Could deep subantarctic convection feed the world deep basins during the Last Glacial Maximum?

Abstract

Simple box model calculations are used to simulate the oceanic circulation during the last glacial maximum (LGM). These experiments show that the main features of the δ13C and Δ14C distributions and of the lysocline depth may be explained by a circulation pattern very different from the modem one. Intermediate and upper deep waters were produced in the North Atlantic Ocean, whereas deep waters of Subantarctic Mode type, forming at the northern edge of the Subantarctic convergence, invaded the main oceanic basins. The Southern Ocean, mainly self ventilated, had a reduced deep component that flew southward along the East Pacific Ridge and the Australian west cost. The thermodynamic fractionation that occurs during air‐sea exchange has only contributed slightly to the glacial deep δ13C distribution through surface water temperature variations.

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

“…11B). Oceanic inorganic carbon is becoming 0.4 heavier during the G/IG transition, which is in good agreement with both modelling studies and data constraints (Curry et al, 1988;Duplessy et al, 1988;Michel et al, 1995). It should be noted that 85% of this calculated oceanic change in δ 13 C can be explained by the increase in the terrestrial carbon stock and only the missing fraction of 15% by changes in the abundance of the two photosynthetic pathways.…”

Northern source for Deglacial and Holocene deepwater composition changes in the Eastern North Atlantic Basin

“…Changes in the AMOC strength are not only related to changes in northward heat transport but also with severe changes in the Atlantic deepwater distribution (e.g. Gherardi et al, 2009;Labeyrie et al, 2005;Michel et al, 1995;Oppo et al, 2003;Sarnthein et al, 1994;Thornalley et al, 2010;Waelbroeck et al, 2011). As the deep ocean may act as a trap for carbon during glacial periods, the reconstruction of deglacial changes in this system are of major interest in order to understand feedback mech- (Adkins, 2013;and citations therein).…”

Characteristics of the deep ocean carbon system during the past 150,000 years: ΣCO 2 distributions, deep water flow patterns, and abrupt climate change

“…Other sources of AABW may replace the Weddell Sea; the Ross Sea and Southern Indian Ocean are possible replacements. Michel et al (34) and Rosenthal (23) have suggested that bottom water formation may occur in the Indian Ocean sector, although they envision quite different initial properties. Michel et al argue for formation of high-⌺CO 2 bottom water (based on very light LGM foraminiferal ␦ 13 C observed in the Indian sector), whereas Rosenthal argues for nutrientdepleted deep water formation (based on Cd evidence).…”