Talk:Ocean heat content

Definition

It is defined as

$H=\rho c_{w}\int _{h2}^{h1}T(z)dz$

$\rho$ - water density, $c_{w}$ - specific heat content, h2 - bottom depth, h1 - top depth, $T(z)$ - temperature profile.

Moved unsourced definition, Prokaryotes (talk) 04:27, 29 September 2013 (UTC)

I don't think that's a good idea. Its a useful formula and should be std in the appropriate textbooks. Who knows, you might even find in from IPCC William M. Connolley (talk) 09:08, 29 September 2013 (UTC)

(user:Giorgiogp2) added a reference, though not really verifiable but appears to be legit now. Prokaryotes (talk) 05:49, 30 September 2013 (UTC)

It is indeed a useful formula, but it's not the formula for ocean heat content. Rather it is one way of defining heat content of a column of water having a uniform temperature at any given depth. If the column has cross-section 1 m² and the constants are in SI units then the integral gives the heat content of that column in joules. If the cross-section is 1 km² then the result is in megajoules. Ocean heat content requires a volume integral, namely over the volume of the ocean suitably coordinatized, and T needs to depend not only on depth z but also the other two coordinates, T(x,y,z) or whatever.

It's also not how NOAA, EPA, etc. define ocean heat content, though it differs only by an additive constant. Oceanographers define it relative to the average heat content (perhaps as defined by a formula like the above) over 1971-2000, analogously to how temperature anomalies are defined. (And in that case it does not matter whether T(x,y,z) in the formula is Celsius or Kelvin since they differ only by an additive constant.)

However one does not need that index to see that since the ocean's mass is 1.4 exatonnes (1.4e21 kg), if it warmed everywhere by 1 °C it would add 4.186*1.4 = 6 yottajoules (5.86e24 J) to OHC, whatever the index. From that, along with the graph in the article showing 0.25 yottajoules (25e22 J) of heat going into the top 2 km, and neglecting any heat content variation below 2 km, we can infer a temperature rise since mid-century of 0.25/6 = 0.04 °C averaged over the whole ocean. Vaughan Pratt (talk) 00:00, 22 October 2013 (UTC)

C-class assessment and importance assignment upgrades

The article's quality score was up-rated from 'Start' to 'C' since it provides a reasonably complete overview of the subject with the recent updates and additions. Importance ratings were also up-rated to 'Mid' with respect to stated goals of the Climate and Ocean projects. Article could be improved by providing some context to the magnitude of the energy and temperature increases. Bikesrcool (talk) 05:13, 27 February 2022 (UTC)

Suggestion to convert to long references style

I'd like to convert this article to long ref style to make it more consistent, easier to move content from one article to another, easier for newcomers. Does anyone object? Pinging User:Bikesrcool. Also, I don't think why many of the refs for the IPCC AR6 report include statements or quotes in the ref list. I think they should be deleted or integrated into the article text. I think they were added by a student earlier this year. EMsmile (talk) 08:11, 7 October 2022 (UTC)

This has now been changed. EMsmile (talk) 12:25, 27 February 2023 (UTC)

Difficulties with saying this in my own words

I am finding it difficult to change this content "to my own words". Originally I thought I could copy from the journal article. It's open access but upon closer inspection I conclude it's not under a compatible licence. So for now I have changed the text to quotes. I know it would be better to say it in my own words but I am a bit stumped with this content. How to do this so that it says the same but is not just close paraphrasing? Is it fair to try a team approach here, hoping that someone who knows more about this content can help to convert this? Or is it better to delete it if I can't say it in my own words? Pinging User:ASRASR and User:Femke. This is the text block in question: Estimating the rates of change in OHC comes with some uncertainties because of the "challenges of making multidecadal measurements with sufficient accuracy and spatial coverage". For instance, there are "significant interannual fluctuations due to El Niño–Southern Oscillation (ENSO) and other natural climate modes, such as the Indian Ocean dipole, with typical periods of less than 10 years". Also, "major volcanic eruptions induce additional interannual OHC fluctuations".. Of course I could paraphrase this in some way but would run the danger of doing "close paraphrasing". (see also my talk page for a discussion about close paraphrasing problems) EMsmile (talk) 12:29, 27 February 2023 (UTC)

What do you think of my rewrite? I've tried to avoid jargon such as 'Indian ocean dipole' and avoid academic wording such as multidecadal and internannual. I've lost some detail, but I think those details do not serve our readers. My main hope with the necessary rewrites is to get more inclusive text, not text that only academics may understand. —Femke 🐦 (talk) 17:18, 27 February 2023 (UTC)

