In:
Climate of the Past, Copernicus GmbH, Vol. 16, No. 3 ( 2020-05-19), p. 867-883
Abstract:
Abstract. Understanding the ocean circulation changes associated
with abrupt climate events is key to better assessing climate variability and
understanding its different natural modes. Sedimentary Pa∕Th, benthic δ13C and Δ14C are common proxies used to reconstruct past
circulation flow rate and ventilation. To overcome the limitations of each
proxy taken separately, a better approach is to produce multiproxy
measurements on a single sediment core. Yet, different proxies can provide
conflicting information about past ocean circulation. Thus, modelling them
in a consistent physical framework has become necessary to assess the
geographical pattern and the timing and sequence of the multiproxy response to
abrupt circulation changes. We have implemented a representation of the 231Pa and 230Th
tracers into the model of intermediate complexity iLOVECLIM, which already
included δ13C and Δ14C. We have further evaluated
the response of these three ocean circulation proxies to a classical abrupt
circulation reduction obtained by freshwater addition in the Nordic Seas
under preindustrial boundary conditions. The proxy response is shown to
cluster in modes that resemble the modern Atlantic water masses. The
clearest and most coherent response is obtained in the deep
(〉 2000 m) northwest Atlantic, where δ13C and Δ14C
significantly decrease, while Pa∕Th increases. This is consistent with
observational data across millennial-scale events of the last glacial.
Interestingly, while in marine records, except in rare instances, the phase
relationship between these proxies remains unclear due to large dating
uncertainties, in the model the bottom water carbon isotope (δ13C and Δ14C) response lags behind the sedimentary Pa∕Th
response by a few hundred years.
Type of Medium:
Online Resource
ISSN:
1814-9332
DOI:
10.5194/cp-16-867-2020
DOI:
10.5194/cp-16-867-2020-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2020
detail.hit.zdb_id:
2217985-9
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