Role of the Ocean in climate change: the carbon story

Irina Marinov

February 08, 2012

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Abstract: Oceans modulate changes in climate via their uptake and storage of heat and carbon dioxide. The future behavior of the oceanic heat and carbon reservoirs is thus critically important for climate. A broad introduction to the changing carbon cycle will be followed by a discussion of two basic questions: (1). How will ocean carbon storage respond to ocean ventilation changes? What will be the resulting feedbacks on atmospheric pCO2? Here I show based on model simulations in an ocean general circulation model that increasing Southern Ocean winds – expected in a future warmer climate – act to decrease the carbon storage in the Southern Ocean and increase atmospheric pCO2. (2) How will ocean biology respond to changes in ocean physics induced by climate change? What will be the resulting feedback on atmospheric pCO2? I attempt to answer this question by analyzing results of 21st century climate simulations in a coupled Earth System Model. I observe different physical, biogeochemical and ecological behavior in the Northern and Southern hemispheres; this hemispheric asymmetry is driven by different shifts in midlatitude westerlies and different changes in stratification in the two hemispheres in a warmer climate.