Geological and Atmospheric Sciences Publications Geological and Atmospheric Sciences 9-1-2016 Bering Sea surface water conditions during Marine Isotope Stages 12 to 10 at Navarin Canyon (IODP Site U1345) Beth E. Caissie Iowa State University, [email protected] Julie Brigham-Grette University of Massachusetts Amherst Mea S. Cook Williams College Elena Colmenero-Hidalgo Universidad de León Follow this and additional works at: https://lib.dr.iastate.edu/ge_at_pubs Part of the Climate Commons, and the Glaciology Commons The ompc lete bibliographic information for this item can be found at https://lib.dr.iastate.edu/ ge_at_pubs/132. For information on how to cite this item, please visit http://lib.dr.iastate.edu/ howtocite.html. This Article is brought to you for free and open access by the Geological and Atmospheric Sciences at Iowa State University Digital Repository. It has been accepted for inclusion in Geological and Atmospheric Sciences Publications by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Bering Sea surface water conditions during Marine Isotope Stages 12 to 10 at Navarin Canyon (IODP Site U1345) Abstract Records of past warm periods are essential for understanding interglacial climate system dynamics. Marine Isotope Stage 11 occurred from 425 to 394 ka, when global ice volume was the lowest, sea level was the highest, and terrestrial temperatures were the warmest of the last 500 kyr. Because of its extreme character, this interval has been considered an analog for the next century of climate change. The Bering Sea is ideally situated to record how opening or closing of the Pacific–Arctic Ocean gateway (Bering Strait) impacted primary productivity, sea ice, and sediment transport in the past; however, little is known about this region prior to 125 ka. IODP Expedition 323 to the Bering Sea offered the unparalleled opportunity to look in detail at time periods older than had been previously retrieved using gravity and piston cores. Here we present a multi-proxy record for Marine Isotope Stages 12 to 10 from Site U1345, located near the continental shelf- slope break. MIS 11 is bracketed by highly productive laminated intervals that may have been triggered by flooding of the Beringian shelf. Although sea ice is reduced during the early MIS 11 laminations, it remains present at the site throughout both glacials and MIS 11. High summer insolation is associated with higher productivity but colder sea surface temperatures, which implies that productivity was likely driven by increased upwelling. Multiple examples of Pacific–Atlantic teleconnections are presented including laminations deposited at the end of MIS 11 in synchrony with millennial-scale expansions in sea ice in the Bering Sea and stadial events seen in the North Atlantic. When global eustatic sea level was at its peak, a series of anomalous conditions are seen at U1345. We examine whether this is evidence for a reversal of Bering Strait throughflow, an advance of Beringian tidewater glaciers, or a turbidite. Disciplines Climate | Earth Sciences | Glaciology Comments This article is published as Caissie, Beth E., Julie Brigham-Grette, Mea S. Cook, and Elena Colmenero- Hidalgo. "Bering Sea surface water conditions during Marine Isotope Stages 12 to 10 at Navarin Canyon (IODP Site U1345)." Climate of the Past 12, no. 9 (2016): 1739. doi:10.5194/cp-12-1739-2016. Posted with permission. Creative Commons License This work is licensed under a Creative Commons Attribution 3.0 License. This article is available at Iowa State University Digital Repository: https://lib.dr.iastate.edu/ge_at_pubs/132 Clim. Past, 12, 1739–1763, 2016 www.clim-past.net/12/1739/2016/ doi:10.5194/cp-12-1739-2016 © Author(s) 2016. CC Attribution 3.0 License. Bering Sea surface water conditions during Marine Isotope Stages 12 to 10 at Navarin Canyon (IODP Site U1345) Beth E. Caissie1, Julie Brigham-Grette2, Mea S. Cook3, and Elena Colmenero-Hidalgo4 1Iowa State University, Ames, Iowa, USA 2University of Massachusetts Amherst, Amherst, Massachusetts, USA 3Williams College, Williamstown, Massachusetts, USA 4Universidad de León, León, Spain Correspondence to: Beth E. Caissie ([email protected]) Received: 8 December 2015 – Published in Clim. Past Discuss.: 19 January 2016 Revised: 4 July 2016 – Accepted: 31 July 2016 – Published: 1 September 2016 Abstract. Records of past warm periods are essential for ine whether this is evidence for a reversal of Bering Strait understanding interglacial climate system dynamics. Marine throughflow, an advance of Beringian tidewater glaciers, or a Isotope Stage 11 occurred from 425 to 394 ka, when global turbidite. ice volume was the lowest, sea level was the highest, and terrestrial temperatures were the warmest of the last 500 kyr. Because of its extreme character, this interval has been con- 1 Introduction sidered an analog for the next century of climate change. The Bering