Naked Science Forum

Life Sciences => Marine Science => Topic started by: MarkPawelek on 05/05/2018 19:12:33

Title: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: MarkPawelek on 05/05/2018 19:12:33
Ocean Acidification (http://ocean.si.edu/ocean-acidification)
by The Ocean Portal Team; Reviewed by Jennifer Bennett (NOAA)

Quote
Even though the ocean is immense, enough carbon dioxide can have a major impact. In the past 200 years alone, ocean water has become 30 percent more acidic

<-- This is a massive blunder by NOAA. It shatters my confidence in "climate scientists".

I think she meant to say that there is 30% more CO2 in the ocean than pre-industrial times.

The statement "30% more acidic" is wrong for 2 reasons:
1) When CO2 (carbon dioxide) dissolves in water only 0.3% of it becomes carbonic acid according to the equation:

CO2(aq)  +  H2O(aq)  <=>  H2CO3(aq)

Most of the CO2 simply dissolves in water without making carbonic acid.

2) Carbonic acid is a weak acid with a Ka = 4.2E-04. Meaning less than 1% of that dissociates according to the formula:

H2CO3(aq) + H2O(aq) <=> H3O+(aq) + HCO3-(aq)
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: chiralSPO on 05/05/2018 21:27:21
Using percentages seems an odd way to discuss acidity, but I don't think that it is being misleading or alarmist. There are two possible interpretations that make sense to me:

(1) Acidity is a measure of the concentration of H+ ions in solution. A 30% increase in the concentration of H+ ions is the same as a 0.11 unit decrease in the pH. The 2nd graphic on the page you linked to suggests that the pH has fallen by about 0.04 units in the last 30 years, so a drop of about 0.1 units in the last 200 years doesn't seem that unreasonable at first glance. Given that the statement including the 30% figure is in a paragraph discussing historic pH, and a later paragraph claims a 0.1 pH unit fall since the Industrial Revolution, this seems most likely to me.

(2) The effective concentration of dissolved CO2 has increased by 30%. Again, in the 2nd graphic it looks like the dissolved CO2 has increased by 12.5% in the last 30 years. Again, it doesn't seem absurd for this to be in line with a 30% increase over 200 years.

Either way, the ambiguity of the claim doesn't change the alarming trend that the data indicate, and bringing attention to an alarming trend is not alarmist in my book.

I don't know the specifics of the methods used to calculate these historic pH's and cannot personally vouch for the soundness of the science, but I caution against dismissing the results without understanding them fully.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 05/05/2018 22:34:07
Ocean Acidification (http://ocean.si.edu/ocean-acidification)
by The Ocean Portal Team; Reviewed by Jennifer Bennett (NOAA)

Quote
Even though the ocean is immense, enough carbon dioxide can have a major impact. In the past 200 years alone, ocean water has become 30 percent more acidic

<-- This is a massive blunder by NOAA. It shatters my confidence in "climate scientists".

I think she meant to say that there is 30% more CO2 in the ocean than pre-industrial times.

The statement "30% more acidic" is wrong for 2 reasons:
1) When CO2 (carbon dioxide) dissolves in water only 0.3% of it becomes carbonic acid according to the equation:

CO2(aq)  +  H2O(aq)  <=>  H2CO3(aq)

Most of the CO2 simply dissolves in water without making carbonic acid.

2) Carbonic acid is a weak acid with a Ka = 4.2E-04. Meaning less than 1% of that dissociates according to the formula:

H2CO3(aq) + H2O(aq) <=> H3O+(aq) + HCO3-(aq)

I'd need to check, but those equilibria are linear functions.
If you put 30% more CO2 in the water then, as you say,  only 0.3% actually reacts to form carbonic acid.
But only 0.3% of the stuff that was there before was in the form of carbonic acid.
So the increase in carbonic acid is 30%

Similarly, if there's an equilibrium where only a small fraction actually dissociates then that same equilibrium means that most of the carbonic acid that was present pre-industrially was dissociated.
and again, that factor affects both the "before" and the "after" so the simplistic expectation is that the acidity rises by 30%

What stops it is the buffering effect of the carbonate ions present. There simply isn't enough data presented to answer the question properly.
But that capacity is finite.
It's also not an equilibrium system- we are adding CO2 faster than the calcite deposits can react with it.

