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Ocean acidification: a non-problem

Ocean acidification has been called "global warming's evil twin" which apparently admits that if global warming existed as a twin, it would be a good one. Is ocean acidification a problem?

Some of the biggest unknowns hide in biology which is not exactly my field but I have spent whole days with it, too. Concerning the figures that are normally listed and that describe the changing pH of the oceans, I have almost no doubt that they're pretty much correct. See

Wikipedia: Ocean acidification
Since 1751 to 1994, the oceans' pH went down from 8.180 to 8.105 or so. The neutral level of pH is 7.

The pH scale is logarithmic: the actual concentration of H3O+ ions is proportional to 10^{-pH} while the concentration of the OH- ions is inversely proportional to the same thing or directly proportional to 10^{+pH}.

The changing pH can be traced to the changing concentration of CO2, and the corresponding ions in water, which pretty easily follows the changes in the atmosphere, by Henry's law and some simple chemistry looking at a few chemical reactions, at least in the short run (in the long run, the extra CO2 in the oceans is being consumed). It is not hard to estimate that the pH indeed has changed by something like almost 0.1 in the last 200 years.

There are very good reasons why chemistry uses this logarithmic pH scale - simply because in typical situations, the possible concentrations of ions go over many decades - they often change multiplicatively by many orders of magnitude (i.e. their logarithms change linearly) - and their products are often required to be constant for chemical equilibrium.

Now, it can be argued that in 100-150 years, the oceans' pH will go to 7.9 or so, under business as usual. It will certainly stay alkaline. But I think that all these qualitative changes are extremely likely, almost obvious. The only question is whether it threatens anyone, or life in the oceans in general. I think that the obvious answer is No. As everyone with an aquarium knows, virtually all fish don't care about the change of pH by 0.5. Most fish actually can live anywhere in pH between 5 and 9.

And e.g. ornate rainbowfish can exist in water as acidic as orange juice, see an article in Australia's ABC, which is 3.5 or so. But the Coca-Cola is more acidic, near 2.5, and the fish could have some trouble to live in it. Nevertheless, the concentrations of H3O+ and OH- ions in orange juice - which is still OK for those fish - differ by 6 orders of magnitude from the concentrations in the current ocean! The concentrations of ions are tiny, anyway: it's the water itself that matters most. You shouldn't miss the forest behind the tree.

Now, these were fish. Obviously, no problems await them. I had to look at other things such as plankton, coral reefs, etc. You will find some diversity of the preferred values of pH and a shift of pH by 0.2 could affect the composition of the species in the ocean.

However, it's surely not able to threaten any major family of organisms in the ocean. In average, I think that the marine life would enjoy a drop of pH from 8.1 to 7.9. It shouldn't be too surprising that I think that the optimum pH for an average marine organism is 7.0 - the pH neutral level - and we have no chance to drop this low by burning fossil fuels because that would essentially need to multiply the CO2 concentrations in the air by a factor of ten. (It's actually closer to 100 because there are many other ions aside from the CO2-related ones in the ocean.)

To summarize, I am 99.99% certain that there is no problem of "ocean acidification" worth talking about. Every year, the average pH is changing by 0.002 or so. No single organism with lifetime comparable to human life or shorter can possibly detect the change. Only the systems - coral reefs - that live for a longer time need to be watched. But there are good reasons to be certain that the slight drop of pH has no significant negative impact on them, either.

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snail feedback (13) :

reader Baco said...

CO2 and water are interesting, as they make the bicarbonate pH buffer system which we ourselves have in our blood, and keeps the serum between pH 7.35-7.45 (hopefully), together with other lesser systems.

Although lacking in symbols for it, here it goes:

CO2 + H2O <--> H(+) + HCO3(-)

HCO3(-) reacts with NaCL to form NaHCO3, the counterpart being HCl. Weak base and strong acid, a buffer system. Protein, which also exists in the sea, can also buffer H+.

So, any expectations that do not take this into account are likely to be unrealistic, as far as I understand.

reader Luboš Motl said...

Dear Baco, I am confident that according to anyone, your reaction is *the* reaction that makes CO2 influence pH of the ocean water. Cheers, LM

reader Baco said...

Thanks, Lubos. I thought better mentioning it, as I never saw it mentioned when discussing ocean acidification.

reader Unknown said...

"Acid Rain" has reared its ugly head again:-

On 8 April 2010, the EPA has launched a blog:-

“…… to expand the conversation on acid rain. Acid rain is a serious environmental problem ………


These people will NEVER give up.

reader Eduardo Ferreyra said...

Somehow in the discussión about ocean acidification the fact that rains are naturally acid has been lost. Rains have pH 5.5 (depends on regional distribution as in some desertic areas it may be sligthly alkaline as in China), But over oceans rains are much more abundant that over land.

