Tuesday, June 18, 2013

New paper finds no evidence of ocean 'acidification' in upper Santa Monica Bay

A new paper published in the Journal of Geophysical Research finds no evidence of ocean "acidification" in the upper 100 meters of the Santa Monica Bay from bi-weekly observations over the past six years. According to the authors, "No statistically significant linear trends emerge in the [biologically significant] upper 100 meters." 

Key points from prior posts on ocean "acidification":

A. Leinweber, N. Gruber

Abstract: We investigate the temporal variability and trends of pH and of the aragonite saturation state, Ωarag, in the southern California Current System on the basis of a 6 year timeseries from Santa Monica Bay, using bi-weekly observations of dissolved inorganic carbon and combined calculated and measured alkalinity. Median values of pH and Ωarag in the upper 20 m are comparable to observations from the subtropical gyres, but the temporal variability is at least a factor of 5 larger, primarily driven by short-term upwelling events and mesoscale processes. Ωarag and pH decrease rapidly with depth, such that the saturation horizon is reached already at 130 m, on average, but it occasionally shoals to as low as 30 m. No statistically significant linear trends emerge in the upper 100 m, but Ωarag and pH decrease, on average, at rates of -0.009 ± 0.006 yr-1 and -0.004 ± 0.003 yr-1 in the 100 to 250 m depth range. These are somewhat larger, but not statistically different from the expected trends based on the recent increase in atmospheric CO2. About half of the variability in the deseasonalized data can be explained by the El Niño Southern Oscillation (ENSO), with warm phases (El Niño) being associated with above normal pH and Ωarag. The observed variability and trend in Ωarag and pH is well captured by a multiple linear regression model on the basis of a small number of readily observable independent variables. This permits the estimation of these variables for related sites in the region.


  1. Very interesting, considering that Anita Leinweber hosted a workshop last October on "Ocean Acidification, the 'other' CO2 problem and its effects on marine life" (ref: http://www.usc.edu/org/cosee-west/PDFs/Anita_flyer_Oct2012fin.pdf ). The workshop was apparently targeted towards K-12 teachers, and claimed that CO2 may be (those weasel words again) the "culprit" behind Harmful Algal Blooms.

    Now we learn from the good Dr. Leinweber that that ocean acidification problem is not such a problem after all. Oh, and according to the Centers for Disease Control, Harmful Algal Blooms may be caused by several things, none of which are CO2 (ref: http://www.cdc.gov/nceh/hsb/hab/default.htm ).

    Perhaps the good Dr. Leinweber should have done her research BEFORE hosting her workshop.

  2. I interviewed Anita Leinweber for an article I wrote for The Catalina Marine Society. At the time of the study’s publication, no statistically significant linear trends had emerged in the upper 100 meters. But this past April (2014), Leinwebier saw a statistically significant trend in surface pH, calculated from additional data which extended to 2013. The pH values in the top meter had been decreasing by about 0.003 per year. (Calculations were not yet complete for other depths.)

    My article: California's Corrosive Ocean, http://www.catalinamarinesociety.org/files/MagVol5No1.pdf, p. 3

    1. Thanks for your comment. I read your article, accessed the data and plotted it for myself. I was quite surprised to find the data at


      shows an increase of pH from ~8 to 8.3 from 2012 to 2013. Furthermore, the data is very noisy in sections indicating calibration problems with the pH meter.

      The data you linked to simply does not support your claim of a statistically significant decrease of pH. If you have other data that show this, please provide a link so I can verify this claim myself.

  3. I apologize if my article was unclear, but the data which Anita Leinweber collected is different than the data you found at the Catalina Marine Society site. Her data were collected at the Santa Monica Bay Observatory (SMBO) mooring from 2003 to 2013. I believe the data you found from 2012-2013 was collected by CMS volunteers near Two Harbors, Santa Catalina Island. So I asked someone at CMS about their data in reference to your comment, and his response was the following:

    "I would not draw any conclusions from the data on the CMS web site as it hasn't been quality controlled yet, a fact mentioned on the web site page where the data are located, and the range of pH values cited are within the accuracy of the instrument, +/- 0.2 units, a value which is also linked on that page. That is, the real pH could have remained constant at 8.2 but we may obtain readings from 8.0 to 8.4 with a reasonable probability. Our YSI simply cannot support measurements required to verify the trends stated in your article, nor is it intended to.

    "You may ask why we are making pH measurements. The reason is that the short term dynamics of pH may be much larger than the uncertainties inherent in our measurements. Indeed, your article points out examples of such; and what happens at Santa Catalina Island is unknown. I attach a paper from Scripps examining pH measurements in the Pt Loma kelp forest and showing that the daily range of pH can be 0.2 units.

    "I'll leave it to the professionals to study the long-term trends."

    The paper he referred can be found here: http://www.biogeosciences.net/9/3917/2012/bg-9-3917-2012.html

    I also asked Anita Leinweber about her data in reference to your comment, and I will post what she says if/when I hear from her.

  4. squid2112 | August 23, 2014 at 9:51 am |

    You do realize that you could dissolve 100% of the atmospheric CO2 into the oceans and you would be hard pressed to measure a change in pH, don’t you?

    Less than 3m of ocean contain more CO2 than all of the atmosphere above it, and the average depth of our oceans is 4km! Our oceans contain more than 4000x’s the concentration of CO2 than our atmosphere, and are buffered by millions of square miles of limestone and other carbon absorbing minerals. This “Ocean Acidification” nonsense is a non-starter and simply displays utter ignorance of the fools touting it.