weekmonth, a new study was published looking at ocean acidification, a (I think under-publicized) side effect of increasing CO2 concentrations. A decent summary can be found at The Atlantic (in their health section, of all places). The researchers (from a wide array of institutions in the US and Europe) focused on Arctic sea snails. While that may sound incredibly boring, there are two main reasons they’re important to study. First, their shells are calcium carbonate, which you’re probably more familiar with as limestone (or perhaps as the active ingredient in most over-the-counter heartburn medications). Calcium carbonate makes up the shells of a lot of sea creatures.
And while we mention antacids, let’s bring up their counterpart, acids. So carbon dioxide naturally dissolves in water to form a somewhat weak acid (you also see this idea come up with discussions of soda sometime – the CO2 from carbonation also dissolves in the soda and makes it acidic). Although that’s a slight simplification because it actually turns out sea water is slightly basic (think the opposite of acidic) and has a pH somewhere around 8.15 , presumably because of the several thousand minerals that are dissolved from the coasts. So if the ocean’s slightly basic, we’re fine, right? Well, the term “acidification” is still accurate because the pH is lower (i.e. more acidic) than it used to be. The process of sea creatures building up the calcium carbonate structures is sensitive to environmental conditions. The carbonate dissolves more in solution with more carbon dioxide and/or lower pH (more acidic). While that may initially sound like a good thing for any critters needing it (there’s more calcium carbonate in the water, right?), chemical equilibrium is a two way street; if it’s easier for something to dissolve, it’s harder to precipitate it back into a solid that might go into a shell. Studies have shown that coral grows slower in acidic water because of this.
So what made this study important? It looked at how acidification affects marine snails (also known more whimsically as “sea butterflies”) in the Antarctic, which are a very important part of the food chain (some marine biologists call them “potato chips of the oceans”). The snails already showed significant signs of their shells dissolving. While this isn’t a death sentence, it does make it easier for them to be eaten or catch diseases, and en masse, that could throw off population.
Of course, it’s important to note the researchers say the blame isn’t all on ocean acidification. Part of the reason the seawater was so acidic was because of upswelling, an phenomena in which deeper water is pushed up to the ocean surface. Deeper water tends to be more acidic (I can’t find why), so these upswells make the surface water abnormally acidic. But upswelling is expected to increase with climate change.