North Atlantic millennial-scale climate variability 910 to 790 ka and the role of the equatorial insolation forcing

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doi: 10.1016/j.epsl.2010.02.016
Author(s): Ferretti, Patrizia; Crowhurst, Simon J.; Hall, Michael A.; Cacho, Isabel
Author Affiliation(s): Primary:
University of Cambridge, Department of Earth Sciences, Godwin Laboratory for Palaeoclimate Research, Cambridge, United Kingdom
Other:
University of Barcelona, Spain
Volume Title: Earth and Planetary Science Letters
Source: Earth and Planetary Science Letters, 293(1-2), p.28-41. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X CODEN: EPSLA2
Note: In English. Supplementary data available in online version. 73 refs.; illus., incl. sketch map
Summary: The Mid-Pleistocene transition (MPT) was the time when quasi-periodic (∼100 kyr), high-amplitude glacial variability developed in the absence of any significant change in the character of orbital forcing, leading to the establishment of the characteristic pattern of late Pleistocene climate variability. It has long been known that the interval around 900 ka stands out as a critical point of the MPT, when major glaciations started occurring most notably in the northern hemisphere. Here we examine the record of climatic conditions during this significant interval, using high-resolution stable isotope records from benthic and planktonic foraminifera from a sediment core in the North Atlantic (Integrated Ocean Drilling Program Expedition 306, Site U1313). We have considered the time interval from late in Marine Isotope Stage (MIS) 23 to MIS 20 (910 to 790 ka). Our data indicate that interglacial MIS 21 was a climatically unstable period and was broken into four interstadial periods, which have been identified and correlated across the North Atlantic region. These extra peaks tend to contradict previous studies that interpreted the MIS 21 variability as consisting essentially of a linear response to cyclical changes in orbital parameters. Cooling events in the surface record during MIS 21 were associated with low benthic carbon isotope excursions, suggesting a coupling between surface temperature changes and the strength of the Atlantic meridional overturning circulation. Time series analysis performed on the whole interval indicates that benthic and planktonic oxygen isotopes have significant concentrations of spectral power centered on periods of 10.7 kyr and 6 kyr, which is in agreement with the second and forth harmonic of precession. The excellent correspondence between the foraminifera δ18O records and insolation variations at the Equator in March and September suggests that a mechanism related to low-latitude precession variations, advected to the high latitudes by tropical convective processes, might have generated such a response. This scenario accounts for the presence of oscillations at frequencies equal to precession harmonics at Site U1313, as well as the occurrence of higher amplitude oscillations between the MIS22/21 transition and most of MIS 21, times of enhanced insolation variability.
Year of Publication: 2010
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Atlantic Ocean; Benthic taxa; Cenozoic; Climate change; Climate forcing; Crosscorrelation; Equatorial region; Expeditions 303/306; Foraminifera; Glaciation; IODP Site U1313; Insolation; Integrated Ocean Drilling Program; Invertebrata; Isotopes; MIS 20; MIS 21; MIS 22; MIS 23; Microfossils; Mid-Atlantic Ridge; Milankovitch theory; North Atlantic; Ocean circulation; Orbital forcing; Oscillations; Paleoclimatology; Periodicity; Planktonic taxa; Pleistocene; Precession; Protista; Quaternary; Stable isotopes; Statistical analysis; Time series analysis
Coordinates: N410000 N410000 W0325700 W0325700
Record ID: 2010074510
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands