Talk:Greenhouse effect

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Section on aerosols[edit]

I've also removed the text block on aerosols that had been added by another student, for the same reason: it overlaps too much with other articles and the content was not up to date. Will use an excerpt instead: 

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There are two major sources of atmospheric aerosols, natural sources, and anthropogenic sources.[1] Natural sources of aerosols include desert dust, sea salt, volcanic ash, volatile organic compounds (VOC) from vegetation and smoke from forest fires. Aerosols generated from human activities include fossil fuel burning, deforestation fires, and burning of agricultural waste. The amount of anthropogenic aerosols has been dramatically increased since preindustrial times, which is considered as a major contribution to the global air pollution. Since these aerosols have different chemical compositions and physical properties, they can produce different radiative forcing effects, to warm or cool the global climate.

The impact of atmospheric aerosols on climate can be classified as direct or indirect with respect to radiative forcing of the climate system. Aerosols can directly scatter and absorb solar and infrared radiance in the atmosphere, hence it has a direct radiative forcing to the global climate system. Aerosols can also act as cloud condensation nuclei (CCN) to form clouds, resulting in changing the formation and precipitation efficiency of liquid water, ice and mixed phase clouds, thereby causing an indirect radiative forcing associated with these changes in cloud properties.[2][3]

Aerosols that mainly scatter solar radiation can reflect solar radiation back to space, which will cool the global climate. All of the atmospheric aerosols have the capability to scatter incoming solar radiation, but only a few types of aerosols can absorb solar radiation. These include black carbon (BC), organic carbon (OC) and mineral dust, which can induce non-negligible warming effects.[4] The emission of black carbon is significant in developing countries, such as China and India. Black carbon can be transported over long distances, and mixed with other aerosols along the way. Solar-absorption efficiency has a positive correlation with the ratio of black carbon to sulphate.[5]


Particle size and mixing ratio can not only determine the absorption efficiency of BC, but also affect the lifetime of BC. The surface albedo of snow and ice can be reduced due to the deposition of absorbing aerosols, which will also cause heating effects.[6] The heating effects of black carbon at high elevations can be as important as carbon dioxide in the melting of snowpacks and glaciers.[7] In addition to these absorbing aerosols, it is found that the stratospheric aerosols can also induce local warming by increasing longwave radiation reaching the surface and reducing outgoing longwave radiation.[8] EMsmile (talk) 23:42, 18 December 2023 (UTC)[reply]

References

  1. ^ McMurry, P.H. (January 2003). "AEROSOLS | Observations and Measurements". Elsevier Enhanced Reader. Academic Press. pp. 20–34. doi:10.1016/B0-12-227090-8/00048-8. ISBN 9780122270901. Retrieved 2022-04-20. {{cite book}}: |website= ignored (help)
  2. ^ Huang, Huilin; Gu, Yu; Xue, Yongkang; Jiang, Jonathan; Zhao, Bin (May 2019). "Assessing aerosol indirect effect on clouds and regional climate of East/South Asia and West Africa using NCEP GFS". Climate Dynamics. 52 (9–10): 5759–5774. Bibcode:2019ClDy...52.5759H. doi:10.1007/s00382-018-4476-9. ISSN 0930-7575. PMC 6501598. PMID 31073262.
  3. ^ Penner, J. E.; Andreae, M. O.; Annegarn, H.; Barrie, L.; Feichter, J.; Hegg, D.; Jayaraman, A.; Leaitch, R.; Murphy, D.; Nganga, J.; Pitari, G. (2001). Aerosols, their Direct and Indirect Effects. Archived from the original on 19 April 2022. Retrieved 21 April 2022.
  4. ^ "Aerosols and their Relation to Global Climate and Climate Sensitivity | Learn Science at Scitable". Nature. Archived from the original on 6 December 2016. Retrieved 2022-01-11.
  5. ^ Ramana, M. V.; Ramanathan, V.; Feng, Y.; Yoon, S.-C.; Kim, S.-W.; Carmichael, G. R.; Schauer, J. J. (August 2010). "Warming influenced by the ratio of black carbon to sulphate and the black-carbon source". Nature Geoscience. 3 (8): 542–545. Bibcode:2010NatGe...3..542R. doi:10.1038/ngeo918. ISSN 1752-0908. Archived from the original on 21 April 2022. Retrieved 21 April 2022.
  6. ^ Hansen, James; Nazarenko, Larissa (2004-01-13). "Soot climate forcing via snow and ice albedos". Proceedings of the National Academy of Sciences. 101 (2): 423–428. Bibcode:2004PNAS..101..423H. doi:10.1073/pnas.2237157100. ISSN 0027-8424. PMC 327163. PMID 14699053.
  7. ^ Ramanathan, V.; Carmichael, G. (April 2008). "Global and regional climate changes due to black carbon". Nature Geoscience. 1 (4): 221–227. Bibcode:2008NatGe...1..221R. doi:10.1038/ngeo156. ISSN 1752-0908. Archived from the original on 10 November 2022. Retrieved 21 April 2022.
  8. ^ Zhou, Y. (January 2014). "Elsevier Enhanced Reader". Atmospheric Research. 135–136: 102–111. doi:10.1016/j.atmosres.2013.08.009. hdl:10138/228853. Retrieved 2022-04-21.