Once you have this  scenario "the shells of some animals are already dissolving in the more acidic seawater" you actually have a problem.
Trying to blame poor reporting  isn't going to solve that.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: MarkPawelek on 06/05/2018 08:49:17
I did back of the envelope calculations (https://www.facebook.com/mark.pawelek/posts/10155546271506623), and found that NOAA exaggerate the acidity increase by more than 3 orders of magnitude. They exaggerate 5560 times.  Or 556000%. Now that's a big number, but NOAA like big numbers.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: MarkPawelek on 06/05/2018 11:20:13
The current ocean pH is due to many ions: anions and cations. One of my critics (Bored Chemist) seems to assume ocean pH is all down to carbonic acid! I don't see how he works that out. Oceans are a soup of ions. For example: Salt is 35000ppm. Carbon is 27ppm. 1300 times more salt than carbon! I prefer my method. Calculate the number [H+]. Calculate the addition of [H+] due to more CO2. Compare the two. I blogged it (https://greenfallacies.blogspot.co.uk/2018/05/ocean-acidification-myth.html).
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: chiralSPO on 06/05/2018 16:42:44
Ocean pH is due to only one thing [H+]. Yes, there are many other ions in solution, each of which might play a role in determining [H+], though not as many as you seem to be indicating (it doesn't matter how much salt there is: Na+, K+, Cl, and Br will have NO effect on pH in the range of plausible pH values, as the pKa values of Cl, and Br are < 0).

There is a complex "buffer" related to concentrations of CO2, HCO3, CO32–, H2PO4, HPO42–, B(OH)3, B(OH)42–, Mg2+, Ca2+, etc.

As you say in your blog:
Quote
I will do "very back of the envelope" calculations here. If I make a mistake, please laugh at me. Then correct me.
I will skip the first step, and focus on the second:

Quote
Assuming the pH of oceans = 8.1, as National Geographic claim, lets do the back of envelope calculations to figure out how much pH may have fallen in the last 200 years.

The mass of oceans is usually given = 1.4E24 grams. How much acid is that?

A pH = 8.1 says that the [H3O++] = 10-8.1 = 7.9433E-09.

Multiply the two. Grams of H+ = 1E16 grams (very approximate!). A lot of hydrogen ions, but then, our oceans are very big.

How many hydrogen ions may we expect from 500Gt of carbon (dissolving as CO2)? The Atomic Mass of C = 12. 500Gt of carbon = 500 × 1000,000,000 t = 500 × 1000,000,000,000,000 g = 50E16 g of Carbon = 50/12 × 1016 moles, or 4E+16.

4E+16 × 0.3% × 0.5% = 6E+11 hydrogen ions. The ratio of hydrogen ions added is 18600:1 We increased the acidity from 18600 to 18601. Big deal! By adding all that CO2 we made the oceans more acidic by 1 extra hydrogen ion in 18600. An addition of 0.0054%, not 30% as NOAA said.

The above approach is fundamentally flawed (I have stricken the primary mistake through). As you point out, the system is buffered, by the equilibrium of H+ CO2, H2CO3, HCO3, and CO32–. This complex buffering means that the linear relationship assumed in the above calculation is not valid. Instead, we need to consider the relationship between all of the species. You have also not considered how much of each of the carbon-related species are already in solution, and what their relationships are to each other and to pH.

I recommend studying up on this more before posting:

https://en.wikipedia.org/wiki/Bicarbonate_buffer_system#Henderson%E2%80%93Hasselbalch_equation
http://www.atmos.umd.edu/~russ/620_04OceanChem.pptx (downloadable lecture slides)

It is also worth emphasizing (and you have noted it, but I think you should consider the ramifications more carefully), that the system is NOT IN EQUILIBRIUM. The pH is not the same everywhere because the ocean is not mixed perfectly well. This means that at the very surface, where the ocean is in contact with the acidifying CO2, the buffer can be temporarily over-burdened, before more bicarbonate comes up from the depths to restore equilibrium. This is bad news for marine life in shallow waters (read: everything you can see while snorkeling), which is damaged by the imbalance, even if it is temporary.

Essentially, the calcium carbonate in the marine organisms serves as the base in the equilibrium.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: chiralSPO on 06/05/2018 17:12:04
Also, please note that I have changed the title of the thread to a QUESTION, to be in line with the policies of this forum.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 06/05/2018 17:52:40
One of my critics (Bored Chemist) seems to assume ocean pH is all down to carbonic acid!

