cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.25921/c880-f473
title: NOAA/WDS Paleoclimatology - Borneo High Resolution Holocene Speleothem Oxygen Isotope Data

description: The El Nino-Southern Oscillation (ENSO) is the primary driver of interannual climate variability in the tropics and subtropics. Despite substantial progress in understanding ocean-atmosphere feedbacks that drive ENSO today, relatively little is known about its behavior on centennial and longer timescales. Paleoclimate records from lakes, corals, molluscs and deep-sea sediments generally suggest that ENSO variability was weaker during the mid-Holocene (4-6 kyrBP) than the late Holocene (0-4 kyrBP). However, discrepancies amongst the records preclude a clear timeline of Holocene ENSO evolution and therefore the attribution of ENSO variability to specific climate forcing mechanisms. Here we present d18O results from a U-Th dated speleothem in Malaysian Borneo sampled at sub-annual resolution. The d18O of Borneo rainfall is a robust proxy of regional convective intensity and precipitation amount, both of which are directly influenced by ENSO activity. Our estimates of stalagmite d18O variance at ENSO periods (2-7 yr) show a significant reduction in interannual variability during the mid-Holocene (3240-3380 and 5160-5230 yrBP) relative to both the late Holocene (2390-2590 yrBP) and early Holocene (6590-6730 yrBP). The Borneo results are therefore inconsistent with lacustrine records of ENSO from the eastern equatorial Pacific that show little or no ENSO variance during the early Holocene. Instead, our results support coral, mollusc and foraminiferal records from the central and eastern equatorial Pacific that show a mid-Holocene minimum in ENSO variance. Reduced mid-Holocene interannual d18O variability in Borneo coincides with an overall minimum in mean d18O from 3.5 to 5.5 kyrBP. Persistent warm pool convection would tend to enhance the Walker circulation during the mid-Holocene, which likely contributed to reduced ENSO variance during this period. This finding implies that both convective intensity and interannual variability in Borneo are driven by coupled air-sea dynamics that are sensitive to precessional insolation forcing. Isolating the exact mechanisms that drive long-term ENSO evolution will require additional high-resolution paleoclimatic reconstructions and further investigation of Holocene tropical climate evolution using coupled climate models. 
description: Subannual oxygen isotope record in six Holocene time windows from stalagmite BA03, Bukit Assam Cave, Borneo, Malaysia, plus decadal average d18O and d13C (as plotted in Figure 3; added 9/14/2017). Provided Keywords: Holocene, ENSO, speleothem, oxygen isotopes. Six Holocene time windows are as follows:
	 2500 yr window: 349.270-400.030mm, 2386.36-2597.86 Cal. year BP 
	 3300 yr window: 474.630-492.600mm, 3234.12-3383.87 Cal. year BP 
	 5200 yr window: 743.770-754.450mm, 5161.41-5225.49 Cal. year BP 
	 5700 yr window: 827.186-838.316mm, 5628.52-5708.02 Cal. year BP 
 	 6700 yr window: 940.150-959.800mm, 6583.78-6740.98 Cal. year BP 
	 8200 yr window: 1054.680-1073.698mm, 8136.82-8316.72 Cal. year BP
DOI: 10.25921/cmfc-b433
title: NOAA/WDS Paleoclimatology - Searles Valley Plant Wax Carbon and Hydrogen Isotopes and GDGTs during the Pliocene