Suitable image for the lead?[edit]

First image of the lead currently: Greenhouse gases allow sunlight to pass through the atmosphere and heat the planet, but then absorb and redirect some of the longwave radiation (heat) the planet emits.
Second image of the lead currently: Energy flows down from the sun and up from the Earth and its atmosphere. When greenhouse gases intercept radiation emitted by Earth's surface, they prevent that radiation from escaping into space, causing surface temperatures to rise by about 33 °C (59 °F).

I think we should generally only have one image for the lead (or an image collage). I don't think this image (see on the right in second position), that is currently in the lead as the second image is suitable at all. I've been looking at it for a while and I simply don't understand it. The images in the lead need to be clear and simple. As per WP:LEADORDER: " As with all images, but particularly the lead, the image used should be relevant and technically well-produced. It is also common for the lead image to be representative because it provides a visual association for the topic, and allow readers to quickly assess if they have arrived at the right page."

This does not apply to the image on the right. I think it should be moved further down and not be in the lead. Separately, what is the exact source for the image? It's your own work, User:Efbrazil? If I click on the link provided in Wikimedia Commons I get to this page: https://climatemodels.uchicago.edu/rrtm/ - which looks completely different (and possibly clearer) than your version.

The other image that is currently the first image of the lead looks good at first sight but I wonder if it actually too simplified.

First image of the lead at greenhouse gas currently: Greenhouse gases trap some of the heat that results when sunlight heats the Earth's surface. Three important greenhouse gases are shown symbolically in this image: carbon dioxide, water vapor, and methane.

Compare with the image used at greenhouse gas, which could equally well be used at greenhouse effect - but probably has its own flaws as well. (third image on the right) EMsmile (talk) 20:53, 24 January 2024 (UTC)[reply]

The second image was arrived at after extended discussion on a Talk Page (either here or elsewhere, I forget). The first image is a simple conceptual introduction that is a foundation for the second, quantitative image that is well explained by its caption. Since the GHE is a technical subject, we shouldn't concede to a vague perception that only one lead image is needed. The second graphic presents numbers that might be better sourced (in the Commons file description page, or in the caption itself), but that's a ~background issue. —RCraig09 (talk) 21:21, 24 January 2024 (UTC)[reply]

Would “block” work better than “trap” in the first sentence?[edit]

Not wanting to restart a long discussion but I only just saw the discussion above and @Rhwentworths interesting point about some people thinking that something is permanently trapped within the CO2 molecule.

Would “block” work better than “trap” in the first sentence or would that just lead to some other misunderstanding do you think? Chidgk1 (talk) 12:09, 25 April 2023 (UTC)[reply]

