A 0.55‐Ma paleotemperature record from the Subantarctic zone: Implications for Antarctic Circumpolar Current development

Abstract

[1] Estimates of summer sea surface temperatures (SSSTs) derived from planktic foraminiferal associations using the Modern Analog Technique and combined with isotopic analyses and determination of ice-rafted debris, mirror the Pleistocene evolution of the planktic Subantarctic surface waters in the Atlantic Ocean. The SSSTs indicate that the isotherms that define the modern polar front zone and Subantarctic front, were located at more northerly latitudes (up to 7°) during most of the investigated period, which covers the past 550 kyr. Exceptions are during climatic optima in the early Holocene, at marine isotope stages (MIS) 5.5, 7.1, 7.5, 9.3, and presumably during MIS 11.3 when SSSTs exceeded modern values by 1°-5°C. The close similarity between the SSST and the Vostok temperature indicates strong regional temperature correlation. Both records show that MIS 9.3 was the warmest period during the last 420 kyr whereas SSSTs obtained for MIS 11.3 are overestimated due to strong carbonate dissolution. Spectral analysis corroborates that the initiation of warming in southern high latitudes heralds the start of deglaciation on the Northern Hemisphere.

Simulating changes in the terrestrial biosphere during the last glacial/interglacial transition

“…Joussaume et al, 1999;Braconnot et al, 2000). Concerning southern hemispheric temperatures new data analyses give strong evidence that temperature signals deduced from Antarctic ice cores are representatitive for the pattern found in the whole Southern Ocean (Becquey and Gersonde, 2003).…”

Strong asymmetry of hemispheric climates during MIS-13 inferred from correlating China loess and Antarctica ice records

“…In contrast, summer sea surface temperature (SSST) in the sub-Antarctic Atlantic during MIS-13 was the lowest among interglacials of the past 550 ka (Becquey and Gersonde, 2003). Lower sea surface temperature was also observed in the Southeast Atlantic (McClymont et al, 2005) and Southwest Pacific (King and Howard, 2000).…”

Mid-depth South Atlantic Ocean circulation and chemical stratification during MIS-10 to 12: implications for atmospheric CO<sub>2</sub>

“…There was little IRD deposition in the North Atlantic during 410-390 ka Helmke and Bauch, 2003), which would tend to argue against changes in NADW production. In contrast, there is some evidence of a regional cooling in the Southern Ocean at 410-415 ka (Becquey and Gersonde, 2002;Cortese et al, 2007). One possibility is that the westerly winds surrounding Antarctica were displaced slightly equatorwards by this cooling, thus weakening the Antarctic Circumpolar Current and reducing the amount of deepwater upwelling (Toggweiler and Russell, 2008).…”