Deep Ocean Storage of Heat and CO 2 in the Fram Strait, Arctic Ocean During the Last Glacial Period

• Main Authors: Ezat, MM, Rasmussen, TL, Hain, MP, Greaves, M, Rae, JWB, Zamelczyk, K, Marchitto, TM, Szidat, S, Skinner, LC
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union (AGU) 2021
• Subjects: Benthic foraminiferal element; Ca; benthic foraminiferal delta O-18; climate change; the Fram Strait; the Last Glacial; the Nordic Seas; Arctic; Arctic Ocean; Tromsø; Climate change; Denmark Strait; Foraminifera*; Fram Strait; Nordic Seas; North Atlantic
• Online Access: https://www.repository.cam.ac.uk/handle/1810/326033; https://doi.org/10.17863/CAM.73490

Funder: Tromsø Research Foundation : A31720 <jats:title>Abstract</jats:title><jats:p>The Fram Strait is the only deep gateway between the Arctic Ocean and the Nordic Seas and thus is a key area to study past changes in ocean circulation and the marine carbon cycle. Here, we study deep ocean temperature, δ<jats:sup>18</jats:sup>O, carbonate chemistry (i.e., carbonate ion concentration [CO<jats:sub>3</jats:sub><jats:sup>2−</jats:sup>]), and nutrient content in the Fram Strait during the late glacial (35,000–19,000 years BP) and the Holocene based on benthic foraminiferal geochemistry and carbon cycle modeling. Our results indicate a thickening of Atlantic water penetrating into the northern Nordic Seas, forming a subsurface Atlantic intermediate water layer reaching to at least ∼2,600 m water depth during most of the late glacial period. The recirculating Atlantic layer was characterized by relatively high [CO<jats:sub>3</jats:sub><jats:sup>2−</jats:sup>] and low δ<jats:sup>13</jats:sup>C during the late glacial, and provides evidence for a Nordic Seas source to the glacial North Atlantic intermediate water flowing at 2,000–3,000 m water depth, most likely via the Denmark Strait. In addition, we discuss evidence for enhanced terrestrial carbon input to the Nordic Seas at ∼23.5 ka. Comparing our δ<jats:sup>13</jats:sup>C and qualitative [CO<jats:sub>3</jats:sub><jats:sup>2−</jats:sup>] records with results of carbon cycle box modeling suggests that the total terrestrial CO<jats:sub>2</jats:sub> release during this carbon input event was low, slow, or directly to the atmosphere.</jats:p>