Comment today: I interviewed Anita Leinweber [author of the paper published in the Journal of Geophysical Research] 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. 3The article links to the data which supposedly shows a statistically significant "acidification" in surface pH, but plotting the data instead shows a very noisy dataset indicative of calibration problems with the pH meter, and a non-significant ~0.2 increase or alkalinization of pH:
|Ocean 'alkalinization' in Santa Monica Bay|
The data clearly does not support the claim of any statistically-significant decrease of pH or 'acidification'. However, it does illustrate that ocean pH routinely changes 0.5 pH units [50% change in H+ protons] or more over the course of a single day, much larger than the claimed "acidification" of 0.1 pH units from pH 8.2 to 8.1 over the past 150 years of industrialization. There is no reliable global ocean data demonstrating any change in pH due to the increase in atmospheric CO2; this claim is largely based upon very sparse data and models. If the oceans are warming, CO2 solubility decreases per Henry's Law, thus limiting the potential of "acidification" from an increase of CO2.
The data also illustrates that pH meters require constant calibration and have surprisingly large measurement uncertainties. That's why there is an open $2 million dollar X-prize competition to develop an ocean pH meter to accurately, affordably, and efficiently measure ocean pH:
There is no reliable evidence that global ocean pH is falling, and this Santa Monica Bay data certainly does not support the alarmist claims of "California's corrosive oceans."
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":
- Doubling of atmospheric levels would only increase dissolved CO2 in the oceans by .48%
- There is no reliable evidence that ocean pH is falling
- Increased CO2 dissolution in the oceans increases calcification of shellfish and coral
- Corals evolved at a time when CO2 levels were 15 times higher than the present
- Laboratory experiments on sea life in which hydrochloric acid is added to the water (not CO2) and without the natural buffers present in the ocean is meaningless to determine effects of increased CO2 levels on sea life
- prior research has failed to consider that organisms can adapt over time to pH changes
- several marine organisms have been shown to be resistant to "acidification"
- prior research has shown the oceans are a net source of CO2 rather than a sink
Variability and trends of ocean acidification in the Southern California Current System: A timeseries from Santa Monica Bay
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.