Oceanic carbon dioxide uptake in a model of century-scale global warming

In a model of ocean-atmosphere interaction that excluded biological processes, the oceanic uptake of atmospheric carbon dioxide (CO₂) was substantially reduced in scenarios involving global warming relative to control scenarios. The primary reason for the reduced uptake was the weakening or collapse of the ocean thermohaline circulation. Such a large reduction in this ocean uptake would have a major impact on the future growth rate of atmospheric CO₂. Model simulations that include a simple representation of biological processes show a potentially large offsetting effect resulting from the downward flux of biogenic carbon. However, the magnitude of the offset is difficult to quantify with present knowledge.