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Matt Ridley is the author of provocative books on evolution, genetics and society. His books have sold over a million copies, been translated into thirty languages, and have won several awards.

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A debate on labels and acidification

Mark Lynas engages me on several issues

Mark Lynas's new book The God Species contains a few pages that dispute my account of ocean acidification in particular. Mark kindly alerted me to this and asked for my reaction. The result was an exchange, which Mark has put up on his blog here, which I mirror here. I thank Mark for taking my arguments seriously and suggesting an exchange of ideas.

Lynas: In my book The God Species I take science writer Matt Ridley to task for downplaying the dangers of ocean acidification. He responded via email, and I to him. Here is the exchange. Matt's final short responses are also included, indented as 'Ridley2′. Square brackets are mine, for clarification.

Ridley: You say [in The God Species]: "Why not just admit candidly that whilst the human advance has been amazing and hugely beneficial, it has also had serious environmental impacts?" Answer: I do. Human beings have serious environmental impacts. I say so and I do not deny them. For example: "Take coral reefs, which are suffering horribly from pollution, silt, nutrient runoff and fishing - especially the harvesting of herbivorous fishes that otherwise keep reefs clean of algae." From megafaunal extinction to alteration of the composition of the atmosphere, I detail lots of changes wrought by humans. On both climate change and ocean acidification, I accept a human alteration of the environment as real. What I argue with is whether the negative impacts are always as great as claimed or the positive ones always as small as claimed. That's quite different from not admitting that there are impacts, serious and otherwise.

Lynas: Fair enough. Everyone is of course entitled to draw their own conclusions - hopefully based on a reasonably non-selective reading of the available scientific evidence - about the relative seriousness of the different environmental challenges we face. That is actually sort of the point of the 'planetary boundaries' exercise: to quanfify numerically the possible limits to human alteration of different Earth system processes, and in so doing highlight their urgency or otherwise. From the 'planetary boundaries 1.0′ exercise which I profile in the God Species book, the conclusion is pretty firmly that biodiversity and climate change are top-level urgent concerns, closely followed by the disruption of the nitrogen cycle, ocean acidification and others. I hope you can see the value in this as a way to ground our discussions and prioritisation efforts somewhat.

In addition, the boundaries all interact, and not always in bad ways - for example, our accidental spreading of large quantities of nitrogen in terrestrial and marine ecosystems, whilst causing problems like biodiversity loss and eutrophication, also has the benefit of increasing carbon uptake and thereby slightly reducing global warming. My strong contention is that we need to consider the boundaries together (assuming they are widely accepted in current or amended form) in any meaningful analysis of how to manage the planet sensibly.

Ridley: Next, to your discussion of ocean acidification. I resent the implication that I am a "denier". What precisely am I denying? I don't deny that oceans are being made lower in pH by human emissions. I don't deny that man-made emissions are affecting climate; (I question the evidence for any large effects through net positive feedbacks). And why use a word deliberately intended to draw a parallel with the offensive lie of holocaust denial? I don't call people like you "climate change liars" when I think you exaggerate the probability of severe harm.

Lynas: Again, fair enough, and although I have used the term in the book elsewhere, I accept that the term 'denier' is problematic. In principle a person could call anyone he or she disagrees with a 'denier'. In fact, due to my stance on nuclear power, I have been called a 'Chernobyl death denier'. So the charge cuts both ways. Were I writing the book now I would perhaps be more careful about any use this term. However, although you are free to "resent the implication" in that I discuss your position in the context of "denialist" websites and the like, I do not actually call you a 'denier'. In fact I talk about the "criticism levelled by Ridley and other ocean acidification sceptics", which is hopefully less objectionable. But please note that I wrote this section of the book in response to your charge in The Rational Optimist that "ocean acidification looks suspiciously like a back-up plan by the environmental pressure groups in case the climate fails to warm". Do you still think this is a reasonable statement scientifically, with its implication that the undeniable lowering of oceanic pH was dreamt up by Greenpeace?

Ridley2: of course I do not mean that Greenpeace dreamt up the pH change, but that the predictions of extreme damage to ecosystems likely to result from this are indeed a convenient 'back-up plan'

Ridley: On the topic of labels, you repeatedly call me a member of "the right". Again, on what grounds? I am not a reactionary in the sense of not wanting social change: I make this abundantly clear throughout my book. I am not a hierarchy lover in the sense of trusting the central authority of the state: quite the opposite. I am not a conservative who defends large monopolies, public or private: I celebrate the way competition causes creative destruction that benefits the consumer against the interest of entrenched producers. I do not preach what the rich want to hear - the rich want to hear the gospel of Monbiot, that technological change is bad, that the hoi polloi should stop clogging up airports, that expensive home-grown organic food is the way to go, that big business and big civil service should be in charge. So in what sense am I on the right? I am a social and economic liberal: I believe that economic liberty leads to greater opportunities for the poor to become less poor, which is why I am in favour of it. Market liberalism and social liberalism go hand in hand in my view. Rich toffs like me have self interest in conservatism, not radical innovation.

Lynas: You are of course free to choose your own political label, and I apologise if I misunderstood your political allegiances. I can't however see you as a member of the 'left' in any way that I understand the term. Perhaps you are a 'market liberal' then or something? How does this position fall then in the conventional left-right political spectrum? Once again, I know how you feel - because in the book I have made an attempt to cross political boundaries somewhat, and criticise much of the green movement for entrenching itself on the far left, I am now attacked - in John Vidal's words in last week's Observer - as a member of a "strange new grouping" of "free market environmentalists" supposedly allied with "US conservative politicians". Well I never!

