast, formate, VA, and p-HBA experience multi-decadal peaks reflecting periods of enhanced biomass burning. Most of the background variations and single peak events are corroborated by other ice core records from Greenland and Siberia. We suggest that the paleofire record from the LF ice core primarily reflects biomass burning episodes from northern Eurasia, induced by decadal-scale climatic variations.
description: Annual averages (1222-2004 AD) of the refractory black carbon (rBC) record obtained from the Lomonosovfonna 2009 ice core
DOI: 10.25921/g651-7298
title: NOAA/WDS Paleoclimatology - Musser - Tonsina Hill - PCMA - ITRDB AK153

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 Raw Measurements file added 2019-02-08.
DOI: 10.25921/gz6b-ww62
title: NOAA/WDS Paleoclimatology - Bir-Uja Cave, Kyrgyzstan 900 Year Stalagmite Isotope and Sr/Ca Data

description: The strength of the North Atlantic Oscillation (NAO) is considered to be the main driver of climate changes over the European and western Asian continents throughout the last millennium. For example, the predominantly warm Medieval Climate Anomaly (MCA) and the following cold period of the Little Ice Age (LIA) over Europe have been associated with long-lasting phases with a positive and negative NAO index. Its climatic imprint is especially pronounced in European winter seasons. However, little is known about the influence of NAO with respect to its eastern extent over the Eurasian continent.
Here we present speleothem records (d13C, d18O and Sr/Ca) from the southern rim of Fergana Basin (Central Asia) revealing annually resolved past climate variations during the last millennium. The age control of the stalagmite relies on radiocarbon dating as large amounts of detrital material inhibit accurate 230Th dating. Present-day calcification of the stalagmite is most effective during spring when the cave atmosphere and elevated water supply by snow melting and high amount of spring precipitation provide optimal conditions. Seasonal precipitation variations cause changes of the stable isotope and Sr/Ca compositions. The simultaneous changes in these geochemical proxies, however, give also evidence for fractionation processes in the cave. By disentangling both processes, we demonstrate that the amount of winter precipitation during the MCA was generally higher than during the LIA, which is in line with climatic changes linked to the NAO index but opposite to the higher mountain records of Central Asia. Several events of strongly reduced winter precipitation are observed during the LIA in Central Asia. These dry winter events can be related to phases of a strong negative NAO index and all results reveal that winter precipitation over the central Eurasian continent is tightly linked to atmospheric NAO modes by the westerly wind systems.
description: Speleothem oxygen and carbon isotope and trace element records from Bir-Uja Cave, Kyrgyzstan, Central Asia
DOI: 10.25921/gg8j-5j89
title: NOAA/WDS Paleoclimatology - Krusic - Mount Smolikas EHS09 - PIHE - ITRDB GREE020

description: We present a June-July drought reconstruction based on the standardized precipitation index (SPI) for the Balkan Peninsula over the period 730-2015 CE. The reconstruction is developed using a composite Pinus heldreichii tree-ring width chronology, from a high-elevation network of eight sites in the Pindus Mountains in northwest Greece, composed of living trees and relict wood. The dataset includes the ring width series of Europe's currently oldest known living tree, dendrochronologically dated to be more than 1075 years old. The spatial coverage of the reconstruction is improved by using an averaged gridded SPI data target derived from a response field that is located north of the study region. Justification for this approach includes the remoteness of instrumental data, the spatial variability of precipitation and synoptic scale circulation patterns. Over the past 1286 years, there have been 51 dry and 43 pluvial events. The driest year during the 1286-year-long period was 1660 and the wettest year was 1482. Comparison with shorter reconstructions and documentary evidence validates the new reconstruction, and provides additional insight into socioeconomic impacts and spatial patterns of extreme events. Fifty-nine of 72 previously undescribed extremes occurred prior to the 17th century. The new reconstruction reveals long-term changes in the number of extremes, including substantially fewer drought and pluvial events in the 20th century. Additional tests on the long-term effects of age structure, replication and covariance changes support the heteroscedastic nature of the reconstructed hydro-climatic extremes.
description: NOAA Template Raw Measurements file added 2019-02-05.
DOI: 10.25921/g8se-tr56
title: NOAA/WDS Paleoclimatology - Uluu-Too Cave, Kyrgyzstan 5000 Year Stalagmite Stable Isotope and S/Ca Data

