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This article is or was the subject of a class project aimed at updating IPCC references to the most recent report (AR6). More details can be found on the course page. Student editor(s): JF726. Updates will be made according to the IPCC citation guide. — Preceding unsigned comment added by JF726 (talk • contribs)

I don't understand what those numbers in bold in brackets in the table "IPCC list of greenhouse gases" are meant to be for. The caption for the colunn says "Mole Fraction [ppt - except as noted]a + Radiative forcing [W m−2] " Why the plus? Should it rather be "radiative forcing are the figures in brackets in bold"? For example for this: 15 (0.0031). But I think we are actually overloading the table here. I would remove those numbers in bold or put them in a separate table maybe? EMsmile (talk) 21:26, 28 January 2024 (UTC)[reply]

Hi User:InformationToKnowledge, where do we stand with this now? Since you moved the table here you probably understand it better than I do. What is your reaction to the concerns that I raised about it? EMsmile (talk) 20:07, 7 April 2024 (UTC)[reply]

@Efbrazil I see that you have made a minor edit to this article on 26th March, soon after my series of fairly major edits on 24th March. Based on that, I can assume that you are not opposed to the changes I made to this article recently, but I'll ask just in case: is there anything which you think this article is still missing, or if some recent edits have accidentally taken it in the wrong direction? If not, then I'll ask for a copyediting pass from GOCE volunteers, and then nominate this article for GA. InformationToKnowledge (talk) 15:35, 6 April 2024 (UTC)[reply]

Thanks for the ping. It's great the you want to get the article up to GA, it's an important one. I think EMsmile is better to run this question by though. My focus here is limited to the graphics, the lead, and vandalism. I could try taking an edit pass through the article if you want me to. Usually my focus is on making articles more readable and accessible. Efbrazil (talk) 16:44, 6 April 2024 (UTC)[reply]

@Efbrazil Well, there are a few questions which I think you might be better placed to answer. I.e.

1. The structure of "Airborne fraction" and "Atmospheric lifetime" sections. I made a range of improvements to them recently, but I think it could still be better. I.e. the earlier definition of the atmospheric lifetime formula wasn't great (Naming a 25-year old study at the start of the sentence, etc.) but it seems like I broke sentence flow somewhere while trying to condense it? Not sure how best to rephrase it, though.
2. In February, one user added a graphic which straddled WP:CALC and WP:OR and effectively directly contradicted article text by claiming that it is possible to assign a single lifetime (or "exponential decay" time) to CO₂. I replaced that with the graph for methane lifetime, which seems like the best one I could find in suitably-licensed sources. However, I am a little concerned that the "adjusted upwards" label in the graph might be misinterpreted. I tried to ensure that the caption explains this, but perhaps it can be made even clearer.
3. I really like the current large table with the greenhouse gases (no surprise, since I moved it here and then made a series of adjustments) but EMsmile has expressed concerns about the current version (see above.) What would be your suggestions for that table, if any?
4. I expanded "Airborne fraction" by mentioning that carbon sinks become saturated in relative (though not absolute) terms under high emissions. Should we also mention that the greenhouse effect from CO₂ (and the other gases?) is logarithmic, with the two effects likely cancelling each other out to produce linear warming? I have added a paragraph on this phenomenon to the lead of Causes of climate change, cited to AR6, but I don't know which part of this article should be mentioning this. (Greenhouse effect should definitely mention this somewhere, but that article is so messy I don't know where to even start editing it.)
5. Since you specifically said that the lead is an area of focus: would you agree that the final paragraph is a little weak? I feel that the final sentence kinda trails off - "the level the United Nations' Intergovernmental Panel on Climate Change (IPCC) says is "dangerous" - OK, and? There has to be a way to make it sound stronger, and I hope you would have some suggestions. The one idea I have is to mention the delayed, post-2100 warming from large emissions in the 21st century. This would likely end up introducing climate sensitivity to the article as well. It is currently not mentioned anywhere, which seems like an oversight. You can't even say it's a way to reduce overlap between this article and greenhouse effect (one of EMsmile's stated goals), since it is not mentioned there either!

InformationToKnowledge (talk) 11:19, 7 April 2024 (UTC)[reply]

I saw your edits in March and thought they are probably good (I am not deeply enough into this topic to really be able to comment on details; I like to help with overall structure, reducing overlap between articles, improving readability, improving leads). So most likely your changes are big improvements. Thanks for that.

