Oceans are acidifying, due to an increase in carbon dioxide in the atmosphere, (for details see this site by the National Oceanic and Atmospheric Administration (NOAA)). We can see this right now from multiple studies. This does not mean that the oceans are actually becoming acidic (which would mean that pH had fallen below 7), but rather that they are becoming less alkaline, moving from a pH of 8.2 to 8.1. Doesn’t sound like much, but it’s huge if you are an ocean dwelling creature.
We can get a peek at historical ocean pH through a variety of methods, and since the time of the industrial revolution (when human actions started driving atmospheric CO2 up) the oceans have become about 30% more acidic. Such acidity has not been seen for 800,000 years and, never, ever has pH dropped this rapidly. On a geologic time scale, this is almost instantly. And it is happening too fast for organisms to evolve a response.
So what’s at stake? Will our boats start to dissolve? No. At a minimum, however, things with shells, and other hard calcified structures, are likely to be profoundly affected. This is because their shells are particularly vulnerable to changes in oceanic water pH. We can see directly what happens with lower alkalinity in the laboratory. Many studies have shown that a number of shelled things cannot tolerate this kind of change, especially in the larval stage. But no one knows what the actual fallout would be ecologically, (it may be good for lobsters, as long as they don’t have to live on coral reefs). How to translate up the laboratory studies to the ecosystem scale is notoriously difficult. However, we do know that ecological systems are highly connected, meaning that a change in something as small as plankton (and see here), can have wild effects that cascade up the food chain.
So although we have high-quality science on the changing seas, we don’t know exactly what the ecological effects will be. But ecological systems tend to be like the game Jenga, in which you try to remove wooden pieces without causing the whole structure to collapse. Eventually, however, if you remove too many blocks, the fall of the entire structure is inevitable. Because our economy is tied to ecosystem services (more on this in another post, but of major concern directly is the 60 billion dollar a year fisheries industry), ecological collapse tends to be a bad thing for most creatures, and most economies.
We are in the middle of a planet-wide experiment on the effect of acidification on oceanic life. If you were sitting on an ethics board, would you approve this experiment?