Our home in space

some remarks on global heating and ocean acidity

Guy Ottewell

Acid in the ocean

The graph of global heating has been going up in step with the graph of atmospheric carbon dioxide, though roughly, because jags in the graph are caused by lesser factors, such as volcanoes and world wars. So there is room for some argument about the details.
        But the graph of ocean acidity goes up exactly in step with the increasing carbon dioxide. It has to. Carbon dioxide in contact with water dissolves into it and forms carbonic acid. More carbon dioxide, more carbonic acid. We know how much more carbon dioxide gas we are generating, we can predict how much more acidity that will cause, we can measure the pH (acidity) of the oceans, and it keeps to prediction.
        There is no room for argument about it. And so there is no room for valid doubt about the whole linked pattern. Human activity has reached a scale at which it is corroding the thin film in which we, and other creatures, live.
        Increasing acidity prevents calcium carbonate from forming in the water. Calcium carbonate is used to make the shells of corals, molluscs, and plankton. Plankton are the base of the marine food-chain. Coral reefs, the “rainforest of the ocean,” cover only one percent of ocean area but support a quarter of all ocean species, and they are already being destroyed by human activity such as fishing with dynamite, as well as by warming water. If the acid in the oceans keeps increasing at its present rate, it will not only hinder formation of calcium carbonate but dissolve it. Alarmingly large areas of coral reefs have already gone white, as dead as bones.
        (Actually ocean acidity goes up somewhat faster than aerial carbon dioxide: rivers add the acid rain caused by power plants; they also add fertilizer runoff from farms, which cause algal blooms, which decay into carbon dioxide directly in the water. So we should say that ocean acidity goes up in step with carbon dioxide in the atmosphere, plus acid rain and fertilizer runoff.)