Deep ocean storage of heat and CO2 in the Fram Strait, Arctic Ocean during the last glacial period

Mohamed M. Ezat, Tine L. Rasmussen, Mathis P. Hain, Mervyn Greaves, James W. B. Rae, Katarzyna Zamelczyk, Thomas M. Marchitto, Sönke Szidat, Luke C. Skinner

Research output: Contribution to journalArticlepeer-review


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, δ18O, carbonate chemistry (i.e., carbonate ion concentration, [CO32-]), 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 modelling. 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 ~2600 m water depth during most of the late glacial period. The recirculating Atlantic layer was characterized by relatively high [CO32-] and low δ13C during the late glacial, and provides evidence for a Nordic Seas source to the glacial North Atlantic intermediate water flowing at 2000-3000 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 δ13C and qualitative [CO32-] records with results of carbon cycle box modelling suggests that the total terrestrial CO2 release during this carbon input event was low, slow, or directly to the atmosphere.
Original languageEnglish
Article numbere2021PA004216
Number of pages13
JournalPaleoceanography and Paleoclimatology
Issue number8
Publication statusPublished - 28 Jul 2021


  • The Nordic Seas
  • The Fram Strait
  • The last glacial
  • Climate change
  • Benthic foraminiferal δ18O
  • Benthic foraminiferal element/Ca


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