Regarding Point 3, see separate entry here on the talk page.

Regarding Point 5, see separate entry here on the talk page. Very important in my opinion: the leads are meant to be summaries of the article. So if you think that climate sensitivity needs to be introduced / linked / explained then please do it first in the main text (new section? existing section?) and then afterwards you can summarise that in the lead as well. EMsmile (talk) 20:17, 7 April 2024 (UTC)[reply]

Thanks, things have changed a lot in this article a since the merge. I think the lead is now more difficult to read and has information that people will not care about. I'll look to make an edit pass overall over the next week or two as I have time. Efbrazil (talk) 20:43, 7 April 2024 (UTC)[reply]

which merge do you mean? EMsmile (talk) 20:49, 7 April 2024 (UTC)[reply]

I don't know if it was because of the merge of "IPCC list of greenhouse gases", but the lead gained the list of greenhouse gases by mole, and that caused it to kind of lose coherence. I tried to just fix it back up. The list is still there, but now has its own non-climate change focused paragraph. Efbrazil (talk) 21:15, 7 April 2024 (UTC)[reply]

In some ways, this is in addendum to the discussion above. Out of these three high-importance and interrelated articles (greenhouse gas here, greenhouse effect and greenhouse gas emissions), I think this one is the closest to GA status, which is why I intend to nominate it soon, but ideally, we would want to have all three at GA, if not FA. Greenhouse effect would need quite a lot of clean-up to be GA-worthy, but I think it is ultimately achievable with more-or-less its current structure.

With Greenhouse gas emissions, though, I am not so sure. To me, at least, that article seems like it would be really hard to read from start to end, and in fact, it gives the impression of two articles being awkwardly combined into one. I have a bold suggestion of renaming it Greenhouse gas emissions by sector - meaning that nearly all the material from that article before Greenhouse gas emissions#Emissions by sector would be moved here, where appropriate. I.e. "Sources" section would become much larger, and Monitoring probably would as well. Ideally, we would end up with two similarly-sized articles whose individual scope is very clear, and also avoid the confusion many readers likely get when they first see the similar names. InformationToKnowledge (talk) 11:41, 7 April 2024 (UTC)[reply]

I see that the greenhouse gas emissions article was originally split off from this one, back in 2021. However, I still think the split went way too far, especially since the split article is now practically double the size of this one - 31 kB (4963 words) vs. 16 kB (2629 words) here. All while it continues to be seen by 3-4 times fewer people than this article.

@ASRASR @BaderMS @Bikesrcool @Efbrazil @EMsmile @RCraig09 @Rhwentworth I'm pinging you because you have actively contributed to either this article, greenhouse gas emissions or both articles fairly recently, so your input is important.

I'll also add that since InformationToKnowledge (talk) 12:00, 7 April 2024 (UTC)[reply]

Conceptually, I think that it is emissions that are more important to readers than the science/techy nature of GHGs. Unfortunately, it's easier for readers to search for "greenhouse gas", so readers end up here to be struck with predominantly techy charts. A navigation hatnote here would help, but a hatnote would probably not be particularly effective at redirecting attention to the ...emissions article. A bold and undoubtedly controversial approach would be to rename the present article Science of greenhouse gases (or similar), and change Greenhouse gas into #REDIRECT to Greenhouse gas emissions. —RCraig09 (talk) 16:43, 7 April 2024 (UTC)[reply]

I was probably the driving force for creating the separate article greenhouse gas emissions and I still stand by that decision. I think it was a good move. I don't think articles need to be made "roughly the same length" - what for? If this article is much shorter than other articles then so be it. I sometimes wonder if all this content is really amenable for an encyclopedia, as everything is related to everything else: So it's very hard to avoid overlap between articles. I've written about that on the talk page of greenhouse effect in the past.

I do wonder whether maybe greenhouse gas and greenhouse effect should be merged into one. I mean the definition of a "greenhouse gas" is that it causes the greenhouse effect. So perhaps it's easier to treat it in one article. Not sure.

But merging back GHG emissions and GHG I would oppose because the scope of GHG emissions is very straight forward and easy to delineate.