No.
I said it's essentially the carbonate/ bicarbonate/ carbonic acid buffer system that regulates the  pH.

There's a reason for that: it's true.
There are only vanishingly small concentrations of other ions like phosphate or borate that would act as pH buffers near the pH of sea water

https://web.stanford.edu/group/Urchin/mineral.html

I'm allowed to assume things that are actually true.

You seem not to have noticed that a solution of sodium chloride is practically neutral.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: MarkPawelek on 06/05/2018 18:55:34
Thankyou for your reply chiralSPO. Consider this:

Quote
Feynman was a truly great teacher. He prided himself on being able to devise ways to explain even the most profound ideas to beginning students. Once, I said to him, "Dick, explain to me, so that I can understand it, why spin one-half particles obey Fermi-Dirac statistics." Sizing up his audience perfectly, Feynman said, "I'll prepare a freshman lecture on it." But he came back a few days later to say, "I couldn't do it. I couldn't reduce it to the freshman level. That means we don't really understand it."
-- Goodstein and Goodstein

Feynman understood that if he could not explain something simply, he did not understand it. That bothered him. I think it should bother us all.

If you can't give me an alternative, simplified, explanation how ocean pH could've become "30% more acidic", then I'm not going to take you seriously. Everything I know and wrote about the behaviour of CO2 dissolving in ocean refutes this 30% claim.

When one gets right down to it, all is obfuscation: NOAA, National Geographic, you. None of you even attempt to justify your beliefs.

I'll stick with my back-of-envelope calculation until I read a better one.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: puppypower on 06/05/2018 20:03:14
The pH scale is logarithmic. If we go from a pH 8 to a neutral pH of 7, for example, we will increase the acid level; H3O+,  by 10 times or from 10-8 to 10-7 moles/liter. This represents a 1000%  increase in acid concentration, based on starting with 10-8. The 30% estimate is connected to going from pH 8.2 to about 8.1

The pH is important to plant growth, since it will determine mineral and nutrient solubility. Most plants like the water/soil slightly acidic pH <7.  The higher acid concentration will make more nutrients available to drive plant growth.

Different types of algae like different pH's. In salt water aquariums, low pH, more acidic, tends to promote algae growth requiring more cleaning of the glass. In freshwater ponds, high pH tends to promote algae. The CO2 and acid level increase will help the ocean unlock nutrients and thereby dial in the algae it needs to take advantage of the CO2 food.  The ocean has done this before so it is not that big of a deal.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 06/05/2018 20:13:01
The only difficult "calculation" we need to do is a conversion of units.
The graph as a best line fit on it which says the pH is falling by 0.00186 pH units per year.
It's hard to know what "the past" was like but lets make a guess.
They talk of acidification since "before industrial times"- call it 200 years.
But almost all the change has been in the last 50 years or so.
So lets extrapolate the 200 year change by multiplying the rate of change by 50
(I recognise I'm doing a great demonstration of "spurious accuracy" here- I will round it off later)
50* 0.00186 = 0.093 pH units.
The current value is 8.08
So the pH was about 0.093 units higher.
8.173

Now convert those to what is actually being talked about- the acidity
OK the concentration of hydrogen ions was 10^-8.173
6.7143 nM
and it's now  10^ -8.08
8.318 nM
So, the change is
1.603nM
Now we need to express that change as a percentage of the original
 that's 100* 1.603/6.714
Which is 24% or so.
Given the assumptions and approximations involved, referring to a figure of about 23.87%  as being "30%" when reporting it in a newspaper seems legitimate enough to me.


Fundamentally, you seem to have forgotten that the factors )of about 0.3% for dissolution vs hydration and about 1% for dissociation to hydrogen ions) apply to the carbon dioxide which is already present naturally, as well as to the added carbon dioxide.

You also seem to have overlooked the fact that the acidity of the oceans was measured directly- that's what a pH is.
So we know how much it has changed (something like 20 or 30%).
Your calculation says it's only of the order of  a thousandth of that.

