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Ocean acidification

Posted on 23 June 2010 by Ove Hoegh-Guldberg

While Andrew Bolt continues his character assassination, let's get back to the facts. There are several misconceptions about ocean acidification that require correction, both here and elsewhere.

1.     “Ocean acidification is not a problem because organisms show a variety of responses (both positive and negative).”

The fact that not all organisms or physiological processes respond in the same way to ocean acidification is well known (Hendriks et al. 2009).  This does not, however, logically lead to the conclusion that ocean acidification is not a problem. Organisms like reef building corals, for example, show a consistent 15-54% reduction in calcification with a doubling of atmospheric CO2.  This is a problem irrespective of whether some other groups ( e.g. some bivalves) don't show this type of response.  Given that corals build and maintain coral reefs, the impacts on this group of organisms alone are likely to be large and negative.  

2.     “Ocean pH varies greatly in time and space.  This variability is much greater than any potential effect of carbon dioxide.”

It is true that ocean pH and carbonate ion concentrations do vary over time and space.  The issue, however, here is whether or not average pH is changing over time.  This is essentially the same distracting argument that some people have about the weather (i.e. day-to-day variability in temperature - "it was cold today, therefore climate change is happening.") and climate change (i.e. long-term trends in average temperature). 

3.     “Organisms like corals have been around for hundreds of millions of years, over which time atmospheric carbon dioxide has varied greatly. Therefore, we don't need to be concerned about ocean acidification.”

The fact that corals have survived as a group over long evolutionary time periods is irrelevant to whether or not current changes in ocean pH will impact their ability to build coral reefs. Having a long evolutionary history, gives little information about whether or not marine calcifiers like corals were rare or not at any particular time. Extinction has never been the issue here.  The issue is as follows:  If corals become rarer (and/or calcify less) due to ocean warming and acidification (e.g. (Bruno and Selig 2007; De'ath et al. 2009) then their ability to build and maintain coral reefs will be diminished. This in turn will decrease the ability of coral reefs to provide ecological services and support to over 500 million people worldwide. 

4.     “Carbon dioxide has been high in the past year coral reefs have continued to lay down calcium carbonate”.

This is not supported by the bulk of scientific studies.  Most of the evidence, reveals that marine calcifiers like corals did not form carbonate reef systems during periods of high CO2 in the past (Veron 2008 etc.).  There are big gaps in the depositions of carbonate during these periods.

5.     “We don't understand how the ocean works hence we do not have good evidence that ocean acidification is occurring.”

Modelling studies based on what are essentially simple geochemical processes have matched the observed decline in ocean pH.  Essentially, while we are there is still much to learn about how the ocean works, there are many empirical studies that show that ocean pH is changing rapidly. An excellent description of this work can be found in Doney et al. (2009).  Ocean acidification is occurring at rates which dwarf anything seen over the recent past.

Bruno, J. F. and Selig, E. R. 2007. Regional decline of coral cover in the indo-pacific: timing, extent, and subregional comparisons. PLoS ONE 2 (1):e711.

De'ath, G., Lough, J. M., and Fabricius, K. E. 2009. Declining Coral Calcification on the Great Barrier Reef. Science 323 (5910):116-119.

Doney, S., Fabry, V., Feely, R., and Kleypas, J. 2009. Ocean Acidification: The Other CO2 Problem. Annual Review of Marine Science 1:169-192.

Hendriks, I., Duarte, C., and Álvarez, M. 2009. Vulnerability of marine biodiversity to ocean acidification: A meta-analysis. Estuarine, Coastal and Shelf Science.

 Veron, J. 2008 Mass extinctions and ocean acidification: biological constraints on geological dilemmas. Coral Reefs 27:459-472.

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Comments 51 to 69 out of 69:

  1. Arabian Sea - with a pH of one of the lowest in the world (less than 7.95) ... In my youth, the first textbook about the life of the sea was, of course, "Sea Life" (Demel, 1974) Professor Demel, the eminent scientist (already dead), a member of many international scientific societies ... Recently, after many years, I found this book. Today I found there the following passages: "The Red Sea is a sea of the world's hottest maximum temperature in summer on the surface to 30oC, with "slots" extremely hot waters with temperatures exceeding 50 ° C and at depths to 2000 meters, not falling below 21.5 ° C ...", they has: "many strange sponge and very rich [...] coral reefs." and: "Persian Gulf, plate, lying on the shelf, the highest in the sea water temperature (up to 36 deg. C) is a place in the richest fishing mollusc (Pteriidae) of global world... " Professor ends like this: "THESE WARM SEA’S CHARACTERIZED MOST DIVERSE AND VARIED LIFE IN OCEANS AS WE KNOW."
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  2. “A team of scientists from the New York-based Wildlife Conservation Society (WCS) has reported a rapid recovery of coral reefs in areas of Indonesia, following the tsunami that devastated coastal regions throughout the Indian Ocean four years ago today. The team, which has surveyed the region's coral reefs since the December 26, 2004 tsunami, looked at 60 sites along 800 kilometers (497 miles) of coastline in Aceh, Indonesia. The researchers attribute the recovery to natural colonization by resilient coral species, along with the reduction of destructive fishing practices by local communities. While initial surveys immediately following the tsunami showed patchy (albeit devastating) damage to coral reefs in the region, surveys in 2005 indicated that many of the dead reefs in the study area had actually succumbed long ago to destructive fishing practices such as the use of dynamite and cyanide to catch fish. [...] It is also possible that the crown of thorns starfish—a marine predator—had caused widespread coral mortality.”
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  3. "THESE WARM SEA’S CHARACTERIZED MOST DIVERSE AND VARIED LIFE IN OCEANS AS WE KNOW." I don't think anyone is suggesting that dropping the pH a few tenths of a point - even a full point or two - or raising the temperature a degree or two or five is incompatible with life, which seems to be the strawman argument you're addressing. Try this thought experiment: change the temperature in the Red Sea to that of the mid-Pacific. What happens to the that "MOST DIVERSE AND VARIED LIFE"? Now change the pH to that of the mid-Pacific. What happens? Now, change both of them, and not over the tens or hundreds of thousands of years that (I'm guessing) the Red Sea biome had to adapt to the current conditions, but in the course of a century or two. What happens?
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  4. Stop whining about C02 Is it an insurmountable intellectual challenge to realize that we're capable of causing more than one problem simultaneously and that different problems may act on different time scales? Please, you can do better.
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  5. VoxRat # 32 - The issue deals with how much of the CO2 that is taken up by the ocean does in fact convert to carbonic acid. From what I've found out only 15% is converted, the balance being held in a "molecular trap" of water molecules. Hence the basis of my post is that not all of the CO2 going into the ocean is converted to carbonic acid and once you've factored that in, the role of SO2 in acidification becomes much more evident...nuff said.
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  6. #44 Peter Hogarth at 20:54 PM on 25 June, 2010 overarching concerns on anthropogenic CO2 (specifically) and reduced alkalinity of the Oceans can be summarized in the following images And you show us this picture: The original one in Feely, et al. PICES Press 16(1), 22-26 (2008) looked like this: Caption: Atmospheric carbon dioxide from Mauna Loa (ppmv) and pCO2 (μatm), and surface ocean pH time series data from Ocean Station Aloha So pCO2 and pH are not from "North Pacific Ocean" in general, but specifically from monthly cruises to the deep-water Station ALOHA (A Long-Term Oligotrophic Habitat Assessment; 22° 45'N, 158° 00'W) as part of the Hawaii Ocean Time-series (HOT). You can have a look at ocean pH at the HOT site by choosing "pH Comparison". It is the pH data trend as derived by the HOT sampling program and looks like this: It is not exactly the graph shown by Feely in light blue, but looks similar. Alas, it is not all actual data, but some measurement (red) overlaid on something calculated by the HOT sampling program in an unspecified way (blue). Values actually measured, then adjusted by HOT look like this: Not quite the trend above, but still. Fortunately HOT also has an ftp site with all the raw data from 206 cruises. ftp://ftp.soest.hawaii.edu/dkarl/hot/water/ If one takes pH measurements from there, gets something like this: Now that's outrageous. There is no way one can get the red line from these raw pH data. The first run, before 2000 is obviously unusable. It is pure junk. But let's have a closer look at the latter part, between 2003 and 2008. N O   T R E N D  whatsoever. Data enhancement like this in any other branch of natural sciences would be considered impermissible. However, it is standard practice in mainstream climate science (sorry, but I am getting angry).
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  7. GeoGuy #55 "From what I've found out only 15% is converted, the balance being held in a "molecular trap" of water molecules." But it turns out you're wrong about that. Where did you get this (mis)information?
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  8. Berényi Péter, if the data you found over the internet do not match what's published you have two possibilities: 1) assume you're doing something wrong or misunderstanding something and eventually ask to the people responsible for the data; 2) assume you're right, get angry at the scientists and join the "it's a conspiracy" crew. You choice. The rest of the readers might want to take a look at the "official" data.