It's very good. I wouldn't have been able to do it because as a complete non-expert I found it hard to decide which detail can be dropped and which can't. I've just now changed one of the sentences further to Ocean heat content measurements had large uncertainty until the time when Argo profiling floats were deployed.. However, I worry a bit that this is actually not really supported by the source where it says that these uncertainties still exist (Estimating the rates of change in OHC comes with some uncertainties). Our sentence makes it sound like because we have the Argo floats it's all easy now? EMsmile (talk) 09:07, 28 February 2023 (UTC)

I'm describing the uncertainty in OHC, not in the rate of change in the OHC, which requires a reliable start point. I'm not sure the later sentence "far from ideal" correctly translates into large uncertainty, so I'll keep the sentence limited to before Argo deployment. I believe the measurements are adequate now that deep Argo has been deployed too. —Femke 🐦 (talk) 17:25, 28 February 2023 (UTC)

Changed it, but without the words large uncertainty. —Femke 🐦 (talk) 17:28, 28 February 2023 (UTC)

References

Definition, cited?

@EMsmile: you readded "Ocean heat content (OHC) is the energy absorbed by the ocean and stored as internal energy or enthalpy for indefinite time periods.". I removed this as I thought it was uncited (as well as scary jargon), but you placed it back in the article like it is cited. Can you confirm that it's cited to Dijkstra? Kumar doesn't mention it, but I'm not in the office this week to check Dijkstra. —Femke 🐦 (talk) 17:12, 28 February 2023 (UTC)

I hadn't thought about it in depth; just thought the definitions sections should have a clear sentence at the start before diving into the depths of integrals and so forth. I've now added another simple definition from the EPA website, what do you think of that? I also checked the IPCC Sixth AR and its glossary but found no info there. Ocean heat content is mentioned a lot but not actually "defined". Maybe because it's so simple, as it's just the heat in the ocean. If there are other/better definitions of OHC, I welcome anyone to add those. EMsmile (talk) 23:51, 28 February 2023 (UTC)

Can you avoid adding unsourced content in front of unrelated citations in the future (second request I believe). If you want to add unsourced text, use a cn tag. Femke (alt) (talk) 08:06, 1 March 2023 (UTC)

Yes, of course. However, what do you mean by "in front of"? Who says that the citation that was for the sentence that follows should also apply to the first sentence when the two sentences are not actually linked in any logical way? EMsmile (talk) 08:59, 1 March 2023 (UTC)

WP:CITING SOURCES says (per WP:INTEGRITY). "Do not add other facts or assertions into a fully cited paragraph or sentence:". In this case, the sentences were logically linked to a lay reader, both dealing with a definition. —Femke 🐦 (talk) 20:14, 1 March 2023 (UTC)

Overlap with ocean temperature

I think we have to be mindful and strategic how we can avoid unnecessary overlap with ocean temperature (an article which I created a few months ago). They would both talk about increases in ocean temperature and the causes for that, as well as the measurement networks that are needed. Ocean temperature is more intuitive for laypersons than OHC so I think both articles are important. EMsmile (talk) 23:51, 28 February 2023 (UTC)

I've re-arranged things a bit to make it clearer that measurements of ocean temperature at various depths are used in the calculation of the OHC. The bulk of info on temperature measurements should therefore reside at ocean temperature, not here, in my opinion. EMsmile (talk) 10:57, 26 June 2023 (UTC)

The lead image is unclear to me

Current image in the lead: Upper ocean heat content has increased significantly in recent decades because oceans have absorbed more than 90% of the excess heat trapped in the atmosphere by human-caused global warming.

Potential better option for the lead: Global Heat Content in the top 2000 meters of the ocean since 1958

Hi User:RCraig09: the lead image for this article (also copied on the right) is one of the graphs that you have created. At first sight it looks easy to understand and impressive but when I looked a bit closer, I felt it's actually confusing. My starting point was that I wanted to replaced "in recent decades" (in the caption) with a year. Then I thought I pick the year where the blue bars turn mostly into red bars. But then I saw the reference point is the average from 1955 to 2006. I am confused why you chose this long (50 year) period as the baseline. It is also confusing for people that the first lot of bars in the graph are therefore blue, showing that the OHC was less in e.g. 1960 than the average value for 1955 to 2006. In summary, I don't think these blue and red bars work well here. I think one of the other images from the graph would work better for the lead, e.g. the one I copied below yours on the right. Here, the reference point seems to be the year 1958 (although I wonder why it's not an average over say 5 years). EMsmile (talk) 11:24, 26 June 2023 (UTC)

References

EMsmile (talk) 11:24, 26 June 2023 (UTC)

The color-coded chart matches that in the NOAA source, though updated. The color-coded chart is more friendly to lay readers, because of the colors, and because it has no jargony text, and because it has only a single trace and not multiple traces. Such color-coding has become very common since the 2018 arrival of Warming stripes. The color coded chart has the advantage of having neat quarterly readings through 2022 and not just unknown-granularity readings through 2020. It's an SVG and not a PNG. I did not choose the baseline; NOAA did. I don't see how the 1960 reading could be "confusing" to anyone; it's just an observation. —RCraig09 (talk) 16:33, 26 June 2023 (UTC)

