Monday, July 02, 2012

Yes, Ocean Acidity Has Increased by 30%

A recent WUWT post featured a letter from Chuck Wiese, who claims that NOAA needs to issue a correction for its "trickery" for claiming that ocean acidification has increased by 30% since the pre-industrial era.

NOAA is right. Wiese is wrong.

Wiese is a former TV weatherman, with a bachelor's degree in meteorology, who believes he is a climate expert, despite having never done research or published in the field (or, as far as I can tell, in any scientific field). He speaks periodically on conservative Lars Larson's Portland radio show, because, of course, Larson would never have on a real expert, who would say things Larson's scoffer audience doesn't want to hear(*).

Acidity is a measure of how readily a substance gives up a proton when it is dissolved in a solution.  A proton is, of course, the nucleus of the hydrogen atom, so chemists denote it as H+.

pH is not the acidity -- is it a function of the acidity, and a useful way to describe the acidity, but it is not the only way to describe the acidity, and it is not the "acidity."

pH = - log10[aH+]

where aH+  is the hydrogen ion activity in a solution. (Note that the solution need not be water -- and the pH will vary accordingly -- though for most common applications it is.) In practice aH+ is the concentration of hydrogen ions, [H+]. pH is a useful number to characterize the acidity, but it is not the acidity. As the commenter Chem Prof wrote on WUWT:
"The original article is correct. A decrease in pH by 0.1 pH units corresponds to a 25.6% increase in relative hydrogen ion concentration, roughly 30 percent to one significant figure."
This calculation is straightforward: if a substance with activity a1 and pH p1 undergoes a change to pH p2, so that its change in pH is Δp = p2 - p1, then the fractional change in acidity is

Δa/a1 = (a2-a1)/a1 = 10-Δp - 1

So is the pH of the ocean changes from 8.2 to 8.1 (Δp = -0.1), then

fractional change in a = 100.1 - 1 = 0.26 = 26%

which rounds to 30%.

Nor is pH restricted to between 1 and 14, as Wiese writes:
"As you also know, there are 14 orders of magnitude that define the pH scale from zero to fourteen units as per this equation."
In fact, there are superacids much, much stronger than the strong acids we all know about (like sulphuric acid, H2SO4). Fluoroantimonic acid, for example, is 2 × 1019 times stronger than pure sulphuric acid. A function different from pH is used to describe such acids.

So indeed, ocean acidity has increased by 30% since pre-industrial times, which corresponds to a pH change of about 0.1. Wiese is wrong.

Update 7/4: This guest post by Chem Prof provides more details.


PS: And, yes, this is an "acidification." The acidity of the ocean has changed -- it has decreased, becoming more acidic. In junior high we're taught to think of substances as either an acid or a base, but in actuality all substances have an acidity (and all have, at the same time, a basicity), and since the acidity is increasing it's "acidification." You could call it "debasification" if you want -- functionally they're the same thing -- but it's the change in the acidic property that is troublesome, so best to call it what it is.

(*) Wiese is the kind of person who, after he called up my university to verify that I had a PhD, and they said they couldn't release that information for privacy reasons, now goes around making insinuations about it (Oregonian comment, April 11, 2011, 5:00 pm: "You claim a Ph.D. in physics.")

4 comments:

Unknown said...

Appell: In your never ending eagerness to validate AGW, your weakness in argument is just as apparent here.

As usual, in your eagerness to discredit your own critics, you miss the point of my letter posted on WUWT entirely.

In every story and in most research done with respect to acidity or alkalinity, the numbers are reported in powers of hydrogen ions, NOT H+ iteslf. Natural variability in pH in the ocean system is at least 5% from the mean of 8.2 pH units or .41 units. That,of course, makes the change of .1 pH units in 100 years WELL WITHIN the natural variability of pH as we have been observing it.

There is no story here unless the pH equation is solved for H+ as NOAA did and swap the number with pH units. That makes it well outside natural variablity and now we have a juicy story. That is completely fraudulent and disengenuous to compare H+ with the pH to take the percentages out of the norms.

You, of course, never mentioned this. Let alone your silly comments about how a few unusual acids can cause a negative pH, yet you then acknowledge this is not the norm. ( So why mention it? What is the significance of those few acids amoungst most others that fall between 0 and 14 pH units? )

This sort of lack of any interest in investigative journalism by you as a claimed scientist is just one reason why I question your academic credentials.

You are quick to point out that I have no doctorate degree compared to your own claim and further, that people like Dr. Fulks ( Ph.D in Astrophysics ) nor I ever did any "research" that was "peer reviewed" in climate science journals, but yet, we find that in addition to you NEVER having been employed at ANY university in ANY sort of position as a faculty member, you have also NEVER published in ANY climate science journal you claim we should have.

Instead of all of the Ph.D "union card" crap you like to pull, you should stick to relevant facts and just prove where your opponents are wrong. You have never been able to do this, Appell, and you also engage in dishonest and disengenuous dialogue such as in this article to attempt to defend the indefensible. That would be my guess as to why you have little credibility with most that you communicate with.

Chuck Wiese
Meteorologist

David Appell said...

Mr. Wiese: pH is not acidity, but a certain function of acidity used for convenience.

NOAA is right. You are wrong.

The Fishmonger said...

NOAA may be right, but it is right in a way that is purposely misleading to the general public, in support of its political agenda. That's the worse kind of right to be.

David Appell said...

NOAA's "agenda" is to do science, and communicate it, as best they can. That means being as accurate as possible, and their claim about acidity does exactly that.

Marine organisms react to the acidity, and that's increasing, and it's a problem.