• Climate

Ocean acidification is expected to harm marine ecosystems overall, cherry-picking can lead to the opposite conclusion

Posted on:  2017-01-10

Key takeaway

Decreasing ocean pH is documented to pose significant risks to marine ecosystems, though the magnitude of the impacts depends on specific species.

Reviewed content

Marine life has nothing whatsoever to fear from ocean acidification.

Source: The Spectator, James Delingpole, Mike Wallace, 2016-04-30

Verdict detail

Cherry-picking: The claim is derived from looking only at a subset of all the available relevant evidence.

Full Claim

The impact on calcification, metabolism, growth, fertility and survival of calcifying marine species when pH is lowered up to 0.3 units […] is beneficial, not damaging. Marine life has nothing whatsoever to fear from ocean acidification.

Ken Caldeira member picture

Ken Caldeira

Senior Scientist, Carnegie Institution for Science

There is much evidence available to falsify this statement. Many experiments have shown substantial negative biological responses at these levels of pH change[1]. Of course, some organisms are relatively unaffected by these levels.
I was involved in an experiment in Australia’s Great Barrier Reef where we added an ‘antacid’ to a plume of seawater, bringing seawater chemistry closer to what it was several hundred years ago. We let that water flow over a patch of reef and measured an increase in the growth rate of the reef. This showed that the increase in acidity caused by our CO2 emissions is already slowing reef growth, harming the reef.

Richard Feely member picture

Richard Feely

Senior Scientist, NOAA's Pacific Marine Environmental Laboratory

The Idso meta-analysis described by Delingpole was never published. It does not take into account the proper method of proportional scaling analysis. It does not demonstrate how negative effects will impact ecosystem services and food-web processes that can have an effect on economically important fish and shellfish. It does not address the impacts we are already seeing on important fish food, such as pteropods (see Bednarsek et al., 2012, 2014; Feely et al., 2016). There are several highly credible published meta-analysis studies (Kroeker et al. ,2013; Wittman & Pörtner, 2013; and Busch and McElhany, 2016) that have told a much different story than Idso’s unpublished work. Delingpole failed to even mention these other studies, which show very significant impacts on several marine taxa. In summary, Delingpole’s article demonstrates a complete lack of appreciation of scientific literature on this topic and the proper choice of scientific methods for data analysis and synthesis that leads to a more accurate understanding of the present-day and future impacts of ocean acidification.

Jean-Pierre Gattuso member picture

Jean-Pierre Gattuso

Research Professor, CNRS, Université Pierre et Marie Curie and IDDRI

The publication [used as a reference to back this claim] is not peer-reviewed, cherry-picks articles and does not involve proper statistical testing.

The comprehensive metanalysis that 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.

Figure showing that “ocean acidification had a significant negative effect on survival, calcification, growth, development and abundance”. Caption: Mean effect of near future acidification on major response variables. Significance is determined when the 95% bootstrapped confidence interval does not cross zero. The number of experiments used to calculate the mean is included in parentheses. *denotes a significant effect. Source: Kroeker et al. (2013)


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