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  9. BP, a suggestion. Rather than become angry, why not follow step-by-step the methods used by HOT and identify where you think they run off the rails, where their method is specifically defective? The graphs you're displaying create a strong impression but your argument boils down to There is no way one can get the red line from these raw pH data. This is remindful of the ocean heat matter. You say it's wrong, but you can't say how, exactly. Just so we're on the same page, here's the method as reported by HOT: Feb 17, 2009 - All HOT pH data presently available through HOT-DOGS were collected using the spectrophotometric method of Clayton and Byrne (1993) and are reported at a constant temperature of 25°C. The +0.0047 unit correction suggested by DelValls and Dickson (1998) has NOT been applied to any HOT data. The 1992-1993 HOT pH data were originally reported on the Seawater Scale, while later data have all been reported on the Total Scale. For the sake of consistency, the 1992-1993 pH data have as of today been converted to the Total Scale according to Lewis and Wallace (1998). The Total Scale values are approximately 0.01 pH units higher than the Seawater Scale values they replace. The cruises affected are HOT 36-47 and HOT 49-50. Prior to 1992, on HOT 23-32, pH measurements were made using a pH electrode calibrated with NBS buffers and were reported on the NBS Scale. Potentiometric measurements of pH are inherently less precise than spectrophotometric measurements. Moreover, the relationship between the NBS Scale and the Total Scale is not exact and depends on characteristics of the electrode employed. Given these difficulties, we have not attempted to correct the pre-1992 data to the Total Scale. They are available in the raw data files via FTP and remain as reported on the NBS Scale, but have been assigned a questionable quality flag and thus are not accessible through HOT-DOGS. References: Clayton, T.D., and R.H. Byrne. 1993. Spectrophotometric seawater pH measurements: total hydrogen ion concentration scale calibration of m-cresol purple and at-sea results. Deep-Sea Res. I 40: 2115-2129. ; DelValls, T.A., and A.G. Dickson. 1998. The pH of buffers based on 2-amino-2-hydroxymethyl-1,3-propanediol (tris) in synthetic seawater. Deep-Sea Res. I 45: 1541-1554. ; Lewis, E., and D.W.R. Wallace. 1998. Program Developed for CO2 System Calculations. ORNL/CDIAC-105. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee.
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  10. Thanks Doug, Riccardo, Berényi Péter at 04:34 AM on 26 June, 2010 It is a shame you get angry instead of taking time to be more thorough and thoughtful. I have always tried to treat your responses and somewhat tangential offerings in a gracious manner. In response to your unnecessary detective trail, allow me to clarify. The image I presented was one of many from sources around the world I could have chosen, but it had the merit of being clear and uncluttered. Here is one from Doney 2010 (which I think you should purchase and read) using updated data, and the image is adapted from Dore 2009 which is free, but which you should also read in full. You question the colour coding of the data presented in my first image. Well here is the correct explanation (from the Doney 2010) image which is at odds with your assumed one. All values are measurement based. You are wrong to simply assume otherwise based on some bias you seem to have, or some quick internet search. Red symbols are partial pressure of CO2 in seawater calculated from measured DIC (dissolved inorganic carbon) and TA (total alkalinity). Green symbols are direct measurements of pH in water-saturated air at in situ seawater temperature. Further let me quote from Doney 2010 as you have previously seen fit to reproduce an image from Doney 2006 to support your argument: “The rates of change in global ocean pH and are unprecedented, a factor of 30 to 100 times faster than temporal changes in the recent geological past, and the perturbations will last many centuries to millennia. The geological record does contain past ocean acidification events, the most recent associated with the Paleocene-Eocene Thermal Maximum 55.8 million years ago. But these events may have occurred gradually enough and under different enough background conditions for ocean chemistry and biology that there is no good paleo-analog for the current situation” Perhaps you should consider my calm measured interpretation of what the experts and Oceanographers around the world are saying, and apologise.
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  11. Berényi Péter at 04:34 AM on 26 June, 2010 I anticipate that some may argue that the ALOHA data set could be some freak regional anomaly. I mentioned that other oceans and regions are showing similar trends. From NOAA coral reef watch for Greater Caribbean region. Data is surface Aragonite saturation state (used because this is related to coral calcification rates). This is directly proportional to carbonate ion concentration, and hence indirectly to pH. It is up to date and based on ongoing geochemical measurements backed by modeling based on satellite measurements of SST etc. Solid points are confirmed measurements, open points are preliminary. Methodology is described here There are also long time series (25 years) for the high North Atlantic Olafsson 2009 and an admittedly limited number of others. Whilst it is true we do not have a global monitoring network for ocean chemistry yet, we do have enough information from continuous independent measurements from various locations to state that the change in Ocean pH (call it what you will, semantics won’t alter the data) is a reality and is directly caused by the increased atmospheric CO2. We know that this pCO2 increase is a global phenomenon, but is interestingly highest in the North Atlantic. Feely 2010 et al call for a new comprehensive integrated observational network to maintain and increase the reliability and coverage of our data. Take a look at the organizations below the author list. This represents a great deal of collective expertise. To gain further insight into the reality of what we are measuring look at the presentations in pCO2 workshop 2007 These are sobering. Increased pCO2 is evident almost everywhere we look, it tracks the steadily rising atmospheric CO2, mostly just below, meaning on average the Ocean is a sink. For example: Many areas previously identified as CO2 sources are now unambiguously net sinks. Global average pH is steadily decreasing in the upper layers. Some small comfort may be derived from the possibility that reducing Arctic ice cover will allow a significant increase in area of open water that will increase the net CO2 sink.