This is personal preference but I don't think this graph is the best we can find. For now, I have changed the caption to make it clearer. I still don't understand why someone (NOAA) would have picked a baseline that is a 50-year average. I think we should look for a better graph. My new caption proposal: Ocean heat content in the upper 700 m of the ocean has been increasing over time. The values given are relative to the baseline, being the average OHC for the time period 1955 to 2006. Red bars means higher OHC than baseline, blue bars means lower OHC than baseline.. Old caption was Upper ocean heat content has increased significantly in recent decades because oceans have absorbed more than 90% of the excess heat trapped in the atmosphere by human-caused global warming. (it had too much info about the cause of the OHC rise, which is not the topic of the graph; and too little information on the graph itself, and how to understand it; that info about the baseline was written in the graph itself but in my opinion it belongs into the caption, otherwise it's not clear why the OHC used to be lower (blue bars)). EMsmile (talk) 08:06, 27 June 2023 (UTC)

— Yes, again we're dealing with your personal preference, again at the expense of substantive content: You write "it's not clear why the OHC used to be lower" but you deleted the description from the source's caption explaining why it used to be lower (namely, because oceans have absorbed more than 90% of the excess heat trapped in the atmosphere by human-caused global warming)! I have replaced that substantive content as it adds meaning to the chart itself.

— Meanwhile your caption repeats a non-substantive explanation that's already recited in the chart's legend, while adding "baseline" jargon, and adding a red/blue description that is intuitively clear. I have left a non-jargony version of that red/blue description for those who don't intuitively recognize that red means hot and blue means cool. —RCraig09 (talk) 12:02, 27 June 2023 (UTC)

1. Once again, we are disagreeing on something regarding charts and captions but that's OK. When I say "personal preference" I am just pointing out that there won't be a "right or wrong" here, just differences in opinion. It would be nice if a third person showed up, as it could help us with the consensus building.

2. I disagree with this part of the caption as I think it overloads the caption too much: "because oceans have absorbed more than 90% of the excess heat trapped in the atmosphere by human-caused global warming". That figure of 90% can also change over time, or is open to further questions (excess heat starting when exactly?) etc. This kind of content should be in the main text but not in the caption. The caption should just describe what is visible in the chart, not dive into the root causes.

3. My question about why the OHC is going up was not referring to why in general but why it happened around the 1990 mark, which is where in your graph the red bars start to dominate over the blue bars. This is counter-intuitive, given that the warming has been taking place a lot longer than 1990. It's due to the reference period chose but it's still not intuitive. A clear caption could explain this.

4. Most readers will read the caption, not the small legend that is inside of the chart. Therefore, I think the caption is more important and it doesn't matter if it repeats some small text that is in the legend of the chart.

5. How come "baseline" is jargon in any way? I don't think this is jargon at all. "Reference value" might be more jargony but is not that bad either. Regarding the blue and red, I think it might be intuitive when it comes to temperatures but not as much when it comes to OHC, so I thought it would be worth explaining.

6. As a general thought: please try to keep an open mind when someone has some queries/concerns over graphs that you have created. You are doing amazing work, creating all these graphs from the IPCC or NOAA data. But please also keep an open mind when someone suggests improvements to the graphs or captions. That's all I am asking for. Everything might be 100% clear in your mind (no wonder: you have created or re-created the graphs) but it might not be 100% clear in the minds of our Wikipedia article readers (I am just one of them; I would love to do focus group discussions to see if other readers have similar problems with some of those graphs and captions... but in the absence of focus group discussions we have to try to put ourselves into their shoes.). EMsmile (talk) 12:31, 27 June 2023 (UTC)

re 2.: No, captions should not just repeat what's visible in the chart. It's redundant. It's wasteful of words and attention. It's possibly insulting to readers. It's your personal presumption that people probably read captions, but probably not legends (?!). The NOAA caption goes beyond what's in the chart—to add useful meaning (even if it's not future proof).

re 3.: The bar chart clearly shows warming, and not just since 1990. The purpose of the chart is so show, intuitively, that OHC has been increasing, not to answer every "why" question that might arise.

re 4.: I've moved part of the legend in the image to explain the "0" line, and made it less obtrusive, precisely because it is a small technical detail that's not important to >90% of readers, and needn't be recited—much less repeated!—in a caption.

re 5.: Look at baseline. Especially in this context, baseline is technical. Outside this context (for most arriving readers), baseline usually refers to lines in sporting events.

re 6.: You are saying baseline is not jargon, and want to emphasize specific baseline periods, but you think people won't immediately appreciate that red means more heat and blue means less heat? There are serious inconsistencies in your estimation of other readers.

