cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.25921/bw0w-5852
title: NOAA/WDS Paleoclimatology - Hughes - Buena Vista - SEGI - ITRDB CA709

description: The first dendroclimatic reconstruction of May 1 snow water equivalent (SWE) was developed from a Sequoiadendron giganteum regional tree-ring chronology network of 23 sites in central California for the period 90-2012 CE. The reconstruction is based on a significant relationship between May 1 SWE and tree-ring growth and shows climate variability from interannual to intercentennial time scales. A regression-based reconstruction equation explains up to 55% of the variance of SWE for 1940-2012. Split-sample validation supports our use of a reconstruction model based on the full period of reliable observational data (1940-2012). Thresholds for May 1 SWE low (15 percentile) and high (80 percentile) years were selected based on the exploratory scatterplots relationship between observed and reconstructed data for the period 1940-2012. The longest period of consecutive low-SWE years in the reconstruction is 2 years and the frequency of the lowest SWE years is highest during the period 710-809 CE. The longest high-SWE period, defined by consecutive wet years, is 3 years (558-560 CE). SWE and its reconstruction positively correlate with northeastern Pacific sea surface temperatures, the low-frequency variability of which may provide some predictive ability. Ultimately, the instrumental record and reconstruction suggest that unlike other sites in the region, twentieth century SWE variability in these Sequoia groves has remained within historical boundaries and relatively buffered from extremes and severe declines, though this is likely to change in coming decades with potentially negative effects on water availability for these trees.
description: NOAA Template Raw Measurements file added 2021-02-22.
DOI: 10.25921/b86b-ht53
title: NOAA/WDS Paleoclimatology - Tumajer - Myslivna - QURO - ITRDB CZEC029

description: Increasing temperatures and recent changes in runoff regimes observed in Central Europe might alter the growth and relative water uptake of floodplain trees. To predict responses of floodplain forests to climate change, it is necessary to determine the climatic controls over tree growth and vessel anatomy. We analysed the responses of tree-ring width and earlywood vessel anatomical parameters (average vessel lumen area, vessel density and total vessel lumen area) of pedunculate oak (Quercus robur L.) growing in a floodplain to hydroclimatic conditions represented by temperature, the drought index (scPDSI), river discharge, groundwater level, and occurrence of floods and drought events. Site chronologies were assembled for floodplain and reference sites and, subsequently, correlated with time series of hydroclimatic conditions. Our results show that radial growth of floodplain trees is particularly positively influenced by temperature during the growing season and during previous year's summer. By contrast, the growth of reference trees is highly drought-limited. Earlywood average vessel lumen area chronologies from both floodplain and reference sites share a positive temperature signal from January to April. However, the effect of water availability (indicated by the drought index) on vessel size is mostly negative for floodplain trees (with a maximum response to the autumn of the year preceding tree-ring formation) and positive or non-significant for reference trees. Vessel density chronologies contain the inverse environmental information as tree-ring width, however, with amplified negative correlations with current year temperatures at floodplain sites. Total vessel area is associated mostly with temperature in previous May and June. The drought index recorded exactly the same information in tree-rings as did river discharges and groundwater levels. The results of both correlation and trend analysis evidence that tree-ring width of floodplain Q. robur unambiguously increases with increasing temperature; on the other hand, droughts can become a serious problem affecting the productivity of reference trees growing in more distal parts of the lowland. Vessel size of Q. robur growing outside the floodplain recently tends to increase with increasing temperatures, making xylem more effective at water transport but also more vulnerable to cavitation.
description: The data represent raw tree-ring width series. One core was extracted from each tree (Quercus robur). NOAA Template Raw Measurements file added 2021-12-29.
DOI: 10.25921/bqmt-2x25
title: NOAA/WDS Paleoclimatology - Northeastern United States 11,000 Year Temperature Reconstructions

