ON THE SENSITIVITY OF THE EOCENE OCEAN CIRCULATION TO ARCTIC FRESHWATER PULSES

The Paleocene/Eocene Thermal Maximum (PETM) corresponds to a period characterized by extreme global warming caused by a massive carbon input into the ocean and atmosphere. It occurred approximately 55 Ma in the early Cenozoic and evidence suggests an ice-free Arctic that exchanged relatively fresh water with the remainder of the global ocean. This study examines the sensitivity of deep-water formation and circulation within the global ocean to freshwater exchange from the Arctic Ocean during the Eocene. Past modeling experiments show how alterations to seaway exchanges can have dramatic effects upon sedimentation, global climate, and ocean circulation. In this study we use the Community Climate Systems Model Version 3 (CCSM-3), including a carbon cycle model, to explore the impact of freshwater exchange between the Eocene Arctic and Atlantic Oceans and the Eocene Artic and Pacific Oceans. Both are compared against a reference run with exchange between the Eocene Arctic and Indian Oceans. Model results are evaluated against core data recovered from Ocean Drilling Program (ODP) samples to examine if the model matched proxies observed for the PETM. This study gives insight into the state of seaway passages between the Artic Ocean and the remainder of the global ocean and their effect upon deep-water formation, circulation, and distribution of geochemical tracers during the PETM. As freshwater is transported to the North Pacific or Atlantic the model simulates a significant relative reduction in salinity, and thereby deep-water formation.