Diverse coral communities persist, but bioerosion escalates in Palau’s low-pH waters
From Woods Hole Oceanographic Institute :
As the ocean absorbs atmospheric carbon dioxide (CO2) released by the burning of fossil fuels, its chemistry is changing. The CO2 reacts with water molecules, lowering the ocean’s pH in a process known as ocean acidification. This process also removes carbonate ions, an essential ingredient needed by corals and other organisms to build their skeletons and shells.
Will some corals be able to adapt to these rapidly changing conditions? If so, what will these coral reefs look like as the oceans become more acidic?
In addition to laboratory experiments that simulate future ocean conditions, scientists are studying coral reefs in areas of the ocean where low pH is naturally occurring to try and answer important questions about ocean acidification, which threatens coral reef ecosystems worldwide.
One such place is Palau, an archipelago in the far western Pacific Ocean. The tropical, turquoise waters of the Palau Rock Islands are naturally more acidic due to a combination of biological activity and the long residence time of seawater within its maze of lagoons and inlets. Seawater pH within the Rock Island lagoons is as low now as the open ocean is projected to be as a result of ocean acidification near the end of this century.
A new study led by scientists at Woods Hole Oceanographic Institution (WHOI) found that the coral reefs there seem to be defying the odds, showing none of the predicted responses to low pH except for an increase in bioerosion — the physical breakdown of coral skeletons by boring organisms such as mollusks and worms. The paper is to be published June 5 in the journal Science Advances.
‘Based on lab experiments and studies of other naturally low pH reef systems, this is the opposite of what we expected,’ says lead author Hannah Barkley, a graduate student in the WHOI-MIT joint program in oceanography.
Experiments measuring corals’ responses to a variety of low pH conditions have shown a range of negative impacts, such as fewer varieties of corals, more algae growth, lower rates of calcium carbonate production (growth), and juvenile corals that have difficulty constructing skeletons.
‘Surprisingly, in Palau where the pH is lowest, we see a coral community that hosts more species, and has greater coral cover than in the sites where pH is normal,’ says Anne Cohen, a co-author on the study and Barkley’s advisor at WHOI. ‘That’s not to say the coral community is thriving because of it, rather it is thriving despite the low pH, and we need to understand how.’
When the research team compared the communities found on Palau’s reefs with those in other reefs where pH is naturally low, they found increased bioerosion was the only shared common feature.
‘Our study revealed increased bioerosion to be the only consistent community response, as other signs of ecosystem health varied at different locations,’ Barkley says.
‘This is important because on coral reefs, the balance between calcium carbonate production and removal by bioerosion and dissolution is very tight,’ adds Cohen. ‘So even if rates of production are not affected by ocean acidification — as we see on Palau — an increase in bioerosion can shift reefs to a state of net calcium carbonate removal, threatening their survival.’
Rapidly changing chemistry
Since the beginning of the Industrial Revolution, ocean pH has fallen by 0.1 pH units, which represents an increase in acidity of approximately 30 percent. For marine life that has evolved over millions of years in relatively stable pH conditions, this kind of rapid change doesn’t allow for much time to adapt. By the end of this century, pH levels are projected to be nearly 150 percent more acidic, resulting in a pH that the oceans haven’t experienced for more than 20 million years.
There are several sites around the world where CO2 is released by undersea volcanic activity that vents up from the seafloor through the base of the reefs, creating a much lower pH environment than is currently found in the open ocean. These ‘natural’ laboratories are giving scientists a rare opportunity to examine what is already happening to corals dealing with lower pH levels predicted for the future.
One example is a coral reef system located among the volcanic islands of Papua New Guinea. Here, streams of gas bubbles rise up from the seafloor, lowering the pH of the overlying seawater. Similar low pH conditions are found at vent sites off Japan, freshwater seeps in Mexico, and upwelling areas in regions of the eastern tropical Pacific Ocean.
‘The coral reef system at the Papua New Guinea vent site is an algae-dominated one with few species of corals,’ says Barkley. ‘We see responses much like those shown in many lab experiments at some of the other naturally low pH coral reef sites as well, particularly lower calcium carbonate production. But we don’t see the same responses across all of the sites, especially not at the coral reefs in Palau Rock Islands. The coral communities there are thriving, except for higher rates of bioerosion.’
