The last five glacial‐interglacial transitions: A high‐resolution 450,000‐year record from the subantarctic Atlantic

Abstract

[1] A submillennial resolution, radiolarian-based record of summer sea surface temperature (SST) documents the last five glacial to interglacial transitions at the subtropical front, southern Atlantic Ocean. Rapid fluctuations occur both during glacial and interglacial intervals, and sudden cooling episodes at glacial terminations are recurrent. Surface hydrography and global ice volume proxies from the same core suggest that summer SST increases prior to terminations lead global ice-volume decreases by 4.7 ± 3.7 ka (in the eccentricity band), 6.9 ± 2.5 ka (obliquity), and 2.7 ± 0.9 ka (precession). A comparison between SST and benthic d 13 C suggests a decoupling in the response of northern subantarctic surface, intermediate, and deep water masses to cold events in the North Atlantic. The matching features between our SST record and the one from core MD97-2120 (southwest Pacific) suggests that the super-regional expression of climatic events is substantially affected by a single climatic agent: the Subtropical Front, amplifier and vehicle for the transfer of climatic change. The direct correlation between warmer DT site at Vostok and warmer SST at ODP Site 1089 suggests that warmer oceanic/ atmospheric conditions imply a more southward placed frontal system, weaker gradients, and therefore stronger Agulhas input to the Atlantic Ocean.Citation: Cortese, G., A. Abelmann, and R. Gersonde (2007), The last five glacial-interglacial transitions: A high-resolution 450,000-year record from the subantarctic Atlantic, Paleoceanography, 22, PA4203,

Interhemispheric coupling, the West Antarctic Ice Sheet and warm Antarctic interglacials

“…A hosing flux of 0.1 Sv into the Southern Ocean applied for 1000 years (equivalent in magnitude to the complete loss of WAIS ice in 650 years) simulated Antarctic SAT cooling of ∼0.5 • C in the preindustrial climate state (Swingedouw et al, 2009). Transient Southern Ocean cooling events of this magnitude would not be inconsistent with "cooling rebounds" of up to ∼1 • C that have been observed in several high southern latitude locations during the later stages of each of the last five terminations (Cortese et al, 2007, and references therein).…”

“…Observational evidence for WPTs in Antarctica is not confined to ice-core records. Notably, a 430 kyr Southern Ocean SST reconstruction (Cortese et al, 2007) at ODP site 1089 (41 • S 10 • E) displayed transient warming during each of these terminations, lasting for 5-9 kyrs and with temperatures 2 to 3.5 • C warmer than present (in addition to a ∼2 • C transient warming lasting for 7 kyr during TI). GCM simulations have thus far failed to produce a warmer Antarctica during the last interglacial (e.g.…”

Abrupt change of Antarctic moisture origin at the end of Termination II

“…The abrupt AXR event cannot be explained by the progressive increase in south Indian ocean sea surface temperature (SST) documented in marine records (21)(22)(23), and must therefore reflect an abrupt geographical shift of the moisture origin toward warmer evaporation conditions linked with changes in atmospheric water vapor transport in the south Indian Ocean sector. This AXR event is evidence for a centennial shift in atmospheric moisture transport to Antarctica.…”

“…The first warming phase (δD increase) is paralleled by a slow deuterium excess rise. The Antarctic warming is mimicked by parallel Austral ocean warming at mid and high latitudes (21)(22)(23). This small deuterium excess rise is interpreted as resulting from the compensation between a warming southern Indian Ocean (inducing higher excess) and an increasing contribution of high latitudes to EDC moisture (inducing a lower excess).…”

The PMIP4 contribution to CMIP6 – Part 2: Two interglacials, scientific objective and experimental design for Holocene and Last Interglacial simulations

“…The major limitation in using the data syntheses by Turney and Jones (2010) and McKay et al (2011) for analysis of the lig127k simulations and associated sensitivity experiments is that they are compilations of information about the maximum warmth during the LIG. Given that warming was not synchronous globally (Bauch and Erlenkeuser, 2008;Cortese et al, 2007;NEEM Community Members, 2013;Govin et al, 2012;Masson-Delmotte et al, 2010;Mor et al, 2012;Winsor et al, 2012), these syntheses do not represent a specific time slice. A more recent compilation by Capron et al (2014) has used harmonized chronologies for ice and marine records to produce records of the change in high-latitude temperature compared to present for four 2000-year long time slabs, and this approach has been expanded to include the fifth time slab (128-126 ka) for comparison with the lig127k simulation (Capron et al, 2017).…”