Debate with Matt Ridley on ocean acidification

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 here and 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.


  1. Barry Woods

    Hi Mark you mention ‘denialist’ websites.
    %or the sake of clarity could you actually identify them.

    I assume you do NOT mean Matt Ridley, Watts up, bishop hill, donna laframboise, judith curry, climate audit, jo nova even realclimategate!

    Many environmentalists would label them as ‘denier’ to exclude them from any debate, these are the same groups that would call you a chernobyl death denier, so it does not work both ways.


    1. J Bowers

      Barry, you’re tone trolling.

      Judith Curry regularly uses the term “alarmist” while reserving “skeptic” for her new found buddies. Watts is a denialist, as in equivalent to an HIV/AIDS denier, which has been in use since the end of the 1980s. You can find many references to “denialism” in the peer reviewed literature when describing those who reject an overwhelming scientific consensus.

      You can add “delayers”, “rejectionists”, “contrarians”, “Luddites” and “fake sceptics”, to counter “CAGW-ers” (Catastrophic Anthropogenic Global Warming…ers), “Fraudsters”, “religious zealots”, “Nazis”, “eco-fascists”, etc.

      Hope that helps.

    2. Barry Woods

      What am I then J Bowers – I write (on occasin) for WUWT. your choice of labels I think says more about you than I. I imagine a neutral observer would see it for the attempt to close down any debate, by abuse.


      Anthony Watts and James Randerson (Guardian environment ) agreeing that denialist had bad connotations and that the Guardian would not use it. Following a polite request from Anthony Watts.

      James Randerton – Guardian

      “We have been discussing such terminology, and some of my colleagues have suggested that Guardian style might be amended to stop referring to “climate change deniers” in favour of, perhaps, “climate sceptics”.

      The editor of our environment website explains: “The former has nasty connotations with Holocaust denial and tends to polarise debate. On the other hand there are some who are literally in denial about the evidence. Also, some are reluctant to lend the honourable tradition of scepticism to people who may not be truly ‘sceptical’ about the science.” We might help to promote a more constructive debate, however, by being “as explicit as possible about what we are talking about when we use the term sceptic”.

      Most if not all of the environment team – who, after all, are the ones at the sharp end – now favour stopping the use of denier or denialist (which is not, in fact, a word) in news stories, if not opinion pieces.”


      Anthony Watts from the same article, including his position on AGW (hardly a denier)

      Anthony Watts: “I call on readers of WUWT to reciprocate this gesture by The Guardian by refraining from labeling others they may disagree with here and at other web forums.

      Let’s all dial back and treat others with the same respect in conversation as you might treat dinner guests having a discussion at home.

      My position has been that there is no debate that the earth has warmed over the past 100+ years, but that the magnitude of the measured warming and the cause(s) remain in debate. The question of whether such warming is beneficial or detrimental depends on who you ask. I’ll also point out that it took our modern society about 150 years of science and technology advances to get where we are now. Doing it cleaner and better won’t be an overnight solution either.”

      J Bowers, compare the above wth your ‘contributions’

    3. J Bowers

      What am I then J Bowers – I write (on occasin) for WUWT.”

      Probably wrong.

    4. Barry Woods

      Probably is progress 😉 !

    5. J Bowers

      Probably is not even wrong.

      By the way, did you ever discuss the Swift Hack email explaining what a scientific trick is? You are that guy who runs Real Climategate, right? You should do it, it’d make you the only rejectionist blogger to have ever done so.

  2. J Bowers

    James Hrynyshyn on Matt Ridley and the Holocene Optimum.

    Matt Ridley caught cherry picking.

  3. J Bowers

    By the way, Mark, don’t get hung up on the label of “right wing” which Ridley objects to, who instead prefers “liberal”. He’s an academic adviser to the GWPF which is run by the grandfather of British neoliberal economics, Nigel Lawson, and Austrian school of economics pundit, Benny Peiser. Their board of advisers, including Ridley, is almost a who’s-who of neoliberal “AGW rejectionists”. These include many who have been utterly and repeatedly trashed on the subject of climate change, and that includes Richard Lindzen in the peer reviewed journals.

