A recent article in Science, “Rising Acidity Brings an Ocean of Trouble” claims that post industrial human CO2 has lowered ocean pH from 8.2 to 8.1. This is an extraordinary claim since there were no preindustrial ARGO floats to establish the baseline. To get some sort of baseline we determine the molar solution if all the purported 1.1 trillion tonnes of human post industrial CO2 were dissolved in an Ocean of distilled water.
Dissolving our CO2 in all 1.3 billion cubic km of ocean would clearly do nothing at all, so to be abundantly fair we limit the dilution to the surface mixed layer which we round to 350 million cubic kilometers. We make this concession even though in reality atmospheric CO2 is actively pumped into the deep ocean by ocean circulation.
Doing some simple math with lots of zeroes we arrive at a 2.35×10-9 molar solution which would lower the pH of our imaginary distilled mixed layer from 7 to 6.95.
This is only half of the acidification claimed in Science and, andWhile it ignores sulfuric and other lesser acid contributions, it is based on the worst possible situation where there is no buffering, the dilution is limited to the mixed layer, and all our CO2 goes into the ocean. In reality the oceans have impressive titratable alkalinity (TA), the deep oceans are a massive CO2 sink, and only about half of incremental atmospheric CO2 is absorbed by the oceans.