Talk:Greenhouse effect

The Greenhouse effect - in common language

All objects emit light that depends on their temperature (thermal radiation). This does not mean the visible light that comes from objects when sunlight falls on them or something like that, but light that depends on their temperature. The hotter the object, the more energetic the light. In ordinary objects this light is invisible, (is, for example, in the infrared region), but if the object is heated more, it begins to illuminate in the visible region (such as red-hot iron).

The sun warms the earth's surface and the earth radiates invisible light depending on its temperature in each place. In the atmosphere there are gases, for example greenhouse gases that "absorb" part of this light and then the molecules begin to rotate and vibrate more and with that it heats up. This is not completely different from what happens in a microwave oven. The microwave oven makes invisible light, which the oven produces in a certain way and the food in it absorbs this light, which causes the molecules in the food to rotate and with that it heats up.

When the earth radiates its invisible light, some of it would just go into space, but when more greenhouse gases are added, more of the heat is absorbed by the atmosphere and some of it is radiated back to the earth.

The problem is mainly fossil fuels, oil, gas and coal. When burned, the greenhouse gas carbon dioxide is formed. Someone may then ask if the man has not always been burning firewood and thereby producing carbon dioxide. Yes, that's right, but what happened then was that plants absorbed the carbon dioxide that was created by the fire, as well as water and sunlight, and produced from it oxygen and carbohydrates, in a process called photosynthesis, so this was a cycle in which the carbon dioxide formed by the fire of the firewood was occupied by other plants and the amount of carbon dioxide remained fairly constant in the atmosphere. When fossil fuels are burned, on the other hand, carbon is added to the carbon cycle and carbon dioxide in the atmosphere, causing increased greenhouse effect, whereas larger portion of the earth’s thermal radiation is absorbed by the atmosphere and some of it is radiated back to earth. It should be noted that part of the added carbon dioxide goes into the sea and causes ocean acidification.

Without the greenhouse effect it would not be habitable on earth, it would simply be too cold, but the increase in greenhouse gases could be causing rapid warming.

Gunnar Björgvinsson (talk) 11:03, 28 October 2021 (UTC)

Hello Gunnar :). Talk pages on Wikipedia are meant to discuss ways to improve the corresponding article. Would you like to see specific changes in the article? Femke (talk) 11:06, 28 October 2021 (UTC)

Hi Femkemilene. I would like my article to be a section in the main article. Is that possible? Gunnar Björgvinsson (talk) 12:31, 28 October 2021 (UTC)

Unfortunately, it's not quite ready to be put in the article. I think you want the article to be easier to understand, right? That's an important goal, a lot of Wikipedia articles are a bit too difficult! However, adding duplicate information in a simpler tone is usually not the right way to do this. Instead, you can propose how the current text should be changed to be easier to understand. Importantly, you need reliable sources to support your text. Femke (talk) 12:53, 28 October 2021 (UTC)

Hi Femkemilene. Ok, I dont feel up to making proposes for changes, however I think the main article would be better if there was a section made for people who have zero knowledge in chemistry and physics, with simple explanations, however I will not do more, for now at least. Regards Gunnar Gunnar Björgvinsson (talk) 10:08, 1 November 2021 (UTC)

Hi Gunnar, are you aware of this page: Greenhouse effect (Simple English)? Simple English Wikipedia is designed to be written using non-technical language in a summary format. It may be the kind of thing you had in mind.Pakbelang (talk) 03:33, 2 November 2021 (UTC)

Hi Femkemilene. Thanks for pointing this page out to me. 46.22.98.93 (talk) 10:25, 3 November 2021 (UTC) Hi Femkemilene Sorry I meant to address Pakbelang. Regards 46.22.98.93 (talk) 10:32, 3 November 2021 (UTC) Hi Pakbelang. Thanks for pointing this out to me. Regards 46.22.98.93 (talk) 10:32, 3 November 2021 (UTC)

@Gunnar Björgvinsson: or anyone - could you check the beginning (lead) of the article is right and improve further? Chidgk1 (talk) 19:13, 8 January 2022 (UTC)