In collaboration with the Palau International Coral Reef Center, members of Cohen’s lab have been conducting fieldwork there since 2011. The research team collected water and coral skeletal core samples from eight sites across the Palau reef system, and deployed pH, light, salinity and flow sensors to characterize the seawater environment in which the corals grew. The research team also collected and analyzed data on the community composition as well.
The skeletal cores were scanned at the Computerized Scanning and Imaging Facility at WHOI. The Computerized Axial Tomography technology generates a 3-D image of the cores, revealing detailed information not visible to the naked eye, including coral growth rates, skeletal densities and the extent of bioerosion.
Using an automated program written in Matlab, the team used the 3-D images to quantify the proportion of the coral skeletons that had been eroded by organisms, and the severity of bioerosion of each coral. As the pH of the reef seawater drops, more frequent and severe bioerosion scars were revealed in the coral scans.
‘We see coral skeletons that are eaten up and have holes on the top and sides. The coral almost looks like Swiss cheese because of the volume that’s been removed,’ says Barkley.
Barkley and her colleagues found bioerosion rates in Palau corals increased eleven-fold as pH decreased from the barrier reefs to the Rock Island bays. When comparing those results to other low pH reef sites, a definite pattern emerged.
‘All of these naturally low pH sites that Hannah compared are different from one another in terms of physical setting, ecological connectivity, frequencies of variability and so on. What she discovered is that the only common and consistent response to -across all these sites is significantly increased bioerosion,’ says Cohen.
‘This paper illustrates the value of comprehensive field studies,’ adds David Garrison, program director in the National Science Foundation’s Division of Ocean Sciences, which funded the research. ‘Contrary to laboratory findings, it appears that the major effect of ocean acidification on Palau Rock Island corals is increased bioerosion rather than direct effects on coral species.’
The riddle of resilience
So how do Palau’s low pH reefs thrive despite significantly elevated levels of bioerosion? The researchers aren’t certain yet, but hope to be able to answer that question in future studies. They also don’t completely understand why conditions created by ocean acidification seem to favor bioeroding organisms. One theory is that skeletons grown under more acidic conditions are less dense making them easier for bioeroding organisms to penetrate coral skeletons. But that is not the case on Palau, Barkley says, ‘Because we don’t see a correlation between skeletal density and pH on Palau.’
A previous study published January 2015 in the journal Geology by Thomas DeCarlo, a member of Cohen’s lab and a co-author on this paper, showed that the influence of pH on bioerosion is exacerbated by high levels of nutrients. That finding implies that local management strategies, such as controlling runoff from land, can help to slow the impact of ocean acidification on coral reef decline. Increased runoff from areas of intense agriculture and coastal development often carries high levels of nutrients that will interact with decreasing pH to accelerate coral reef decline.
Though coral reefs cover less than one percent of the ocean, these diverse ecosystems are home to at least a quarter of all marine life. In addition to sustaining fisheries that feed hundreds of millions of people around the world, coral reefs protect thousands of acres of coastline from waves, storms, and tsunamis.
‘On the one hand, the results of this study are optimistic,’ Cohen says. ‘Even though many experiments and other studies of naturally low pH reefs show that ocean acidification negatively impacts calcium carbonate production, as well as coral diversity and cover, we are not seeing that on Palau. And that gives us hope that some coral reefs — even if it is a very small percentage — might be able to withstand future levels of ocean acidification. But there’s also a cautionary side, even for those coral communities able to maintain their diversity and growth as the oceans become more acidic, increased rates of bioerosion and dissolution seem inescapable.’
###
Along with Barkley, Cohen, and DeCarlo, the team included Yimnang Golbuu of the Palau International Coral Reef Center, Victoria Starczak of WHOI, and Kathryn Shamberger of Texas A&M University.
Additional funding for this work was provided by The Dalio Foundation, Inc., The Tiffany & Co. Foundation, The Nature Conservancy, and the WHOI Access to the Sea Fund.
Absurd. Where do they imagine stable pH for millions of years?