description: A decline of hemlock (Tsuga) populations at ca 5.5 ka (thousands of calibrated radiocarbon years before 1950 AD) stands out as the most abrupt vegetation change of the Holocene in North America, but remains poorly understood after decades of study. Recent analyses of fossil pollen have revealed a concurrent, abrupt oak (Quercus) decline and increases in the abundance of beech (Fagus) and pine (Pinus) on Cape Cod in eastern Massachusetts, but the replacement of drought-tolerant oaks by moisture-sensitive beeches appears inconsistent with low lake levels in the region at the same time. The oak and beech changes are also limited to coastal areas, and the coastal-inland differences require an explanation. Here, we develop a new lake-level reconstruction from Deep Pond, Cape Cod by using a transect of sediment cores and ground-penetrating radar (GPR) profiles to constrain the past elevations of the sandy, littoral zone of the pond. The reconstruction shows that a series of multi-century episodes of low water coincide with the abrupt hemlock and oak declines, and interrupt subsequent phases of hemlock recovery. The lake-level variations equal precipitation deficits of ~100 mm superimposed on a Holocene long moisture increase of >400 mm. However, because moisture deficits do not easily explain the oak and beech changes, we also evaluate how the climate preferences of the regional vegetation changed over time by matching the fossil pollen assemblages from Deep Pond with their modern equivalents. Reconstructions of the precipitation requirements of the vegetation correlate well even in detail with the lake-level record (r = 0.88 at Deep Pond), and indicate close tracking of effective moisture (precipitation minus evapotranspiration) by the vegetation despite the abrupt species declines, which could have decoupled climate and vegetation trends. Reconstructions of the temperature preferences of the vegetation indicate that coastal sites may have cooled by 0.5-2.5 C after ca 5.5 ka, while inland sites warmed by 0.5-1 C. The change in coastal temperature preferences agrees with sea surface cooling in the western Atlantic Ocean of >1 C. Consequently, the persistence of low hemlock abundance after 5.5 ka in the northeast U.S. may have resulted from oceanic changes that produced multi-century droughts and thus delayed the post-decline recovery of hemlock populations.
description: This dataset was contributed as part of the Temperature-12k project (https://doi.org/10.25921/4RY2-G808). Data were contributed to the project from the original data generators, who are listed in the Investigator field of this template file. Additional notes regarding the use of these data in the Temperature-12k project can be found in the LiPD file listed as an Online_Resource of this template file. Note added by Temperature-12k authors: 50-yr binned.
DOI: 10.25921/bm6c-gb10
title: NOAA/WDS Paleoclimatology - Coulthard - Gunn Creek - PIPO - ITRDB CANA639

description: The recent intensification of floods and droughts in the Fraser River Basin (FRB) of British Columbia has had profound cultural, ecological, and economic impacts that are expected to be exacerbated further by anthropogenic climate change. In part due to short instrumental runoff records, the long-term stationarity of hydroclimatic extremes in this major North American watershed remains poorly understood, highlighting the need to use high-resolution paleoenvironmental proxies to inform on past streamflow. Here we use a network of tree-ring proxy records to develop 11 subbasin-scale, complementary flood- and drought-season reconstructions, the first of their kind. The reconstructions explicitly target management-relevant flood and drought seasons within each basin, and are examined in tandem to provide an expanded assessment of extreme events across the FRB with immediate implications for water management. We find that past high flood-season flows have been of greater magnitude and occurred in more consecutive years than during the observational record alone. Early 20th century low flows in the drought season were especially severe in both duration and magnitude in some subbasins relative to recent dry periods. Our Fraser subbasin-scale reconstructions provide long-term benchmarks for the natural flood and drought variability prior to anthropogenic forcing. These reconstructions demonstrate that the instrumental streamflow records upon which current management is based likely underestimate the full natural magnitude, duration, and frequency of extreme seasonal flows in the FRB, as well as the potential severity of future anthropogenically forced events.
description: Fraser River Basin, British Columbia, Canada Tree-Ring Data NOAA Template Raw Measurements file added 2021-12-29.
DOI: 10.25921/btys-4568
title: NOAA/WDS Paleoclimatology - Maxwell - Hoot Woods - CYOV - ITRDB IN012