Alas, you have turned the lede into nonsense. Do you really think the GHE only works at night? William M. Connolley (talk) 20:52, 8 January 2022 (UTC)

It was not mean to imply only at night - if it read like that I misworded it by misreading https://climatekids.nasa.gov/greenhouse-effect/ - I was only trying to do a quick fix to make the lede better than before as requested in the talk section below - I have no idea how quickly the heat leaves the planet's night side compared to the day side - if you have more time feel free to correct everything properly Chidgk1 (talk) 07:01, 9 January 2022 (UTC)

Naughty NASA Climate Kids! As a non-expert, I've made a quick fix (tweaked) based on the remaining source, please find a better simple explanation. Cite 37 to FAQ 1.3 – AR4 WGI Chapter 1: Historical Overview of Climate Change Science attributed to Stephen Schneider looks pretty good, but surely there's a newer source? . . .dave souza, talk 20:07, 9 January 2022 (UTC)

New section is started below. —RCraig09 (talk) 23:31, 9 January 2022 (UTC)

Mini-review of article in paper

This article was assessed in a paper by Dunn et al (2021). The paper is behind a paywall. It argues that

• The first paragraph is inaccurate. (I feel it's also ungrammatical)
• The rest of the lead suffers from ineffective explanation, both conceptual and procederal. Noticing more grammar errors.
• The body has not enough clear images, and suffers from ineffective procedural explanations.

Procedural explanations is typically not something you'd see much in an encyclopedia, but I do understand their feedback on the lede. Don't have time to tackle it in next x months, so if somebody else wants to have a go. Femke (talk) 18:16, 6 January 2022 (UTC)

I replaced the first sentence. But I object on principle to paying to read the paper. It seems from the abstract that, although it is not much, their students do get some benefit from Wikipedia. So we should not have to pay to read the article in order to improve the articles to benefit their students further. They should make the article freely available in the hope Wikipedia editors will read it and take action thus benefiting their students. But I am too lazy at the moment to write to them and suggest that. Chidgk1 (talk) 15:36, 8 January 2022 (UTC)

@Chidgk1: Paying to access articles is absurd, obviously, but there are other ways to access them. Emailing the authors is one option worth considering, and Wikipedia:WikiProject Resource Exchange/Resource Request is another. There's another option, but obviously I'd never recommend a pirate site. Guettarda (talk) 16:08, 8 January 2022 (UTC)

While I agree, it may not be up to the authors. Publishers demand a lot of money to have open access. Femke (talk) 16:10, 8 January 2022 (UTC)

Authors always have the option to share single copies of article. Some people might choose not to do so, but most journals explicitly include this right for authors. Guettarda (talk) 16:15, 8 January 2022 (UTC)

There isn't more in the paper anyway (did not check all supplementary data) Femke (talk) 16:11, 8 January 2022 (UTC)

William M. Connolley It seems you think I made the lede worse - from "inaccurate" to "nonsense". The paper above did not actually say what was inaccurate about the previous lede so it was hard for me to amend. Maybe you can explain what was inaccurate about the previous lead - maybe it was something very specific which just needed a word or 2 changing? Thanks RCraig09 for your corrections. Chidgk1 (talk) 07:10, 9 January 2022 (UTC)

The first paragraph was only one sentence which read "The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without this atmosphere." It now reads "The greenhouse effect is the warming of the world due to greenhouse gases in the atmosphere trapping the Sun's heat." William M. Connolley - so has that solved the inaccuracy? Chidgk1 (talk) 17:28, 9 January 2022 (UTC)

not quite. The GHE is present on other planets and star systems. And greenhouse gases aren't the only particles causing it. Femke (talk) 17:44, 9 January 2022 (UTC)

Thanks for the aerosols cite. After that yes I see the first sentence is still not quite right. Before proposing a better one does anyone know what was inaccurate about the original one? As we don't want to reintroduce that inaccuracy. Chidgk1 (talk) 17:58, 9 January 2022 (UTC)

