Oceans take up 15 – 40% of anthropogenic CO, and so far roughly 40% of the carbon from fossil fuel combustion has been taken up into the oceans. Because the Revelle factor increases with increasing CO, a smaller fraction of the anthropogenic flux will be taken up by the ocean in the future.  Current annual increase in atmospheric CO is approximately 4 gigatons of carbon.  This induces climate change that drives carbon concentration and carbon-climate feedback processes that modifies ocean circulation and the physical and chemical properties of seawater, which alters CO uptake. Overfishing and the plastic pollution of the oceans contribute to the degraded state of the world's biggest carbon sink.