    1. Barry Woods

      if you look at who is involved in the GWPF,you see cross bench support, labour liberal conservative.

      You see individuals that are brave enough to put up with the abuse and inuendo that they recieve from the Bob Wards, and J Bowers of the world..

      Graham Stringer MP (labour) sat down alongside Lord Lawson, at the Spectator debate on this issue.

    2. J Bowers

      But it’s still a rogue’s gallery of neolib denial. The rest are extras.

    3. Barry Woods

      well that is you opinion, why the abuse.

    4. J Bowers

      What abuse?

  4. Philip


    You mentioned in passing the decline in suphate pollution in the US and Europe, and of course I agree with you that this is a genuine cause to celebrate. I’m a little curious though to understand more clearly your further point about this decline causing a subsequent boost to global warming. If you look at the global figures for sulphate emissions –, figure 3a – you find that, when you take into account those from elsewhere, they’ve been pretty much static since the late 1960s. Naively, the effect of the associated aerosols on global warming should have been more or less static as well. Is this not the case, or are there other related effects that invalidate this conclusion?

  5. Jack

    I’m very wary of Ridley

    “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”

    ‘creative destruction’ is a rather unfortunate way of putting it… I think it belies a reckless arrogance (yes I know where the term comes from):
    someone recently wrote a pro capitalism book called Ferraris For All. I think that’s what it was called… I daresay he made some good points but he spoiled it rather badly from the get go. I think he got the title from a group of school children in India when asked what they most wanted in life, most, or a lot, of them answered Ferraris.

    I actually happen to think Ferraris are rather impressive, even beautiful, creations. I wonder how many of these children were girls? probably none, not directly at least, but oh, I’m sure the boys were in no doubt that Ferraris would enhance their pulling power (manifestation of sexual selection without honourable intentions) – if they could find roads not too congested, and not too remote, to cruise on. But if all the boys get flash cars then, well, they’re largely back at square one.

    It all says a lot about the nature of the ‘capitalism’ the author has in mind. Yes, supposedly free, free of moralising socialist dictators telling people what’s good for them (tut tut, I hear Diana Coyle say). Such a ‘free’ capitalism, is largely free of concern for, say, the depleting aquifers in Punjab and laying waste the world’s resources – and the future prospects of the majority of boys who want flash cars and more so any off-spring they may have.

    It also reminds me of a form of ‘feminism’ going under the banner ‘Slutwalk’ such reckless, shameless, arrogance has far greater consequences than a run on a bank, though it’s all related as Ridley (Red Queen) should know. He understands only too well the Tails of Lekcess;

    “Even a survey of fifteen powerful leaders of the feminist movement revealed that they wanted still more powerful men. As Buss’s colleague Bruce Ellis put it, ‘Women’s sexual tastes become more, rather than less, discriminatory as their wealth, power and social status increases.”

    On that theme, take The Lost Land Of The Volcano series where naturalists etc doing commendable work exposing the scale of deforestation in New Guinea and discovering threatened fauna and flora in .


    The cameraman, Gordon Buchanan, filming birds of paradise; The Disco Scenario. He’s good at what he does and he’s basically right I suppose, but he seems oblivious to the irony of what he’s saying. Not so much anthropomorphizing as Gordomorphizing. “gets the best choice of women, and he gets the *best* women.” Interesting emphasis of value judgement “it’s very easy to understand” say’s he nodding self assuredly.

    I wonder how he’d put his slant on Bowerbirds with their material acquisitiveness or Bonobo monkeys or, more to the point, Montane and Prairie Voles?

    Perhaps Ridley might care to enlighten us.

  6. J Bowers

    Mark, you might find this of interest (H/T to Hank Roberts):

    Setting the record straight almost impossible

    “The effect of misinformation on memory and reasoning cannot be completely eliminated, even after it has been corrected numerous times, say Australian psychologists.