The earlier sentence said that the GHE was "the warming of the world...". That sentence is wrong. The warming of the world is a result of the GHE, but does not constitute the GHE itself. —RCraig09 (talk) 18:44, 9 January 2022 (UTC)

Ah I meant what was wrong with the sentence that the academics said was inaccurate which was "The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without this atmosphere."? Chidgk1 (talk) 19:14, 9 January 2022 (UTC)

@Dave souza: I like your recent improvement to what I wrote in the lede, but since it's fairly specific and detailed, I'm concerned about sourcing. I suggest you provide the source. —RCraig09 (talk) 20:19, 9 January 2022 (UTC)

Oops, I commented above. It's based on a quick reading of Vaclav Smil (2003), and a look at ref 37 FAQ 1.3 – AR4 WGI Chapter 1: Historical Overview of Climate Change Science attrib. Steve Schneider, but surely a better source can be found? I'm not an expert. . . dave souza, talk 20:31, 9 January 2022 (UTC)

By the way the first sentences of Norwegian and Polish featured articles only mention gases - so we may pull ahead of them soon. Chidgk1 (talk) 18:10, 9 January 2022 (UTC)

we've now got a highly technical sentence. I think it would be good to collect some definitions from high quality sources in a separate section here, and then craft an accurate sentence than 15-yr olds would still understand. I probably don't have time till feb/March.. Femke (talk) 21:11, 9 January 2022 (UTC)

Ok, a simpler first sentence could be "The greenhouse effect means that a planet's atmosphere lets energy from its sun through to heat the planet's surface, but then hinders heat from the surface from radiating to space so that the surface warms more than it would have done without the atmosphere." Anyway, my aim was a quick fix to get reasonable accuracy, and the rest of the paragraph needs to be simpler when time permits. . . dave souza, talk 22:55, 9 January 2022 (UTC)

New section is started below. —RCraig09 (talk) 23:31, 9 January 2022 (UTC)

It seems you think I made the lede worse - from "inaccurate" to "nonsense" - no; the previous version was accurate. Your version was worse; the current version is still worse than the original. Why are we accepting the assertions of a paper that no-one has read that the original was inaccurate, and why are people that don't really understand it trying to "improve" it? As a Kluw, anything called "climatekid" is not a good source William M. Connolley (talk) 09:45, 10 January 2022 (UTC)

This version of the original? . . dave souza, talk 11:07, 10 January 2022 (UTC)

Yes William M. Connolley (talk) 11:16, 10 January 2022 (UTC)

Thanks! This seems to be the most recent version with that wording. . dave souza, talk 12:16, 10 January 2022 (UTC)

I tried to mail pdunn2@usc.edu.au

Dear Professor Dunn,

Thank you for your interesting paper on STEM articles on Wikipedia. It has sparked a discussion amongst us Wikipedia editors at https://en.wikipedia.org/wiki/Talk:Greenhouse_effect#Mini-review_of_article_in_paper

Re this particular article on the greenhouse effect could you possibly tell us what was the inaccuracy you found in the first paragraph? We are trying to improve the article - which will hopefully benefit your students in future.

More generally, as we would like to encourage more Wikipedia editing from everyone, would it be possible to make your useful paper freely available? If a wider variety of people edit then that could improve the articles even further for your students.

Finally perhaps you have heard of https://wikiedu.org/ which aims to help you and your students share your knowledge with the world.

Feel free to reply either to this email or directly on the above "talk page".

---

but the email is rejected

550 SPF Sender Invalid - envelope rejected - https://community.mimecast.com/docs/DOC-1369#550 [9c_i0Ee7NLmWDCgVNCC0fw.au20]

Maybe something wrong with their "Blocked Senders Policy" as I get same problem trying to mail their IT department. Could someone else try please Chidgk1 (talk) 15:44, 10 January 2022 (UTC)

What is inaccurate in the body of the article?

