41 research outputs found
Data Descriptor: A global multiproxy database for temperature reconstructions of the Common Era
Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all continental regions and major ocean basins. The records are from trees, ice, sediment, corals, speleothems, documentary evidence, and other archives. They range in length from 50 to 2000 years, with a median of 547 years, while temporal resolution ranges from biweekly to centennial. Nearly half of the proxy time series are significantly correlated with HadCRUT4.2 surface temperature over the period 1850-2014. Global temperature composites show a remarkable degree of coherence between high-and low-resolution archives, with broadly similar patterns across archive types, terrestrial versus marine locations, and screening criteria. The database is suited to investigations of global and regional temperature variability over the Common Era, and is shared in the Linked Paleo Data (LiPD) format, including serializations in Matlab, R and Python.(TABLE)Since the pioneering work of D'Arrigo and Jacoby1-3, as well as Mann et al. 4,5, temperature reconstructions of the Common Era have become a key component of climate assessments6-9. Such reconstructions depend strongly on the composition of the underlying network of climate proxies10, and it is therefore critical for the climate community to have access to a community-vetted, quality-controlled database of temperature-sensitive records stored in a self-describing format. The Past Global Changes (PAGES) 2k consortium, a self-organized, international group of experts, recently assembled such a database, and used it to reconstruct surface temperature over continental-scale regions11 (hereafter, ` PAGES2k-2013').This data descriptor presents version 2.0.0 of the PAGES2k proxy temperature database (Data Citation 1). It augments the PAGES2k-2013 collection of terrestrial records with marine records assembled by the Ocean2k working group at centennial12 and annual13 time scales. In addition to these previously published data compilations, this version includes substantially more records, extensive new metadata, and validation. Furthermore, the selection criteria for records included in this version are applied more uniformly and transparently across regions, resulting in a more cohesive data product.This data descriptor describes the contents of the database, the criteria for inclusion, and quantifies the relation of each record with instrumental temperature. In addition, the paleotemperature time series are summarized as composites to highlight the most salient decadal-to centennial-scale behaviour of the dataset and check mutual consistency between paleoclimate archives. We provide extensive Matlab code to probe the database-processing, filtering and aggregating it in various ways to investigate temperature variability over the Common Era. The unique approach to data stewardship and code-sharing employed here is designed to enable an unprecedented scale of investigation of the temperature history of the Common Era, by the scientific community and citizen-scientists alike
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Detection of El Nino and decade timescale variations of sea surface temperature from banded coral records: Implications for the carbon dioxide cycle. Proc. AGU Chapman Conference on Natural CO2 changes, Tampa, Florida, Jan. 1984
Stable oxygen isotope ratios from
annually banded corals are correlated with historical
records of sea surface temperature in
the central and eastern tropical Pacific Ocean.
E1Nino events between 1929 and 1976 are detected
using this method, but there are discrepancies
between the records of E1Ninos from
corals and those determined using historical
hydrographic and meteorologic data. The average
annual depletion of 6âąs0 during E1Nino events
is greater at the Galapagos Island sites
(0.45Ăž/oo) than at the Fanning and Canton
Island sites in the mid-Pacific (0.20-0.30Ăž/oo
and <0.2Ăž/oo, respectively). Of prime importance
is evidence of decade time scale variability of
sea surface temperature (SST) in the tropical
Pacific. In particular, annually averaged SST
appears to have been 0.5Ăž-1ĂžC higher in the
eastern tropical Pacific during the 1930's than
during subsequent years. A significant net
flux of CO2 from the surface ocean to the
atmosphere is envisioned during these periods
of higher SST
Recommended from our members
Detection of El Nino and decade timescale variations of sea surface temperature from banded coral records: Implications for the carbon dioxide cycle. Proc. AGU Chapman Conference on Natural CO2 changes, Tampa, Florida, Jan. 1984
Stable oxygen isotope ratios from
annually banded corals are correlated with historical
records of sea surface temperature in
the central and eastern tropical Pacific Ocean.
E1Nino events between 1929 and 1976 are detected
using this method, but there are discrepancies
between the records of E1Ninos from
corals and those determined using historical
hydrographic and meteorologic data. The average
annual depletion of 6âąs0 during E1Nino events
is greater at the Galapagos Island sites
(0.45Ăž/oo) than at the Fanning and Canton
Island sites in the mid-Pacific (0.20-0.30Ăž/oo
and <0.2Ăž/oo, respectively). Of prime importance
is evidence of decade time scale variability of
sea surface temperature (SST) in the tropical
Pacific. In particular, annually averaged SST
appears to have been 0.5Ăž-1ĂžC higher in the
eastern tropical Pacific during the 1930's than
during subsequent years. A significant net
flux of CO2 from the surface ocean to the
atmosphere is envisioned during these periods
of higher SST
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Sources of carbon to deep-sea coral skeletons
Radiocarbon measurements in deep-sea corals from the Little Bahama Bank were used to determine the source of carbon to the skeletal matrices. Specimens of Lophelia,
Gerardia, Paragorgia johnsoni and Corallium noibe were sectioned according to visible growth
rings and/or stem diameter. We determined that the source of carbon to the corals accreting
organic matter was primarily from surface-derived sources. Those corals that accrete a cal- cerous skeleton were found to obtain their carbon solely from dissolved inorganic carbon
(DIC) in sea water from the depth at which the corals grew. These results, in conjunction with
growth-rate studies using short-lived radioisotopes, support the use of deep-sea corals to recon- struct time histories of transient and non-transient tracers at depth in the oceans
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Seasonal cycles of manganese and cadmium in Galapagos coral
Manganese-to-calcium ratios in corals from the eastern and western Galapagos demonstrate regional differences in seasonal trace metal cycling. The variability of trace metal-to-calcium ratios within the Galapagos Islands points to their unique geographic setting as a major factor. This region is influenced by several major oceanic currents (e.g., the South Equatorial Current, the Equatorial Undercurrent, and the Panama, or El Niño, Current) and by extremely intense upwelling. Manganese-to-calcium ratios in a banded coral Pavona clavus from Isabela Island, the westernmost island in the Galapagos, have distinct seasonal cycles for the non-El Niño Southern Oscillation (ENSO) years 1946â1950, with lower ratios following intensified seasonal upwelling. Cadmium/calcium ratios show less distinct seasonal cycles. The near-moderate ENSO event in 1951 is marked by the disruption of seasonal cycles in Full-size image (<1 K) and Full-size image (<1 K) ratios. In contrast, corals from islands further east in the Galapagos (Hood Island, 1964â1973, Linn et al., 1990; San Cristobal, 1965â1979, Shen and Sanford, 1990), have stronger seasonal Full-size image (<1 K) signals, with higher ratios following seasonal upwelling, and less distinct seasonal cycles in Full-size image (<1 K) ratios one-half year out of phase with Full-size image (<1 K) variations. Average Full-size image (<1 K) ratios are lower for these corals from locations further east, indicating that Urvina Bay appears to have an additional localized source of Mn (Shen and Sanford, 1990). In general, these regional variations in seasonal trace metal cycling are consistent with coral stable isotope signals and with their geographic locations. These variations are important to consider in using coral records to reconstruct and interpret oceanographic events occurring prior to historical records