A “critical” climatic evaluation of last interglacial (MIS 5e) records from the Norwegian Sea

Abstract

Sediment cores from the Norwegian Sea were studied to evaluate interglacial climate conditions of the marine isotope stage 5e (MIS 5e). Using planktic forminiferal assemblages as the core method, a detailed picture of the evolution of surface water conditions was derived. According to our age model, a step‐like deglaciation of the Saalian ice sheets is noted between ca. 135 and 124.5 Kya, but the deglaciation shows little response with regard to surface ocean warming. From then on, the rapidly increasing abundance of subpolar forminifers, concomitant with decreasing iceberg indicators, provides evidence for the development of interglacial conditions sensu stricto (5e‐ss), a period that lasted for about 9 Ky. As interpreted from the foraminiferal records, and supported by the other proxies, this interval of 5e‐ss was in two parts: showing an early warm phase, but with a fresher, i.e., lower salinity, water mass, and a subsequent cooling phase that lasted until ca. 118.5 Kya. After this time, the climatic optimum with the most intense advection of Atlantic surface water masses occurred until ca. 116 Kya. A rapid transition with two notable climatic perturbations is observed subsequently during the glacial inception. Overall, the peak warmth of the last interglacial period occurred relatively late after deglaciation, and at no time did it reach the high warmth level of the early Holocene. This finding must be considered when using the last interglacial situation as an analogue model for enhanced meridional transfer of ocean heat to the Arctic, with the prospect of a future warmer climate.

The meridional temperature gradient in the eastern North Atlantic during MIS 11 and its link to the ocean–atmosphere system

“…This assumption is corroborated by both high alkenone SST values and a low relative abundance of the Neogloboquadrina pachyderma (s) in the smaller size fraction during this time. A similar timing in sea-surface dynamics is recognized for the last interglacial (MIS 5e) when the climate optimum occurred also during the second half of MIS 5e (Bauch and Erlenkeuser, 2008;Van Nieuwenhove et al, 2011). During the present interglacial, on the contrary, the Nordic Seas experienced the SST optimum early, directly after Termination I until the Mid-Holocene (e.g., Bauch et al, 2001aBauch et al, , 2001bCalvo et al, 2002;Andersson et al, 2010).…”

Effects of orbital forcing on atmosphere and ocean heat transports in Holocene and Eemian climate simulations with a comprehensive Earth system model

“…For the Eemian simulation the comparison with proxy data is even more complicated, since the distribution of continental ice sheets in the Northern Hemisphere and their deglaciation is still under debate (e.g., Bauch and Erlenkeuser, 2008). The subsequent freshwater inputs into the ocean which alter the ocean circulation and the climatic response are not considered in this study.…”

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).…”