Research Communication: An International Tree-Ring Isotope Data Bank- A Proposed Repository For Tree-Ring Isotopic Data

The International Tree-Ring Data Bank (ITRDB) is an invaluable resource, providing access to a massive and growing cache of tree-ring data. Oxygen, carbon, nitrogen and hydrogen isotope treering studies, which have provided valuable climatic and ecological information, have proliferated for decades so an ITRDB expansion to include isotopic data would likewise benefit the scientific community. An international tree-ring isotope databank (ITRIDB) would: (1) allow development of transfer functions from extended isotopic data sets, (2) provide abundant tree-ring isotopic data for meta-analysis, and (3) encourage isotopic network studies. A Europe network already exists, but the international data bank proposed here would constitute a de facto global network. Associated information to be incorporated into the database includes not only the customary ITRDB entries, but also elements peculiar to isotope chronologies. As with the current ITRDB, submission of data would be voluntary and as such it will be crucial to have the support of the tree-ring isotope community to contribute existing and forthcoming isotope series. The plan is to institute this isotope database in 2010, administered by the National Climatic Data Center.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]

Comment on “Non-Mineralized Fossil Wood” by George E. Mustoe (Geosciences, 2018)

We were pleased to see the summary article in Geosciences on fossil wood by George E. [...

Seasonal patterns of riverine carbon sources and export in NW Greenland

Abstract Glacial runoff exports large amounts of carbon (C) to the oceans, but major uncertainty remains regarding sources, seasonality, and magnitude. We apportioned C exported by five rivers from glacial and periglacial sources in northwest Greenland by monitoring discharge, water sources (δ18O), concentration and composition of dissolved organic carbon (DOC), and ages (14C) of DOC and particulate organic C over three summers (2010–2012). We found that particulate organic C (F = 1.0366–0.2506) was generally older than DOC in glacial sourced rivers and likely sourced from the physical erosion of aged C pools. Most exported DOC showed strong seasonal variations in sources and discharge. In summer, mean DOC ages ranged from modern to 4,750 cal years BP (F = 1.0022–0.6291); however, the annual C flux from glacially sourced rivers was dominated by young, plant‐derived DOC (F = 0.9667–1.002) exported during the spring freshet. The most aged DOC (F = 0.6891–0.8297) was exported in middle to late summer at lower concentrations and was glacial in origin. Scaled to the whole of Greenland using model‐estimated runoff, we estimate a total riverine DOC flux of 0.29% to 0.45% ± 20% Tg C/year. Our flux results indicate that the highest C fluxes occur during the time of year when the majority of C is modern in age. However, higher melt rates from the Greenland ice sheet and longer growing seasons could result in increasing amounts of ancient C from the Greenland ice sheet and from the periglacial landscape to the ocean

Pristine Early Eocene Wood Buried Deeply in Kimberlite from Northern Canada

We report exceptional preservation of fossil wood buried deeply in a kimberlite pipe that intruded northwestern Canada's Slave Province 53.3±0.6 million years ago (Ma), revealed during excavation of diamond source rock. The wood originated from forest surrounding the eruption zone and collapsed into the diatreme before resettling in volcaniclastic kimberlite to depths >300 m, where it was mummified in a sterile environment. Anatomy of the unpermineralized wood permits conclusive identification to the genus Metasequoia (Cupressaceae). The wood yields genuine cellulose and occluded amber, both of which have been characterized spectroscopically and isotopically. From cellulose δ(18)O and δ(2)H measurements, we infer that Early Eocene paleoclimates in the western Canadian subarctic were 12-17°C warmer and four times wetter than present. Canadian kimberlites offer Lagerstätte-quality preservation of wood from a region with limited alternate sources of paleobotanical information

Estimates of Arctic land surface temperatures during the early Pliocene from two novel proxies

During the Pliocene (2.6 to 5 Ma ago) atmospheric CO_2 levels have been estimated as similar to or slightly above present levels (Tripati et al., 2009; Pagani et al., 2010), and yet Earth's climate was considerably different. Recent evidence suggests that although global temperatures were 2–3 °C warmer than pre-industrial, Arctic warming may have been amplified during the Pliocene. Thus precise temperature records of this interval are required to assess the sensitivity of Earth's climate to persistent levels of CO_2 between 365 and 415 ppm.We present records of two independent proxies for terrestrial growing-season temperatures at the Early Pliocene Beaver Pond site on Ellesmere Island. δ^(18)O values of cellulose from well-preserved peat constrain the δ^(18)O values of meteoric water to − 20.7 ± 0.3‰, which we combined with δ^(18)Ovalues of aragonitic freshwater molluscs found within the peat in order to calculate mollusc growth temperatures. This approach results in an average growing-season temperature of 14.2 ± 1.3 °C. Temperatures were independently derived by applying carbonate ‘clumped isotope’ thermometry to mollusc shells from the same site, indicating an average growing-season temperature of 10.2 ± 1.4 °C. A one-way ANOVA indicates that the differences between the two techniques are not significant as the difference in mean temperatures between both methods is no different than the difference between individual shells using a single technique. Both techniques indicate temperatures ~ 11–16 °C warmer than present (May–Sept temperature = − 1.6 ± 1.3 °C) and represent the first thermodynamic proxy results for Early Pliocene Ellesmere Island

Mean monthly δ¹⁸O and δ²H of precipitation at Yellowknife (Station 7193401, 62.28°N, 114.27°W, 205 m, [41]), shown in relation to inferred values of environmental waters accessed by Panda <i>Metasequoia</i>.

<p>A. Monthly values for the five-year measurement period (1989–1993) depict a local meteoric water line (LMWL) that deviates only slightly from the Global Meteoric Water Line (GMWL). The Panda cellulose isotopic values, once converted to the composition of environmental water (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0045537#pone-0045537-t001" target="_blank">Table 1</a>), plot on the LMWL. B. Magnification of the shaded grey in A, showing mean monthly isotopic values for months between May and September, corresponding mean monthly temperatures for the observation period (<i>n</i> = 5), and the mean value derived from Panda wood cellulose (<i>n</i> = 4). C. Temperature dependency of modern precipitation δ²H at Yellowknife and the inferred range of values obtained from Panda cellulose, with extrapolated temperature estimates (dashed vertical line). D. As for C, but for precipitation δ¹⁸O.</p

Study site and fossil wood from the Panda kimberlite pipe.

<p>A. Location of the Ekati diamond mine. B. Situation of the Panda kimberlite in relation to other pipes that comprise the property. C. Morphology of the Panda kimberlite pipe <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0045537#pone.0045537-Nowicki1" target="_blank">[8]</a> and occurrence of wood. D. Fossil wood encrusted in olivine-rich volcaniclastic kimberlite. E. Photograph of the specimen characterized in this study. The wood was split when removed from the ore, revealing a sliver of opaque amber (9.5 cm long by 0.5 cm wide) in the xylem. F. RLS in transmitted light showing uniseriate and biseriate bordered pits and cross-fields. G. TLS showing rays stacked 3–26 cells high. H. SEM (TS) of ring boundary with earlywood (left) and latewood (right). I. Close-up of tracheids in TS and calcite crystals within cells (arrows). J. Cross-section of ray with cross-field pits. K and L. Close-ups of cross-field pits. M. TLS close-up of rays. N. Radial longitudinal section showing four contiguous rows of ray parenchyma cells with smooth end walls and no separation between the individual rows of cells.</p