description: Understanding the historic variability in the hydroclimate provides important information on possible extreme dry or wet periods that in turn inform water management plans. Tree rings have long provided historical context of hydroclimate variability of the U.S. However, the tree-ring network used to create these countrywide gridded reconstructions is sparse in certain locations, such as the Midwest. Here, we increase (n = 20) the spatial resolution of the tree-ring network in southern Indiana and compare a summer (June-August) Palmer Drought Severity Index (PDSI) reconstruction to existing gridded reconstructions of PDSI for this region. We find both droughts and pluvials that were previously unknown that rival the most intense PDSI values during the instrumental period. Additionally, historical drought occurred in Indiana that eclipsed instrumental conditions with regard to severity and duration. During the period 1962-2004 CE, we find that teleconnections of drought conditions through the Atlantic Meridional Overturning Circulation have a strong influence (r = -0.60, p < 0.01) on secondary tree growth in this region for the late spring-early summer season. These findings highlight the importance of continuing to increase the spatial resolution of the tree-ring network used to infer past climate dynamics to capture the sub-regional spatial variability. Increasing the spatial resolution of the tree-ring network for a given region can better identify sub-regional variability, improve the accuracy of regional tree-ring PDSI reconstructions, and provide better information for climatic teleconnections.
description: Eastern Deciduous Forest, Climate response, Palmer Drought Severity Index NOAA Template Raw Measurements file added 2020-09-03.
DOI: 10.25921/bctc-me65
title: NOAA/WDS Paleoclimatology - Maxwell - Meltzer Woods - FRNI - ITRDB IN022

description: Tree-ring reconstructions of streamflow can provide long-term perspectives of flow variability that may be useful in management strategies for water resources. Relative to other portions of the United States, there is a dearth of tree-ring based streamflow reconstructions in the Midwest. The Wabash River is an important water resource in Indiana and Illinois where many sectors rely on it. Here, to better understand the historic hydroclimate within the Wabash River Basin, we reconstructed June-September streamflow for a tributary of the Wabash River using three statistical approaches: the traditional basin approach, and the recently-developed climate-footprint, and drought-reconstruction approaches. Our reconstructions explained 53-71% of the variance for the common period (1941-1984). We find that in our three reconstructions, there are extreme droughts and pluvials that exceed those during the instrumental period, including a sustained five-decade low-flow event in the early 19th century. Overall, we find that the traditional basin approach produced the most robust model but had the shortest reconstruction length of the three approaches, as it requires the predictor chronologies to be derived from within the basin. Our results indicate that there are merits and drawbacks to each approach with the general pattern of sacrificing variance explained for reconstruction length.
description: Streamflow, Eastern Deciduous Forest NOAA Template Raw Measurements file added 2020-09-03.
DOI: 10.25921/bwze-0521
title: NOAA/WDS Paleoclimatology - Eastern Equatorial Atlantic Primary Productivity, Sea Surface Temperature and Salinity Reconstructions over the last 44 kyr

description: In order to better explore quantitative reconstructions of net primary productivity (NPP) conditions using a dinoﬂagellate cyst (dinocyst)-based transfer function method, we revised the tropical Atlantic modern dinocyst database n=208 (Marret et al., 2008). Modern assemblages from the worldwide dinocyst atlas (Zonneveld et al., 2013) were added to provide a better geographical coverage of the South Atlantic Ocean. The environmental dataset was updated using the World Ocean Atlas 2013 for sea-surface temperature (SST) and sea-surface salinity (SSS) data, as well as for 1997–2017 mean NPP values recorded during SeaWifs and MODIS spatial programs. New environmental datasets were tested using anomalies regarding mean latitudinal SST as a potential index to track past upwelling activity. Finally, preindustrial NPP values, simulated with the IPSL-CM5ALR model developed at the Institut Pierre Simon Laplace (IPSL) have been added to the dinocyst environmental database to provide NPP values consistent with the mean age of “modern” dinocyst assemblages. The transfer function method using the updated modern database was then applied to fossil dinocyst assemblages of core KZAI-01, retrieved oﬀ the Congo River mouth and covering the last 43.2kyr. Our results indicate a dominant orbital forcing, with higher primary productivity values reconstructed during precession minima (MIS 3 and the last deglaciation) and enhanced by a maximum of obliquity during the last deglaciation and the Holocene. The synchronicity between high upwelling intensity and high terrigenous inputs during high NPP period (e.g. during the last Deglaciation) highlighted the prevalent role of river-induced upwelling activity, which is speciﬁc to the Congo River. These results have improved our understanding of the environmental forcing leading to major trophic changes in the intertropical area.
description: Metadata are from the Temperature-12k project (https://doi.org/10.25921/4RY2-G808). Data are from the supplemental material of Hardy et al. 2018 (https://doi.org/10.1016/j.palaeo.2018.06.025).
DOI: 10.25921/bvnz-s956
title: NOAA/WDS Paleoclimatology - South Pacific Convergence Zone 1,300 Year SPCZ Index Reconstruction