description: Ancient lake deposits in the Mojave Desert indicate that the water cycle in this currently dry place was radically different under past climates. Here we revisit a 700 m core drilled 55 years ago from Searles Valley, California, that recovered evidence for a lacustrine phase during the late Pliocene. We update the paleomagnetic age model and extract new biomarker evidence for climatic conditions from lacustrine deposits (3.373–2.706 Ma). The MBT′5Me temperature proxy detects present-day conditions (21 ± 3°C, n = 2) initially, followed by warmer-than-present conditions (25 ± 3°C, n = 17) starting at 3.268 and ending at 2.734 Ma. Bacterial and archeal biomarkers reveal lake salinity increased after 3.268 Ma likely reflecting increased evaporation in response to higher temperatures. The δ13C values of plant waxes (−30.7 ± 1.4‰, n = 28) are consistent with local C3 taxa, likely expanded conifer woodlands during the pluvial with less C4 than the Pleistocene. δD values (−174 ± 5‰, n = 25) of plant waxes indicate precipitation δD values (−89 ± 5‰, n = 25) in the late Pliocene are within the same range as the late Pleistocene precipitation δD. Microbial biomarkers identify a deep, freshwater lake and a cooling that corresponds to the onset of major Northern Hemisphere glaciation at marine isotope stage marine isotope stages M2 (3.3 Ma). A more saline lake persisted for ~0.6 Ma across the subsequent warmth of the late Pliocene (3.268–2.734 Ma) before the lake desiccated at the Pleistocene intensification of Northern Hemisphere Glaciation.
description: Provided Keywords: biomarker, plant wax, carbon isotopes, hydrogen isotopes, GDGT
DOI: 10.25921/c6ww-vr97
title: NOAA/WDS Paleoclimatology - Qin - Huangwan Tomb, Jingyuan - PITB - ITRDB CHN093

description: The Qin and Western Han dynasties (221 BCE to 24 CE) represent an era of societal prosperity in China. However, due to a lack of high-resolution paleoclimate records it is still unclear whether the agricultural boost documented for this period was associated with more favorable climatic conditions. Here, multiparameter analysis of annually resolved tree-ring records and process-based physiological modeling provide evidence of stable and consistently humid climatic conditions during 270 to 77 BCE in northern China. Precipitation in the Asian summer monsoon region during the Qin–Western Han Dynasties was ~18 to 34% higher compared to present-day conditions. In shifting agricultural and pastoral boundaries ~60 to 100 km northwestward, possibility up to 200 km at times, persistently wetter conditions arguably increased food production, contributing to the socioeconomic prosperity around 2,200 y ago. A gradual wetting trend in the western part of arid northwestern China since the 1980s resembles the historical climate analogue, suggesting that similar benefits for regional environmental and agricultural systems may reoccur under current climate change, at least in the near term.
description: tree-ring data during Qin-Western Han Dynasties. site ranges: ~36.5-37 N  103.8-104.8 E  2338–2456 m
DOI: 10.25921/c5c1-y887
title: NOAA/WDS Paleoclimatology - Iniguez fire data from Rincon Peak RP10 - IMPD USRPK_10

description: Spatial and temporal patterns of fire history are affected by factors such as topography, vegetation, and climate. It is unclear, however, how these factors influenced fire history patterns in small isolated forests, such as that found on Rincon Peak, a “sky island” mountain range in southern Arizona, USA. We reconstructed the fire history of Rincon Peak to evaluate the influences of broad-scale (i.e., climate) versus local-scale (i.e., topographic) factors on fire occurrence and extent. We evaluated both fire scars and tree demography (natality and mortality) to investigate surface fire and crown fire events. The fire history of a 310 ha study area surrounding the top of Rincon Peak was reconstructed by tree-ring sampling in 21 plots. Between 1648 and 1763, spreading fires on Rincon Peak were controlled primarily by regional climate. Widespread surface fires occurred during drought years, and were generally synchronized with regional fire events known from an extensive network of other fire history studies. After 1763, fire extent was apparently limited by local factors (i.e., fuels) as frequent fires continued to burn, but were limited to the southern part of the study area until a widespread fire occurred in 1819. Landscape fires (i.e., fires that scarred ≥2 plots) were absent from the entire study area between 1819 and 1867 despite continued burning in adjacent mountain ranges. Multiple lines of evidence indicate that the 1867 fire was both a surface and a stand-replacing event that killed most trees within a 60 ha patch. Our findings suggest that past climatic variations had important effects on fire regimes and age structures of small, fragmented ponderosa pine (Pinus ponderosa) landscapes like Rincon Peak. Given anticipated climate changes, the rich biodiversity harbored in these steep, isolated landscapes will be critical habitat in the migration of species and should therefore be considered high conservation priority.
description: 
This dataset was contributed as part of the North American Tree-ring Fire Scar Synthesis (NAFSS) project (https://www.ncei.noaa.gov/access/paleo-search/study/34853). Data were contributed to the project from the original data generators.