When your calculation doesn't agree with reality, it is not because reality has made a mistake.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 06/05/2018 20:18:40
None of you even attempt to justify your beliefs.
If you try actually reading, rather than ranting, you will find that I did justify my opinions.
Twice before you wrote that silly  assertion, and once more, in detail.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: chiralSPO on 06/05/2018 20:57:57
Thankyou for your reply chiralSPO. Consider this:

Quote
Feynman was a truly great teacher. He prided himself on being able to devise ways to explain even the most profound ideas to beginning students. Once, I said to him, "Dick, explain to me, so that I can understand it, why spin one-half particles obey Fermi-Dirac statistics." Sizing up his audience perfectly, Feynman said, "I'll prepare a freshman lecture on it." But he came back a few days later to say, "I couldn't do it. I couldn't reduce it to the freshman level. That means we don't really understand it."
-- Goodstein and Goodstein

Feynman understood that if he could not explain something simply, he did not understand it. That bothered him. I think it should bother us all.

If you can't give me an alternative, simplified, explanation how ocean pH could've become "30% more acidic", then I'm not going to take you seriously. Everything I know and wrote about the behaviour of CO2 dissolving in ocean refutes this 30% claim.

When one gets right down to it, all is obfuscation: NOAA, National Geographic, you. None of you even attempt to justify your beliefs.

I'll stick with my back-of-envelope calculation until I read a better one.

That you do not accept my answer does not necessarily imply that I am wrong--that is one of four possibilities:

1) I am wrong.
2) I am correct but did not explain it properly.
3) I am correct and explained it properly, but you did not understand.
4) I am correct and explained it properly, you did understand, but refuse to accept that you were wrong.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: MarkPawelek on 06/05/2018 21:03:57
1)
Quote
The graph as a best line fit on it which says the pH is falling by 0.00186 pH units per year.
Where did that come from?  Out of the blue. No graph. No way to make such a graph when one considers the variation in ocean pH and ocean currents.

2) Read what?  Lecture slides written using a program I don't have on my computer. Talk about 'obfuscation', you are second to none.  Accusing you of obfuscation is certainly not 'ranting'.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 06/05/2018 21:06:35
Where did that come from?
From the graph which you
cited here and
quoted on your blog..
Read what?
This thread.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: MarkPawelek on 06/05/2018 21:08:10
Quote
That you do not accept my answer
What answer?  You gave no alternative explanation beyond: 1) this is too complex to discuss therefore 2) acidification must be 30% just like NOAA said. I do not think that's an explanation.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 06/05/2018 21:23:28
Hi
Here's a copy of the graph from your blog if I can get this to work


* Graph.png (538.97 kB . 1228x841 - viewed 2469 times)

Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 06/05/2018 21:28:34
That you do not accept my answer does not necessarily imply that I am wrong--that is one of four possibilities:

1) I am wrong.
2) I am correct but did not explain it properly.
3) I am correct and explained it properly, but you did not understand.
4) I am correct and explained it properly, you did understand, but refuse to accept that you were wrong.

I'm leaning towards option 4
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 06/05/2018 21:31:03
What answer?  You gave no alternative explanation beyond: 1) this is too complex to discuss therefore 2) acidification must be 30% just like NOAA said. I do not think that's an explanation.
He gave an answer which explained WHY YOU ARE WRONG, which is sufficient to show that you are wrong.
It doesn't say anyone else is right.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: chiralSPO on 06/05/2018 22:08:08
Quote
That you do not accept my answer
What answer?  You gave no alternative explanation beyond: 1) this is too complex to discuss therefore 2) acidification must be 30% just like NOAA said. I do not think that's an explanation.

No... I provided links that show the equations you need to use rather than the simplistic and wrong equation you showed. Perhaps this one will be easier to understand: https://en.wikipedia.org/wiki/Carbonic_acid#Acidity_of_carbonic_acid
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: MarkPawelek on 06/05/2018 22:49:31
I am sorry. I missed the wikipedia Henderson/Hasselbalch equation (https://en.wikipedia.org/wiki/Bicarbonate_buffer_system#Henderson%E2%80%93Hasselbalch_equation) before. I will use their equation, but not their pKa because their equation is for blood, and pKa in seawater is slightly less than they give. I can use this for an alternative back-of-envelope equation, which I'm confident refutes NOAA too. I'll eat my hat if it does not.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 07/05/2018 09:37:09
I am sorry. I missed the wikipedia Henderson/Hasselbalch equation (https://en.wikipedia.org/wiki/Bicarbonate_buffer_system#Henderson%E2%80%93Hasselbalch_equation) before. I will use their equation, but not their pKa because their equation is for blood, and pKa in seawater is slightly less than they give. I can use this for an alternative back-of-envelope equation, which I'm confident refutes NOAA too. I'll eat my hat if it does not.
Go and buy a marzipan  hat (or maybe rice-paper if you don't like almonds)
We already have the numbers.
I already did the calculation .
The change is of the order or 24%

So, if your "improved" equation doesn't give an answer somewhere near what NOAA gave, you are simply wrong.