I also don't understand why it would be beneficial to make the title longer to become Greenhouse gas emissions by sector. But any such proposal should be placed at the talk page of greenhouse gas emissions rather than here.EMsmile (talk) 20:03, 7 April 2024 (UTC)[reply]

Right, I decided to continue the renaming discussion there. I still strongly support reorganizing and ultimately renaming that article, though. And the greenhouse effect would be too difficult to merge here, because phenomena like lapse rate, equivalent emission altitude, etc. would be very difficult to explain here without losing the focus of the article. InformationToKnowledge (talk) 08:08, 8 April 2024 (UTC)[reply]

I've removed the last para of the lead as in my opinion it doesn't really fit here. It strays into other topic areas but without explaining things properly. Also, it doesn't work as a summary of the article. We should ensure the lead is a good summary. The purpose of the lead is not to try and explain again all the different facets of climate change...

++++++++++

According to Berkeley Earth, average global surface temperature has risen by more than 1.2 °C (2.2 °F) since the pre-industrial (1850–1899) period as a result of greenhouse gas emissions. If current emission rates continue then temperature rises will surpass 2.0 °C (3.6 °F) sometime between 2040 and 2070, which is the level the United Nations' Intergovernmental Panel on Climate Change (IPCC) says is "dangerous".^[1]

++++++++ EMsmile (talk) 20:13, 7 April 2024 (UTC)[reply]

EMsmile (talk) 20:13, 7 April 2024 (UTC)[reply]

I restored the last sentence of that paragraph as it fit will as the concluding sentence for the prior paragraph. The first sentence of the last paragraph remains cut. I think it reads well now and helps to address the point you raised. Efbrazil (talk) 21:09, 7 April 2024 (UTC)[reply]

I still think this sentence doesn't fit in the lead as it digresses into other areas and is not summarising content from the main text: "If current emission rates continue then temperature rises will surpass 2.0 °C (3.6 °F) sometime between 2040 and 2070, which is the level the United Nations' Intergovernmental Panel on Climate Change (IPCC) says is "dangerous".". I guess this comes down to the question: should this article digress & expand into other areas, talk about greenhouse gas emissions, observed temperature rises, mitigation methods, Paris Agreement? I think no. We can briefly link across to those things in the appropriate places of the main text but we should refrain from repeating this kind of content in depth in this article, nor in the lead. I'll start a separate section on this topic below. EMsmile (talk) 10:13, 8 April 2024 (UTC)[reply]

Why should we consider emission sources as on topic but emission limits as off topic? Greenhouse gases are primarily interesting to people because they are causing climate change, and what people need to know is that we need to limit them. Without that last sentence, the text will leave people with the impression that climate change is not a problem and that changes are not needed. Efbrazil (talk) 18:20, 8 April 2024 (UTC)[reply]

I think general sources of GHGs could be on-topic, but the amounts of emissions and by which sector would not be. I don't think that last sentence in the lead is warranted as the lead is meant to be a summary of the article. Where in the article would you place content about "If current emission rates continue then temperature rises will surpass 2.0 °C (3.6 °F) sometime between 2040 and 2070, which is the level the United Nations' Intergovernmental Panel on Climate Change (IPCC) says is "dangerous"."? (And what is "dangerous" anyway) It would have to go into a section emissions, which I don't think this article needs. It's not up to us to educate/nudge people onto climate action with each of these articles. Otherwise we would also have to add further sentences to say "methods to reduce emissions include...", "you could all reduce your meat and dairy intake to reduce emissions" and so forth. EMsmile (talk) 21:46, 8 April 2024 (UTC)[reply]

This is kind of the other half of the discussion happening down below. The leads, as I see them, are primarily about being an introduction to the topic area. Somebody could easily be getting oriented to the topic of climate change for the first time on this landing page. I don't see a problem with the lead putting a topic in a context that is not the focus of the article. To address the issue of the article content not reflecting the lead, I put in an excerpt from the climate change mitigation article. Efbrazil (talk) 22:57, 8 April 2024 (UTC)[reply]

I've replied to this in the section below. I have a small disagreement with you here. I see the role of leads differently. EMsmile (talk) 09:17, 9 April 2024 (UTC)[reply]

I think we need to reach consensus on the question of "Should this article expand into the topic of GHG emissions?". I think it should not. Instead, it can use excerpts from the GHG emissions article (that one needs to be improved and re-structured). But anything to do with emissions that come from human activities should be kept very brief. Otherwise we end up merging the articles together again and I don't think that would be wise. I think when people come to this page they want to know what GHG are. If they want to know how much humans emit each year then they can head over to the GHG emissions article.