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  12. #60 Peter Hogarth at 10:21 AM on 26 June, 2010 It is a shame you get angry instead of taking time to be more thorough and thoughtful Yes, it is. Let me apologize for that. Fortunately you guys are here to set things straight. What I have actually done is to lump together pH measurements for all sites (there are 24 of them, STNNBR 1-19,50-52,60-61) and all depths (down to 4909.7 dbar, that's about 4821 m). This is what is shown in the graphs above and this is why pH values are so low. Now I see mean surface values are defined as average of measurements taken between 0-30 dbar, that is, the upper 30 m of ocean. As for the sites, Aloha is STNNBR 2. I can see two more, Kahe (1) and Kaena (6). Could not find documentation for the rest. It may be due to the fact neither hot*.sea nor Readme.water.woce referenced in the BEACH Water Column Chemical Data Format Document are to be found at the FTP site. Click to enlarge As 87.4% of all measurements were performed at STNNBR 2 (Aloha), depth must be the real problem. At that site only 17.2% of measurements were done "at surface" (down to 30 dbar). With these in mind I will redo my analysis and let you know the results. I assume pH calculations based on other parameters were done by the co2sys. As source code is not available at the CDIAC site, it is a bit cumbersome to perform a proper audit. Documentation of algorithms implemented is also deficient. IMHO no scientific work should be based on closed source applications.
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  13. Well it's a good thing that Peter, Riccardo and Doug were here to audit the auditor, isn't it? Let's see what kind of language we find in the "audit": "Outrageous, impermissible, no trend whatsoever." All generously sprinkled with subtle suggestions of incompetence or fraud, based on a superficial and rather incompetent "audit" that the auditor himself now acknowledges as needing to be entirely redone. Perhaps BP should hold on the emotional response, the grandiloquent language and the veiled suggestions of fraud or incompetence until absolute certitude is established that someting is amiss.
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  14. Berényi Péter at 01:56 AM on 27 June, 2010 Being charitable, I see what you have done on your final charts. With hindsight an obvious misunderstanding that should be very quickly clarified here. When we talk about “ocean acidification” we are really talking about pH changes in the upper layers, and not the entire water column. As you have found, deeper waters are much less alkaline anyway (pH around 7.6 at around 700m in this case) and clearly it is the interaction with increasing atmospheric CO2 in the upper layers that is driving the “acidification” process - top down. If you had tracked down and read Dore 2009 (linked above) and looked at figures 1 and 2 you might have saved yourself a bit of aggravation. The variation of pH with depth, and the rate of change of pH with depth, for both the measured and “calculated” values, are shown in figure 2 and it is definitely worth showing on this thread, though I would advise looking at the original, as there is a pleasing level of detail. Hope this is all starting to make sense.
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  15. @VoxRat "... a century or two ...” - you must compared with: “... a rapid recovery of coral reefs in areas of Indonesia, following the tsunami ... [2004 -2009]” As was the myth about the current rapid growth of abnormal pH, I recommend: http://omniclimate.wordpress.com/2009/02/04/a-shell-game-behind-ocean-acidification/
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  16. "... growth ..." - of course not pH but change of pH
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  17. Arkadiusz Semczyszak #65 "“... a rapid recovery of coral reefs in areas of Indonesia, following the tsunami ... [2004 -2009]” Because some ecosystems can recover rapidly from some kinds of damage is not much of a case that a global acidification of the oceans is nothing to worry about. "As was the myth about the current rapid [change] of abnormal pH" What "myth" is that, exactly? "I recommend: http://omniclimate.wordpress.com/2009/02/04/a-shell-game-behind-ocean-acidification/ " Yes. I think we all agree that there have been times in the past when atmospheric [CO2] (and presumably ocean-surface acidity) were considerably higher. And we all agree that life can survive even under the extreme conditions of deep ocean volcanic vents. No one is saying CO2-induced acidification (or temperature rise, or anything else) is going to sterilize the planet. The point is: what happens when you abruptly change critical parameters (like pH, Omega-arag, and temperature) to ecosystems that have adjusted to current conditions over millions of years? I'm not so confident, as you appear to be, that the answer is "nothing much".
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  18. #67 VoxRat at 20:34 PM on 28 June, 2010 ecosystems that have adjusted to current conditions over millions of years Global climate went crazy about 3 million years ago and the instability due to the general cooling trend is getting ever worse. Like a bad case of microphone whine. Current ecosystems are adjusted to this ever changing environment. It is part of the reason humans could afford to have an oversized brain in spite of its huge energy costs and cooling problems. If conditions are kept constant, there is no point whatsoever in being able to figure out what to do in case conditions would change. Keep in mind that all the endangered coral reefs of the world are substantially younger than twenty thousand years. Eighteen thousand years ago present day reef sites were on high ground, 120 m above sea level. That; and the arithmetic fact one hundred fifty times twenty thousand makes three million.
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  19. BP #68 Specifically with respect to pH, though the subject of this discussion... Your graph doesn't have anything to say about the extent or rapidity of pH changes. I guess when these guys http://www.sciencedaily.com/releases/2009/05/090519111031.htm publish their findings we'll have something to compare current trends with.
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  20. At a talk last night David Archibald finished by showing a picture of some coral and CO2 bubbling past. Well they were bubbles, but he said it was CO2 and the coral looked dead to me and he said there were fish swimming around though I couldn't see any in the photo. What do you make of his claim that coral is resililent to acidification?
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  21. JC #70 "At a talk last night David Archibald finished by showing a picture of some coral and CO2 bubbling past. " CO2 bubbling past!? That would indicate that the water is saturated with CO2. "What do you make of his claim that coral is resililent to acidification? " It looks to me it's worth the paper it's printed on. Assuming it's not printed.
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  22. CO2 bubbling? A piece of ocean acting like a soda pop? Sorry but that looks like total nonsense at first glance.
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  23. @geo guy @13.  Concerning scrubbers.  Would it be possible to to put scrubbers to use around the world to start cleaning the air in the atmosphere?  Is that even feasible?

