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More evidence that ocean acidification is unlikely to do harm

David Middleton has an interesting essay on ocean pH here.

Like me he finds the literature replete with data suggesting that a realistic reduction in alkalinity caused by CO2 increases will do no net harm to marine ecosystems. For example:

A recent paper in Geology (Ries et al., 2009) found an unexpected relationship between CO2 and marine calcifers. 18 benthic species were selected to represent a wide variety of taxa: “crustacea, cnidaria, echinoidea, rhodophyta, chlorophyta, gastropoda, bivalvia, annelida.” They were tested under four CO2/Ωaragonite scenarios…

The effects on calcification rates for all 18 species were either negligible or positive up to 606 ppm CO2. Corals, in particular seemed to like more CO2 in their diets…

This study alone gives the lie to the claim made in the high priests’ critique of my Times article that no average net effect can still mean harm, because it can mean (say) an ocean with more jellyfish and fewer corals. Shrimps, corals, starfish, red algae, green algae, snails, clams, and worms — all either unaffected or beneficially affected. Sounds pretty diverse to me.

What is really noticeable is that whereas the alarmists’ papers are full of words like `may’ and `can’ (for example,

The tolerance range and optimal value can be expected to vary between species, and may change through individual acclimation or genetically-driven selective adaptation. Nevertheless, increased frequency of extremes and/or relatively small changes in mean values can be damaging, with stress impacts that may affect health or reproduction…)

by contrast Middleton’s post is full of…graphs. Real data.

Here’s one that I’ve referred to before, showing that coccolithophores like higher CO2 levels.




This one was especially amazing. It’s a graph Middleton made from data used by a paper in Science.

Notice three things:

First, the calcification rate on the Great Barrier Reef has been rising, not falling, over recent centuries, at a time when CO2 levels have been rising. Just as I have been saying: CO2 dissolves in seawater to make HCO3 and HCO3 is the fuel corals use for calcification. Other things being equal CO2 fertilises coral growth.

Second, note that tiny little drop in the red line at the end. This is how the authors of the study describe that tiny little drop:

[Corals’] skeletal records show that throughout the GBR, calcification has declined by 14.2% since 1990, predominantly because extension (linear growth) has declined by 13.3%. The data suggest that such a severe and sudden decline in calcification is unprecedented in at least the past 400 years.

Third, note the drop-off in sample size near the end.

Truly, I am gobsmacked. As Middleton comments:

It is “cherry-picking” of the highest order, if that last data point really is the basis of this claim

(If it’s not, they are welcome to write in and say what is.)

By Matt Ridley | Tagged:  Uncategorized