As a reminder, this is how the article looked before the content about emissions was split off into a separate article three years ago in May 2021: https://en.wikipedia.org/w/index.php?title=Greenhouse_gas&oldid=1015449252 . I still think the split was a good idea.

And this is how the pageviews are looking: https://pageviews.wmcloud.org/?project=en.wikipedia.org&platform=all-access&agent=user&redirects=0&range=all-time&pages=Greenhouse_gas%7CGreenhouse_gas_emissions%7CGreenhouse_effect (GHG is coming down a bit, GHG emissions is going up, greenhouse effect has also gone down a bit but is still high at around 700 pageviews per day. EMsmile (talk) 10:21, 8 April 2024 (UTC)[reply]

But anything to do with emissions that come from human activities should be kept very brief. Otherwise we end up merging the articles together again One does not logically follow the other. The whole reason why I brought up this matter in the first place is because the emissions article currently covers at least three topics in a fairly awkward manner:

1. How much do humans (that is, humanity in general) emit of certain greenhouse gases each year?
2. How many greenhouse gases are emitted by the specific sectors of human activity?
3. How many greenhouse gases are emitted by certain countries and individuals in those countries/across class levels, etc.?

(Not even counting the stuff on monitoring/accounting of GHGs, etc.)

Everything to do with point 1) can be transferred to this article, and still leave the emissions article at a comfortable 3k words or thereabouts.

when people come to this page they want to know what GHG are. and the reason why they want to know what GHGs are is because they are concerned over the high levels of human emissions. It doesn't really make sense to have the table in this article showing how the concentrations of basically every GHG went up substantially over the past couple of centuries yet not explain why, outside of that awful excerpt. In fact, the third paragraph of the lead here already alludes to how much humans have already emitted, so some content on this is completely justified. InformationToKnowledge (talk) 10:42, 8 April 2024 (UTC)[reply]

Actually, I would take that content about emissions out of the lead... Following your line of thought you could equally argue that people come to this article to understand how the greenhouse effect works, what climate change is, how to mitigate it and so forth. Somewhere we have to draw the line in this kind of encyclopedic structure, as otherwise every article would cover everything... The content about the human GHG emissions fits nicely at greenhouse gas emissions.

I still think it could work to merge greenhouse gas with greenhouse effect. You dismissed this with And the greenhouse effect would be too difficult to merge here, because phenomena like lapse rate, equivalent emission altitude, etc. would be very difficult to explain here without losing the focus of the article. but I am not convinced. Can GHGs really be fully explained without explaining what the GH effect is? You mentioned "loosing the focus". I think the focus should be about this (similar to how it currently is):

• what makes something a GHG
• Which GHGs are there
• How are GHGs measured and monitored
• What's the past, current, future concentration
• What's the role of humans here (very briefly touching on emissions + sending people to the right sub-article)
• How GHGs concentrations could be removed (very briefly + sending people to the right sub-articles)

Why spread the content about emissions over several articles - I don't see a benefit in that. EMsmile (talk) 11:59, 8 April 2024 (UTC)[reply]

As I see it, all 3 of these articles are primarily interesting in the context of climate change. So what I would say is that they should all cover the issue of climate change in general, but each should have a different focus. For each article, this is what I imagine that question is:

• Greenhouse gas: What gases are greenhouse gases and why?
• Greenhouse effect: What makes global warming happen?
• Greenhouse gas emissions: What are we doing that causes climate change and how can we get it under control?

Combining articles is problematic, as each term is very searchable and has a different focus. For instance, the greenhouse effect article doesn't care about the individual gases, just their general behavior. Efbrazil (talk) 19:03, 8 April 2024 (UTC)[reply]

I agree with some of your points but for the article on "greenhouse gas emissions" I don't quite agree with your proposed focus of "What are we doing that causes climate change and how can we get it under control?". The part on "What are we doing that causes climate change" is in causes of climate change, and the part on "how can we get it under control?" is in climate change mitigation and individual action on climate change, isn't it? The article on GHG emissions should just be on how much GHGs are emitted, from which sector, what are the trends, how is this monitored. EMsmile (talk) 21:50, 8 April 2024 (UTC)[reply]

I'd separate how we think of the scope of the lead of these articles from how we talk about the content of the articles. The leads are introductions to topics and need to put the topics in context. The substance of the articles can be more focused.