Block has it's own problems, like it implies a wall that completely stops progress. Trap is commonly used in government sources and educational materials and is arguably more accurate, as ghg molecules absorb heat radiation. I don't see value in revisiting this. Efbrazil (talk) 16:24, 25 April 2023 (UTC)[reply]
I agree with Efbrazil's comment. —RCraig09 (talk) 16:58, 25 April 2023 (UTC)[reply]
Interesting thought... and, I don't think substituting "block" for "trap" without further word-smithing would improve matters.
I think that, ideally, language would have the following properties:
  • Clarifies that what is happening is a reduction in heat flow, not something that is all-or-nothing
  • Doesn't suggest heat being "stuck" anywhere, and especially not in CO2 molecules or air
  • Doesn't encourage the misunderstanding that time delays are involved
  • Doesn't encourage the idea that the GHE is mainly about what happens at the surface, rather than being ultimately about energy-balance at the top of the atmosphere
  • Is accessible due to either widely-used language or being very clear
  • Doesn't convince people they "understand" when they're actually locking on to a false interpretation
  • Compatible with what is described in primary sources
  • Concise and clear
These criteria are in tension with one another. Unfortunately, I don't see a simple solution. It's a tricky issue in general, and the constraints of Wikipedia make it even trickier.
"partially block" is better than "block" because of the all-or-nothing issue.
I'm noticing that "trapping" plays into the idea of "heat" as being a thing that be just be somewhere (which is the popular notion of heat, but NOT the technical notion of heat), while "block" is relevant to the notion of "heat" involving energy in motion (which is the technical notion). But, you can't just say "partially block heat" because most people don't understand that technically, "heat" inherently refers to energy in motion; so, you need to refer to something like blocking "heat flow" or "heat loss."
I imagine there is little enthusiasm for further rewriting. But, just to think it through, how could one in principle tweak "The greenhouse effect occurs when greenhouse gases in a planet's atmosphere trap some of the heat radiated from the planet's surface."? Maybe the final part of the sentence could be something like:
  • "...partially block the flow of heat radiated from the planet's surface."
  • "...inhibit the flow..." / "...constrict the flow..." / "...reduce the flow..." / "...impede the flow..."
Unless wording like that stimulates excitement in an editor, this probably won't go anywhere in practice. Rhwentworth (talk) 21:32, 25 April 2023 (UTC)[reply]
I agree that both "block" have "trap" misleading implications, even though they're commonly used in explanations. A more precise description might be something like:
Gaseous carbon compounds (such as CO2) in the atmosphere inhibit excess surface heat from radiating into space. A high level of such compounds can result in a cumulative build-up of heat (from sunlight) primarily in the oceans; this is what is meant by CO2 trapping heat.
I hope this can be clarified further for a non-technical audience. Martin Kealey (talk) 04:00, 8 February 2024 (UTC)[reply]
I think we should phrase proposals as a difference from what's there now. We also need to keep the lead accessible and avoid technical wording there.
While I'm fine with keeping things as they are, I wouldn't be opposed to a change from trap to insulate. For instance, this change would be fine by me:
The greenhouse effect occurs when greenhouse gases in a planet's atmosphere trap some of the heat radiated from the planet's surface insulate the planet's surface from losing heat to space, raising its temperature. This process happens because stars emit shortwave radiation that passes through greenhouse gases, but planets emit longwave radiation that is partly absorbed by greenhouse gases. That difference reduces the rate at which a planet can cool off in response to being warmed by its host star. Adding to greenhouse gases further reduces the rate a planet emits radiation to space, raising its average surface temperature. Efbrazil (talk) 19:00, 8 February 2024 (UTC)[reply]
I think the word "insulate" comes with its own set of problems. I think it's unclear and it makes me think of the insulation layers we put around our houses in the Northern hemisphere to reduce our heating costs. I guess others (perhaps in children's books) have talked about "a blanket" that is wrapped around Earth and causes Earth to heat up. Perhaps a similar concept to "insulate". Not sure. EMsmile (talk) 16:32, 10 February 2024 (UTC)[reply]
Insulation is a material that reduces the pass through of heat or sound or electricity. A gas can be an insulator. A blanket is just a type of insulation. I like the insulate word as it paints a better mental model than the word "trap".
Do you have a different idea for wording? If not, do you prefer the trap wording or the insulate wording? Efbrazil (talk) 20:31, 11 February 2024 (UTC)[reply]
Hmmm, I have no strong view on this and am happy to follow your lead. Happy to change to insulate if you feel that it works better than trap or block? EMsmile (talk) 08:56, 1 March 2024 (UTC)[reply]

It seems the paragraph "Effect on surface cooling: .... effect of greenhouse gases." needs elaboration[edit]

So that for a layman like me can better understand. Can anybody help? Thanks. ThomasYehYeh (talk) 14:06, 12 February 2024 (UTC)[reply]