    Assistant Professor Ullrich Ecker and colleagues from The University of Western Australia outline their findings in a recent article published in Psychonomic Bulletin and Review .

    Ecker says this effect, known as ‘continued influence effect of misinformation’, occurs even if the retraction itself is understood, believed, and remembered.
    “If you believe in something strongly and it’s really important to you as a person [your worldview] you will cling to that no matter what,” Ecker remarks.

    He says one example of this is climate change.

    “People who believe strongly in the free market, those opposed to any kind of regulations … will be much more likely to continue to believe humans are not causing climate change even in the face of overwhelming scientific evidence that humans are causing climate change.”

    Seems appropriate.

  7. Barry Woods

    I wonder if China and India are going to stop burning LOTS of coal?!
    Do they not care about the oceans, or just not believe the hype?

    One Indian state’s extra planned coal powered stations are more tha the UK’s ENTIRE electrity generation, and they could get carbon credits!
    An impecable source (The Guardian)

    “A single Indian state is to build a new fleet of coal-power stations that could make it one of the world’s top 20 emitters of carbon emissions – on a par with countries such as Spain or Poland.

    In an echo of the Chinese economy in the 1990s which depended on the exploitation of vast reserves of coal, India last year approved plans for 173 coal-fired power stations expected to provide an extra 80-100 gigawatts (GW) of electricity capacity within a few years. Many are expected to be fuelled by cheap coal imported from Australia, Indonesia and southern Africa, but applications to mine more than 600m tonnes of coal in India have been lodged.”

    1. J Bowers

      I wonder why China’s racing ahead with renewables? I wonder why China’s smacking heavy CO2 emitting biusinesses with a CO2 tax in their next Five Year Plan?

    2. Barry Woods

      Rejectionist’ is a new one, neolib denial is also not exactly unabusive either….what exactly am I rejecting, for example, sea levl rises of 2M, 3m, 7m (flannery) or a more realistic 20 to 30 cm?

      I was talking about INDIA, any thoughts on that, but does anybody believe that China’s emissions are going anywhere but up as well? As coal and nuclear are racing way ahead of nuclear by any comparitive measure.

      As for trick’s Professor Judith Curry, Professor Jonathan Jones and Paul Dennis are more eloquent than I. Try ‘hiding the decline (part I,II & III) at Climate Etc.

    3. Barry Woods

      Oops, meant to say coal & nuclear are racing ahead of renewables…

  8. J Bowers

    Barry, for someone with a blog that has Climategate in the title, I’m very surprised that you haven’t even read the emails. I’ve read Joan of Arc’s* blog on the subject of “hide the decline”, by the way, and find it misled or misleading.

    But the classic mistake you make is that you’re confusing “Hide the decline” with “Mike’s trick”. They’re completetly unrelated and have nothing whatsoever to do with each other. It;’s the same 101 mistake that Richard Muller made, which also demonstrated that he had zero grasp of the subject when he was pronouncing foul play by climate scientists before he found out that his own analysis matched that of…. the climate scientists.

    The “decline” is about northern tree-rings, whereas “Mike’s trick” is about global temperatures. Unrealted. But here’s another one of those emails (as you haven’t bothered with them), which demonstrates that there is such a thing as a “trick of the trade” in science…

    # 1200162026
    “I would note that the distribution of rejection rates is like the distribution of precipitation in that it is bounded by zero. A quick-and-dirty way to explore this possibility using a “trick” used with precipitation data is to apply a square root transformation to the rejection rates, average these, then reverse transform the average. The square root transformation should yield data that is more nearly Gaussian than the untransformed data.”

    In the case of Michael Mann’s “trick”, the instrumental and reconstructed temperatures were clearly labelled. Where Phil Jones’s application of it was used, the WMO requested he simplify a graphic for their pamphlet cover. Big deal.

    The “decline” has also been openly discussed in the peer reviewed literature since 1995 (Jacoby & D’Arrigo 1995). Gasp, big secret! Here’s a Google Scholar search with 1,530 hits on the search term ‘dendrochronolgy divergence’.