“As the ocean absorbs atmospheric carbon dioxide (CO2) released by the burning of fossil fuels, its chemistry is changing”
To say that in an unbiased and more scientific way would be:
It is widely postulated that the constantly adjusting chemistry of the ocean absorbs an undetermined percentage of the atmospheric carbon dioxide (CO2) released by the burning of fossil fuels, as well as a significantly greater quantity of natural emission.
Sort of spoils the intent of the propaganda, though…
As with the entire universe, we ought to just observe and be amazed until our collective consciousness matures to the milestone of conceptual understanding.
Make that “conceptual cognizance” for the record.
So perhaps “very few” corals than survive in a highly acidic environment (less “acidic” than pure Dihydrogen monoxide of course). But bioerosion is “inescapable” based on the sample of 1?
I’m betting bioerosion is not anything new. Seems like more “breaking news” that an ocean ph must be 8.0 or above to be healthy otherwise we’ll call it “ACID”. (with respects to Dr. Timothy Leary) 😉
If it were all from dissolved CO2, how much does the estimated global average surface pH change since the industrial revolution imply of anthro-emitted CO2 has remained in the ocean surface waters?
Lessee here.
So if the earth were to slip into another period of glaciation, where it spends 90%+ of it’s time, the oceans would drop about 350 feet, and some HUGE percentage of existing coral would die. Probably 99% of it.
Seems like if you’re really worried about coral you’d want to keep the earth warm.
To keep the earth warm…
Palau sits on the high edge of the Phillipine plate, has something like 300 islands of volcanic origin, has 3800mm p.a. average rainfall. None of this mentioned in their report?
Oh, I love this sort of crap. In other words they have no idea what’s going on, it was a great surprise to find it happening but of course scientists must know almost everything, so we’ll just say that they “don’t completely understand”.
Of course this is not untrue, having no idea is “consistent” with “don’t completely understand”. Like being broke is consistent with not being completely rich.
We need to remember this next time we hear that they “don’t completely understand” the hydrological cycle : evaporation, convection, cloud formation and precipitation, that is what really controls the climate and makes the earth a hospitable environment for life.
Lets’ get the chemistry right here. CO2 forms carbonic acid (H2CO3), which is a weak acid that goes into equilibrium with bicarbonate, its dissociation product. Bicarbonate (HCO3-) is also a weak acid that goes into equilibrium with its dissociation product, carbonate (CO3-2), which in turn is in equilibrium with calcium carbonate (CaCO3), the solid ionic substance that forms coral. Calcium carbonate is less soluble in warm water than in cold water. So, there is an extended equilibrium form CO2 to calcium carbonate and more CO2 means the entire sequence moves toward making more calcium carbonate, which is Le Chatelier’s Principle. And, ignored by all the non-chemists in the above article, an equilibrium cannot affect itself; it is just ignorance, willful or not, that would allow them to make such a claim. Only an outside source of protons (H+), given off by an acid, such as sulfuric or hydrochloric acid, would be able to affect this equilibrium.
Furthermore, carbonic acid is a weak acid and seawater is a complex mixture of ions that comprise a complex buffer system which resists changes in acidity or pH. To be so ingenuous as to pretend that carbonic acid can change the pH of seawater is to have failed freshman chemistry. Sure, CO2, dissolved in distilled water, lowers its pH, but the same CO2 in seawater will have undetectable effects. None of any pH change that they claim to observe, which, by the way, have all been in the normal range known for seawater pH, can be from increased CO2. For scientists to take such simplistic and uninformed views of how things so basic as acids and bases behave means we should rethink their doctoral degrees and think about demoting these people to non-doctoral level, more like scam-artist, actually.
In addition, photosynthesis is an alkalizing process, such that, during the day, photosynthesis by algae and phyto plankton can raise the pH of seawater in a bay or estuary from about pH 8 to over 10. Marine organisms are much more resilient than the alarmists would want us to know. In fact, as CO2 is the fuel for photosynthesis, increased CO2 is a boon for photosynthetic organisms, being food for them.
It is an evil political agenda that needs to pretend that CO2, which is plant food for all photosynthetic organisms, would be bad for our planet. It makes just as much sense for them to claim that oxygen, a waste product from plants, is indeed waste and thus air pollution, despite the fact that we need it to live as non-photosynthetic beings.
