Deep Ocean Storage of Heat and CO2 in the Fram Strait, Arctic Ocean During the Last Glacial Period. Issue 8 (28th July 2021)

• Record Type: Journal Article
• Authors: Ezat, Mohamed M.; Rasmussen, Tine L.; Hain, Mathis P.; Greaves, Mervyn; Rae, James W. B.; Zamelczyk, Katarzyna; Marchitto, Thomas M.; Szidat, Sönke; Skinner, Luke C.
• Is Part Of: Paleoceanography and paleoclimatology. Volume 36:Issue 8(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-07-28
• Subjects: Benthic foraminiferal element/Ca -- benthic foraminiferal δ18O -- climate change -- the Fram Strait -- the Last Glacial -- the Nordic Seas; Paleoceanography -- Periodicals; Paleoclimatology -- Periodicals; 551.46
• DOI: 10.1029/2021PA004216
• Languages: English
• ISSNs: 2572-4517

Abstract

Abstract: 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 18 O, carbonate chemistry (i.e., carbonate ion concentration [CO3 2− ]), 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 [CO3 2− ] and low δ 13 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 13 C and qualitative [CO3 2− ] records with results of carbon cycle box modeling suggests that the total terrestrial CO2 release during this carbon input event was low, slow, or directly to the atmosphere. Key Points: Ambiguous interspecies differences in benthic foraminiferal δ 18 O from the Nordic Seas for the last glacial maximum are due to bioturbation Deep ocean temperature and δ 18 O in central Fram Strait were ∼1.5°C and 1‰ higher during the last glacial maximum Intermittent Nordic Seas outflow through Denmark Strait could have been the source of glacial North Atlantic water at 2–3 km water depth