Sea is ideally situated to record how opening or clos- Predictions and modeling of future climate change require ing of the Pacific–Arctic Ocean gateway (Bering Strait) im- a detailed understanding of how the climate system works. pacted primary productivity, sea ice, and sediment transport Reconstructions of previous warm intervals shed light on in- in the past; however, little is known about this region prior terhemispheric teleconnections. The most recent interglacial to 125 ka. IODP Expedition 323 to the Bering Sea offered period with orbital conditions similar to today was approxi- the unparalleled opportunity to look in detail at time peri- mately 400 ka, during the extremely long interglacial known ods older than had been previously retrieved using gravity as Marine Isotope Stage (MIS) 11. CO2 concentration av- and piston cores. Here we present a multi-proxy record for eraged approximately 275 ppm, which is similar to pre- Marine Isotope Stages 12 to 10 from Site U1345, located industrial levels (EPICA Community Members, 2004). The near the continental shelf-slope break. MIS 11 is bracketed transition from MIS 12 into MIS 11 has been compared to the by highly productive laminated intervals that may have been last deglaciation (Dickson et al., 2009), and extreme warmth triggered by flooding of the Beringian shelf. Although sea ice during MIS 11 has been considered an analog for future is reduced during the early MIS 11 laminations, it remains warmth (Droxler et al., 2003; Loutre and Berger, 2003), al- present at the site throughout both glacials and MIS 11. though the natural course of interglacial warmth today has High summer insolation is associated with higher produc- been disrupted by anthropogenic forcing (IPCC, 2013). tivity but colder sea surface temperatures, which implies that Despite the work done to characterize the warmth of productivity was likely driven by increased upwelling. Mul- MIS 11 in the terrestrial realm (Candy et al., 2014; Melles et tiple examples of Pacific–Atlantic teleconnections are pre- al., 2012; Prokopenko et al., 2010), as well as the North At- sented including laminations deposited at the end of MIS 11 lantic (Bauch et al., 2000; Chaisson et al., 2002; Dickson et in synchrony with millennial-scale expansions in sea ice in al., 2009; Milker et al., 2013; Poli et al., 2010), little is known the Bering Sea and stadial events seen in the North At- about this interval from the North Pacific and Bering Sea lantic. When global eustatic sea level was at its peak, a se- region (Candy et al., 2014). Modeling studies describe sev- ries of anomalous conditions are seen at U1345. We exam- eral mechanisms for linking the Atlantic and Pacific through oceanic heat transport on glacial–interglacial timescales (De- Published by Copernicus Publications on behalf of the European Geosciences Union. 1740 B. E. Caissie et al.: Bering Sea surface water conditions 160° E 180° 160° W 140° W 2 Background 70° N East Siberian Sea 2.1 Global and Beringian sea level during MIS 11 Beaufort Sea n The maximum height of sea level during MIS 11 is an open oastal plai c c Chukchi Sea ti rc question with estimates ranging from 6 to 13 m above present A sea level (a.p.s.l.) (Dutton et al., 2015) to 0 m a.p.s.l. (Rohling Lake Kotzebue et al., 2010; Rohling et al., 2014). The discrepancy may El’gygytgyn stem from large differences between global eustatic (Bowen, BS Nome GA 2010) or ice-volume averages (McManus et al., 2003) and re- AS SLI 60° N gional geomorphological or micropaleontological evidence N (van Hengstum et al., 2009). Regional isostatic adjustment P U1345 BSC due to glacial loading and unloading is now known to be KC B significant, and regional highstands may record higher than U1343 Bering Sea expected sea levels if glacial isostasy and dynamic topogra- phy have not been accounted for, even in places that were U1341 U1340 m never glaciated (PAGES Past Interglacials Working Group, ANS rea n St ska 2016; Raymo and Mitrovica, 2012; Raymo et al., 2011). 50° N ODP 884 Ala For example, Raymo and Mitrovica (2012) suggest eustatic sea level during MIS 11 was 6–13 m a.p.s.l. globally and near 5 m a.p.s.l. locally in Beringia, yet MIS 11 shorelines Figure 1. Map of Beringia with locations of cores mentioned in are at C22 m today in northwestern Alaska (Kaufman and the text (U1345 (red dot), and U1340, U1341, U1343, and ODP Site 884 (grey dots)). Locations of place names from the text are Brigham-Grette, 1993) due to these complex geophysics. labeled: Aleutian North Slope Current (ANS), Anadyr Strait (AS), Regardless of the ultimate height of sea level, the transition Bristol Bay (B), Bering Strait (BS), Bering Slope Current (BSC), from MIS 12 to MIS 11 records the greatest change in sea Gulf of Anadyr (GA), Kamchatka Current (KC), Navarin Canyon level of the last 500 ka (Rohling et al., 2014); sea level rose (N), Pribilof Islands (P), and St.