Impact of Weddell Sea shelf progradation on Antarctic bottom water formation during the Miocene

Abstract

The Weddell Sea is a main location of bottom water formation and, thus, an important component of global ocean circulation. In this study we examine the ocean and climatic responses to a shelf progradation induced by ice sheet advance and glacially transported sediments during the Miocene, using a general circulation model. Our investigations show that relative to a Miocene standard bathymetry, a farther southerly placed shelf break, as reconstructed in a state‐of‐the‐art bathymetry for the Weddell Sea, enables enhanced Antarctic Bottom Water (AABW) formation and gyre transport during the middle Miocene for both relatively high and low atmospheric CO2 concentrations. Furthermore, CO2 sensitivity experiments show that an atmospheric CO2 decline for a setup with the southerly placed shelf break of a new bathymetry has only a minor impact on AABW formation, while the standard setup shows an increase. In combination, these impacts may explain the pronounced deep water formation in the southern high latitudes from the middle Miocene to the late Miocene.

Late Cretaceous climate simulations with different CO2 levels and subarctic gateway configurations: A model‐data comparison

“…We employ an atmosphere‐ocean general circulation model (AOGCM) which was developed at the Max Planck Institute for Meteorology in Hamburg. The model has been successfully applied to test a variety of paleoclimate hypotheses, ranging from the late Paleocene/early Eocene and Oligocene climate [ Heinemann et al ., ; Walliser et al ., ], the Miocene climate [ Knorr et al ., ; Knorr and Lohmann , ; Forrest et al ., ; Stein et al ., ; Huang et al ., ; Stärz et al ., ], the Pliocene [ Stepanek and Lohmann , ] as well as glacial [ Gong et al ., ; Zhang et al ., , ; Köhler et al ., ; Abelmann et al ., ] and interglacial climates [ Wei and Lohmann , ; Wei et al ., ; Lohmann et al ., ; Pfeiffer and Lohmann , ]. In our Late Cretaceous simulations, we used the coupled ocean‐atmosphere configuration with prescribed vegetation (described below).…”

The Weddell Gyre, Southern Ocean: Present Knowledge and Future Challenges

“…For example, at its southernmost margin, just in front of today's Filchner‐Ronne ice shelf, sediments deposited since the Jurassic are up to 12 km thick (Huang et al, ; Jokat & Herter, ). Miocene continental shelf progradation, its impact on AABW formation, and the evolution to present sediment transport processes and deposits in the southeastern Weddell Sea were reconstructed by seismic‐stratigraphy and modeling (Huang et al, ). These data show that the Antarctic ice sheets were quite dynamic since at least the Mid‐Miocene.…”

Back to the Future: Using Long-Term Observational and Paleo-Proxy Reconstructions to Improve Model Projections of Antarctic Climate

“…For ice sheets, improved knowledge of bathymetry can help to reconstruct the occurrence of pinning points favoring the stability of the ice sheet and formation of ice shelves [43,61]. For the ocean, it helps to more realistically simulate regional circulations, the formation of AABW and heat exchange across the continental shelf edge (e.g., [62]). Paleo-morphological features of current bathymetry can be used to infer the type of ice sheet flow, the occurrence and pathways of release of meltwater [63], pathways of bottom water formation and feedbacks with surrounding oceanic water masses.…”