Cristin-resultat-ID: 1834626
Sist endret: 29. september 2020, 09:31
Resultat
Vitenskapelig foredrag
2019

Cancellation of the precessional cycle in δ18O records during the Early Pleistocene

Bidragsytere:
  • Anne Morée
  • Tianyi Sun
  • Anaïs Bretones
  • Eivind Olavson Straume
  • Kerim Hestnes Nisancioglu og
  • Geoffrey Gebbie

Presentasjon

Navn på arrangementet: American Geophysical Union (AGU) Fall Meeting
Sted: San Francisco
Dato fra: 9. desember 2019
Dato til: 15. desember 2019

Arrangør:

Arrangørnavn: AGU

Om resultatet

Vitenskapelig foredrag
Publiseringsår: 2019

Beskrivelse Beskrivelse

Tittel

Cancellation of the precessional cycle in δ18O records during the Early Pleistocene

Sammendrag

Deep-sea δ18O records show a pronounced difference in Milankovitch periodicity between the Early and Late Pleistocene. δ18O is interpreted as a proxy for ice sheet volume and temperature, which led to the conclusion that glacial-interglacial cycles considerably changed their rhythm during the mid-Pleistocene. This transition is referred to as the mid-Pleistocene Transition (MPT). Specifically, the precessional component of the Milankovitch cycles is absent in Early Pleistocene δ18O records, despite its continuous presence in solar insolation forcing to the ice sheets. Climate feedbacks involving (sea) ice, geological processes and carbon and nutrient cycling have been proposed as causes of this marked change. We however show that the absence of an Early Pleistocene precession signal in deep-sea δ18O records could be the result of destructive interference of the precessional cycle in the interior ocean. Such cancellation is caused by the anti-phasing of the precessional cycle between the North Atlantic and Southern Ocean deep-water sources (see Figure). We explore the potential for cancellation in the transient setup of the Total Matrix Intercomparison model for a wide range of source signal strengths. Our results show that cancellation can cause the absence of the precessional signal due to cancellation in the interior South-Atlantic, Indian and Pacific basins. Cancellation is especially widespread for a relative end-member contribution typical for the Early Pleistocene. We therefore conclude that the precessional component is likely incompletely archived in Early Pleistocene δ18O records, and appears as an actual change in Milankovitch periodicity across the MPT. Proxies not susceptible to cancellation of precession (such as those currently retrieved across the MPT from Antarctica) would be able to verify to what extent deep-sea δ18O correctly represents Pleistocene climate.

Bidragsytere

Anne Lien Moree

Bidragsyterens navn vises på dette resultatet som Anne Morée
  • Tilknyttet:
    Forfatter
    ved Geofysisk institutt ved Universitetet i Bergen

Tianyi Sun

  • Tilknyttet:
    Forfatter
    ved University of Texas at Austin

Anais Magali Bretones

Bidragsyterens navn vises på dette resultatet som Anaïs Bretones
  • Tilknyttet:
    Forfatter
    ved Institutt for geovitenskap ved Universitetet i Bergen

Eivind Olavson Straume

  • Tilknyttet:
    Forfatter
    ved Senter for Jordens utvikling og dynamikk ved Universitetet i Oslo

Kerim Hestnes Nisancioglu

  • Tilknyttet:
    Forfatter
    ved Institutt for geovitenskap ved Universitetet i Bergen
1 - 5 av 6 | Neste | Siste »