Talk:Ocean acidification

First sentence

The first sentence is not quite correct. We're using a 2005 source to make time-travelling claims towards 2021. @Dtetta, who seems to have last played with the dates in this sentence. I tried to update this with the latest IPCC report, but they do not seem to make a statement around average pH. The statement from NOAA is more conservative In the 200-plus years since the industrial revolution began, the concentration of carbon dioxide (CO2) in the atmosphere has increased due to human actions. During this time, the pH of surface ocean waters has fallen by 0.1 pH units. Possible solutions:

• We can use: this 2023 ERL article figure 1. This source claims a drop from 8.15 to 8.05 since 1950, from the Copernicus Marine Service. I'm not sure if that's the gold standard (Copernicus does do ERA5, which is the gold standard for reanalysis of atmospheric variables).
• We can use the NOAA source and say it's dropped by 0.1.
• We can omit it altogether.
• this paper says globally averaged pH was 8.17 in 1880, further supporting that our first sentence may be wrong. —Femke 🐦 (talk) 16:35, 25 March 2023 (UTC)

I'm leaning towards the first source, but maybe somebody has more insight here. —Femke 🐦 (talk) 16:27, 25 March 2023 (UTC)

Have added the first paper. IPCC SPM has similar numbers in their graph from modelled pH measurements. I can't see a modern source with the data we have in the lead, so I think this will at least be a step forward. —Femke 🐦 (talk) 16:42, 25 March 2023 (UTC)

Yes that’s a good catch. You need to reconcile it with a sentence later in the lead that also references those dates in pH levels. “The change in pH from 8.25 to 8.14 represents a nearly 30% increase in hydrogen ion concentration in the world's oceans. .” I think the change of .1 unit is more important than the absolute pH levels for most people. The article about acidification, not necessarily the relative alkalinity and pH of the worlds oceans. The 0.1 unit option also seems fine to me. Dtetta (talk) 16:49, 25 March 2023 (UTC)

I've reconciled it sort of (I'm saying "A drop of 0.11, rather than the drop). Can be done more elegantly if we get a source which converts a 0.1 drop to a percentage increase. It's important info for scicomm, so didn't want to remove it in the meantime. —Femke 🐦 (talk) 16:52, 25 March 2023 (UTC)

Per WP:AVRC, I don't think we need a source to do high school mathematics (I get that some may differ).

The calculation is straightforward:

10^8.05/10^8.15= 141253754.5/112201845.4= 1.258925≈26% S Philbrick(Talk) 20:59, 26 March 2023 (UTC)

Another option would be to just change the dates so that the text and source are consistent. Not sure it’s all that important that we capture 2021 pH rather than 2005. Dtetta (talk) 16:52, 25 March 2023 (UTC)

The 2009 source we use for the conversion to 30% doesn't state the pH levels we're talking about at all. It just happened to be compatible with the removed 2005 source.. —Femke 🐦 (talk) 17:02, 25 March 2023 (UTC)

That makes sense to me. Dtetta (talk) 17:21, 25 March 2023 (UTC)

I am very pleased to see edits occurring as a result of discussion on talk pages. I wish it happened more often.

That said I have some concerns about the decisions reached. I was initially troubled by seeing a reference to 0.11 in the second paragraph in view of the fact that the second sentence talks about a change from 8.15 to 8.05. I see from the talk discussion that the second paragraph trying to make an illustrative point about the fact that a change in pH means a rather large change hydrogen ion concentration. However, if one is going to give an example, one option is to pick a round number value (such as 0.10) or a number relevant to the discussion (which coincidentally is also 0.10). While the value of 0.11 happens to correspond to values reported in this article 11 days ago 15 March 2023, Those values are no longer in the article. I am also concerned about rounding 28.8% to 30%. I do get that were trying to give a rough idea of what the numbers mean, but we should either find some way to explain why we are using 0.11 and then used two decimal places, 29%, or better yet use the number that happily is both a round number 0.10 and represents the difference in the reported numbers in the first paragraph and round 25.8925% to 26%.

