Seawater in the open ocean is typically at a pH of 8.0-8.5 on a scale of 0-14, where 0 is the most acidic, 14 is most basic and 7 is neutral. Ocean acidification from increased CO2 is predicted to make the ocean less basic, perhaps to pH 7.5 under so-called worst-case projections.
How do I know that increased CO2 will not kill the coral reefs and shellfish? Let me count the ways.
First, contrary to popular belief, at 400 parts per million (0.04 per cent), CO2 is lower now in the atmosphere than it has been during most of the 550 million years since modern life forms emerged during the Cambrian period. CO2 was about 10 times higher then than it is today.
Corals and shellfish evolved early and have obviously managed to survive through eras of much higher CO2 than present levels. This alone should negate the “predictions” of species extinction from CO2 levels nowhere near the historical maximum.
Second, due to its high concentration of basic elements such as calcium and magnesium, seawater has a powerful buffering capacity to prevent large swings in pH due to the addition of CO2.This self-correcting capacity of seawater will ensure the pH will remain well within levels conducive to calcification, the process whereby shells and coral structures are formed. Marine shells are largely made of calcium carbonate, the carbon of which is derived from the CO2 dissolved in the seawater.
Third, and most interesting, there are freshwater species of clams and mussels that manage to produce calcareous shells at pH 4-5, well into the acidic range. They are able to do this because a mucous layer on their shell allows them to control the pH near the surface and to make calcification possible beneath the mucous layer.
Fourth, ocean acidification proponents invariably argue that increased CO2 will also cause the oceans to warm due to a warming climate. Yet they conveniently ignore the fact that when water warms the gases dissolved in it tend to “outgas”.
It’s the same phenomenon that happens in a glass of cold water taken from the fridge and placed on a counter at room temperature. The bubbles that form on the inside of the glass as it warms are the gases that were dissolved in the colder water. So in theory a warmer sea will have less CO2 dissolved in it than a cooler one.
This is one of the Achilles Heels of the ocean acidification hypothesis and the “CO2 controls temperature” hypothesis in general. Many who believe CO2 is the “control knob” of climate point to the 420,000-year record of climate from the Vostok ice cores taken in Antarctica. They show a strong correlation between CO2 and temperature, but it is clear that changes in CO2 tend to follow changes in temperature rather than preceding them.
We are told CO2 is too high and we will suffer for it. Nothing could be further from the truth.
We should celebrate CO2 as the giver of life it is.