I don't understand why you are still trying to argue against reality.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: alancalverd on 07/05/2018 22:23:50
So the pH value at one location off the coast of a volcanic island has changed a bit in the last 20 years. That's science.

" In the past 200 years alone, ocean water has become 30 percent more acidic" That's journalism.

The mean pH at Station Aloha seems to have levelled off around 8.08 between 2000 amd 2010. That's observation.

It will be interesting to see whether current volcanic events in the region have any noticeable effect. Science again.

Frankly, I have difficulty measuring pH of even fairly homogeneous stuff like blood, distilled water  or photographic chemicals to 3 significant figures in a laboratory. Given the depth, currents ,temperature variability, weather variability ,rainfall, evaporation, and pseudocyclic ecology at every depth of the Pacific Ocean, I'm not sure what "ocean pH at Aloha" even means, let alone how it is measured to 4 or 5 sig figs with a 200-year-old electrode, nor what its global significance may be.

We live in an unstable world. Fact.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: chiralSPO on 08/05/2018 12:09:11
I am sorry. I missed the wikipedia Henderson/Hasselbalch equation [nofollow] before. I will use their equation, but not their pKa because their equation is for blood, and pKa in seawater is slightly less than they give. I can use this for an alternative back-of-envelope equation, which I'm confident refutes NOAA too. I'll eat my hat if it does not.
So what flavor is your hat?
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 08/05/2018 19:47:07
Frankly, I have difficulty measuring pH of even fairly homogeneous stuff like blood, distilled water  or photographic chemicals to 3 significant figures in a laboratory.
There is no mechanism by which your incompetence affects other people's results.
Part of your problem may involve
(1) thinking blood is homogeneous (the pH inside a red blood cell is different from the pH outside it)
(2) failing to understand the effects of buffering capacity when trying to measure the pH of very dilute solutions such as distilled water - You did remember to use a double junction electrode, didn't you?
(3) failing to take account of reactions of the silver/ silver chloride electrode commonly used as a reference with thiosulphate (specifically used because it reacts with silver salts) and  photographic developers which are... also specifically chosen because they react with silver salts.

There are probably other issues.

The mean pH at Station Aloha seems to have levelled off around 8.08 between 2000 amd 2010. That's observation.
No, the data show a clear downward trend.
That's the real observation

" In the past 200 years alone, ocean water has become 30 percent more acidic" That's journalism.
Rounding the data to "30%" is reasonable as both journalism and as a scientific presentation of a valid extrapolation of the data.

It will be interesting to see whether current volcanic events in the region have any noticeable effect. Science again.
True, but that effect will be local, rather than global so it isn't strongly related to the worldwide issue.
I'm not sure what "ocean pH at Aloha" even means, let alone how it is measured to 4 or 5 sig figs with a 200-year-old electrode
Nobody said it would.

Are you planning to share a headgear based meal with Mark?
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: alancalverd on 09/05/2018 07:22:24
Someone has chosen to fit  a straight line to the 1988-2006 data. But I think you would get a better fit with a steeper line up to 2000 and a shallower one thereafter. A classic example of making the data fit the model, which can lead to policy-based evidence-making, self-deception, and all sorts of flat-earth nonsense if unchecked.

To revert to the OP
Quote
In the past 200 years alone, ocean water has become 30 percent more acidic
looks to me like a global statement of historic results, but the only evidence presented in this discussion seems to be 18 years' data from one admittedly unstable and uncharacteristic point on the globe, and a linear regression with R2 < 0.3 indicating that the data is mostly noise or nonlinear.

Remember the old joke about three men in a train, seeing two cows in Patagonia

Politician: "The vast majority of Patagonian cows are black"

Mathematician: "On an insignificant sample, one might hypothesise that half the cows in Patagonia are black"

Physicist: "0300 UTC, Patagonia. Two bovine quadrupeds observed, at least one side of one of which is black."

Happy to eat a hat made from nori or plaited sea spaghetti, but not just yet.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: evan_au on 09/05/2018 09:17:38
Quote from: ChiralSPO
The pH is not the same everywhere because the ocean is not mixed perfectly well.
This struck me while looking at the graph - the concentration of CO2 in the ocean does not track the concentration of CO2 in the atmosphere very well.
- However, the concentration of CO2 in the ocean is strongly (inversely) correlated with the pH of the ocean, suggesting that dissolved CO2 is a major driver of ocean acidification.