I am also interested in the source of the change in pH. An earlier version of the article had values 8.25 and 2.14, corresponding two years 1751 and 2021, which was sourced to Jacobsen. (As a minor note that source didn't mention 2021, it referenced 2004, but that issue is moot if we're not going to use that reference)

The new values are sourced to this letter. I've searched but I haven't found where the values or the dates are specified. Is it possible a different source was intended?--S Philbrick(Talk) 20:48, 26 March 2023 (UTC)

Happy to go with the routine calculation. That makes more sense and leads to a more accurate conversion. The historical pH information is in figure 1f of the letter. —Femke 🐦 (talk) 21:11, 26 March 2023 (UTC)

Thanks S Philbrick(Talk) 22:16, 26 March 2023 (UTC)

I also have my doubts about this sentence Between 1950 and 2020, the average pH of the ocean surface fell from approximately 8.15 to 8.05. It's a very prominent sentence, very simple and clear sounding. I had copied it also to ocean and seawater. However, I am a bit concerned as those figures are not even mentioned in the abstract of the paper but we read them off from Figure 1f. Is this justifiable? Also, in this section: Ocean_acidification#Predictions_for_future_pH_and_rate_of_change later in the article we have a table that uses data from the WG 1 report (I had added the table after modifying or deleting a previous table that was in an earlier version of this article). These figures are taken from Figure TS.11 on page 75.

For the current pH value it says there 8.08 (so a bit higher than the 8.05 value). But I feel this is all a bit unsatisfying. Why do we have to read numbers off a graph (I've literally just printed out Figure TS 11 and used a ruler to read off the values. This can't be the best way of doing it.) If none of the publications that we cite give the actual pH values but only give graphs then perhaps this is telling us something. We probably need to point out to our readers that these are all just approximations. So rather than making it sound so simple "the pH value is currently 8.05" should we rather give a range? Or find a suitable publications that gives the numbers explicitly rather than in graphs? EMsmile (talk) 11:28, 4 May 2023 (UTC)

Maybe we could say it like this (this is how I have just changed it at ocean)?: The pH value at the surface of oceans (global mean surface pH) is currently in the range of 8.05 to 8.08. - I think it would be good if we made it clear to people that there is no one correct figure but these are estimates and hence there can be a bit of a range. (and even small changes are very important) EMsmile (talk) 11:36, 4 May 2023 (UTC)

Makes sense to put less emphasis on it if you couldn't find the number explicitly either. Maybe only mention the 0.1 decline in the lead, and have the paper estimate in the body?

I'm impressed you managed to read that IPCC graph. I would put slightly less trust in such a zoomed-out graph, small errors in plotting may skew the result. —Femke 🐦 (talk) 18:59, 5 May 2023 (UTC)

I am really quite stumped about this all. Why do the other publications not give the pH values as text but only as graphs? Is it because of uncertainty? Strange. We also have the graph in the lead that shows the pH drop, it comes from Our World in Data here. When I click there on "sources" underneath the graph I get to this page which gives an error message:

https://hahana.soest.hawaii.edu/hot/products/products.html. Another place to look could be the annual UN reports on SDG 14, as ocean acidification is one of the targets/indicators (see here).

Another aspect is the issue of "what is surface pH?". I have been talking to Tim Jickells about that over e-mail in connection with edits I am making at ocean about pH and alkalinity. The pH reduces naturally at depth. He wrote to me: "One important point which you do absolutely correctly note in the various sections, is that the big acidification issue at the moment is in the surface ocean waters, approximately the upper 100m. The average depth of the ocean is about 4km, so there is a large body of deeper water where the natural gradients from 8.2 to about 7.8 still exists and it will take a very long to acidify these waters, and equally a long time to recover from that acidification." - I am planning to include something about that in the ocean article, and maybe also here at ocean acidification (?). I am thinking like this:

"The definition of global mean surface pH refers to the top layer of the water in the ocean, up to 20 or 100 m depth (depending on the definition used) (??). The average depth of the ocean is about 4 km, and the pH value further down below (lower than 100 m) has not yet been affected by ocean acidification in the same way.  There is a large body of deeper water where the natural gradients from 8.2 to about 7.8 still exists and it will take a very long to acidify these waters, and equally a long time to recover from that acidification. But as the top layer of the ocean is crucial for its marine productivity, any changes to the pH value of the top layer (or surface) can have many knock-on effects. (see also effects of climate change on oceans)" (refs would be the same that I've used for alkalinity there, i.e. textbook by Jickells Chapter 9 and textbook by Emmerson & Hedges Chapter 4; NB I don't have access to those textbooks but Tim said they would be correct to use as refs (?)).

