The Ocean Is Not Getting Acidified

Guest Post by Willis Eschenbach

There’s an interesting study out on the natural pH changes in the ocean. I discussed some of these pH changes a year ago in my post “The Electric Oceanic Acid Test“. Before getting to the new study, let me say a couple of things about pH.

The pH scale measures from zero to fourteen. Seven is neutral, because it is the pH of pure water. Below seven is acidic. Above seven is basic. This is somewhat inaccurately but commonly called “alkaline”. Milk is slightly acidic. Baking soda is slightly basic (alkaline).

Figure 1. pH scale, along with some examples.

The first thing of note regarding pH is that alkalinity is harder on living things than is acidity. Both are corrosive of living tissue, but alkalinity has a stronger effect. It seems counterintuitive, but it’s true. For example, almost all of our foods are acidic. We eat things with a pH of 2, five units below the neutral reading of 7 … but nothing with a corresponding pH of 12, five units above neutral. The most alkaline foods are eggs (pH up to 8) and dates and crackers (pH up to 8.5). Heck, our stomach acid has a pH of 1.5 to 3.0, and our bodies don’t mind that at all … but don’t try to drink Drano, the lye will destroy your stomach.

That’s why when you want to get rid of an inconvenient body, you put lye on it, not acid. It’s also why ocean fish often have a thick mucus layer over their skin, inter alia to protect them from the alkalinity. Acidity is no problem for life compared to alkalinity.

Next, a question of terminology. When a base is combined with an acid, for example putting baking soda on spilled car battery acid, that is called “neutralizing” the acid. This is because it is moving towards neutral. Yes, it increases the pH, but despite that, it is called “neutralizing”, not “alkalizing”.

This same terminology is used when measuring pH. In a process called “titration”, you measure how much acid it takes to neutralize an unknown basic solution. If you add too much acid, the pH drops below 7.0 and the mixture becomes acidic. Add too little acid, and the mixture remains basic. Your goal in titration is to add just enough acid to neutralize the basic solution. Then you can tell how alkaline it was, by the amount of acid that it took to neutralize the basic solution.

Similarly, when rainwater (slightly acidic) falls on the ocean (slightly basic), it has a neutralizing effect on the slightly alkaline ocean. Rainwater slightly decreases the pH of the ocean. Despite that, we don’t normally say that rainwater is “acidifying” the ocean. Instead, because it is moving the ocean towards neutral, we say it is neutralizing the ocean.

The problem with using the term “acidify” for what rainwater does to the ocean is that people misunderstand what is happening. Sure, a hard-core scientist hearing “acidify” might think “decreasing pH”. But most people think “Ooooh, acid, bad, burns the skin.” It leads people to say things like the following gem that I came across yesterday:

Rapid increases in CO2 (such as today) overload the system, causing surface waters to become corrosive.

In reality, it’s quite the opposite. The increase in CO2 is making the ocean, not more corrosive, but more neutral. Since both alkalinity and acidity corrode things, the truth is that rainwater (or more CO2) will make the ocean slightly less corrosive, by marginally neutralizing its slight alkalinity. That is the problem with the term “acidify”, and it is why I use and insist on the more accurate term “neutralize”. Using “acidify”, is both alarmist and incorrect. The ocean is not getting acidified by additional CO2. It is getting neutralized by additional CO2.

With that as prologue, let me go on to discuss the paper on oceanic pH.

The paper is called “High-Frequency Dynamics of Ocean pH: A Multi-Ecosystem Comparison” (hereinafter pH2011). As the name suggests, they took a look at the actual variations of pH in a host of different parts of the ocean. They show 30-day “snapshots” of a variety of ecosystems. The authors comment:

These biome-specific pH signatures disclose current levels of exposure to both high and low dissolved CO2, often demonstrating that resident organisms are already experiencing pH regimes that are not predicted until 2100.

First, they show the 30-day snapshot of both the open ocean and a deepwater open ocean reef:

Figure 2. Continuous 30-day pH measurements of open ocean and deepwater reef. Bottom axis shows days. Vertical bar shows the amount of the possible pH change by 2100, as estimated in the pH2011 study.

I note that even in the open ocean, the pH is not constant, but varies by a bit over the thirty days. These changes are quite short, and are likely related to rainfall events during the month. As mentioned above, these slightly (and temporarily) neutralize the ocean surface, and over time mix in to the lower waters. Over Kingman reef, there are longer lasting small swings.

Compare the two regions shown in Fig. 1 to some other coral reef “snapshots” of thirty days worth of continuous pH measurements.

Figure 3. Thirty day “snapshots” of the variation in pH at two tropical coral reefs. Bottom axis shows days.

There are a couple of things of note in Figure 3. First, day-to-night variations in pH are from the CO2 that is produced by the reef life as a whole. Also, day-to-night swings on the Palmyra reef terrace are about a quarter of a pH unit … which is about 60% more than the projected change from CO2 by the year 2100.

Moving on, we have the situation in a couple of upwelling areas off of the California coast:

Figure 4. Thirty day pH records of areas of oceanic upwelling. This upwelling occurs, among other places, along the western shores of the continents.

Here we see even greater swings of pH, much larger than the possible predicted change from CO2. Remember that this is only over the period of a month, so there will likely be an annual component to the variation as well.

Figure 5 shows what is going on in kelp forests.

Figure 5. pH records in kelp forests

Again we see a variety of swings of pH, both long- and short-term. Inshore, we find even larger swings, as shown in Figure 6.

Figure 6. Two pH records from a near-shore and an estuarine oceanic environment.

Again we see large pH changes in a very short period of time, both in the estuary and the near-shore area.

My conclusions from all of this?

First, there are a number of places in the ocean where the pH swings are both rapid and large. The life in those parts of the ocean doesn’t seem to be bothered by either the size or the speed these swings.

Second, the size of the possible pH change by 2100 is not large compared to the natural swings.

Third, due to a host of buffering mechanisms in the ocean, the possible pH change by 2100 may be smaller, but is unlikely to be larger, than the forecast estimate shown above.

Fourth, I would be very surprised if we’re still burning much fossil fuel ninety years from now. Possible, but doubtful in my book. So from this effect as well, the change in oceanic pH may well be less than shown above.

Fifth, as the authors commented, some parts of the ocean are already experiencing conditions that were not forecast to arrive until 2100 … and are doing so with no ill effects.

As a result, I’m not particularly concerned about a small change in oceanic pH from the change in atmospheric CO2. The ocean will adapt, some creatures’ ranges will change a bit, some species will be slightly advantaged and others slightly disadvantaged. But CO2 has been high before this. Overall, making the ocean slightly more neutral will likely be beneficial to life, which doesn’t like alkalinity but doesn’t mind acidity at all.

Finally, let me say that I love scientific studies like this, that actually use real observations rather than depending on theory and models. For some time now I’ve been pointing out that oceanic pH is not constant … but until this study I didn’t realize how variable it actually is. It is a measure of the “ivory tower” nature of much of climate science that the hysteria about so-called “acidification” has been going on for so long without an actual look at the actual ocean to see what difference a small change towards neutrality might actually make.

My best regards to everyone,

w.

NOTE: For those hard-core scientists that still want to call adding a small amount of acid to a basic solution “acidifying” the basic solution, and who claim that is the only correct “scientific terminology”, I recommend that you look at and adopt the scientific terminology from titration. That’s the terminology used when actually measuring pH in the lab. In that terminology, when you move towards neutral (pH 7), it’s called “neutralization”.