Sample Storage Location: Laboratory of Tree-Ring, University of Arizona
Dating Method: Dated
Related ITRDB_Chronology: Not Applicable

Fire scar data from this site are available in FHX2 format at:
  https://www.ncei.noaa.gov/pub/data/paleo/firehistory/firescar/northamerica/usrpk_10.fhx
along with associated metadata at:
  https://www.ncei.noaa.gov/pub/data/paleo/firehistory/firescar/northamerica/usrpk_10-noaa.txt
DOI: 10.25921/cznb-x933
title: NOAA/WDS Paleoclimatology - Wiles - Cedar Lake Yellow Cedar - CHNO - ITRDB AK193

description: This is the first study to generate and analyze the climate signal in blue intensity (BI) tree-ring chronologies from Alaska yellow-cedar (Callitropsis nootkatensis (D. Don) Oerst. ex D.P. Little). The latewood BI chronology shows a much stronger temperature sensitivity than ring width and can thus provide information on past climate. The well-replicated BI chronology exhibits a positive January–August mean maximum temperature signal for 1900–1975, after which it loses temperature sensitivity following the 1976–1977 shift in northeastern Pacific climate. The positive temperature response appears to recover and remains strong for the most recent decades, but the coming years will continue to test this observation. This temporary loss of temperature sensitivity from about 1976 to 1999 is not evident in ring width or in a change in forest health but is consistent with prior work linking cedar decline to warming. A confounding factor is the uncertain influence of a shift in color variation from the heartwood–sapwood boundary. Future expansion of the yellow-cedar BI network and further investigation of the influence of the heartwood–sapwood transitions in the BI signal will lead to a better understanding of the utility of this species as a climate proxy.
DOI: 10.25921/ccyt-aw04
title: NOAA/WDS Paleoclimatology - O'Connor fire data from Pinalenos_M22, Southeast Arizona - IMPD USM22001

description: In recent decades fire size and severity have been increasing in high elevation forests of the American Southwest. Ecological outcomes of these increases are difficult to gauge without an historical context for the role of fire in these systems prior to interruption by Euro-American land uses. Across the gradient of forest types in the Pinaleño Mountains, a Sky Island system in southeast Arizona that experienced two relatively large high-severity fires in the last two decades, we compared fire characteristics and climate associations before and after the onset of fire exclusion to determine the degree of similarity between past and recent fires. We use a gridded fire scar and demography sampling network to reconstruct spatially explicit estimates of fire extent and burn severity, as well as climate associations of fires from individual site to landscape scales from 1640 to 2008 C.E. We found that patterns of fire frequency, size, and severity were relatively stable for at least several centuries prior to 1880. A combination of livestock grazing and active fire suppression after circa 1880 led to (1) a significant reduction in fire spread but not fire ignition, (2) a conversion of more than 80% of the landscape from a frequent, low to mixed-severity fire regime to an infrequent mixed to high-severity fire regime, and (3) an increase in fuel continuity within a mid-elevation zone of dry mixed-conifer forest, resulting in increased opportunities for surface and crown fire spread into higher elevation mesic forests. The two most recent fires affecting mesic forests were associated with drought and temperature conditions that were not exceptional in the historical record but that resulted in a relative proportion of high burn severity up to four times that of previous large fires. The ecological effects of these recent fires appear to be more severe than any fire in the reconstructed period, casting uncertainty upon the recovery of historical species composition in high-severity burn patches. Significant changes to the spatial pattern, frequency, and climate associations of spreading fires after 1880 suggest that limits to fuel loading and fuel connectivity sustained by frequent fire have been removed. Coinciding factors of high fuel continuity and fuel loading, projected lengthening of the fire season, and increased variability in seasonal precipitation suggest that large high-severity fires, especially in mixed-conifer forests, will become the predominant fire type without aggressive actions to reduce fuel continuity and restore fire-resilient forest structure and species composition.
description: This dataset was contributed as part of the North American Tree-ring Fire Scar Synthesis (NAFSS) project (https://www.ncei.noaa.gov/access/paleo-search/study/34853). Data were contributed to the project from the original data generators.
DOI: 10.25921/c3a2-wa39
title: NOAA/WDS Paleoclimatology - Vacchiano - Bazena - LADE - ITRDB ITA065

