Carbon isotope records reveal precise timing of enhanced Southern Ocean upwelling during the last deglaciation

Giuseppe Siani (1) , Elisabeth Michel (2, 3) , Ricardo de Pol-Holz (4) , Tim Devries (5) , Frank Lamy (6) , Mélanie Carel (1) , Gulay Isguder (2, 3) , Fabien Dewilde (2, 3) , Anna Lourantou (2, 7)

1 IDES - Interactions et dynamique des environnements de surface
2 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
3 PALEOCEAN - Paléocéanographie
4 Departamento de Oceanografía [Concepción]
5 AOS - Department of Atmospheric and Oceanic Sciences [Los Angeles]
6 AWI - Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung = Alfred Wegener Institute for Polar and Marine Research = Institut Alfred-Wegener pour la recherche polaire et marine
7 LOCEAN - Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques

The Southern Ocean plays a prominent role in the Earth’s climate and carbon cycle. Changes in the Southern Ocean circulation may have regulated the release of CO₂ to the atmosphere from a deep-ocean reservoir during the last deglaciation. However, the path and exact timing of this deglacial CO₂ release are still under debate. Here we present measurements of deglacial surface reservoir ¹⁴C age changes in the eastern Pacific sector of the Southern Ocean, obtained by ¹⁴C dating of tephra deposited over the marine and terrestrial regions. These results, along with records of foraminifera benthic–planktic ¹⁴C age and δ¹³C difference, provide evidence for three periods of enhanced upwelling in the Southern Ocean during the last deglaciation, supporting the hypothesis that Southern Ocean upwelling contributed to the deglacial rise in atmospheric CO₂. These independently dated marine records suggest synchronous changes in the Southern Ocean circulation and Antarctic climate during the last deglaciation.

Domaines: Océan, Atmosphère

Giuseppe Siani, Elisabeth Michel, Ricardo de Pol-Holz, Tim Devries, Frank Lamy, et al.. Carbon isotope records reveal precise timing of enhanced Southern Ocean upwelling during the last deglaciation. Nature Communications, 2013, 118 (4), pp.2758. ⟨10.1038/ncomms3758⟩. ⟨hal-01495322⟩