The little publicized fact is that, over the last 50 years, all of the world’s coral reefs have been thriving as the result of higher CO2, growing at 30 to 50% of previous rates. And, if the oceans grew warmer, coral reefs could expand into high latitudes, meaning more coral not less, in addition to the lowered solubility of calcium carbonate in warmer waters, making reefs more stable than ever.
So what you’re saying is that these learned scientists could have gotten all their shocking, new answers from any pet store that deals with salt water tanks and/or micro reefs.
Thankyou Higley. And the others above. You have reminded me of my 1st year university chemistry and the nature of equilibrium!
higley7
Wouldn’t it be a little more accurate to say that CO2 and water form H2CO3?
As you point out, the CO2 doesn’t add any H ions to the solution, but since most of that H2CO3 dissociates to HCO3 +H, there is an increase in H ions, which is buffered away by the formation of bicarbonate from carbonate and those H ions.
The argument is that the carbonate ions result from the dissociation of calcium carbonate that is the shells of molluscs and coral structures.
As I understand it, the solution is prevented from becoming more acidic by virtue of the formation of the weak (amphoteric) acid, bicarbonate. Clearly a difference between the addition of an acid to a solution and the formation of an acid in a solution.
I think that, although the building of calcium carbonate by these organisms is not understood, it is bicarbonate that they use and expel H via proton pumps; a standard mechanism throughout biology. This gives rise to a very high concentration of H surrounding the organism and it’s a local lowering of pH that they did themselves. They have the foresight to coat themselves in a thin protein layer and that means that live corals are not actually exposed to the more acidic solution.
Is this basically correct? And what effect does the saturation of Ca++ have?
Another example showing that NATURE IS RESILIENT.
Life relentlessly removes CO2 from the environment, primarily by forming limestone but also fossil fuels, until it hits a “floor”, the level near which plants die, and continually “bounces” off of it. That was the condition of the earth before Man came to the rescue by burning fossil fuels. Here’s to a more healthy level of around 1,500ppm (0.15%).
“So how do Palau’s low pH reefs thrive despite significantly elevated levels of bioerosion?”
This is the type of linear thinking that hides the answers to such questions. For a start, corals do have to deal with predators large and small and also “bioerosion” results in buffering the pH locally by dissolving carbonate, making raw materials for making more coral reef – this is an equilibrium problem. Also, wouldn’t a scientist be thinking about the fact that CO2 not only results in some carbonic acid formation but this at the same time is the building block of carbonate for the coral structure and shell fish shells. All you need is adequate lime in the water.
That’s something I’ve often thought.
At a push, on the scale of a single organism/shell, they could argue that the solid calcium (carbonate) already in place would wash away into the bulk ocean as it (slowly) dissolves.
On the scale of the great barrier reef, hundreds of thousands of square kilometers, the bulk of that calcium is going nowhere. And there isn’t enough CO2 to dissolve it, even if the ocean could wash the solution away.
It built up over aeons, and would take as long to disperse.
Wow! This is so amazing that we’re going to have to go back year after year and snorkel around these incredible vibrant reefs with more stuff going on than we ever could have imagined and can’t even fit into the model of destruction in our little heads. Send more money, it costs a lot to get to Palau! (But lots of Marines got there: via Wikipedia “… In 1944 the United States captured Palau, after the costly Battle of Peleliu when more than 2,000 Americans and 10,000 Japanese were killed….”
As water warms it’s ability to hold CO2 diminishes.
How do Warmists reconcile their claims of rising sea temperatures with increasing absorption of CO2?
To be fair to them, that’s not what warmest say. They are very much aware of the outgassing of CO2. The absorption of CO2 is due to an increase in partial pressure pCO2, an effect stronger than the T effect.
How does this jibe with the negligible pH change at the surface? I think bio-uptake is also keeping the surface out of equalibrium with the temp and pressure.
Perhaps Trenberth’s some missing heat is hiding in bio-chemicals and this is also a mechanism for transporting heat to the deep ocean.
‘That’s not to say the coral community is thriving because of it, rather it is thriving despite the low pH, and we need to understand how.’
Yeah, they don’t have a preset agenda thru which all findings are interpreted! In REAL science, all possible causes for an effect are considered and ruled out before making such a statement … NOT in climate “science” however! When the Higgs was found [and it had to have a probability the experimental results weren’t just by chance of less than 1 in two MILLION … climate “science” once they have a remotely plausible reason involving dire climate change, never, ever considers alternate explanations!!!!!!!
