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Free keywords:
Carbon; Carbon dioxide; Carbonation; Dissolution; Global warming; Surface waters, Deep-water formation; Earth system model; Intermediate waters; Ocean biogeochemistry; Ocean stratification; Overturning circulation; Paleocene-eocene thermal maximums; PETM, Oceanography
Abstract:
The Paleocene-Eocene Thermal Maximum was a transient, carbon-induced global warming event, considered the closest analog to ongoing climate change. Impacts of a decrease in deepwater formation during the onset of the Paleocene-Eocene Thermal Maximum suggested by proxy data on the carbon cycle are not yet fully understood. Using an Earth System Model, we find that changes in overturning circulation are key to reproduce the deoxygenation and carbonate dissolution record. Weakening of the Southern Ocean deepwater formation and enhancement of ocean stratification driven by warming cause an asymmetry in carbonate dissolution between the Atlantic and Pacific basins suggested by proxy data. Reduced ventilation results in accumulation of remineralization products (CO2 and nutrients) in intermediate waters, thereby lowering O2 and increasing CO2. As a result, carbonate dissolution is triggered throughout the water column, while the ocean surface remains supersaturated. Our findings contribute to understanding of the long-term response of the carbon cycle to climate change. ©2018. The Authors.