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
DOI: 10.25921/c7x0-h948
title: NOAA/WDS Paleoclimatology - Anjohibe, Madagascar d18O, d13O and Trace Metal Data Over the Past 27,000 years

description: The low latitude Indian Ocean is warming faster than other tropical basins, and its interannual climate variability is projected to become more extreme under future emissions scenarios with substantial impacts on developing Indian Ocean rim countries. Therefore, it has become increasingly important to understand the drivers of regional precipitation in a changing climate. Here we present a new speleothem record from Anjohibe, a cave in northwest (NW) Madagascar well situated to record past changes in the Intertropical Convergence Zone (ITCZ). U-Th ages date speleothem growth from 27 to 14 ka. δ18O, δ13C, and trace metal proxies reconstruct drier conditions during Heinrich Stadials 1 and 2, and wetter conditions during the Last Glacial Maximum and Bølling–Allerød. This is surprising considering hypotheses arguing for southward (northward) ITCZ shifts during North Atlantic cooling (warming) events, which would be expected to result in wetter (drier) conditions at Anjohibe in the Southern Hemisphere tropics. The reconstructed Indian Ocean zonal (west-east) sea surface temperature (SST) gradient is in close agreement with hydroclimate proxies in NW Madagascar, with periods of increased precipitation correlating with relatively warmer conditions in the western Indian Ocean and cooler conditions in the eastern Indian Ocean. Such gradients could drive long-term shifts in the strength of the Walker circulation with widespread effects on hydroclimate across East Africa. These results suggest that during abrupt millennial-scale climate changes, it is not meridional ITCZ shifts, but the tropical Indian Ocean SST gradient and Walker circulation driving East African hydroclimate variability.
DOI: 10.25921/cz5y-9657
title: NOAA/WDS Paleoclimatology - East Asia 600 Year Seasonal Temperature Reconstructions using Tree-Ring Records

description: Seasonal differences of extra-tropical temperature are crucial components of the Earth's climate system. However, the relatively short observational record, especially for East Asia, has limited progress in understanding seasonal differences. In this study, we identify ten tree-ring chronologies separately correlated with local winter (December-February) temperatures and twelve different tree-ring chronologies separately correlated with summer (June-August) temperatures across East Asia. Using these discrete seasonal tree-ring chronologies, we develop two independent winter and summer temperature reconstructions covering the period 1376-1995 CE for East Asia, and compare them with model simulations. Our reconstructions show a more significant volcanic cooling and earlier onset of modern warming in summer than in winter. The reconstructed summer-minus-winter temperature difference decreased since as early as the late 19th century, which has driven the current state of seasonal difference to outside the natural variability range since the 1370s. Climate models could generally reproduce the variability and trends in seasonal reconstructions, but might largely underestimate seasonal differences due to the fact that seasonal expressions on external forcing and modes of internal variability are too small. Our study highlights the importance of using proxy-based seasonal reconstructions to evaluate the performance of climate models, and implies a substantial weakening of seasonal temperature differences in the future.
description: Winter (DJF), summer (JJA) and summer-minus-winter temperature changes for East Asia over the period 1376-1995 CE was reconstructed by tree-ring records across East Asia. Data are reported as air surface temperature anomalies with respect to 1961-1990 CE.
DOI: 10.25921/c0v0-xe63
title: NOAA/WDS Paleoclimatology - Lafon fire data from Brush Mountain, Ridge and Valley - IMPD USBM0001

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: This dataset was contributed as part of the North American Tree-ring Fire Scar Synthesis (NAFSS) project (https://www.ncei.noaa.gov/access/paleo-search/study/34853). Data were contributed to the project from the original data generators.