I can make the same statement … Climate science seems to be thriving despite the low intelligence, and obvious bias of it’s scientists! See, works there, too!
The period with most prolific coral growth was the Cretaceous when CO2 levels in the atmosphere varied between 1000 and 2000 ppm. pH must have been much lower than than today. I never understood the fear of acidification considering this geological fact. I never heard an alarmist biologist referring to the geological history of high CO2 and abundant carbonate deposition.
It is unlikely the pH of the oceans was much lower than today due to CO2. In fact, the concentration of the buffering ion HCO3- was undoubtedly much higher than today, thus the ocean even MORE resistant to pH change.
JoNova posted on this some days ago where it was dissected at length;
http://joannenova.com.au/2015/06/researchers-astonished-coral-reefs-thriving-in-a-more-acidic-ocean/
Below is the relevant post I placed on Jo’s blog
__________________________
Sigh!
Here we go again!
I wonder if any of those so called ocean pH researchers have ever read any of this NOAA stuff on ocean pH measurements before “being surprised” and making their claims.
Quoted from the paper;——-
Rapidly changing chemistry;
Since the beginning of the Industrial Revolution, ocean pH has fallen by 0.1 pH units, which represents an increase in acidity of approximately 30 percent. For marine life that has evolved over millions of years in relatively stable pH conditions, this kind of rapid change doesn’t allow for much time to adapt.
[ / ]
And from the NOAA; [ below]
[ Apologies as this is long read below but needs to be read in full to understand that ocean pH measurements are in just as bad a state of accurate calibration as global temperature data which hasn’t stopped the alarmist scare stories on Ocean acidification, another total misnomer from the alarmists as the ocean is alkaline and probably has been for a couple of billion years past.]
—————
Issues related to pH measurement technique and data reporting in the pre-1990 era
*****
While seawater pH measurements have been made on some oceanographic expeditions starting with the first measurements that were made by Sørensen and Palitzsch (1910), most of the earlier data have proven to be problematic for a number of reasons that we will describe below.
In addition, there is the added problem of data sparseness in any given year for the earlier data sets, which makes the determination of a global annual mean value for a particular time period to be quite challenging, necessarily increasing its likely uncertainty.
During the period from 1910 thru 1988 the most common method for measuring pH was the potentiometric method using hydrogen ion sensitive glass electrodes coupled with a reference electrode (Dickson, 1993a). This method suffers from a number of measurement and calibration issues (i.e., temperature of measurement and conversion to in situ temperature, calibration for use in a high ionic strength medium, glass electrode drift, reference electrode drift, and liquid junction potential issues) that have led to significant measurement uncertainties that are difficult to quantify adequately.
In recent years the spectrophotometric pH method described by Byrne and Breland (1989) has been shown to be about one order of magnitude more precise.
Its accuracy has been improved over the years since then.
Over the years, pH has been expressed on one of four different scales: (1) the total hydrogen scale, [H+]T; (2) the free hydrogen scale [H+]F, (3) the seawater scale, [H+]SW, and (4) the NBS scale aH(NBS) (Dickson, 1984; Zeebe and Wolf-Gladrow, 2007).
The differences in the respective pH values can be significant.
For example, for a seawater condition of salinity = 35 and temperature = 25°C the difference between pHT and pHNBS is greater than 0.1.
The exact difference cannot be determined easily as it is, to some extent, dependent on the exact design of the liquid junction used in the potentiometric pH cell.
Unfortunately, a large number of the earlier data sets submitted to the National Ocean Data Center does not include any information indicating how pH was calibrated (and thus the pH scale being used).
All of the earlier (before 1975) glass electrode measurements (and many more recent ones) were calibrated against NBS style buffers with an ionic strength of 0.1 mol kg–1.
The liquid junction potential of the pH cell is sensitive to ionic strength and to the composition of the solution it is in, so moving the electrodes from these low ionic strength buffers to the higher ionic strength of seawater (0.72 mol kg–1) makes apparent pH readings drift for a period of time.
Furthermore, different electrode designs can result in differing pH readings (Dickson, 1984).