Regarding the definition of "surface" this is what I wrote to him:

What is even the definition of “surface” in those graphs. You mentioned 100 m but I am guessing this is not formalized anywhere?

In the Wikipedia article on sea surface temperature (https://en.wikipedia.org/wiki/Sea_surface_temperature) I had written:

Sea surface temperature (SST), or ocean surface temperature, is the water temperature close to the ocean's surface. The exact meaning of surface varies according to the measurement method used, but it is between 1 millimetre (0.04 in) and 20 metres (70 ft) below the sea surface.

I didn’t even have a reference for that statement because I think Baylor Fox-Kemper gave it to me from his own knowledge. Do you have a reference for this?

I also checked the IPCC WG 1 glossary and it says this, i.e. no mention of how many metres:

Sea surface temperature (SST): The subsurface bulk temperature in the top few metres of the ocean, measured by ships, buoys and drifters. From ships, measurements of water samples in buckets were mostly switched in the 1940s to samples from engine intake water. Satellite measurements of skin temperature (uppermost layer; a fraction of a millimetre thick) in the infrared or the top centimetre or so in the microwave are also used, but must be adjusted to be compatible with the bulk temperature.

He has replied to me as follows:

"The text you have looks fine. The key issue in terms of the penetration of ocean acidification is the way the surface water mixes with deeper water which depends on the temperature - in the tropics the warm surface layer of about 100m is quite stable and doesn't mix much with deeper water, while near the poles winter cooling and storms makes the surface layer denser and it mixes to great depth and then stratifies again in summer, so there isn't a simple single depth. In the ocean wiki there is a discussion of the photic depth which again is about 100m and is related to this heated surface layer. You can't explain everything on a short wiki article so I think what you have seems fine."

So in summary: I think we do need to highlight to our readers that pH changes with depth and that this article is about surface pH. Some of the different measurements could be related to a different definition of "surface pH"? - And we need to adjust some of the "certain sounding" wording regarding current pH values in the second sentence of the lead. We could say "it's complicated because..." and give more of a range/approximation...

Perhaps we could also reach out to relevant IPCC authors from the chapter of the WG I report for their advice?

As part of the project that I am working on, we did reach out to people at several universities who referred as on to people at NOAA and so we had immensely useful inputs from Gabby Kitch from NOAA, see above on the talk page; Gabby helped us a lot to improve it (if anyone is curious: compare it with the version from say 6 January 2022 which is round about when I first started to edit this article)

Unfortunately, Gabby was pulled away to another work assignment so the last bit of improvements and modifications that needed doing didn't get completed in that round of editing (which took place around November last year). Thanks, Femke, for becoming involved recently! We needed that extra pair of fresh eyes and bright mind that you brought to the table. It's such an important article & topic; would be a pity it if would linger at low quality. EMsmile (talk) 11:51, 7 May 2023 (UTC)

Related to this, Tim Jickells also wrote to me this about stratification which we should perhaps highlight as well in one way or another (so far, we only mention ocen stratification once in the article): "As you say you can look at stratification as either keeping the problem in the upper layer and protecting the deep waters or as making the problem in the surface waters worse - its two sides of the same coin, but this stratification issue is an important fact of ocean behaviour."EMsmile (talk) 09:44, 8 May 2023 (UTC)

Also, I checked the UN report from the HLPF in 2022 because pH is an indicator for Target 14.3 of SDG 14 ("This target has one indicator: Indicator 14.3.1 is the "Average marine acidity (pH) measured at agreed suite of representative sampling stations". However, it doesn't say anything about actual pH values. This organisation that is meant to monitor that indicator: Intergovernmental Oceanographic Commission. Pinging User:ASRASR into the conversation. EMsmile (talk) 09:58, 8 May 2023 (UTC)

