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Abstract
This dissertation consists of four independent but complimentary studies. The four chapters that follow the introduction are related by a desire to understand the mechanisms underlying the global ocean carbon sink, the implications of these mechanisms for the present and future carbon budget, and the relevance of these mechanisms to the development of effective climate policy assessments. In Chapter 2, we perform a series of parameter sensitivity studies in an ocean general circulation model (OGCM) to show that the oceanic light-water volume and the strength of diapycnal mixing in the pycnocline jointly control the magnitude of the global ocean carbon sink, while the magnitude of the wind-generated surface transport out of the Southern Ocean controls the regional distribution of this uptake. In Chapter 3, we perform a similar sensitivity analysis in the same OGCM to explore the mechanisms controlling the storage of deliberately injected carbon. We show that, while the retention efficiency of deep injection would be high enough to partially mitigate the near-term concentration peak, several unresolved issues related to impacts are likely to limit the widespread deployment of this technology. In Chapter 4, we examine the implications of the oceanic uptake response for the goal of stabilizing future atmospheric carbon concentrations. We find that a decline in emissions of 1% yr -1 beginning today would place the peak atmospheric concentration near 475 ppm and that, when mitigation is postponed, options disappear, on average, at the formidable rate of ∼9 ppm yr-1, meaning that delays of more than a decade will likely preclude stabilization below a pre-industrial doubling unless future developments in technology increase the rate at which emissions can be reduced. In Chapter 5, we consider the political barrier to action in greater detail and suggest that participation and compliance in an international climate agreement are likely to be greatest when care is taken to set targets that properly balance equity and free-riding concerns. We conclude in Chapter 6 by suggesting some ideas for future work that we hope will further constrain the mechanisms governing the ocean carbon sink.