—RCraig09 (talk) 18:30, 28 June 2023 (UTC)

Interesting about your analogy from sport fields. I am a non-native English speaker (German is my mother tongue) and that might explain why the word "baseline" has a different meaning for you than it has for me. I would not have associated it with lines on sports fields. So I think we just have to accept that what one person considers "jargon" someone else might not, especially if they reside in different countries / speak different languages as their mother tongue.

I appreciate that you have made an effort to change the graph. (I had to clear my cache to see the change). I think it's better than before although am not sure if everyone will understand what is meant with "0" = 1955-2006 average. But I can't think of a better way to do it if it has to be shown in the graph itself. I would have thought spelling it out clearly in the caption would be better but so be it.

I still think that this could also be called jargon: "have absorbed more than 90% of the excess heat"; the value refers to which starting year exactly, is it 1850? And will that 90% value stay constant for the next 20 years or will it likely drop, once the ocean's capacity to absorb more heat is reached? The sentence raises more question than it answers and is overly simplistic. I would drop it.

My opinion is that my proposal for a caption was better (the last sentence could be removed, I don't care about that): Ocean heat content in the upper 700 m of the ocean has been increasing over time. The values given are relative to the baseline, being the average OHC for the time period 1955 to 2006. Red bars means higher OHC than baseline, blue bars means lower OHC than baseline. But I won't press this point any further because I can see you feel strongly about it and it would just lead to frustration on both sides. Maybe at one point in the future, someone else will join the discussion on this talk page and provide a third opinion. Until then, let's move on. And thanks again for the work you do on all these graphs. EMsmile (talk) 11:18, 29 June 2023 (UTC)

I am glad the 90% value is now dropped from the caption. I also enquired about this with Tim Jickells (who has helped me a lot with the ocean article in the past). Here is his answer: "The figure does seem to show that ocean heat content has been increasing quite sharply so I can see why it might be worth keeping. How about a caption that is less dominated by the 90% term which seems to cause the concern, the explanation of that term seems to be in the detail in the article. The caption could say something like

"The figure show the striking increase in ocean heat content over recent decades as the oceans absorb most of the excess heat created by human induced global warming"". So rather than "a large portion" it would be "most of". Also I like his suggestion of "striking increase" (or strong increase?).

My suggestion would be (and I don't think that we need to stress "upper" in the caption; it's measured in the top 700 m, as per the explanation in the graph but physics would dictate that ocean heat content of the entire ocean is going up):

"There has been a striking increase in the ocean heat content during recent decades as the oceans absorb most of the excess heat created by human induced global warming". EMsmile (talk) 16:03, 30 June 2023 (UTC)

Copied from below is a comment by RCraig09: ""striking" is non-WP:NEUTRAL editorial commentary and should not be used." OK. How about this for a caption: "There has been a significant (or: clear? or strong? or obvious?) increase in the ocean heat content during recent decades as the oceans absorb most of the excess heat created by human-induced global warming". EMsmile (talk) 08:36, 3 July 2023 (UTC)

The simplest and cleanest approach is to avoid editorial characterizations altogether, unless a neutral characterization from a very unbiased reliable source is available. "Clear" is subjective, "strong" is relative and value-laden; and "obvious" is subjective. Just say it has increased. If an intensifier is needed, however, "substantially" sounds neutral. —RCraig09 (talk) 02:45, 4 July 2023 (UTC)

True. Even "substantially" contains a judgement, so I've now left off the adjective altogether. I have now made the caption this: There has been an increase in the ocean heat content during recent decades as the oceans absorb most of the excess heat created by human-induced global warming.. I am proposing to wikilink excess heat to Earth's energy budget, do you agree? I am proposing to also change the redirect from excess heat, see talk page there. EMsmile (talk) 10:06, 4 July 2023 (UTC)

The 8 October 2023 "Version 4" of File:1955- Ocean heat content - NOAA.svg now has only red bars, no blue bars. The red bars rise from the bottom of the chart. This charting method differs from many (most?) recent global warming-related bar charts in which reliable sources color-code the bars (see relevant bar charts in Google search results), but it is graphically simpler. —RCraig09 (talk) 18:38, 8 October 2023 (UTC)

File:Land_vs_Ocean_Temperature.svg

Land vs Ocean Temperature

By the way, could you (Rcraig09) please also take the 90% sentence out of this image that you had created for sea surface temperature?: https://en.wikipedia.org/wiki/Sea_surface_temperature#/media/File:Land_vs_Ocean_Temperature.svg (I don't see why that graph should anyway have that kind of "graph title"; it makes it less usable for various purposes. The graph title should be in the caption rather. EMsmile (talk) 16:03, 30 June 2023 (UTC)

I'm busy today, but... "striking" is non-WP:NEUTRAL editorial commentary and should not be used. Separately, I agree that the caption for File:Land_vs_Ocean_Temperature.svg should be changed, but User:Efbrazil should be the one to consider that issue. —RCraig09 (talk) 16:27, 30 June 2023 (UTC)

Yeah, there's room for improvement, thanks for looping me.