So maybe ocean currents, winds or el Nino bring deep water to the surface, which reflect an older (lower) concentration of atmospheric  CO2?
- Of course, as the surface waters laden with increased CO2 cool and descend to lower depths at the poles, this reservoir of  slightly higher pH will be consumed.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: alancalverd on 09/05/2018 16:35:46
As far as I can tell by simply zooming on the graph, the ocean p[CO2] exactly anticorrelates with the atmospheric value. This isn't entirely surprising as we know that the seasonal variation of atmospheric  p[CO2] at Mauna Loa is itself anomalous - the maximum concentration each year occurs in summer, when the anthropogenic emission is lowest.

So we are back to known chemistry: for a given atmospheric partial pressure, the equilibrium concentration of CO2  in water decreases with increasing temperature.

Edit: And now I realise that this will cause confusion! p[X] is standard nomenclature for partial pressure of a dissolved gas and increases with concentration [X], whilst pH is an inverse function of [H+]!
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: jeffreyH on 09/05/2018 19:00:18
Care need to be taken when interpreting data. Do we know the intricate workings of our own atmosphere or could we learn by studying other examples?
https://www.newscientist.com/article/dn22572-heavy-hydrogen-excess-hints-at-martian-vapour-loss/
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 09/05/2018 19:31:33
People are now playing a new game.
It's called "I can interpret this graphical representation of the data, better than the people who generated (and thus had access to) the real data."

It's great fun.
It isn't science.


This isn't entirely surprising as we know that the seasonal variation of atmospheric  p[CO2] at Mauna Loa is itself anomalous - the maximum concentration each year occurs in summer, when the anthropogenic emission is lowest.
With a seasonal variation from 20 to 24 C over the year, Hawaii hardly has a Summer to be anomalous about.

Seasonal CO2 variation is fairly well understood.
https://scripps.ucsd.edu/programs/keelingcurve/2013/05/07/why-are-seasonal-co2-fluctuations-strongest-in-northern-latitudes/

Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 09/05/2018 19:34:32
As far as I can tell by simply zooming on the graph, the ocean p[CO2] exactly anticorrelates with the atmospheric value.

Are we talking about the same graph? [ Invalid Attachment ]

Are you saying that the red dots go up, and the blue ones go down, or the other way round?
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: jeffreyH on 09/05/2018 22:49:58
The planet will still be here long after the human race is gone. The universe isn't here to be kind to us. Maybe we should stop examining our own navels.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: alancalverd on 10/05/2018 08:08:10
The Scripps link is interesting.  Fortunately the first Comment offers a more comprehensive  explanation of what actually happens in one sentence, but it is noticeable that the principal student essay is a bit vague about the actual phasing and amplitude of the cycle.

And yes, the expanded graph does show an anticorrelation between atmospheric and ocean CO2.

Both observations are entirely consistent with what we learned at school about biology and physical chemistry. It's just interesting to see how nature behaves on a large scale pretty much as it does in a test tube.

As for "offering a better interpretation" of someone else's data, it is mere curiosity that makes me wonder why anyone would fit a straight line to data that does not appear linear and indeed cannot be linear.

Nor would I dismiss the obvious seasonal cycle of Mauna Loa CO2 concentration (which is so regular and so significant that the observers themselves draw attention to it) because "With a seasonal variation from 20 to 24 C over the year, Hawaii hardly has a Summer to be anomalous about." The job of science is to explain what happens, not to pretend it can't.

The outstanding problem with climate science is the damn data!
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 10/05/2018 19:16:46
the expanded graph does show an anticorrelation between atmospheric and ocean CO2.
Seriously?
What graph do you mean, and what do you mean by anti-correlation?
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: chiralSPO on 10/05/2018 20:05:09
The overall trend-lines for each are definitely correlated. It is hard to tell from the graphic without expanding, but it looks like the noise could be anti-correlated. This could make sense, as the overall amount of CO2 is increasing, as indicated by both trend-lines, but day-to-day (or whatever) variations in temperature will cause the distribution of CO2 to differ-with warmer temperatures increasing atmospheric concentrations at the expense of marine concentrations, while cooler temperatures increase marine concentrations at the expense of atmospheric.

