Browsing by Subject "Palaeoclimate"

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    Data Descriptor: Daily observations of stable isotope ratios of rainfall in the tropics
    (Nature Research, 2019-10-08) Munksgaard, Niels C.; Kurita, Naoyuki; Sánchez-Murillo, Ricardo; Ahmed, Nasir; Araguas, Luis; Balachew, Dagnachew L. Balachew; Bird, Michael I.; Chakraborty, Supriyo; Chinh, Nguyen Kien; Cobb, Kim M.; Ellis, Shelby A.; Esquivel-Hernández, Germain; Ganyaglo, Samuel Y.; Gao, Jing; Gastmans, Didier; Kaseke, Kudzai F.; Kebede, Seifu; Morales, Marcelo R.; Mueller, Moritz; Poh, Seng Chee; dos Santos, Vinícius; Shaoneng, He; Wang, Lixin; Yacobaccio, Hugo; Zwart, Costijn; Earth Sciences, School of Science
    We present precipitation isotope data (δ2H and δ18O values) from 19 stations across the tropics collected from 2012 to 2017 under the Coordinated Research Project F31004 sponsored by the International Atomic Energy Agency. Rainfall samples were collected daily and analysed for stable isotopic ratios of oxygen and hydrogen by participating laboratories following a common analytical framework. We also calculated daily mean stratiform rainfall area fractions around each station over an area of 5° x 5° longitude/latitude based on TRMM/GPM satellite data. Isotope time series, along with information on rainfall amount and stratiform/convective proportions provide a valuable tool for rainfall characterisation and to improve the ability of isotope-enabled Global Circulation Models to predict variability and availability of inputs to fresh water resources across the tropics.
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    Subglacial precipitates record Antarctic ice sheet response to late Pleistocene millennial climate cycles
    (Springer, 2022-09-15) Piccione, Gavin; Blackburn, Terrence; Tulaczyk, Slawek; Rasbury, E. Troy; Hain, Mathis P.; Ibarra, Daniel E.; Methner, Katharina; Tinglof, Chloe; Cheney, Brandon; Northrup, Paul; Licht, Kathy; Earth and Environmental Sciences, School of Science
    Ice cores and offshore sedimentary records demonstrate enhanced ice loss along Antarctic coastal margins during millennial-scale warm intervals within the last glacial termination. However, the distal location and short temporal coverage of these records leads to uncertainty in both the spatial footprint of ice loss, and whether millennial-scale ice response occurs outside of glacial terminations. Here we present a >100kyr archive of periodic transitions in subglacial precipitate mineralogy that are synchronous with Late Pleistocene millennial-scale climate cycles. Geochemical and geochronologic data provide evidence for opal formation during cold periods via cryoconcentration of subglacial brine, and calcite formation during warm periods through the addition of subglacial meltwater originating from the ice sheet interior. These freeze-flush cycles represent cyclic changes in subglacial hydrologic-connectivity driven by ice sheet velocity fluctuations. Our findings imply that oscillating Southern Ocean temperatures drive a dynamic response in the Antarctic ice sheet on millennial timescales, regardless of the background climate state.