description: Central Asia is located at the confluence of large-scale atmospheric circulation systems. However, the number of Holocene climate records is still low in most parts of this region and insufficient to allow detailed discussion and comparisons to disentangle the complex climate history and interplays between the different climatic systems. Here, we present the first stalagmite record from arid Central Asia (south-western Kyrgyzstan) by using d18O, d13C, and micro x-ray fluorescence (uXRF)-sulfur data spanning the last 5000 years. The cave hosting stalagmite Uluu-2 is ideally suited to identify past shifts in seasonal variations in precipitation in this part of the world. Comparison of instrumental and paleo-isotopic studies demonstrates that the Uluu-2 speleothem isotope composition faithfully records climate changes and responds to shifts in the proportion of moisture derived from mid-latitude Westerlies during the winter/spring season. The reconstructions suggest that the area was characterized by a dry climate from 4700 to 3900 yr BP, interrupted by a wet episode around 4200 yr BP. Further drier conditions also occurred between 4000 and 3500 yr BP. Wetter conditions were re-established at ca. 2500 yr BP, after another dry episode between 3000 and 2500 yr BP. With the exception of two short dry events (1150 and 1300 yr BP), the period after 1700 yr BP shows moderate to wet conditions. Regional comparisons suggest that the strength and position of the Westerly winds control climatic shifts in arid Central Asia, leading to complex local responses.
description: Speleothem stable isotope (d18O and d13C) and trace element (S/Ca) records from Uluu-Too Cave, Kyrgyzstan, Central Asia for the past 5,000 years. Provided keywords: Uranium/Thorium dated stalagmite, precipitation reconstruction
DOI: 10.25921/g01a-rj53
title: NOAA/WDS Paleoclimatology - Guliya Ice Cap Ice Thickness Data

description: Despite their high value and importance for various glaciological applications, detailed ice thickness measurements of alpine glaciers are still very limited. Knowledge of bedrock topography is essential for paleoglaciological studies. The Guliya ice cap located on the Tibetan Plateau is one of the highest and largest ice caps in mid-low latitude regions. A detailed ground-penetrating radar (GPR) survey was conducted on the Guliya ice cap in 2015 using 20 and 40 MHz frequency antennas. An empirical Bayesian kriging method was used for ice thickness interpolation and uncertainty assessment. GPR measurements revealed complex basal topography of the Guliya glacier with a maximum thickness of 371.12 ± 13 m. The internal reflections caused by changes in the dielectric properties were registered on the 40 MHz radargrams at the summit and were attributed to density variations. As a result of this fieldwork, one of the largest ice thickness datasets in High Mountain Asia was obtained. Guliya glacier elevation changes were assessed by differencing digital elevation models. The glacier gained mass from 2000 to 2015 with an average rate of 0.270 ± 0.11 m w.e. a-1 at the summit and 0.279 ± 0.11 m w.e. a-1 at the lower elevations.
description: Ground-penetrating radar (GPR) ice thickness measurements for two areas (Plateau and Summit) of the Guliya Ice Cap, Tibetan Plateau, China
DOI: 10.25921/gnzw-w086
title: NOAA/WDS Paleoclimatology - Schwarzsee ob Sölden, Austria Holocene Chironomid-Inferred July Temperature

description: Few well-dated, quantitative Holocene temperature reconstructions exist from high-altitude sites in the Central Eastern Alps. Here, we present a chironomid-based quantitative reconstruction of mean July air temperatures (TJuly) throughout the Holocene for a remote high-mountain lake, Schwarzsee ob Sölden, situated above the treeline at 2796 m a.s.l. in the Austrian Alps. Applying a chironomid-temperature inference model developed from lakes of the Alpine region to a high-resolution chironomid record from the lake provides evidence for early Holocene (ca 10000-8600 cal yr BP) TJuly of up to 8.5 C, i.e. >4 C above the modern (1977-2006) mean July temperature. The reconstruction reveals the so-called '8.2-ka cold event' centered at ca 8250-8000 cal yr BP with temperatures ca 3 C below the early-Holocene thermal maximum. Rather warm (ca 6 C) and productive conditions prevailed during ca 7900-4500 cal yr BP. The chironomid record suggests a climate transition between ca 5200 and 4500 cal yr BP to cooler TJuly. A distinct cooling trend is evident from ca 4500 until ca 2500 cal yr BP. Thereafter, the study site experienced its coldest conditions (around 4 C or less) throughout the rest of the Holocene, with the exception of the warming trend during the late 20th century. Beside other factors, the Northern Hemisphere summer insolation seems to be the major driving force for the long-term trends in TJuly at high altitudes in the Eastern Alps. Due to the extreme location of the lake and the limited temperature range represented by the applied calibration data set, the chironomid-based temperature reconstruction fails to track phases of the late-Holocene climatic history with TJuly cooler than 4 C. Further chironomid-based palaeoclimate model and down-core studies are required to address this problem, provide more realistic TJuly estimates from undisturbed high-altitude lakes in the Alps, and extract a reliable regional temperature signal.
description: July air temperature reconstruction based on chironomid head capsules from Holocene sediments collected in Schwarzsee ob Sölden, Austria
DOI: 10.25921/gwrf-qv50
title: NOAA/WDS Paleoclimatology - Paleo-pCO2 Database Oligocene/Miocene Stomata CO2 Data