This problem can be largely eliminated by calibrating the pH cell against standard buffer solutions such as 2-amino-2-methyl-1,3-propanediol (Tris) in synthetic seawater (DelValls and Dickson, 1998; Nemzer and Dickson 2005).
When these procedures are followed carefully, the uncertainty of a potentiometric measurement of seawater pH (expressed total hydrogen ion conentration) can be less than 0.02.
The problem is that this approach was not implemented routinely until the 1990s (Dickson, 1993a,b; Dickson et al., 2007).
Whether measured on a ship or back in a shore-based laboratory, pH results have to be corrected back to the in situ temperature at which the samples were originally collected to provide an estimate of the in situ pH.
If the difference between the temperature of measurement (usually around room temperature) and the in situ temperature is more than 7 degrees Centigrade, these corrections can be quite large (>0.1 pH units).
Unfortunately, much of the supporting metadata (records of the measurement temperature, the in situ temperature and the mathematical formula for conversion of the data from one temperature to the other) was not given to NODC along with the data files (Boyer et al., 2013).
Hence, in many cases, we are not certain what pH value is being reported (measured versus in situ). We suspect that a significant fraction of the historical pH values were reported at laboratory temperature and were never corrected back to the in situ temperature.
In many cases, the measurement temperature was not reported as part of the metadata package, making later temperature correction impossible (Boyer et al., 2013).
The lack of information as to whether the pH values were reported as measured versus in situ, and the lack of documentation on measurement temperature will lead to large pH uncertainties in the earlier database.
***********
And there you have it!
Nobody is sure what the ocean pH actually was only a couple of decades ago which hasn’t stopped them one bit from making another huge scare story based on nothing more than some assumed ocean pH levels, a mirror image of the severe problems in assessing global temperatures.
With almost exactly the same solutions.
Just make it up as you go along.
And the scarier the better.
Apologies! Link to the NOAA article; “Quality of pH Measurements in the NODC Data Archives”
http://www.pmel.noaa.gov/co2/story/Quality+of+pH+Measurements+in+the+NODC+Data+Archives
ROM –
The seas vary between 7.5 and 8.5 and around the coastlines the ph can vary rapidly over the day depending on many factors.
The Bearings sea has been measured at 8.2 at the surface and 20 meters down at 7.8.
The seas are not all one pH level and uniformly changing.
Mass coral mortality at all coral sites around the world has been monitored since 1870.
But if you feel that the seas PH has been accurately measured then you could claim the $1,000,000 reward for the devise that is accurately measuring this because so far no one has claimed the reward.
Rom,
apologies for the dramatics, only scan read your opening and got the wrong impression.
I enjoy the juxtaposition of odd things, such as …
“ The coral almost looks like Swiss cheese …”
… when, in the same week, I have been informed that Swiss cheese has fewer holes then previously – because milk is too clean:
http://www.cbsnews.com/news/no-holes-in-your-swiss-cheese-heres-why/
The first great era of reef building after the Precambrian was the Devonian. The reef building organisms were colonial rugose corals, tabulate corals and stromatoporoids. Nearly all the fossil reefs of Eastern Aust are from this time and a barrier reef 1700 km surrounded the Kimberly terrain in Western Aust. It is reasonably well agreed amongst geologists that the concentration of atmospheric CO2 then was between 17 and 18 TIMES greater than it is now. CO2 levels subsequently decreased rapidly parallel to the rapid evolution of land plants and all the reefs disappeared. Food for thought?
Well knock me over with a feather…..
Corals have been around since the dawn of time, when CO2 levels were much higher. They managed to live and thrive then, so why did anyone think they could not do the same now?
Ralph
Ocean chemistry has remained as is today for 500million years. Dissolution of CO2 does not reduce carbonate ions but increases them due to the bicarbonate reaction that follows the dissolution this adding these building blocks and reducing pH. So the above description of the (non) problem is wrong from para 1.
I’m sorry. I kept reading for a while to try and find out how they defined bioerosion. It started to look like dancing around on the head of a pin and I had to stop. So, what’s their definition? Biological activity – as opposed to dying reefs?