That's a pretty vague complaint. Generally if you are confused by something on wikipedia the best thing to do is to follow the references or google the topic, develop an understanding of the issue yourself, then update the wikipedia page to help others with the confusion you were having. Efbrazil (talk) 17:19, 12 February 2024 (UTC)[reply]
Hi Efbrazil in theory I agree with you but in practice I think we cannot expect all Wikipedia editors to upskill themselves and fully understand the science on everything. I think ThomasYehYeh's work is useful: As far as I know they are translating English articles to Chinese and in the process they point out sentences that are too hard to understand. The person who wrote the sentence in question (or anyone else with a good understanding of the topic), in this case User:Rhwentworth might then be prompted to take another look and improve the reading ease. In this case, I think this sentence ought to be simplified and made easier to understand: Latent heat transport and thermals provide non-radiative surface cooling which partially compensates for this reduction, but there is still a net reduction in surface cooling, for a given surface temperature.. EMsmile (talk) 09:03, 1 March 2024 (UTC)[reply]
By the way, I used the readability tool (in the tools section on the right side) for this article and it's not too bad: not too many sentences come up in red. The Flesch reading score comes up as 40.82 which is surprisingly good for a technical article. EMsmile (talk) 09:03, 1 March 2024 (UTC)[reply]
Thanks, well said on both your comments. Two points. First, this is quite a ways down in the article, and we've already presented simpler explanations earlier on, so I think it is OK to be more technical here. Second, I personally don't find the sentence confusing, so it's hard for me to fix it. Here is a rewording, but I don't know that it's better:
Heat transfer away from Earth's surface also happens through conduction and convection, but by absorbing radiation the net effect of Earth's atmosphere is to warm the surface. Efbrazil (talk) 16:28, 1 March 2024 (UTC)[reply]

Do GHGs "intercept" outgoing radiation?[edit]

I noticed that two of the image captions use the verb "to intercept" ("GHGs intercept outgoing radiation"). Is this a suitable verb and if so, should we also use it in the main text? Or, if we don't use it in the main text, should we change it in the captions? Maybe rather "interact with" or "block"? I think elsewhere we have used the verbs "to block" or "to trap". EMsmile (talk) 07:56, 17 April 2024 (UTC)[reply]

We bounce around on wording because there's no ideal way to say things. The correct way is too long: GHGs absorb infrared radiation, then the heat is transferred into the atmosphere, then the atmosphere reemits infrared in all directions, which includes back downwards towards Earth's surface, keeping it warmer than it would be otherwise. I would not mess much with the wording that is there right now.
Also, the comment on my last edit on the page got cut off. What I meant to say is that infrared radiation isn't a process, it's a thing. In general, please try to be more careful when you split sentences. Consider condensing sentences instead of splitting them, and try reading the content out loud to yourself before saving any changes. Efbrazil (talk) 16:07, 17 April 2024 (UTC)[reply]
yes, but I think for laypersons it's confusing if we keep using different terminology. Why use "to intercept" in the two image captions but not in the main text? I think it's better to be consistent and use the same terminology throughout, not bounce around. As a layperson one thinks that a different term means something else.
Regarding this sentence, which I had split into two rather than using the bit in brackets: In contrast, Earth's surface has a much lower temperature, so it emits longwave radiation at mid- and far-infrared wavelengths (also called thermal radiation or radiated heat). I don't think it's clear to a layperson what exactly is called "radiated heat". Also why do we think we need to tell people (in the lead) about this alternative scientific term? I suggest to either drop the part in brackets completely or to move it into a separate sentence. Let's not overload people with too much technical jargon in the lead.
Note that "radiated heat" is not mentioned a second anywhere in the article so it is really important to mention it in the lead? EMsmile (talk) 20:11, 17 April 2024 (UTC)[reply]
Fair enough, I removed the parenthetical. What we had there was also incorrect as well, as all thermal radiation is heat radiation, including sunlight. Rhwentworth will be pleased.
My main concern with the removal was not having an accessible term for describing what the Earth's surface emits. I think "radiated heat" is most intuitive, but of course it's not technically accurate. We do talk about heat radiation a few times in the article, search on radiation heat flow and radiant heat and radiative heat.
To make up for the loss of accessibility I added a sentence describing what thermal radiation is. Hopefully that helps. It's a sticky wicket. Efbrazil (talk) 17:11, 18 April 2024 (UTC)[reply]
As for the issue of "intercept", I think it's fine to change those two instances to "absorb" if you want. They mean the same thing to me in that context, so I am not too fussed about it either way. Efbrazil (talk) 17:14, 18 April 2024 (UTC)[reply]
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