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.")