BIROn - Birkbeck Institutional Research Online

    Global climate stabilisation by chemical weathering during the Hirnantian glaciation

    Pogge von Strandmann, Philip A.E. and Desrochers, A. and Murphy, M. and Finlay, A. and Selby, D. and Lenton, T. (2017) Global climate stabilisation by chemical weathering during the Hirnantian glaciation. Geochemical Perspective Letters 3 (2), pp. 230-237. ISSN 2410-339X.

    [img]
    Preview
    Text
    Pogge von Strandmann 2017 Hirnantian Li + SI.pdf - Published Version of Record
    Available under License Creative Commons Attribution.

    Download (4MB) | Preview

    Abstract

    Chemical weathering of silicate rocks is a primary drawdown mechanism of atmospheric carbon dioxide. The processes that affect weathering are therefore central in controlling global climate. A temperature-controlled “weathering thermostat” has long been proposed in stabilising long-term climate, but without definitive evidence from the geologic record. Here we use lithium isotopes (δ7Li) to assess the impact of silicate weathering across a significant climate-cooling period, the end-Ordovician Hirnantian glaciation (~445 Ma). We find a positive δ7Li excursion, suggestive of a silicate weathering decline. Using a coupled lithium-carbon model, we show that initiation of the glaciation was likely caused by declining CO2 degassing, which triggered abrupt global cooling, and much lower weathering rates. This lower CO2 drawdown during the glaciation allowed climatic recovery and deglaciation. Combined, the data and model provide support from the geological record for the operation of the weathering thermostat.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): silicate weathering, weathering thermostat, mass extinction, Ordovician, carbon cycle
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    Depositing User: Philip Pogge von strandmann
    Date Deposited: 19 Jun 2017 15:18
    Last Modified: 27 Jul 2019 21:29
    URI: http://eprints.bbk.ac.uk/id/eprint/18990

    Statistics

    Downloads
    Activity Overview
    138Downloads
    119Hits

    Additional statistics are available via IRStats2.

    Archive Staff Only (login required)

    Edit/View Item Edit/View Item