description: The South Pacific Convergence Zone (SPCZ) is the largest rain belt in the Southern Hemisphere and a key driver of precipitation variability, impacting South Pacific island communities. Our millennial-long reconstruction is based on a trans-Pacific tree-ring network, containing chronologies sensitive to changes in the SPCZ because of its pervasive nature, spatial extent, and link to the El Nino-Southern Oscillation. The reconstruction explains 58% of variance in the instrumental SPCZ index from 1911-1998. El Nino-Southern Oscillation cycles are identified throughout the reconstruction period. Multidecadal periodicities wax and wane, coinciding with a sustained eastward shift during the Medieval Climate Anomaly (~1,000-1,200 CE). We find large volcanic eruptions increased the tendency for the SPCZ to be displaced eastward. The reconstruction helps improve our understanding of past hydroclimatic behavior in the southwest Pacific and can be used to validate general circulation model projections for Pacific Island communities and the wider region in the 21st century.
description: Tree-ring based reconstruction of the South Pacific Convergence Zone Index (the normalised sea level pressure difference between Apia, Samoa and Suva, Fiji) from 700 CE to 1998 CE, derived using a nested, principal components-based regression model. Also provided is an array file of 300 pseudo-reconstructions used to calculate the uncertainty interval.
DOI: 10.25921/b9nw-tr46
title: NOAA/WDS Paleoclimatology - Treml - Pálenica - PISY - ITRDB SVK012

description: Extreme tree growth reductions represent events of abrupt forest productivity decline and carbon sequestration reduction. An increase in their magnitude can represent an early warning signal of impending tree mortality. Yet the long-term trends in extreme growth reductions remain largely unknown. We analyzed the trends in the proportion of trees exhibiting extreme growth reductions in two Central-European conifer species - Pinus sylvestris (PISY) and Picea abies (PCAB) - between 1901 and 2018. We used a novel approach for extreme growth reduction quantification by relating their size to their mean recurrence interval. Twenty-eight sites throughout Czechia and Slovakia with 1120 ring width series representing high- and low-elevation forests were inspected for extreme growth reductions with recurrence intervals of 15 and 50 years along with their link to climatic drivers. Our results show the greatest growth reductions at low-elevation PCAB sites, indicating high vulnerability of PCAB to drought. The proportions of trees exhibiting extreme growth reductions increased over time at low-elevation PCAB, decreased recently following an abrupt increase in the 1970-1980s at high-elevation PCAB, and showed nonsignificant trends in high- and low-elevation PISY. Climatic drivers of extreme growth reductions, however, shifted over time for all site categories as the proportion of low-temperature-induced extreme growth reductions declined since the 1990s, whereas events caused by drought consistently increased in frequency during the same period. We observed higher growth volatility at the lower range of distribution compared with the upper range margin of PISY and PCAB. This will undoubtedly considerably impact tree growth and vitality as temperatures and incidence of drought in Central Europe are expected to further increase with ongoing climate change.
description: Extreme growth reductions in Central-European Pinus sylvestris (PISY) and Picea abies (PCAB). NOAA Template Raw Measurements file added 2021-12-29.
DOI: 10.25921/bzep-ze85
title: NOAA/WDS Paleoclimatology - Karpukhin - Vyazma archaeological - QUSP - ITRDB RUSS284