The main takeaway, however, should not be the relationship between noise in the data, as there is no systemic error indicated. Rather, we should be concerned with the overall trend.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 10/05/2018 21:15:33
It's possible that the noise has an inverse correlation.
Who cares?
The measured variables are clearly correlated.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: alancalverd on 11/05/2018 16:22:02
Here in the real world, we take every measurement as a measurement. Xome folk deduce "signal" by imposing a model on a sequence of measurements, and dismiss the variances from that model as "noise", but whilst that is the way of politics, philosophy, religion and economics, it isn't good science.

I looked at the expanded graph of seasonal variation of atmospheric [CO2]   and compared it point-by-point with the ocean [CO2] concentration. What comes out of that comparison is that ocean [CO2] decreases in the short term  as the temperature rises, which is entirely to be expected, but as I have remarked before, atmospheric [CO2] increases anomalously as temperature rises in the northern hemisphere.

You can of course draw crude trend lines through all the data, but I think that misses a lot of interesting information. There is no doubt that atmospheric and ocean [CO2] have risen over the periods measured, but the short-term detail suggests that the underlying mechanism is more interesting than merely "anthropogenic". That's the problem with science - it makes us question what civilians dismiss as "obvious", and leads to all sorts of things like aeroplanes, nuclear power, antibiotics.....
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 11/05/2018 18:47:31
You are right- assuming that we wish to look at the CO2 in air and sea, but ignore the effect of time - which is important in the real world.
All you have done is highlight a phase lag. It's interesting in it's way. Obviously, it's an artefact of a system that's being driven by a "rapidly" osculating  driver- the Sun's annual variation. It's a little like the observation that, in the UK at night time the sea is hottest (compared to the air) in Autumn, rather than Summer even though the weather in general is hottest in Summer.
But the fact is that both are rising with time.

You say "but the short-term detail suggests that the underlying mechanism is more interesting than merely "anthropogenic"."
well, that's "sort of" good- because nobody was saying the short term variation was anthropogenic.
The thing we need to do something about is the bloody great big change. The change that's driven by anthropocentric releases of CO2 that we know about, and can quantify quite well by either looking at fuel duty receipts in government taxes or at profits of oil companies. (we can also get better estimates, but those ones are good enough) to show the point.
The noise on that may be correlated any which way- but it's weather rather than climate.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: alancalverd on 11/05/2018 22:52:10
It is the phase relationship between temperature and CO2 that questions the accepted "wisdom" of anthropogenic climate change.

Drawing straight lines through wobbly data is a reasonable way of demonstrating gross correlation to a naive audience, but temporal phase analysis demonstrates causality
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 12/05/2018 00:58:28
Drawing straight lines through wobbly data
You have plausibility to the extent that this trend is "wobbly"

* wobbly.JPG (29.08 kB . 442x221 - viewed 1583 times)

Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 12/05/2018 01:10:07
It is the phase relationship between temperature and CO2 that questions the accepted "wisdom" of anthropogenic climate change.
Which is plainly a bit silly.
Whether the CO2 takes a few months to turn up in the sea water isn't the issue here.
The "wisdom" of anthropogenic climate change is based on a number of factors; let us know which you disagree with.

(1) Humans have been burning a lot of fossil fuels in the last hundred years or so.
(2) That generates CO2  which (at least on a scale of centuries) ends up in the atmosphere.
(3) We know this because the excess CO2 in the air  tallies with the  stuff we have added.
(4) The CO2 levels in the air are rising.
(5) The added stuff has an "ancient" carbon dating age- which is consistent with it being from fossil fuel but not with it being from any more recent source.
(6) Additional CO2 in the air  means that more of the Sun's incoming radiation is trapped by the Earth- because that's what physics tells us..
(7) The temperature is rising.

Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: MarkPawelek on 13/05/2018 11:05:39
Quote
" In the past 200 years alone, ocean water has become 30 percent more acidic" That's journalism.

No. That is settled science according to the climate Stasi. It is on the NOAA website. The important point I made was NOAA's claim that ocean pH has risen by 30% is junk science. This is why people are laughing at the settled science of climate change. Why so many people voted for Trump.  You can blame it on journalists. I will blame it on the Royal Society. They are the people who wrote to journalists telling them not to criticise official climate science, whom NOAA certainly are.