The point of the title of the graph is to highlight why the temperatures differ- it is that the ocean is absorbing excess heat from global warming. If global temperatures were not changing, then land and ocean surface temperatures would essentially match, as they did prior to climate change. The over 90% number really deserves to be highlighted, and this graph seemed to be a good place to do it.

Anyhow, that's the background, but I see that there's issues in making that fact the title of the graph, particularly because I wasn't clear I was talking about global warming.

Maybe I could remove the title but add a label in the graph in smaller font. It could read "Oceans absorb over 90% of heat from global warming" and then point to the gap between ocean and land surface temperatures. Would that work for people? Efbrazil (talk) 17:08, 30 June 2023 (UTC)

The most concise summary descriptive title is normally best, since charts usually show bare-bones facts but leave "why" to captions or narrative. In this case, a simple title would be something like "Growing disparity in surface temperatures". To minimize the amount of text in the chart, maybe just add "Excess heat from global warming" and point to the gap. Removing the "90%" figure helps make the chart future-proof. For clarity, the widest part of the gap (since 1980) could be shaded in a manner suggested by the blue part of this chart (as a vague suggestion). . . . . (Side thought: your chart has been translated into at least two other languages and is used directly in seven other Wikipedias, so changing the legends might wreak unknown havoc in those other locations depending on how they caption and describe the chart.) —RCraig09 (talk) 05:58, 1 July 2023 (UTC)

I think over 90% is sadly true for quite a while and good to point out. I'm not sure a title is really necessary. How about this look:

https://drive.google.com/file/d/12SJDNXxunFUHZRaEmufUWre6DvuQsAAO/view?usp=sharing Efbrazil (talk) 14:22, 2 July 2023 (UTC)

Sorry, I don't think the large horizontal swath communicates the growing heat absorption disparity. At best, it draws attention to the disparity in ~2020 rather than the growing disparity over time. I think the "90%" figure is probably ~true over a long term, but, again, that truth may best be explained in the caption, possibly in concert with shading between the upper trace and lower trace since the ~1980 blast-off. If the "90%" figure is mentioned in an in-graphic legend, its font size should be smaller and clearly associated with the (possibly-shaded) area between the traces. I can't think of a single time I've seen a graphic that told the "why" but omitted an objective "what" title (like "Growing disparity in surface temperatures"). —RCraig09 (talk) 15:30, 2 July 2023 (UTC)

Thanks for this discussion. Can we please have a graph that has no text overlain on it, as such text makes the graph less versatile. If the text is important let's just have it in the caption of the graph so that for different uses of the graph, different captions can be used. That 90% figure opens up too many questions for lay persons, such as: "90% of what exactly (measured from which starting point), will the oceans always absorb 90% of the heat? Is that good or bad? If the oceans absorb so much, does that mean we don't really have to worry much about warming on land because all the warming takes place in the ocean?".

Also on the y-axis on the left it mentions "pre-industrial" levels but could we add a year in addition; is it 1850? I think this would make it more tangible for laypersons as not everyone would know what "pre-industrial" levels are (alternatively, this kind of information could be in the caption). Anything that you want to say and point out about the chart could easily go into the summary/description field in Wikimedia Commons, and then Wikipedia editors can pick and choose from there which detail they want to include in the caption. EMsmile (talk) 08:34, 3 July 2023 (UTC)

Several changes made and now live. Note that translated versions are not directly impacted, as translations are not in the file, but rather separate files. I looked at captions of foreign wikis using this image and they did not seem to clash with the changes I made:

• Title updated to simply be "what", including removing the vertical axis title as the main title covers the vertical axis title
• Data now goes from 1950 to 2022 instead of from 1880 to 2020
• Baseline of data is 1951 to 1980 instead of IPCC pre-industrial baseline

Efbrazil (talk) 23:38, 3 July 2023 (UTC)

User:Efbrazil: Maybe it's best to upload a new svg chart dedicated to the specific purpose you've been aiming at. The special-purpose chart could have the same chart simplifications you have made, but include shading and maybe a small legend as I've described above. As an aside, I think it's distracting to my bowling buddies and Amazon delivery guy to see specific reference to a 19xx-19yy average which they won't care about; you could just title it "Temperature variation (disparity?) at Earth's surface" or similar. —RCraig09 (talk) 02:41, 4 July 2023 (UTC)

Well, I'm not aiming at anything with the current version- I pulled the 90%+ value entirely as neither you nor EMSmile were fans of it.

