Phase relationship and surface water mass change in the Northeast Atlantic during Marine Isotope Stage 11 (MIS 11)

Abstract

Planktic foraminiferal census data, faunal sea surface temperatures (SSTs) and oxygen isotopic and lithic records from a site in the northeast Atlantic were analyzed to study the interglacial dynamics of Marine Isotope Stage (MIS) 11, a period thought to closely resemble the Holocene on the basis of orbital forcing. Interglacial conditions during MIS 11 persisted for approximately 26 ka. After the main deglacial meltwater processes ceased, a 10- to 12-ka-long transitional period marked by significant water mass circulation changes occurred before surface waters finally reached their thermal maximum. This SST peak occurred between 400 and 397 ka, inferred from the abundance of the most thermophilic foraminiferal species and was coincident with lowest sea level according to benthic isotope values. The ensuing stepwise SST decrease characterizes the overall climate deterioration preceding the increase in global ice volume by ∼ 3 ka. This cooling trend was followed by a more pronounced cold event that began at 388 ka, and that terminated in the recurrence of icebergs at the site around 382 ka. Because the water mass configuration of early MIS 11 evolved quite differently from that of the early Holocene, there is little evidence that MIS 11 can serve as an appropriate analogue for a future Holocene climate, despite the similarity in some orbital parameters.