PS: Redone calculations using the Henderson/Hasselbalch equation is no more favourable to NOAA than my back-of-envelope calculation. Thanks for that.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 13/05/2018 13:40:55
PS: Redone calculations using the Henderson/Hasselbalch equation is no more favourable to NOAA than my back-of-envelope calculation. Thanks for that.
Show your working.
Also, since I already did the calculation, would you like to show where I got it wrong?
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: puppypower on 13/05/2018 14:08:27
The 30% increase in acid is an artifact of the logarithmic scale use for pH. The 30% is real, but is being used as an emotional magic trick.

To explain how the tricks works, say we start with a pH of 8. This means we have a H3O+ concentration of 10-8 moles/liter. If we started with a pH of 7, we start with 10-7 moles per liter. This is ten times as much H3O+.

If we added 10-8 moles per liter of extra acid to the beaker that has pH of 8, we get a total of 2 x 10-8 moles per liter or a 100% increase. If we added the 10-8 moles per liter to a pH of 7, we only increase the acid level by 10%. Say we started at pH of 9 or 10-9 moles per liter and add 10-8 moles per liter of acid, that is a 1000% increase. If we add that to a pH of 6, that is now a 1% increase.

The question is what sounds worse; 1%, 10%, 100% or 1000% increase? The bigger percent numbers sound the worse, yet all use the same amount of acid. It is math number  trick designed to take advantage of ignorance of the logarithm scale.

It works similar to the trace elements reported in environmental remediation studies. If we have 1 PPM or 150 PPB of mercury, the 1 part per million is more than 150 parts per billion. However, to some people, 150 sounds worse than 1, if one is not sure what ppb and ppm mean. Not everyone is familiar with the logarithm scale and will take the percent at face value; apples to apples instead of apples to oranges. 

Say we freeze the amount of CO2 emissions to the 2017 level world wide. Say in 2018, the same amount of acid is added to the oceans. Since the pH lowered from 2016 to 2107, the percent change will fall next year. If we wanted to do a magic trick, we can say that by simply freezing the CO2 emission to 2017 levels, we can get the acid level change to  1% in less that 20 years. This looks very promising to the untrained eye.

It is possible, due to the logarithmic scale, to increase the CO2 each year by 1%, and still get the acid percent to fall, since the overall pH will continue to fall and the logarithmic scale will diminished the impact.


Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 13/05/2018 14:39:19
The 30% increase in acid is an artifact of the logarithmic scale use for pH.
If you calculate that actual concentrations of hydrogen ions and extrapolate back you get a change of about 30%.
There is no exaggeration or fakery involved.
The ocean- as measured- has about a quarter to a third more acid in it than it used to.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: alancalverd on 13/05/2018 23:22:59
Quote
The concept of pH was first introduced by the Danish chemist Søren Peder Lauritz Sørensen at the Carlsberg Laboratory in 1909[4] and revised to the modern pH in 1924 to accommodate definitions and measurements in terms of electrochemical cells.

which casts some doubt on the "200 year" claim. Was anyone really titrating Aloha seawater against a standard base in 1818?

Extrapolation over 200 years is clearly a very sound scientific substitute for evidence. The number of cars on UK roads decreased between 2007 and 2009 from 30.2 to 30.1 million, so extrapolating from a straight line best fit clearly demonstrates that there were 40 million cars on UK roads in 1807. That is 4 cars for every person, 80 years before the first car was made! Shock, horror, headlines, we are all doomed.....
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 14/05/2018 19:51:35
which casts some doubt on the "200 year" claim. Was anyone really titrating Aloha seawater against a standard base in 1818?
Yes- in a way.
The standard base they used was a saturated solution of calcium carbonate and they observed that when you added seawater no further dissolution of the carbonate took place.
 Had you not realised this when you asked?
The data is reported in the first web page cited in this thread.
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: RjMaan on 24/06/2018 08:46:29
Actually, the larger amount of carbon dioxide when reacts with the rain water. I forms Carbonic acid which is the major component of acidification. For exact percentage you can check them on authentic sites like Wikipedia and Qanda (https://qanda.typicalstudent.org/).
Title: Re: How can climate scientists claim 30% acidification of the ocean due to CO2?
Post by: Bored chemist on 24/06/2018 09:18:55
Actually, the larger amount of carbon dioxide when reacts with the rain water. I forms Carbonic acid which is the major component of acidification.
Actually it doesn't.

Why do you keep posting pointless little bits like this?