Question about sentence on increasing alkalinity

I question this sentence, it seems to me a bit unclear; is it important, does it need to stay but be improved? This will cause an elevation of ocean alkalinity, leading to the enhancement of the ocean as a reservoir for CO_2, which would cause further invasion of CO₂ from the atmosphere to the ocean. I came to this as I was searching about alkalinity content in this article. Have just added a para about alkalinity at ocean with the help of Tim Jickells. I have also worked on alkalinity recently and am currently thinking how to link or repeat content about alkalinity from here. Will also ask Tim about this. EMsmile (talk) 13:15, 29 March 2023 (UTC)

I've now deleted this sentence as I think it does not add value here and is just confusing. I had also checked this with Tim Jickells and this is what he wrote to me on e-mail: "If you can increase ocean alkalinity it can increase CO2 uptake so I think this has been proposed but as the OA article makes clear it is not simple, cheap or without side effects." EMsmile (talk) 11:54, 4 May 2023 (UTC)

References

Question about sentence on unchanging alkalinity?

I had added this sentence: "The total alkalinity in the ocean is however neither increasing or decreasing based on the gas exchange of carbon dioxide in the atmosphere with the seawater.". Femke removed it with the words "better explained later (sentence was ambiguous, 'based on' often means "which we know based on measurements of"))". I don't understand why you removed it? Where is this issue about alkalinity explained later in the article?

The original wording in the IPCC report was this by the way, which is something I had added to alkalinity: "The total alkalinity in the ocean is "not affected by the exchange of carbon dioxide gas between seawater and the atmosphere". This means that the increasing carbon dioxide level in the atmosphere, due to greenhouse gas emissions, does not alter the alkalinity in the ocean even if it does result in a reduction in pH value (called ocean acidification).

So "based on" could be changed to "due to"? I had made it "based on" to avoid close paraphrasing from "affected by"... EMsmile (talk) 11:48, 30 March 2023 (UTC)

The new sentence I think you propose is: The total alkalinity in the ocean is however neither increasing or decreasing due to the gas exchange of carbon dioxide in the atmosphere with the seawater. This is ambiguous. It can mean:

• Alkalinity would normally change, but it's not because of the exchange of gas
• Alkalinity is unchanged, despite the existence of gas exchange

Neither of those reflects sufficiently well what the source says. Do we know that alkalinity is constant? It may be affected by other impacts. CO2 is not in gaseous form in the ocean, so that's a second minor misstatement.

I believe the following does accurately portray the source: the absorbtion of CO2 from the atmosphere does not affect the ocean's alkalinity. Note that I've simplified the gas exchange by absorbtion (the subset of exchange that's actually happening), made the sentence active rather than passive, and maintained the original meaning.

Of course, at this point the reader has no idea what alkalinity is or why it is relevant. Further down the page we have a similar statement: Ocean alkalinity is not changed by ocean acidification, but over long time periods alkalinity may increase due to carbonate dissolution and reduced formation of calcium carbonate shells. So the information was already in the article in a different format, in a section talking about alkalinity enhancement, so in context. —Femke 🐦 (talk) 16:25, 30 March 2023 (UTC)

Thanks for these explanations. Your new wording of the absorbtion of CO2 from the atmosphere does not affect the ocean's alkalinity is indeed much better. I've have added that into the section of the article that explains the fundamentals, together with an explanation to the reader why alkalinity is relevant here, and a reference to the section where more about alkalinity enhancement will be explained. Do you think it's OK now like this? EMsmile (talk) 12:12, 4 May 2023 (UTC)

References

Need clarification

"A study in 2008 examining a sediment core from the North Atlantic found that while the species composition of coccolithophorids remained unchanged for the industrial period 1780 to 2004, the calcification of coccoliths has increased by up to 40% during the same time." The wordings of "the calcification of coccoliths has increased by up to 40% during the same time" seem to be very vague to me, can anyone help clarify? Thanks. ThomasYehYeh (talk) 05:52, 17 December 2023 (UTC)

I've improved the wording, please check. EMsmile (talk) 08:33, 6 March 2024 (UTC)

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