Are they taking that fact into account, or it has been totally ignored by our ocean "experts"?

reader Luboš Motl said...

Dear Eduardo, please, don't get carried away.

Rains can have whatever pH they have - but it's clearly a fact that the ocean's pH is 8.1 or so, regardless of the rains' pH. So there must be other drivers that don't allow ocean's pH to drop to 5.5 or whatever you say. They're arguably in some kind of quasi-equilibrium that has kept the oceans' pH around 8 for many, many years.

Nothing is expected to change about the overall amount of rain. We don't enter any "global raining" era. But indeed, the rain may also bring the CO2 itself faster under the water. But the increasing proportion of CO2 in the air matters much more than the increasing amount of rain - because the rain surely hasn't increased by 50% in the last century which CO2 has.

reader Eduardo Ferreyra said...

Lubos, my intention was not to say that rains will acidify (or btter reduce ocean's alkalinity) but to point to something that "theoretically" should have reduced the alkalinity since many millions ago and has not.

Ocean acidification is, of course, another lousy pony used by the Warmist Light Brigade in its charge against the artillery positioned on both sides of the hills of Reality Valley.

reader Clothcap said...

Hi Lubos, couple of things. Volcanism and tectonic activity increased this century, I've seen estimates around 20%. Maybe more than 70% of such activity is under water. Sulphur and CO2 emissions can occur from both.
The surface layer has around 51 times as much CO2 as the air. I've seen this statement: "99% of absorbed CO2 remains as CO2, of the 1% that gets changed, a small fraction goes to forming acid. Of that small fraction, a small fraction can be ascribed to human emissions."
SPPI has some decent pieces on the subject:
Jen Marohasy took an interest:
Coral Calcification and Ocean Acidification Revisited

I have to wonder, greenpeace often bang the acid drum. The commie-socialist one world gov wannabe Rockefeller bros fund them. Their club of rome's motto - "...In searching for a new enemy to unite us, we came up with the idea that pollution, the threat of global warming, water shortages, famine and the like would fit the bill."
Seems a likely source for the origin of the acid nonsense.

reader Unknown said...

Being a biologist, I am shaking with laughter about this acid ocean nonsense. A pH change of 0.002 is not even measurable with standard equipment. Biological systems have a remarkable flexibility, far beyound our imagination. We humans do not have the power to change the acidity of the oceans. Have you ever considered what happens around the deep sea smokers? Temperatures above 100 C, pressures above 100 bar, pH below 2. And still life. Maybe not as we know it, but it's life Jim.

reader Den siste mohikanen said...

PH in ocean water change by an order of magnitude (1 PH point) naturally in some coastal waters.

That might be good to remember...

reader Unknown said...

As the daily variation in acidity (0.24 )is much greater than the long term trend I canot see what all the fuss is about other than another bout of alarmism.

That plus a 50 generation adaption time for natural selection to work.

reader Anonymous said...

I have been researching ocean acidification for some time and writing about the various issues involved on my blog, and I have to say that I take issue with this post and some of the comments on it.

For example, the author gives an unsourced assertion that 'Most fish actually can live anywhere in pH between 5 and 9.' As an aquariast, I find this claim... fishy :)

It also seems problematic to consider fish in isolation, when they are impacted by the effects of OA on other members of their ecological community. De'ath et al. (2009) write:

'Coral calcification is an important determinant of the health of reef ecosystems, because tens of thousands of species associated with reefs depend on the structural complexity provided by the calcareous coral skeletons.'

It seems fallacious to claim that fish will be fine under a high CO2 world when there are good reasons to think that there will be negative impacts on the reefs which provide them and their food web with habitat.

The author continues:

'I think that the marine life would enjoy a drop of pH from 8.1 to 7.9. It shouldn't be too surprising that I think that the optimum pH for an average marine organism is 7.0 - the pH neutral level'

This is indeed very surprising to me, especially in regards to calcifying organisms such as corals, which depend on a high carbonate saturation state. This saturation state is controlled on short time scales by pH, and simple considerations of carbonate chemistry will show that even a drop of 0.1 pH will significantly alter the carbonate saturation state. The author glosses over corals, and does not even mention the effects on other organisms - Gazeau et al. 2007, for example, demonstrate that increased CO2 inhibits calcification among shellfish. The effects of acidification upon calcifying phytoplankton (important oceanic carbon sinks) are also not mentioned.

For those who are interested, I have made a short video about OA here:
and I have put together a series of articles discussing common misconceptions about OA. For example, I explain why the rate at which environmental variables (like temperature or pH) change is as important as their value. Be sure to check them out!

Take care,

reader Unknown said...

Thanks for the YouTube video topologicocean. The video is very convincing. If one drops a piece of frozen CO2 into the oceans and that piece is about 1/8 the volume of the oceans, the ocean will become more acidic.

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