Interglacial Paleoclimate in the Arctic

Abstract

Marine Isotope Stage 11 from~424 to 374 ka experienced peak interglacial warmth and highest global sea level~410-400 ka. MIS 11 has received extensive study on the causes of its long duration and warmer than Holocene climate, which is anomalous in the last half million years. However, a major geographic gap in MIS 11 proxy records exists in the Arctic Ocean where fragmentary evidence exists for a seasonally sea ice-free summers and high sea-surface temperatures (SST;~8-10°C near the Mendeleev Ridge). We investigated MIS 11 in the western and central Arctic Ocean using 12 piston cores and several shorter cores using proxies for surface productivity (microfossil density), bottom water temperature (magnesium/calcium ratios), the proportion of Arctic Ocean Deep Water versus Arctic Intermediate Water (key ostracode species), sea ice (epipelagic sea ice dwelling ostracode abundance), and SST (planktic foraminifers). We produced a new benthic foraminiferal δ 18 O curve, which signifies changes in global ice volume, Arctic Ocean bottom temperature, and perhaps local oceanographic changes. Results indicate that peak warmth occurred in the Amerasian Basin during the middle of MIS 11 roughly from 410 to 400 ka. SST were as high as 8-10°C for peak interglacial warmth, and sea ice was absent in summers. Evidence also exists for abrupt suborbital events punctuating the MIS 12-MIS 11-MIS 10 interval. These fluctuations in productivity, bottom water temperature, and deep and intermediate water masses (Arctic Ocean Deep Water and Arctic Intermediate Water) may represent Heinrich-like events possibly involving extensive ice shelves extending off Laurentide and Fennoscandian Ice Sheets bordering the Arctic. Key Points:• The Arctic Ocean experienced warm sea-surface temperatures and seasonally sea ice-free conditions during interglacial Marine Isotope Stage 11 • Peak warmth and minimal sea ice occurred during the middle to late part of the interglacial followed by increased land ice and ice shelves • Heinrich-like events occurred in the Arctic during the MIS 12-MIS 11 transition (Termination V) and during the MIS 11-MIS 10 transition Supporting Information:• Supporting Information S1• Data Set S1

A multi-proxy reconstruction of sea ice extent and primary productivity during Marine Isotope Stage 11 in the Bering Sea

“…12. This contrasts with records from the Arctic Ocean, which indicate high SSTs (~8-10 °C near the Mendeleev Ridge) between 410 and 400 ka (Cronin et al, 2019). There is evidence that tidewater glaciers in Beringia advanced whilst eustatic sea level was still high, an example of the 'out-of-phase glaciations' observed during interglacial periods in this region.…”

“…The transition from MIS 12 to 11 (Termination V) has been compared to the last deglaciation (Dickson et al, 2009), and MIS 11 is considered a partial analogue for current and future warming (Droxler and Farrell, 2000;Masson-Delmotte et al, 2006;, although it is important to recognize that the natural course of Holocene warming has been disrupted by anthropogenic activity Palumbo et al, 2019;Cronin et al, 2019).…”

“…MIS 11 is further characterized by increased carbonate production at high latitudes, massive expansion of coral reefs, and strong thermohaline circulation (Droxler & Farrell, 2000). During MIS 11c, Antarctica experienced temperatures 2°C warmer than today (Jouzel et al, 2007), the Arctic Ocean was seasonally ice-free (Cronin et al, 2019), boreal forest extended across Greenland, which may have been largely ice-free ) and large lakes in Siberia were anomalously productive .…”

“…Although the natural course of Holocene warming has been disrupted by anthropogenic activity, such that past interglacials cannot be used as straightforward analogs for the present climate, several interglacials of the past 800 ka warrant further study as partial analogs for the evolution of Holocene climate (Yin & Berger, 2015;Past Interglacials Working Group of PAGES, 2016). These include the Marine Isotope Substages 5e (Kukla et al, 1997), 9e , 11c McManus et al, 2003;Yin & Berger, 2015;Cronin et al, 2019) and 19c (Tzedakis et al, 2009(Tzedakis et al, , 2012Pol et al, 2010;Tzedakis, 2010;Yin & Berger, 2015;Vavrus et al, 2018).…”

Calcareous nannofossils anchor chronologies for Arctic Ocean sediments back to 500 ka

“…This implied that while it evolved globally during MIS 8, it did not migrate into the Arctic until after the penultimate glaciation (MIS 6). The late Quaternary (MIS 7 to present) chronology developed for AO96/12-1PC (Jakobsson et al, 2000(Jakobsson et al, , 2001(Jakobsson et al, , 2003 underpins much of the subsequent paleoceanographic research in the Arctic (Spielhagen et al, 2004;O'Regan et al, 2008;Polyak et al, 2013;Cronin et al, 2019). The occurrence of E. huxleyi in AO96/12-1PC has even been used to age-calibrate recognized Arctic foraminiferal assemblage zones, like the Bulimina aculeatea zone, which is now widely used to identify MIS 5 sediments from across the Arctic Ocean (Cronin et al, 2014).…”