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  24. @geo guy that should read "start cleaning the CO2 out of the atmosphere"

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  25. Great idea. We already have one. It’s called C4 perennial grasses in symbiosis with AMF. [1]

    C4 carbon fixation - Wikipedia

    C4 metabolism originated when grasses migrated from the shady forest undercanopy to more open environments,[2] where the high sunlight gave it an advantage over the C3 pathway. [3]

    … Today, C4 plants represent about 5% of Earth's plant biomass and 3% of its known plant species.[4][5] Despite this scarcity, they account for about 23% of terrestrial carbon fixation.[6][7] Increasing the proportion of C4 plants on earth could assist biosequestration of CO2 and represent an important climate change avoidance strategy.

    Glomalin is Key to Locking up Soil Carbon

    Of course that “scrubber machine” while capable of cooling the planet: Cenozoic Expansion of Grasslands and Climatic Cooling is currently plowed, herbicided, burned, overgrazed, undergrazed, eroded, paved over and otherwise molested to the point that it basically no longer works very well. This means approximately 1/2 of emissions goes into the oceans and that's why we have ocean acidification. If we put that back in the soil where it belongs, then we solve both problems at once. Two birds with one stone. (actually a whole flock of birds but that is for a different thread)

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  26. Scrubbers are technically feasible - see the IPCC WG3 report or perhaps look at Lackner's work. After all, everyone who thinks they need a car could have one these??? Whether economically feasible or more to the point, cheaper than just transitioning from FF, is another story.

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