Cold Water in a Warm World: Investigating the Origin of the Nordic Seas' Unique Surface Properties During MIS 11

Doherty, John M.; Thibodeau, Benoît

doi:10.3389/fmars.2018.00251

Cited by 10 publications

(10 citation statements)

References 76 publications

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“…McManus et al (1999) first showed at ODP Site 980 in the subpolar North Atlantic Ocean that significant suborbital variability over the last 500 ka occurred when ice sheets reached a critical size. This variability was later confirmed by Helmke and Bauch (2003), , and Kandiano et al (2016) for the Nordic seas and in midlatitudes of the northeast North Atlantic by Voelker et al (2010), Rodrigues et al (2011), Doherty and Thibodeau (2018), and Kandiano et al (2017). Figure 4 shows several of these proxy records for the period MIS 12 through MIS 10 (450 to 350 ka) going from north (top, panel 4a) to south (bottom, panel 4j).…”

Section: Paleoceanography and Paleoclimatologymentioning

confidence: 75%

Interglacial Paleoclimate in the Arctic

Cronin

Keller

Farmer

et al. 2019

Paleoceanog and Paleoclimatol

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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

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Section: Paleoceanography and Paleoclimatologymentioning

confidence: 75%

Interglacial Paleoclimate in the Arctic

Cronin

Keller

Farmer

et al. 2019

Paleoceanog and Paleoclimatol

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“…In addition to its user friendliness, the model allows for a mechanistic evaluation of the impact of increased freshwater input on thermohaline circulation through time, which is difficult to achieve analytically. Therefore, SAMDEC provides a robust framework to test the response of thermohaline circulation between the North Atlantic and the Arctic Ocean to changes in freshwater forcing which has possibly played a role in observed temperature and/or salinity gradients in the past (e.g., Bauch et al, 2012;Doherty and Thibodeau, 2018;Kandiano et al, 2016;Thibodeau et al, 2017), as well as in future projections (e.g., IPCC, 2013).…”

Section: Resultsmentioning

confidence: 99%

“…The current weak state of the Atlantic meridional overturning circulation (AMOC) is an unprecedented event over the 1,500 years (Caesar et al, 2018;Rahmstorf et al, 2015;Thibodeau et al, 2018;Thornalley et al, 2018). Warming from greenhouse gases and increased high-latitude freshwater fluxes are the main potential culprits for such weakening.…”

Section: Introductionmentioning

confidence: 99%

A Stella® version of the Arctic Mediterranean Double Estuarine Circulation model: SAMDEC v1.0

Thibodeau¹,

Lambert²

2019

Preprint

Self Cite

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The Arctic Mediterranean can be described as a double estuarine circulation regime. This observed circulation feature, which connects the North Atlantic to the Arctic Ocean, is composed of two interconnected branches of circulation: an overturning circulation, where dense water formed in the Nordic Seas returns toward the Atlantic and an estuarine circulation, where the East Greenland Current exits the Arctic Mediterranean. A conceptual box model has previously built upon Henry Stommel’s original version, concluding that a double estuarine circulation is less sensitive to perturbations in northern freshwater input than an overturning circulation in isolation. This extended model exhibits a similar freshwater sensitivity to several coupled atmosphere-ocean general circulation models (AOGCMs), which require about 1 Sv of freshwater input to induce a transition to a qualitatively weakened overturning in the Atlantic Ocean. Besides the amount of freshwater that would be required to abruptly weaken the Atlantic overturning circulation, it is essential to determine over what time scale such a transition could occur. To address this temporal aspect of potential abrupt transitions in a double estuarine circulation, we built a numerical version of the box-model in Stella®. The Stella® version of the Arctic Mediterranean Double Estuarine Circulation model (SAMDEC) is thus a new and widely-available numerical box-model representing the Arctic Mediterranean Double Estuarine Circulation and is intended to provide a numerical tool to easily solve this double estuarine theoretical framework. In addition to its simplicity of use, one of the most important added values of SAMDEC is the ability to easily determine and visualise transition times between two circulation regimes at very low computing cost, making it a valuable tool for research and education. This allows for a quantitative assessment of the response of the Arctic Mediterranean circulation to variable freshwater fluxes and temperature changes over short and long time scales. To highlight the features of SAMDEC, we showcase here two freshwater flux scenarios; 1) increased freshwater input in the Nordic Seas, which is most comparable to common ‘hosing’ experiments; and 2) increased freshwater input in the Nordic Seas and the Arctic. Similar to previous experiments performed with AOGCMs, the weakening caused by realistic freshwater addition is relatively slow during the first 100 years of simulation and increases thereafter. Finally, under a realistic freshwater increase, SAMDEC indicates that 88 to 176 years are needed to achieve a 15% weakening of the overturning. Overall, SAMDEC can provide insights into the dynamic of transition between circulation regimes under changes in freshwater input for both near-future and geological timescale investigations. A light version of the model can be accessed online with any internet browser and the full model can be downloaded, modified and used on a personal computer.

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“…Hearty et al, 2007;Naish et al, 2009;Pollard and DeConto, 2009). However, Pliocene model results were shown to be highly dependent on the choice of climate and ice sheet models (de Boer et al, 2015;Dolan et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of the Antarctic ice sheets to the warming of marine isotope substage 11c

et al. 2021

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Abstract. Studying the response of the Antarctic ice sheets during periods when climate conditions were similar to the present can provide important insights into current observed changes and help identify natural drivers of ice sheet retreat. In this context, the marine isotope substage 11c (MIS11c) interglacial offers a suitable scenario, given that during its later portion orbital parameters were close to our current interglacial. Ice core data indicate that warmer-than-present temperatures lasted for longer than during other interglacials. However, the response of the Antarctic ice sheets and their contribution to sea level rise remain unclear. We explore the dynamics of the Antarctic ice sheets during this period using a numerical ice sheet model forced by MIS11c climate conditions derived from climate model outputs scaled by three glaciological and one sedimentary proxy records of ice volume. Our results indicate that the East and West Antarctic ice sheets contributed 4.0–8.2 m to the MIS11c sea level rise. In the case of a West Antarctic Ice Sheet collapse, which is the most probable scenario according to far-field sea level reconstructions, the range is reduced to 6.7–8.2 m independently of the choices of external sea level forcing and millennial-scale climate variability. Within this latter range, the main source of uncertainty arises from the sensitivity of the East Antarctic Ice Sheet to a choice of initial ice sheet configuration. We found that the warmer regional climate signal captured by Antarctic ice cores during peak MIS11c is crucial to reproduce the contribution expected from Antarctica during the recorded global sea level highstand. This climate signal translates to a modest threshold of 0.4 ∘C oceanic warming at intermediate depths, which leads to a collapse of the West Antarctic Ice Sheet if sustained for at least 4000 years.

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Cold Water in a Warm World: Investigating the Origin of the Nordic Seas' Unique Surface Properties During MIS 11

Cited by 10 publications

References 76 publications

Interglacial Paleoclimate in the Arctic

Interglacial Paleoclimate in the Arctic

A Stella® version of the Arctic Mediterranean Double Estuarine Circulation model: SAMDEC v1.0

Sensitivity of the Antarctic ice sheets to the warming of marine isotope substage 11c

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