This publication is not peer-reviewed, cherry-picks articles and does not involve proper statistical testing. It does not, therefore, does qualify as a killer analysis! The comprehensive metanalysis was performed by Kroeker et al. (2013) revealed decreased survival, calcification, growth, development and abundance in response to acidification when the broad range of marine organisms is pooled together. However, the magnitude of these responses varies among taxonomic groups.

Kroeker K., Kordas R., Crim R., Hendriks I., Ramajo L., Singh G., Duarte C. & Gattuso J.-P., 2013. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology 19:1884-1896.

Incorrect: The effect of warming is completely overwhelmed by the effect of increased atmospheric CO2. Hence, the ocean will continue to absorb massive amounts of CO2 in the future, despite ocean warming.

Incorrect: the decline in pH is easily measured in serial oceans and seas.

Some fast-growing species are indeed able to develop some level of adaptation after several hundreds of generation. Overall, there is evidence that all all past episodes of ocean warming, acidification and deoxygenation have led to mass extinctions. Furthermore, there is no calcifier close to CO2 vents, suggesting that adaptation has limited capabilities.

Some calcifying species were indeed abundant in the Cretaceous, a time at which the atmospheric CO2 concentration was high. However, seawater alkalinity was also high due to intense weathering on land. Hence, the concentration of carbonate ions (CO3, which controls calcification) was elevated. That compensation does not happen today and will not happen in the near future because total alkalinity does not change significantly on time scales of centuries. There is ample evidence in the literature for that.

This publication is not peer-reviewed and from someone who has no qualification in any of the ocean sciences (he has training in terrestrial ecology).

This is plain wrong. Precise measurements of pH are very difficult and only since 1988 one can reach the precision required to measure small changes in pH as a function of time. The decline in pH since that date is clear and unambiguous. It confirms the very simple relationship that exist between atmospheric pCO2 and pH in the surface ocean. No need to involve sophisticated model to show that the decline in surface ocean pH has been 0.1 unit since the industrial revolution.

This is incorrect. Browman has not published a review on the subject. He rather edited a special issue of the ICES Journal of Marine Science. For a review of the literature, including a metaanalysis, see Kroeker et al. (2013). Furthermore, Browman issued a statement on Twitter: [The journalist] cherry-picked our conversation and presents phrases out of context – seemingly in order to be sensational – despite the fact that I told him that the press was part of the “exaggeration” problem. See: http://tinyurl.com/jm3y3xn.

Kroeker K., Kordas R., Crim R., Hendriks I., Ramajo L., Singh G., Duarte C. & Gattuso J.-P., 2013. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology 19:1884-1896.

This is mentioned nowhere in the scientific literature.

As mentioned above, this is not a truthful summary of the scientific literature.

That is not a truthful summary of the scientific literature. Check, for example, the meta-analysis of Kroeker et al. (2013) who describe processes and organisms that do not seem to be affected by ocean acidification.

Kroeker K., Kordas R., Crim R., Hendriks I., Ramajo L., Singh G., Duarte C. & Gattuso J.-P., 2013. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology 19:1884-1896.

That is incorrect. No peer-reviewed article claim that the ocean will become acid (pH < 7).

The expression "ocean acidification" was actually introduced in 2001 by Broecker and Clark. But the chemical processes involved have been know for a very long time at least the1950s) and the impact of low pH (elevated acidity) on marine organisms since the early 1900s. The earliest experiments even predate the definition of pH by Sørensen in 1909.

Broecker W. & Clark E., 2001. A dramatic Atlantic dissolution event at the onset of the last glaciation. Geochemistry Geophysics Geosystems 2, 2001GC000185. )

I recommend to also consider report to the EU published in 2007. It looked at the 15,000 additional deaths in France caused by the heat wave in August 2003. It also looked at the excess mortality in 12 European countries during the summer 2003:

In total, more than 80,000 additional deaths were recorded in 2003 in the twelve countries concerned by excess mortality compared to the 1998‐2002 period. Whereas 70,000 of these additional deaths occurred during the summer, still over 7,000 occurred afterwards. Nearly 45,000 additional deaths were recorded in August alone, as well as more than 11,000 in June, more than 10,000 in July and nearly 5,000 in September. The mortality crisis of early August extended over the two weeks between August 3rd and 16th. 15,000 additional deaths were recorded in the first week and nearly 24,000 in the second. The excess mortality in this second week reached the exceptional value of 96.5% in France and over 40% in Portugal, Italy, Spain and Luxembourg. Excess mortality exceeded 20% in Germany, Switzerland and Belgium and 10% in all the other countries.

I am sure that whether this demonstrated increase in mortality due to an heat wave will be partly compensated by a putative decline in mortality in colder regions does not make any difference to the families of the 80,000 people who passed away in just 4 months.

Robine J.-M., Cheung S. L., Le Roy S., Van Oyen H. & Herrmann F. R., 2007. Report on excess mortality in Europe during summer 2003. EU community Action Programme for Public Health, Grant Agreement 2005114. Heath Wave Project 2003. http://ec.europa.eu/health/ph_projects/2005/action1/docs/action1_2005_a2_15_en.pdf

This is an incorrect statement which has already been debunked before, including by two of the authors of the paper this manuscript referee to.

Hurd C. L., Cornwall C. E., Dupont S., Gattuso J.-P., Hoegh-Guldberg O., Gao K. & Lagos N. A., 2015. Ocean acidification: Laboratory seawater studies are justified. Nature 525:187.

This is meaningless. First, I cannot find where the statistics come from. Second, it is not unexpected that several papers published in the issue showed little or no impact because the call for papers specifically welcomed such contributions. The bias is therefore very high. I recommend using the unbiased dataset investigated by Kroeker et al. (2013). It does demonstrate negative impacts on some processes and groups of organisms.

Kroeker K. et al., 2013. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology 19:1884-1896.

As I have shown above, the publication bias towards negative impacts is not a major one. I am not sure which are the influential journals referred to but the most lively controversy about ocean acidification took place in the high visibility journals Science and Nature. It opposed negative and positive views of the impact of ocean acidification coccolithophores he statement that influential journals. So this statement is wrong.

I would be interested to know which journals and organisations are responsible in Dr. Browman's opinion.

Extreme values are useful for physiologists to elucidate the cellular and molecular pathways confering susceptibility or resistance to elevated CO2. Yang et al. (2016; fig. 8d) showed that most of the data on the biological response to ocean acidification archived in a World Data Centre were collected at pCO2 values below 1000 uatm, in agreement with the business-as-usual CO2 emission scenario.

Yang Y.et al., 2016. Data compilation on the biological response to ocean acidification: an update. Earth System Science Data 8:79-87.

It is not a review that is being discussed but a special issue of a scientific journal.

A publication bias towards positive results is inherent to all fields of research. But I believe that it is far from being as bad as the article suggests. The most recent and comprehensive meta-analysis of the impact of ocean acidification shows that many processes and taxonomic groups exhibit no statistically significant response (Kroeker et al., 2013). This demonstrates that many non-calamitous papers are published.

Kroeker K. et al., 2013. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology 19:1884-1896.