    * A term used in adulation at her own blog where she has done nothing to contradict it.

    1. Barry Woods

      Well I have read the emails…

      and the issue is what was presented to policymakers, who I imagine even make it through the summaries.. I don’tthink they will be diving into the actuall literature to discover that what they have been presented is a lot more ceratin than th eliterature justifies…

      I tend to agree with Professor Jonathon Jones, Professor Judith Curry, and Paul Denniss..

      The other question that needs asking, why Phil Jones, did you feel the NEED to ask others to delete emails relating to the IPCC process, and the NEED to hide ‘declines’ and not present data that is available.

      Lest of course policymakers realise that maybe proxies aren’t quite as good as they are made out…

      J Bowers why not start your own blog and tell the world, very easy to do… 😉

    2. J Bowers

      You’re Gish Galloping. How is Jonathan Jones’s FOI even remotely relevant to what you were talking about? Has Judith Curry ever published on global temperature or dendrochronolgy, or even detection and attribution?

      I think your point is to smear. The irony.

  9. Barry Woods

    sigh – I still can’t type…

    Professor Jonathgon Jones (from links above) – criticising Sir Paul Nurse / Sir John Beddington ? as well (suposed leaders of UK science)

    Professor J Jones:
    “However, “hide the decline” is an entirely different matter. This is not a complicated technical matter on which reasonable people can disagree: it is a straightforward and blatant breach of the fundamental principles of honesty and self-criticism that lie at the heart of all true science. The significance of the divergence problem is immediately obvious, and seeking to hide it is quite simply wrong. The recent public statements by supposed leaders of UK science, declaring that hiding the decline is standard scientific practice are on a par with declarations that black is white and up is down. I don’t know who they think they are speaking for, but they certainly aren’t speaking for me.

    I have watched Judy Curry with considerable interest since she first went public on her doubts about some aspects of climate science, an area where she is far more qualified than I am to have an opinion. Her latest post has clearly kicked up a remarkable furore, but she was right to make it.

    The decision to hide the decline, and the dogged refusal to admit that this was an error, has endangered the credibility of the whole of climate science. If the rot is not stopped then the credibility of the whole of science will eventually come into question.”

  10. Doug Mackie

    The chemistry of ocean acidification is indeed deceptively complex. Our 18 part series over at John Cook’s skeptical science attempts to explain it. The link is to the introductory post. Parts 1-7 (of 18) have been published. More to come.

  11. J Bowers

    Requiem for the sea: State of the Seas report concludes “negative changes” to the oceans exceed IPCCs worst case scenarios.

    Main points from the PDF of Rogers, A.D. & Laffoley, D.d’A. 2011. International Earth system expert workshop on ocean stresses and impacts. Summary report. IPSO Oxford, 18 pp.

    • Human actions have resulted in warming and acidification of the oceans and are now causing increased hypoxia.

    • The speeds of many negative changes to the ocean are near to or are tracking the worst-­‐case scenarios from IPCC and other predictions. Some are as predicted, but many are faster than anticipated, and many are still accelerating.

    • The magnitude of the cumulative impacts on the ocean is greater than previously understood

    • Timelines for action are shrinking.

    • Resilience of the ocean to climate change impacts is severely compromised by the other stressors from human activities, including fisheries, pollution and habitat destruction.

    • Ecosystem collapse is occurring as a result of both current and emerging stressors.

    • The extinction threat to marine species is rapidly increasing.

    The participants concluded that not only are we already experiencing severe declines in many species to the point of commercial extinction in some cases, and an unparalleled rate of regional extinctions of habitat types (eg mangroves and seagrass meadows), but we now face losing marine species and entire marine ecosystems, such as coral reefs, within a single generation. Unless action is taken now, the consequences of our activities are at a high risk of causing, through the combined effects of climate change, overexploitation, pollution and habitat loss, the next globally significant extinction event in the ocean. It is notable that the occurrence of multiple high intensity stressors has been a pre-requisite for all the five global extinction events of the past 600 million years (Barnosky et al., 2009).


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