The advantage of putting the 1951-1980 baseline in the title is it avoids having to label the vertical axis entirely, minimizing overall wordiness. Efbrazil (talk) 03:45, 4 July 2023 (UTC)

1. I see the value of conveying the "excess heat" in a new specific-purpose graphic, but with something like the blue shading in File:202107 Percent of global area at temperature records - Global warming - NOAA.svg. Separately, you could miniaturize the base-period content as I did in File:1955- Ocean heat content - NOAA.svg. That way, the important stuff is shown explicitly, and techy trivia is minimized. —RCraig09 (talk) 04:53, 4 July 2023 (UTC)

2. A second alternative is a completely new graphic that shows Land-minus-Ocean graph—a single trace—as a function of time. For emphasis, you could add shading under the trace as in File:1910- Fertility rate - United States.svg. That approach would make it appropriate to explicitly mention differential heat capture with in-graphic legends. —RCraig09 (talk) 05:22, 4 July 2023 (UTC)

Thanks, User:Efbrazil, I like the updated graph, it makes it simpler and more versatile (for several Wikipedia articles); any details that the editor wants to point out can be added to the caption below the graph. - One day, I really have to learn how to create/modify such graphs myself. Is there a tutorial or good page somewhere in the Wikipedia help pages to show how it's done? - For the article sea surface temperature, I would prefer to have a graph that shows only the sea surface temp (not the temperature over land) and also that doesn't say "ocean surface" but "sea surface" as that seems to be the standard term used (or, since there would be only one line, it wouldn't need a legend at all). I think this would be useful to have as a graph for the sea surface temperature article. Thanks. EMsmile (talk) 07:37, 4 July 2023 (UTC)

Glad you like it! My reading above of what you and Craig say is that you can live with the chart as it is now, so I won't make further changes unless you think they're necessary. There's tradeoffs to discuss with any further changes.

Craig and I dump our collective SVG wisdom here: Wikipedia:SVG help. Take a look and let us know if you have newbie questions we could help with there. Efbrazil (talk) 20:11, 5 July 2023 (UTC)

First uploaded 6 July 2023.

This chart is what I had in mind. The chart emphasizes the growing difference between land and ocean temperature with a shaded area. I was thinking of putting a downward-pointing arrow in the shaded area to abstractly indicate flux through the ocean's surface, but then decided not to add such an arrow because it might imply heat went "from land to ocean". The new chart has a concise and objective title, reduces the baseline-period verbiage to a teensy-font-size level non-prominence, and explains the "90%" figure that has long been prominent in your chart. This new drawing is specific to this (OHC) article, and isn't designed to substitute for the broadly used File:Land_vs_Ocean_Temperature.svg. —RCraig09 (talk) 18:51, 6 July 2023 (UTC)

Nice! I would change the text to say "Oceans absorb over 90% of heat from global warming"

Reasoning:

• Scientific american said 92% a few years ago, and I believe the number has been ticking up since then
• I think saying "excess heat" is less clear than saying "heat from global warming". Being explicit focuses the mind on how much the ocean is dampening the effects of global warming. Excess heat could mean whatever.

Otherwise I like it. Efbrazil (talk) 20:49, 6 July 2023 (UTC)

References

the red shading is interesting and does draw attention nicely. I wouldn't add that big text block next to the graph though; this kind of info should go into the caption below the graph where it can then be adjusted easily by other Wikipedians without having to change the graph (this makes the graph more versatile).

Can we please call it "sea surface temperature" in the legand, not "ocean surface temperature"? It seems to me that the standard term is sea surface temperature.

Separately, could one of you two please create a chart for me that shows only one line: the sea surface temperature? It could be used in the lead for the sea surface temperature article.

Thanks for pointing me to Wikipedia:SVG_help, seems overwhelming at first but I will try to learn more about this. EMsmile (talk) 21:02, 6 July 2023 (UTC)

Hot off the press —RCraig09 (talk) 04:19, 7 July 2023 (UTC)

User:Efbrazil, Scientific American recited "as much as 90 percent of the globe’s extra heat", so I changed the wording to "about 90%" which offers a degree of future-proofing.

User:EMsmile As I mentioned above, this file is intended for limited use—probably in this OHC article only. Scientific American refers to ocean quite consistently (>25 to 1 over sea), plus sea is more colloquial/informal/vague. I see that File:Global Sea Surface Temperature.jpg is outdated, so I'll try to do a SST in upcoming days. —RCraig09 (talk) 21:52, 6 July 2023 (UTC)

I would love for everything to be consistently called ocean, not sea... Have you seen the various debates I've had at the talk page of sea and ocean? The two articles actually duplicate each other a lot and sea should be merged into ocean in my opinion. Nevertheless it seems that the current convention is that when it comes to the surface, people talk of sea, as in sea surface temperature. But when it comes to the 3-dimensional aspects, going into the depth of the ocean, then it's "ocean", not "sea". Hence ocean heat content and ocean temperature for the deeper temperatures. Any chance you'd like to weigh in on the discussion at sea? See e.g. here and the year before (it's quite a minefield though): https://en.wikipedia.org/wiki/Talk:Sea#The_section_on_environmental_issues EMsmile (talk) 22:18, 6 July 2023 (UTC)