description: The article discusses the results of dendrochronological and radiocarbon dating of tree rings of oak tomb boards and elements of the coffins of the medieval cemetery of Vyazma in Smolensk Region. The study compares the results of dendrochronological, calibrated radiocarbon dating and simulated wiggle-match dating. As a result of this work, the first absolutely dated tree-ring chronology by oak for the archaeological sites of the European Russia was developed with a total span of 233 years (1074-1306). In the geographic network of absolutely dated dendrochronological oak scales developed for Europe, the Vyazma tree-ring chronology is its easternmost point. The purpose of the article is to provide the scientific community with a tree-ring oak chronology that can be used in endroarchaeological, dendroclimatological and dendroecological studies. The developed chronology demonstrates a stable relationship with the tree-ring chronologies by oak originating from alluvial deposits of the rivers Western Dvina and Vilia near the town of Smargon (North-West Belarus).
description: dendrochronological dating of archaeological materials. Collection ID: vz17pogrR NOAA Template Raw Measurements file added 2020-11-18.
DOI: 10.25921/b68b-cg28
title: NOAA/WDS Paleoclimatology - Indus River 600 Year Streamflow Reconstructions

description: Our understanding of the full range of natural variability in streamflow, including how modern flow compares to the past, is poorly understood for the Upper Indus Basin because of short instrumental gauge records. To help address this challenge, we use Hierarchical Bayesian Regression with partial pooling to develop six centuries long (1394-2008 CE) streamflow reconstructions at three Upper Indus Basin gauges (Doyian, Gilgit, and Kachora), concurrently demonstrating that Hierarchical Bayesian Regression can be used to reconstruct short records with interspersed missing data. At one gauge (Partab Bridge), with a longer instrumental record (47 years), we develop reconstructions using both Bayesian regression and the more conventionally used principal components regression. The reconstructions produced by principal components regression and Bayesian regression at Partab Bridge are nearly identical and yield comparable reconstruction skill statistics, highlighting that the resulting tree ring reconstruction of streamflow is not dependent on the choice of statistical method. Reconstructions at all four reconstructions indicate that flow levels in the 1990s were higher than mean flow for the past six centuries. While streamflow appears most sensitive to accumulated winter (January-March) precipitation and summer (May-September) temperature, with warm summers contributing to high flow through increased melt of snow and glaciers, shifts in winter precipitation and summer temperatures cannot explain the anomalously high flow during the 1990s. Regardless, the sensitivity of streamflow to summer temperatures suggests that projected warming may increase streamflow in coming decades, though long-term water risk will additionally depend on changes in snowfall and glacial mass balance.
description: Tree-ring based reconstructions of mean January-December annual discharge in m3/s of the Indus River at Doyian, Gilgit, and Kachora between 1394-2005 CE, and mean May-September (MJJAS) flow at Partab Bridge between 1430-2004 CE.
DOI: 10.25921/b0e1-3v98
title: NOAA/WDS Paleoclimatology - Southern Indian Ocean G. bulloides Core-top Area Density Data

description: The area density proxy of foraminiferal shell thickness and calcification intensity has the potential to provide information about past ocean CO2 content and has the benefit of small sample requirements, simple analytical techniques, and the ability to re-use the analyzed foraminifera for other paleo-proxies. Using a series of multicore core-tops collected from the southeastern Indian Ocean (1.8–3.8 km water depth), we evaluate the reliability of utilizing area density values of Globigerina bulloides from sediment cores to estimate surface ocean carbonate parameters. Because foraminifera in marine sediments can rarely be considered “pristine” (or “glassy”), we grouped area density measurements of shells to designate various stages of diagenesis. Visual signs of alteration were apparent at area density values as low as ∼0.122 × 104 µg/µm2, with deviations from the “pristine” endmember beginning at area density values of ∼0.087 × 104 µg/µm2. We find that increases in area density overprint the surface ocean carbonate signature in thicker (>0.122 × 104 µg/µm2 shells), but small increases associated with marine sedimentary burial and diagenesis can be accounted for, allowing this proxy to be applied back in time. Reconstructing the distribution of area density values in a given sample has the potential to provide valuable information on overall sample preservation by estimating the percent of well-preserved shells (<0.122 × 104 µg/µm2; %wp) in a given sample. Our %wp metric has the potential for use as a proxy for lysocline variability in addition to assessing the suitability of marine sediment samples for surface ocean reconstructions.