A new kind of witchy interaction is underway in the oceans, report the authors of a new paper in Environmental Science & Technology.
William G. Sunda and Wei-Jun Cai created a model to predict how CO2 from water pollution - that is, runoff from chemical fertilizers (farms), human waste (sewage), and animal waste (feedlots, ranches), plus nitrogen oxide from fossil fuel burning - might interact with the better-known source of CO2 that enters the ocean from the atmosphere, much of it a result of fossil fuel burning.
In either case, too much CO2 entering the ocean lowers the pH of seawater, which raises the acidity of the waters, preventing many marine organisms from getting access to the calcium carbonate needed to make their shells or skeletons. The result, called ocean acidification - sometimes called the "other CO2 problem," global warming being the original - is already impacting commercial oyster beds in the Pacific Northwest. This process has been firmly on the scientific radar for the past 10+ years.