Thanks for creating that graph for me and for adding it to sea surface temperature. It's perfect! Sending a very clear message. (further discussions about its usage there, if needed, could be held at the talk page of sea surface temperature). Thanks. EMsmile (talk) 11:15, 7 July 2023 (UTC)

I'm not sure where you get "about 90" from. The exact quote from the scientific american article I linked to above is "The oceans account for about 92% of the Earth’s energy imbalance. This is why we are having increased bouts of strong storms (hurricanes, typhoons) and flooding events." Efbrazil (talk) 15:34, 7 July 2023 (UTC)

Your quote was from a quote from one individual later in the article. Earlier in the article, the narrative says "MUCH-NEEDED INDEPENDENT CONFIRMATION Scientists know the ocean plays a critical role in the global climate, helping to absorb excess heat from the warming atmosphere. Oceans may store as much as 90 percent of the globe’s extra heat." —RCraig09 (talk) 16:52, 7 July 2023 (UTC)

I believe that is a different measure- it is the amount of extra heat that has been stored over all time, whereas the 92% number is how much is currently being absorbed year to year. To quote from our fine climate change article, it uses these sources to also make the "over 90%" claim:

The thermal energy in the global climate system has grown with only brief pauses since at least 1970, and over 90% of this extra energy has been stored in the ocean. Efbrazil (talk) 21:00, 7 July 2023 (UTC)

References

I don't think it's worth introducing more verbiage into a graphic's legend, to distinguish between annual uptake and cumulative uptake since a certain date. By saying "about xx%" in the legend, we're reasonably future-proofing the graphic. —RCraig09 (talk) 22:24, 7 July 2023 (UTC)

User:RCraig09 I reread the sources. The distinction is "store" (up to 90) vs "absorb" (which is in the 92-93% range). Since you are saying "absorb" on the graph you should be using the higher number. Additionally, we have the two most authoritative sources- IPCC and NOAA- saying 92-93%. No reason to reference the scientific american article as a source. Efbrazil (talk) 15:30, 8 July 2023 (UTC)

First uploaded 6 July 2023.

 Done Changed to "at least..." in diagram's Version 3. —RCraig09 (talk) 18:44, 8 July 2023 (UTC)

@Efbrazil: I just discovered User:Femke recently uploaded File:WhereIsTheHeatOfGlobalWarming2023.svg which cites https://doi.org/10.5194/essd-15-1675-2023, whose Figure 9 says 89%' for 1971-2020. I'm surmising that Figure 9's "Earth heat inventory" refers to storing—and not absorbing as our diagram now says (?). —RCraig09 (talk) 03:33, 11 July 2023 (UTC)

Remove one of the two lines from the chart in the lead?

There has been an increase in ocean heat content during recent decades as the oceans absorb most of the excess heat created by human-induced global warming. This chart shows annual estimates for the first 2,000 meters and the first 700 meters of ocean depth.

My proposal is that we take out one of the two lines in the chart (which is currently the lead image) so as to not confuse people. It would suffice to just have the "top 2000 meters" line, wouldn't it? EMsmile (talk) 11:19, 18 April 2024 (UTC)

References

EMsmile (talk) 11:19, 18 April 2024 (UTC)

• No. The chart shows different different accumulations of heat through different depths. It's not confusing. —RCraig09 (talk) 15:10, 18 April 2024 (UTC)

Why do layperson readers need to know about different accumulations at different depths? Why not show 3 depths then? What's special about 700 m and 2000 m? I think we should only show the most important line (in the lead). Other lines can come later in the main text. As it is now, the reader has to think through why there are two lines. One line would get to the main point straight away. Unless there is something specific about 700 m and 2000 m. If there is, then let's explain it in the caption. - But I would say let's keep it simple. EMsmile (talk) 16:02, 18 April 2024 (UTC)

The reason is the data is only for 700 and 2000. See here:

https://www.ncei.noaa.gov/access/global-ocean-heat-content/index.html

I agree it's unfortunate that that's the only data available. It would be much more elegant if it was something like 1000 and 2000. As is, it is hard to understand the point of the chart.