1. Acidification
IPCC says:
The air-sea exchange of CO2 is determined largely by the air-sea gradient in pCO2 between atmosphere and ocean. Equilibration of surface ocean and atmosphere occurs on a time scale of roughly one year. Gas exchange rates increase with wind speed (Wanninkhof and McGillis, 1999; Nightingale et al., 2000) and depend on other factors such as precipitation, heat flux, sea ice and surfactants. The magnitudes and uncertainties in local gas exchange rates are maximal at high wind speeds. In contrast, the equilibrium values for partitioning of CO2 between air and seawater and associated seawater pH values are well established (Zeebe and Wolf-Gladrow, 2001; see Box 7.3). AR4, ¶7.3.4.1 Overview of the Ocean Carbon Cycle, p. 528.
IPCC’s carbonate equations are 7.1 and 7.2 in Box 7.3: Marine Carbon Chemistry and Ocean Acidification, p. 529.
More detail in an updated reference from the same authors is Zeebe, R. E., and D. A. Wolf-Gladrow, Carbon dioxide, dissolved (ocean). Encyclopedia of Paleoclimatology and Ancient Environments, Ed. V. Gornitz, Kluwer Academic Publishers, Earth Science Series, in press 2008. Here, at least, the authors are more accurate than IPCC ever manages to be by specifying not equilibrium, but thermodynamic equilibrium. The solution to the carbonate equations is pH dependent, and is graphed in what is known as the Bjerrum plot. Id., p. 9.
Thermodynamic equilibrium requires simultaneous thermal equilibrium, mechanical equilibrium, and chemical equilibrium. The surface layer of the ocean is NEVER in thermodynamic equilibrium. It is stirred by wind and wave motion and irradiated by the Sun. IPCC’s equilibration time scale is not one year, but rather whatever the time span is for the ocean surface to remain liquid. The surface layer is where the radiation and thermal exchanges with the ocean occur to the atmosphere and the deep ocean, and it is remarkable for its entrained air, hence the alternate name of the mixed layer. The surface layer runs from about 25m to 200m in depth.
The story about acidification is fatally flawed and not fit for public consumption.
2. Adaptation
Will some corals be able to adapt to these rapidly changing conditions?
Life survives changes in the environment not just by adaptation, requiring genetic changes, but by its robustness, its tolerance to changes and methods of adjustment. The latter include such obvious things as changes in color, deciduation, changes in fur thickness, fat layers. Before appealing to required evolutionary changes, the scientist needs to determine the ranges of tolerance of any species in its existing form.
What the hell?! Why have half the coral reefs disappeared from the world?!
Denial is strong with this one.
[“Half the coral reefs”?? .mod]
There are exposed, fossilised, coral reefs that are millions of years old here in Australia where sea levels were at least 3m higher than today at places like Fairbridge Bluff and Point Maxwell.
Interesting fact: Most people believe that as CO2 dissolves into the ocean, the buffering capacity of the ocean decreases. In actuality, as more CO2 dissolves into the ocean, its buffering capacity is INCREASING. As more CO2 dissolves into the water….
H2CO3 +CaCO3 -> 2HCO3- (CaCO3 comes from the vast (many gigatons) limestone deposits)
More HCO3- means the concentration of the buffering ion that keeps the pH of the ocean at ~pH 8 is increasing. A .1M solution of HCO3- solution has a much larger capacity than a 0.0001M solution. In addition, at constant pH, as HCO3- ion concentration increases, CO3– increases as well since
Ka2 = [H+][CO3=]/[HCO3-].
The ocean acidication scare is totally without merit. The oceans were basic when CO2 was 6000ppm and life was flourishing in the oceans, probably way better than they are today at a mere 400ppm.
I have handy a Bjerrum Plot of the carbonic acid system. Not really very strange, I AM a professional chemist.
This shows that the aqueous equilibrium of H2CO3 HCO3- CO3+ is dominated by the bicarbonate ion HCO3- over the pH range from 6.37 to 10.36. At the pH midpoint, 8.36, the bicarbonate ion is 100 times (!) as concentrated as either the carbonic acid or the carbonate ion. This is a good thing, since the bicarbonate ion is the one required for plankton and mulloscs to produce the carbonate shells they need for their skeletons/homes/reefs.
Most atmospheric carbon dioxide absorbed by the oceans will end up on the ocean floor…as limestone.