description: Recent variations in the concentration of atmospheric carbon dioxide ([CO2]atm) have been shown to affect carbon fixation during photosynthesis and are correlated with anatomical and physiological changes observed in leaves of woody dicots. These include changes in stomatal frequency and size and in d13C values. These attributes can be measured on organically preserved leaf fossils, and therefore can be used as proxies for Earth's atmospheric CO2 history. This study tests the link between [CO2]atm and global temperature for the late Oligocene and early Miocene using fossil leaves collected from Ethiopia, by estimating [CO2]atm using a leaf gas exchange model. The results of this study show a statistically significant [CO2]atm rise from ~390 ppm in the late Oligocene to ~870 ppm in the early Miocene. These values demonstrate a positive correlation between [CO2]atm and global average temperature, contrary to some previous studies for this time interval. The results of this study have important implications for understanding future climate change driven by rising [CO2]atm.
description: Stomata Paleo-CO2 data from Tesfamichael et al. 2017, contributed to the Paleo-pCO2 Database
DOI: 10.25921/gxv3-p084
title: NOAA/WDS Paleoclimatology - Guliya Ice Core, Tibet 340 Year Trace Elements Data

description: A continuous record of 29 trace elements (TEs) has been constructed between 1650 and 1991 CE (Common Era) from an ice core retrieved in 1992 from the Guliya ice cap, on the northwestern Tibetan Plateau. Enrichments of Pb, Cd, Zn and Sb were detected during the second half of the 19th century and the first half of the 20th century (~1850-1950) while enrichments of Sn (1965-1991), Cd and Pb (1975-1991) were detected during the second half of the 20th century. The EFs increased significantly by 20% for Cd and Sb, and by 10% for Pb and Zn during 1850-1950 relative to the pre-1850s. Comparisons of the Guliya TEs data with other ice core-derived and production/consumption data suggest that Northern Hemisphere coal combustion (primarily in Western Europe) is the likely source of Pb, Cd, Zn, and Sb during the 1850-1950 period. Coal combustion in Europe declined as oil replaced coal as the primary energy source. The European shift from coal to oil may have contributed to the observed Sn enrichment in ~1965 (60% EF increase in 1975-1991), although regional fossil fuel combustion (coal and leaded gasoline) from western China, Central Asia, and South Asia (India, Nepal), as well as Sn mining/smelting in Central Asia, may also be possible sources. The post-1975 Cd and Pb enrichments (40% and 20% EF increase respectively in 1975-1991) may reflect emissions from phosphate fertilizers, fossil fuel combustion, and/or non-ferrous metal production, from western China, Central Asia, and/or South Asia. Leaded gasoline is likely to have also contributed to the post-1975 Pb enrichment observed in this record. The results strongly suggest that the Guliya ice cap has recorded long-distance emissions from coal combustion since the 1850s with more recent contributions from regional agriculture, mining, and/or fossil fuel combustion. This new Guliya ice core record of TEs fills a geographical gap in the reconstruction of the pollution history of this region that extends well beyond modern instrumental records.
description: Guliya ice core 340 year trace elements data, including 5-year median concentration, enrichment factor (EF), and excess concentrations for Cd, Sb, Zn, Pb, Sn, Al, and Fe.
DOI: 10.25921/g9qc-4110
title: NOAA/WDS Paleoclimatology - Azpeleta Tarancón fire data from Solon, south central New Mexico - IMPD USS--001

description: Records of past fire occurrence from tree rings, charcoal found in lake sediments, and other proxies. Parameter keywords describe what was measured in this data set.  Additional summary information can be found in the abstracts of papers listed in the data set citations.  Additional information on the International Multiproxy Database (IMPD) data set procedures are also available.

description: Tarancón fire data from Solon, south central New Mexico - IMPD USS--001