For instance, I think an article on GGE needs to raise the issue of mitigation in the lead, as that's why people care about GGE in the first place. However, I think it's fine if the article content only briefly stubs the issue of mitigation and points users instead towards the climate change mitigation article. Efbrazil (talk) 22:30, 8 April 2024 (UTC)[reply]

Ah, we might have a small disagreement (or difference in focus) about the role of the lead. Personally, I focus on the summary aspect of the lead. Similar to the abstract of a scientific paper. This does include an intro to the topic of course but the lead should not contain any content that is not also in the main text. And it should not include much details with regards to numbers, unless they are very much key to understanding what's going on.

Looking at WP:LEAD, I see "This page in a nutshell: The lead should identify the topic and summarize the body of the article with appropriate weight." This sounds good to me.

In general, we should actually put far more attention to the lead of Wikipedia articles than we currently tend to do. Especially the first paragraph of the lead is so important. Loads of people won't read any further than the first paragraph.

FYI, I am currently going through all the 135 articles that we have in our list in our project and work on improving the readability of all the leads. Step 2 would be to expand the lead lengths. Most of them are too short. I aim for 450 to 500 words. EMsmile (talk) 09:16, 9 April 2024 (UTC)[reply]

Sounds good! Ping me if you want help with any of them. I also love obsessing over lead text. I should probably undertake following a few more pages in that list.

For some of those articles (like this one) I imagine that our primary audience is middle schoolers, often from developing nations, who are using this resource to get oriented to the topic for the first time. To me that means avoiding jargon and appropriately framing the topic and making the text accessible and interesting. I do not want their eyes to glaze over while they're reading the text. I want them to come away from the lead interested in and caring about the topic. Efbrazil (talk) 16:30, 9 April 2024 (UTC)[reply]

I feel that this discussion hasn't been properly concluded yet. InformationToKnowledge what are your thoughts about this article now? EMsmile (talk) 09:47, 19 June 2024 (UTC)[reply]

There was a hatnote that User:RCraig09 had proposed which User:Efbrazil removed again. The hatnote was: This article is about the science behind greenhouse gases. For how greenhouse gases affect climate change, see Greenhouse gas emissions. I'd like to discuss this a bit further because I think a hatnote might indeed be helpful. If readers come to this page and expect to find the full spectrum of information, it might be useful to point them to the right place. But perhaps it could be like this This article is about the physical properties of greenhouse gases. For their role in climate change, see greenhouse effect. For the amounts of greenhouse gases emitted by human activities, see greenhouse gas emissions. (or too long like this? Superfluous?). EMsmile (talk) 09:19, 10 April 2024 (UTC)[reply]

I think a hatnote is not just helpful, but critical, because of overlapping concepts. A longer hatnote is appropriate: to distinguish GHGs, GHeffect, Emissions, other uses. —RCraig09 (talk) 16:14, 10 April 2024 (UTC)[reply]

I don't oppose the idea of a hatnote, but I strongly oppose any wording which contains the suggestion that this article does not already explain "how greenhouse gases affect climate change" or "their role in climate change". I would argue that the "Properties" section - and in particular, the excerpt from radiative forcing - provides all the explanation lay readers truly need to know, and well over half of the content now present in greenhouse effect verges on extraneous (like Wikipedians trying to impress each other with what they found than to create a cohesive and readable encyclopedia entry, if I'm to be uncharitable).