Ridley: Back to acid. You say that what I say is false because acid rain was real. I never said it was not. The acidification of rain by sulphur and nitrogen emissions is not at issue, only the degree to which it affected forest survival and growth rates. I made that quite clear in my Times article but you missed it. The cataclysmic claims made in the 1980s about the likely effect of acid rain on forest growth in Germany stand in stark contrast to what actually happened - before any legislation took effect.

Lynas: Sulphate pollution declined massively in both the US and Europe due to legislation in the 1980s - cap and trade in the US, mandatory flue desulphurisation in the EU. This has largely solved the acid rain problem in this part of the Northern hemisphere, although at the price of boosting global warming somewhat by reducing the aerosol albedo in the atmosphere. I don't think this is controversial. And it was undoubtedly due to intergovernmental regulation - in Europe sulphur emissions began to reduce in about 1980, when legislation really began to bite. Can't we celebrate this as a success: rational regulation of a real pollutant thanks to visionary policies, which solved an environmental problem? Why play it down as if it were always a non-issue?

Ridley2: Because it was a non-issue - in terms of effect on forest. It's a myth that clean-air legislation had any effect on forest health. There was not a decline in sulphur emissions till the very end of the 1980s at the earliest, but forest biomass was increasing throughout the 1980s.

Ridley: You accuse me of cherry-picking and misinterpreting scientific studies. How can a peer-reviewed meta-analysis of more than 300 peer-reviewed papers, the main paper I cite [on ocean acidification], be a cherry-pick? And in what way do I misinterpret it? I quote it accurately. Not one of my critics on the ocean acidity issue has laid a glove on any scientific fact that I cite in my book or my article. They merely blow smoke at me by accusing me of leaving things out, or of doing things I do not. Read my responses to them here and hereand here.

An especially good example is the matter of bicarbonate. Did you know that bicarbonate ions increase in concentration with rising dissolved CO2? Did you know that many corals and other calcifiers such as coccolithophores use bicarbonate rather than carbonate as raw material for making skeletons? I did not till I drilled into the scientific literature and found these facts. Somehow a cursory reading of the media had failed to transmit them. Yet three of my critics said that while it is true that bicarbonate increases, carbonate decreases, and then implied that I deny this. I don't, haven't and won't. The obfuscation and distortion practised by the critics rounded up by New Scientist on this issue did shock me somewhat.

Lynas: The answer to your first two questions is yes and yes. Whilst the top-line chemistry of calcium carbonate dissolving in (or being less likely to be precipitated out of) seawater made more acidic by the addition of carbonic acid is intuitively rather simple, everyone also knows that this is an over-simplification. The discussion was too technical for me to include in the main text of my book, but I did put in an endnote pointing out that: "Carbonic acid dissociates into bicarbonate and hydrogen ions (protons). Most marine organisms use carbonate for their shells, and amounts of carbonate (CO3 2-) tend to be depleted as a result of this process." The essential chemistry is explained in much more detail than I am competent to attempt by Feely et al, 2009 (PDF), in the journal Oceanography (vol 22, no 4). I am still not clear where you disagree, and how you manage to conclude thereby that the ocean acidification problem is overblown.

Ridley2: I do not accept that you are right to say "most marine organisms…", because of recent literature showing that many use bicarbonate as the starting point for shell manufacture. I strongly recommend an afternoon spent reading Hendriks et al 2010 (Estuarine, Coastal and Shelf Science 86:157 - $) [who] found that the ion chemistry inside the bodies of calcifiers is more important than that outside them, and there is evidence that some of them - eg coccolithophores - actually find it energetically easier to deposit carbonate shells at slightly lower pH.

Ridley : You then accuse me of a 'mistake' and an 'error' because I say "environmentalists like to call this a 30% increase of acidity". What's the mistake? Where's the error? Environmentalists do like to call it that. They are not wrong, and I do not say they are wrong. It IS a 30% increase in acidity. I merely point out that this is the most alarming way of describing it compared with others. So you have accused me of an error and a mistake that I have not made. This is an unattractive thing to have done, and I would be grateful for a correction in the next printing of your book.

Lynas: I'm afraid the error is yours, and this should be easy to establish. You wrote in the Times piece of 4 November 2010 ('Who's afraid of acid in the ocean? Not me' - $ - this is the piece I quoted in my book) the following:

"The dissolution of carbon dioxide in the oceans may lower the pH slightly to about 7.9 or 7.8 by the end of the century at the worst [from the pre-industrial value of 8.2]. Environmentalists like to call this a 30 per cent increase in acidity, because it sounds more scary than a 0.3 point (out of 14) decrease in alkalinity, but no matter. It is still well within the bounds of normal variation."

This is indeed a mistake, because a 0.3 decrease in pH is not a 30 per cent increase in acidity - it is much more than that. As Feely et al state: "These CO2 levels would result in an additional decrease in surface water pH of 0.3 units from current conditions, 0.4 from pre-industrial, by 2100, which represents an increase in the ocean's hydrogen ion (H+) concentration by 2.5 times relative to the beginning of the industrial era." So if a 0.4 units decrease in pH represents a 150 percent increase in acidity, then a 0.3 units decrease represents much more than a 30 percent increase - it is in fact more than 100 percent. Are you now happy to admit that you got this wrong? (Even if, ironically, it led to you *understating* the 'scary' environmentalist case!) If I may venture an explanation, perhaps this mistake arose because you confused the observed 0.1 unit decrease in pH with the future prediction of 0.3/0.4 units? What we have seen so far indeed equates to about a 30 percent increase in acidity since the pre-industrial oceans thanks to human emissions of CO2.

Ridley2: You are right and I am wrong. I did get muddled between the 0.3 and the 0.1, just as you say. My Times piece should have said 150%. I still find this a misleading way of describing it, given that the entire pH range would covers many thousands of percent, or more.