The Ocean’s Acid Test might just be another scary story?

It seems that most of the scientific literatures and media reports I’ve been looking at so far in this blog share the common believe and even try to persuade us that Ocean Acidification is going to be another global environmental disaster by the end of this century, caused by anthropogenic CO₂ increase. Have you been wondering if this is actually true or not? How reliable are these scientific experiments and findings? Or, they are just another ‘scary story’ or ‘horror film’ portrayed by the scientists and media, like climate change after all?

In this post, I’m not trying to dispute the scientific evidences and media reports that I’ve reviewed in this blog. Instead, I wish to provide a holistic view of this ocean acidification phenomenon and avoid leading you to any particular views e.g. ‘ocean acidification is detrimental’.

The first critique that I want to look into is a report produced by the Science and Public Policy Institute (SPPI), published on the 5^th January 2011. It mainly challenges the video ‘Acid Test:  The Global Challenge of Ocean Acidification’ produced by the National Resources Defense Council (NRDC) as a new propaganda film, which I’ve posted in my first entry. Through reviewing over 100 scientific literatures, the SPPI criticizes strongly of the NRDC documentary ‘reveals nothing of substance’ (Knappenberger, 2010), which has provided no empirical evidence of this ocean acidification catastrophic theory proposed by most of the scientists. They further argued that ocean acidification is impossible to cause catastrophic disruption to the world’s marine ecosystems; in the past geologic era, levels of CO₂ are 20 times higher than today has promoted coral development (SPPI, 2010). Ridgwell has further supported this argument that ‘ocean pH in the past was indeed lower than now during the Cretaceous, and probably lower than anything we will manage in the future’ (Ridley, 2011). In addition, ocean acidification induced by CO2 increase is actually beneficial to most marine calcifiers, especially coccolithophores and coral reef building (SPPI, 2010).

Matt Ridley, who is also an ‘ocean acidification critic’ made similar arguments of this ocean’s acid test challenge. In the article ‘The Threat of Ocean Acidification is greatly exaggerated’, Ridley responds to his critique on his book ‘The Rational Optimist’ in the New Scientist. In his book, he strongly emphasized that ‘ocean acidification may not be the widespread problem conjured into the 21^st Century’, which is completely opposite to projections made by Orr et al. (2005) and Hoegh-Guldberg et al. (2007) that I have previously reviewed in this blog. Ridley has also made the following main arguments:

1.   Ocean pH is not actually turning acidic, but less basic only. The current average ocean pH is about 8.1, which is alkaline and well above neutral (pH=7).

2.   Even ocean pH do experience significant temporal (daily) and spatial variation, some marine organisms, e.g. a four-decade-old-mussels learned to cope with this acidity fluctuation.

3.  There is no evidence of coral danger ‘may be extreme’ e.g. coral bleaching depends more on the rate of change than the absolute temperature (even his critic Hoegh-Guldberg accepts this point). It is therefore even more unconvincing to assume that a 0.1 unit of pH drop since the Industrial Revolution will cause a catastrophic effect on marine ecosystem (SPPI, 2010)

4.  Most literatures disregard the fact that the corals are able to recover quickly from episodic bleaching. In fact, corals are now more resilient and adaptive to thermal stresses.

5.  Ocean acidification increases bicarbonate ion concentration which promotes biological precipitation of carbonate ions by marine organisms (calcification) e.g. some coccolithophores deposit carbonate shells easier at slightly lower pH

Both the SPPI and Matt Ridley’s skepticism of the ocean’s acid test are logical and convincing. However, as Ridley said in his critique, views and opinion about the ocean acidification phenomenon depends on different interpretation of the scientific evidences. In other words, it also depends on the assumptions made about this phenomenon. And of course, assumptions differ among different scientists and many other literature authors, so assumptions can always be challenged and changed constantly. Although both critics argued that there is currently no empirical evidence to support the dominant ocean acidification theory, none of them were able to provide solid evidence and projections on the impacts of ocean acidification either. Since the ocean is an open system and constantly subject to climatic and other environmental changes, there are still significant levels of uncertainty in both the optimistic and pessimistic views about the oceans. Therefore, it is very hard to draw a conclusion of whether ocean acidification is beneficial, detrimental, or simply having no effect on the oceans.

However, in the environmental justice point of view, anthropogenic impacts on the world’s oceans should never be ignored. Because of the definite high uncertainties of the oceans future, the oceans should therefore be even more closely monitored to produce more certain projections, thus leading us to make sensible decisions about the future.