Sample Storage Location: University of Tennessee, Dept. of Geography & Sustainability
Dating Method: crossdated
Related ITRDB_Chronology: Not Applicable

Fire scar data from this site are available in FHX2 format at:
  https://www.ncei.noaa.gov/pub/data/paleo/firehistory/firescar/northamerica/usbm0001.fhx
along with associated metadata at:
  https://www.ncei.noaa.gov/pub/data/paleo/firehistory/firescar/northamerica/usbm0001-noaa.txt
DOI: 10.25921/cfnb-w541
title: NOAA/WDS Paleoclimatology - Mašek - 06VA Kokořínsko - PISY - ITRDB CZE041

description: Inter-annual climatically driven growth variability of above-ground biomass compartments (for example, tree stems and foliage) controls the intensity of carbon sequestration into forest ecosystems. However, understanding the differences between the climatic response of stem and foliage at the landscape level is limited. In this study, we examined the climate-growth response of stem and leaf biomass and their relationship for Pinus sylvestris (PISY) and Picea abies (PCAB) in topographically complex landscapes. We used tree-ring width chronologies and time series of the normalized difference vegetation index (NDVI) derived from high-resolution Landsat scenes as proxies for stem and leaf biomass, respectively. We then compared growth variability and climate-growth relationships of both biomass proxies between topographical categories. Our results show that the responses of tree rings to climate differ significantly from those found in NDVI, with the stronger climatic signal observed in tree rings. Topography had distinct but species-specific effects: At moisture-limited PISY stands, stem biomass (tree rings) was strongly topographically driven, and leaf biomass (NDVI) was relatively insensitive to topographic variability. In landscapes close to the climatic optimum of PCAB, the relationship between stem and leaf biomass was weak, and their correlations with climate were often inverse, with no significant effects of topography. Different climatic signals from NDVI and tree rings suggest that the response of canopy and stem growth to climate change might be decoupled. Furthermore, our results hint toward different prioritizations of biomass allocation in trees under stressful conditions which might change allometric relationships between individual tree compartments in the long term.
DOI: 10.25921/c8jq-6r19
title: NOAA/WDS Paleoclimatology - Mašek - 07NS Kokořínsko - PISY - ITRDB CZE042

description: Inter-annual climatically driven growth variability of above-ground biomass compartments (for example, tree stems and foliage) controls the intensity of carbon sequestration into forest ecosystems. However, understanding the differences between the climatic response of stem and foliage at the landscape level is limited. In this study, we examined the climate-growth response of stem and leaf biomass and their relationship for Pinus sylvestris (PISY) and Picea abies (PCAB) in topographically complex landscapes. We used tree-ring width chronologies and time series of the normalized difference vegetation index (NDVI) derived from high-resolution Landsat scenes as proxies for stem and leaf biomass, respectively. We then compared growth variability and climate-growth relationships of both biomass proxies between topographical categories. Our results show that the responses of tree rings to climate differ significantly from those found in NDVI, with the stronger climatic signal observed in tree rings. Topography had distinct but species-specific effects: At moisture-limited PISY stands, stem biomass (tree rings) was strongly topographically driven, and leaf biomass (NDVI) was relatively insensitive to topographic variability. In landscapes close to the climatic optimum of PCAB, the relationship between stem and leaf biomass was weak, and their correlations with climate were often inverse, with no significant effects of topography. Different climatic signals from NDVI and tree rings suggest that the response of canopy and stem growth to climate change might be decoupled. Furthermore, our results hint toward different prioritizations of biomass allocation in trees under stressful conditions which might change allometric relationships between individual tree compartments in the long term.