I would be fine with This article is about the physical properties of greenhouse gases. For the amounts of greenhouse gases emitted by human activities, see greenhouse gas emissions. for now. I still think that if the other article is reorganized and renamed to Sources of greenhouse gas emissions, then a hatnote would become unnecessary. InformationToKnowledge (talk) 17:07, 10 April 2024 (UTC)[reply]

The version from I2W makes sense to me with a tick of wordsmithing to expand the scope of what the GGE article is covering:

This article is about the physical properties of greenhouse gases. For how human activities are adding to greenhouse gases, see greenhouse gas emissions. Efbrazil (talk) 17:13, 10 April 2024 (UTC)[reply]

Change made. Efbrazil (talk) 22:09, 12 April 2024 (UTC)[reply]

I've just made some changes to the structure and to the lead:

• I've tried to improve the reading ease score of the lead. Now only 3 sentences remain in red with the readability tool. They are these ones: "Other greenhouse gases of concern include chlorofluorocarbons (CFCs and HCFCs), hydrofluorocarbons (HFCs), perfluorocarbons, SF6, and NF3.", "Further contributions come for example from cement manufacturing and deforestation. Methane emissions originate from agriculture, fossil fuel production, waste, and other sources." - We can probably leave them as they are.
• I've added to the lead (4th para) more info about natural sources of GHGs.
• I've shortened the last para of the lead a bit, as I think it digresses into other areas. But perhaps OK to leave it like it is now so that the broader context becomes clearer (but not make it longer).
• I've changed the overall structure so that we have more main level headings and fewer level-2 headings.
• I've added more about natural sources to the main text (do we want to keep the excerpt from the carbon cycle or remove it?).
• I've moved the info on "removal from the atmosphere" from being a main level heading to a sub-level heading under "sources".
• I don't know if we really need the section on "needed emission cuts"? In my opinion this digresses too much into the greenhouse gas emissions article which we have prominently linked to in several places now. EMsmile (talk) 08:53, 17 April 2024 (UTC)[reply]

I see that you (Efbrazil) have removed this sentence from the lead: "There are two types of sources of greenhouse gases in the atmosphere: Natural sources and human-made sources." I would like to put that (or something similar) back in. I think it's useful to distinguish between what is "natural" (without humans) and what has come from humans (burning of fossil fuels etc.). And the carbon cycle is about more than just CO2, isn't CH4 also part of the carbon cycle? True, some of the other GHGs have nothing to do with the carbon cycle but the two main ones do. The carbon cycle article does explain how methane is part of it. We could also mention the nitrogen cycle for N2O if you think that's relevant.

Compare also with the main text where we also have a section on "sources" with the two sub-headings being "natural sources" and "human made sources"... EMsmile (talk) 20:01, 17 April 2024 (UTC)[reply]

Hi User:Efbrazil, just a little ping today as those questions of mine from 17 April haven't been answered yet? Thanks. EMsmile (talk) 09:48, 19 June 2024 (UTC)[reply]

Thanks for the ping! Methane is not part of the carbon cycle, only carbon is (hence the name).

I reorganized things and added a bit to the last paragraph about natural levels of carbon dioxide, touching on paleoclimatology. Hopefully that addresses your concern. I don't think it is necessary to declare "two types of sources" as we cover the carbon cycle, which is the natural source, plus we cover human sources in detail. We could tilt the lead to talking more about naturally occurring greenhouse gases that are not CO2, but that would be a lot of work that would also require cuts. Efbrazil (talk) 17:36, 20 June 2024 (UTC)[reply]

I am surprised you say that "Methane is not part of the carbon cycle". As far as I know, methane is indeed part of the carbon cycle, why should it not be? It's CH4 after all. See also carbon cycle. Sentence copied from the internet: "Methane's role in the carbon cycle highlights its significance in both natural processes and human activities, influencing global climate dynamics through its interactions with other components of the carbon cycle." EMsmile (talk) 10:03, 21 June 2024 (UTC)[reply]

Yeah, it's probably over simplifying to say methane isn't part of the carbon cycle, but it usually is treated separately. CO₂ is the focus of the the carbon cycle because it can take thousands of years to be absorbed by the planet, and that process of absorption is the carbon cycle. Methane only lasts 7-12 years in the atmosphere and then oxidizes into CO₂. The residual warming it creates after breaking down into CO₂ isn't a significant part of CO₂ emissions. The reason is that methane is 80+ times more powerful than CO₂ as a greenhouse gas, so the vast majority of its impact happens before breaking down. So the typical way things are presented is that methane causes a spike and then disappears, while CO₂ is a building force that must be absorbed through the carbon cycle. Efbrazil (talk) 19:53, 21 June 2024 (UTC)[reply]