Craig- if the point is stratification, might it be a good idea to plot how much heat per cubic meter from 0 to 700, then how much heat per cubic meter from 700 to 2000? That could be calculated from the data set if you use something like this for calculating volume by depth: https://www.researchgate.net/figure/Depth-distributions-of-seafloor-area-ocean-volume-the-number-of-model-grid-points_fig1_311245778

Also, maps of heat content are interesting, like this one:

https://www.climate.gov/media/13226 Efbrazil (talk) 16:16, 18 April 2024 (UTC)

No, there is nothing "special" about 700 and 2000. There does not need to be something "special"; that's the available data. Three levels would be OK, also. Five levels would be OK, also. Especially in a science article we should not be afraid to make people "think through" things in a simple chart. Importantly, this simple chart in a science article shows heat has penetrated progressively to multiple depths—a realization that takes readers a few seconds of "thinking through". There is a difference between simplifying expression of a concept, versus "dumbing down" an important concept. —RCraig09 (talk) 17:17, 18 April 2024 (UTC)

You moved to the lead of Ocean temperature. Won't people have to "think it through"?

Efbrazil, heat/m³ would be an estimate made by a Wikipedia editor; and the colored chart is likely to change significantly over time (the traces in the current line chart will probably remain similar in shape, over time). —RCraig09 (talk) 17:17, 18 April 2024 (UTC)

Fair enough. If your point is stratification, how about adapting this graphic:

https://www.climate.gov/media/13056

It makes the layered heating point more clearly I think than yours does, plus it includes the deep ocean.

Here are the other climate.gov graphics, including a 2022 heat map that I find interesting. I had no idea that the area around Japan was an ocean heating hot spot, and the weakening of the AMOC is pretty clear as well:

https://www.climate.gov/news-features/understanding-climate/climate-change-ocean-heat-content Efbrazil (talk) 18:00, 18 April 2024 (UTC)

Efbrazil, I certainly have no objection to including heat at greater depths, though the NOAA charts only go back to ~1993, and the deepest-ocean "cone" stops in 2012. As a graphist I'd have some difficulty resolving how to represent the way the 0-2300 and 2300-6560 ft (not coincidentally, 700 and 2000 m), whose lines "cluster" based on those two categories. The existing (two-line) graphic is based on a reliable source that in effect summarizes the NOAA chart in almost exactly the way you're suggesting, except for the limited-time "cone" for 1993-2012. —RCraig09 (talk) 18:14, 18 April 2024 (UTC)

Maybe we should promote a heat map to be the lead image after fixing the font sizes and such. This graphic is interesting:

https://www.climate.gov/media/15576

If you stare at that map for a while a lot jumps out:

• Heating seems to be most pronounced at 40 degree latitude lines in both Northern and Southern hemispheres, about where the jet streams are
• Heating on eastern seaboards tails out into the ocean as the oceans absorb the heat of the land (as per jet stream flow)
• You can see AMOC weakening as water there warms and water over the open atlantic cools, perhaps partly due to meltwater from Greenland as well

Efbrazil (talk) 18:45, 18 April 2024 (UTC)

I'm mildly opposed, as heat maps will probably change faster than the basic shape of a 2- or 3-line graphic. Plus, most readers will not "stare at the map for a while", much less have the wherewithal to deduce what causes certain patterns. It would be a good graphic for a section that details the phenomena you describe, so that the map has meaning for the dedicated reader and isn't just puzzling decoration. —RCraig09 (talk) 19:32, 18 April 2024 (UTC)

The heat map might be confusing because it doesn't give any indication of depth. Actually now I see its unit is W/m2. Then I thought to myself hang on, what is the unit of OHC? In our lead graph it's Zeta-joules. Later in the article we say "areal density of ocean heat content" with a unit of W/m2. So we need to ensure we don't confuse our readers, or perhaps explain better that there is OHC in ZJ and then there is OHC in W/m2.

I think the current chart that we have is fairly OK but I think it would be even more lay-person friendly if it didn't have two lines. Wouldn't it be just as easy to delete one of the two lines? What speaks against it? Aren't we trying to make the point in the lead image that the OHC is going up over time? (for any depth range that is chosen, whether it's from 0 to 2000 m, or from 0 to 700 m).

And I am not sure if the caption is ideal when it says "ocean heat content has increased to greater depths". It's the temperature that is increasing to greater depths. But the OHC is integrated over depth. So of course OHC gets higher the more of the depth is taken into the equation.

Could we actually show the increase of OHC over time for the entire depth of the ocean (if anyone has tried to compute that)? Sorry if these are dumb questions. It's not my area of expertise. EMsmile (talk) 21:50, 18 April 2024 (UTC)

I am proposing this as a new caption for the lead image: The ocean heat content (OHC) has been increasing for decades as the ocean has been absorbing most of the excess heat resulting from greenhouse gas emissions from human activities. The graph shows OHC calculated to a water depth of 700 and to 2000 meters.. Might need further tweaking. EMsmile (talk) 21:56, 18 April 2024 (UTC)

(for comparison, the previous caption was this which I felt was slightly harder to understand: As oceans have absorbed most of the excess heat created by human-induced global warming during recent decades, ocean heat content has increased to greater depths.) EMsmile (talk) 22:00, 18 April 2024 (UTC)