According to the paper above the body of the article is inaccurate, but the paper does not say how. William M. Connolley or anyone - do you know what is inaccurate in the body of the article? As there are 3 featured articles in foreign languages could we replace parts of this article with translations from those? Chidgk1 (talk) 07:39, 9 January 2022 (UTC)

Possibly the inaccuracy is the mention of aerosols - as although it has a global warming potential and causes radiative forcing the black carbon article does not refer to any of its effects as a "greenhouse effect". So maybe aerosols should be removed from this article? Chidgk1 (talk) 13:38, 9 January 2022 (UTC)

The paper stated that the first paragraph was inaccurate, not other parts. That said, the IPCC AR6 definition says "greenhouse gases, clouds and some aerosols" cause a greenhouse effect. So it's only partially incorrect. Femke (talk) 16:45, 9 January 2022 (UTC)

Oh yes thanks you are right - it is the procedural explanation and visuals they say are lacking in the article as a whole Chidgk1 (talk) 17:20, 9 January 2022 (UTC)

The phrase "greenhouse gases, clouds and some aerosols" makes does not acknowledge that clouds are a type of aerosol. I do think there is is value in distinguishing clouds from other aerosols that cause radiative forcing. We should also distinguish between liquid aerosols and solid aerosols (such as black carbon). –Pakbelang (talk) 10:03, 15 January 2022 (UTC)

Initial GHE definition in lede

Sourced definitions:

1. "The greenhouse effect is a process that occurs when gases in Earth's atmosphere trap the Sun's heat. This process makes Earth much warmer than it would be without an atmosphere." —From NASA Climate Kids
2. "The greenhouse effect is the way in which heat is trapped close to Earth's surface by “greenhouse gases.” These heat-trapping gases can be thought of as a blanket wrapped around Earth, keeping the planet toastier than it would be without them. Greenhouse gases include carbon dioxide, methane, nitrous oxides, and water vapor. (Water vapor, which responds physically or chemically to changes in temperature, is called a "feedback.") Scientists have determined that carbon dioxide's warming effect helps stabilize Earth's atmosphere. Remove carbon dioxide, and the terrestrial greenhouse effect would collapse. Without carbon dioxide, Earth's surface would be some 33°C (59°F) cooler." —From NASA Global Climate Change
3. "The Sun powers Earth’s climate, radiating energy at very short wavelengths, predominately in the visible or near-visible (e.g., ultraviolet) part of the spectrum. Roughly one-third of the solar energy that reaches the top of Earth’s atmosphere is reflected directly back to space. The remaining two-thirds is absorbed by the surface and, to a lesser extent, by the atmosphere. To balance the absorbed incoming energy, the Earth must, on average, radiate the same amount of energy back to space. Because the Earth is much colder than the Sun, it radiates at much longer wavelengths, primarily in the infrared part of the spectrum (see Figure 1). Much of this thermal radiation emitted by the land and ocean is absorbed by the atmosphere, including clouds, and reradiated back to Earth. This is called the greenhouse effect." —From AR4 WGI FAQ1.3 (2007)
4. "Some atmospheric gases absorb and re-emit infrared energy from the atmosphere down to the Earth’s surface. This process, the greenhouse effect, leads to a mean surface temperature that is 33 °C greater than it would be in its absence. If it were not for the greenhouse gas effect, Earth’s average temperature would be a chilly -18 °C. . . . The Earth has a natural greenhouse effect due to trace amounts of water vapour (H2O), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) in the atmosphere. These gases let the solar radiation reach the Earth’s surface, but they absorb infrared radiation emitted by the Earth and thereby lead to the heating of the surface of the planet." —From WMO
5. "The Sun, which is the Earth's only external form of heat, emits solar radiation mainly in the form of shortwave visible and ultraviolet (UV) energy. As this radiation travels toward the Earth, the atmosphere absorbs about 25% of it, and about 25% is reflected by the clouds back into space. The remaining radiation travels unimpeded to the Earth and warms its surface. The Earth releases back to space the same amount of energy it has absorbed from the Sun. However, the Earth is much cooler than the Sun, so the energy re-emitted from the Earth's surface is much weaker, in the form of invisible longwave infrared (IR) radiation, sometimes called heat radiation. If you stand close to a hot object, but do not touch it, you can feel how the IR radiation heats your skin, although you cannot see the IR rays. . . . Gases that absorb and trap this IR radiation, such as water vapor (H2O), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are known as "greenhouse gases". The atmosphere acts like the glass in a greenhouse, allowing much of the shortwave solar radiation to travel through unimpeded, but trapping a lot of the longwave heat energy trying to escape back to space. This process makes the temperature rise in the atmosphere just as it does in the greenhouse. This is the Earth's natural greenhouse effect and keeps the Earth 33 °C warmer than it would be without an atmosphere, at an average 15 °C (59° F). —From NOAA Global Monitoring Laboratory
6. "the greenhouse effect is the natural warming of the earth that results when gases in the atmosphere trap heat from the sun that would otherwise escape into space. . . . Sunlight makes the earth habitable. While 30 percent of the solar energy that reaches our world is reflected back to space, approximately 70 percent passes through the atmosphere to the earth’s surface, where it is absorbed by the land, oceans, and atmosphere, and heats the planet. This heat is then radiated back up in the form of invisible infrared light. While some of this infrared light continues on into space, the vast majority—indeed, some 90 percent—gets absorbed by atmospheric gases, known as greenhouse gases, and redirected back toward the earth, causing further warming." —From Natural Resources Defense Council
7. "The infrared radiative effect of all infrared-absorbing constituents in the atmosphere. Greenhouse gases (GHGs), clouds, and some aerosols absorb terrestrial radiation emitted by the Earth's surface and elsewhere in the atmosphere. These substances emit infrared radiation in all directions, but, everything else being equal, the net amount emitted to space is normally less than would have been emitted in the absence of these absorbers because of the decline of temperature with altitude in the troposphere and the consequent weakening of emission. An increase in the concentration of GHGs increases the magnitude of this effect; the difference is sometimes called the enhanced greenhouse effect. The change in a GHG concentration because of anthropogenic emissions contributes to an instantaneous radiative forcing. Earth's surface temperature and troposphere warm in response to this forcing, gradually restoring the radiative balance at the top of the atmosphere." —From IPCC Sixth Assessment Report working group 1 glossary (2021)
8. The Earth’s climate system is powered by solar radiation (Figure 1.1). Approximately half of the energy from the Sun is supplied in the visible part of the electromagnetic spectrum. As the Earth’s temperature has been relatively constant over many centuries, the incoming solar energy must be nearly in balance with outgoing radiation. Of the incoming solar shortwave radiation (SWR), about half is absorbed by the Earth’s surface. The fraction of SWR reflected back to space by gases and aerosols, clouds and by the Earth’s surface (albedo) is approximately 30%, and about 20% is absorbed in the atmosphere. Based on the temperature of the Earth’s surface the majority of the outgoing energy flux from the Earth is in the infrared part of the spectrum. The longwave radiation (LWR, also referred to as infrared radiation) emitted from the Earth’s surface is largely absorbed by certain atmospheric constituents—water vapour, carbon dioxide (CO2), meth- ane (CH4), nitrous oxide (N2O) and other greenhouse gases (GHGs); see Annex III for Glossary—and clouds, which themselves emit LWR into all directions. The downward directed component of this LWR adds heat to the lower layers of the atmosphere and to the Earth’s surface (greenhouse effect). The dominant energy loss of the infrared radiation from the Earth is from higher layers of the troposphere. The Sun provides its energy to the Earth primarily in the tropics and the subtropics; this energy is then partially redistributed to middle and high latitudes by atmospheric and oceanic transport processes. —From IPCC Fifth Assessment Report working group 1, Chapter 1 p. 126 [glossary looks the same as AR6 above]
9. A greenhouse lets in solar energy (mostly in the form of visible light), which keeps it warm ... primarily because its glass windows prevent the wind from carrying away heat. ... The greenhouse effect occurs on our planet because the atmosphere ... contains greenhouse gases [which] are special in that they absorb heat. In doing so, they warm the atmosphere around them. Not all gases are greenhouse gases. In fact, nitrogen and oxygen – the most abundant gases in the atmosphere – aren't greenhouse gases. Fortunately for life on Earth, which depends on some atmospheric warming to exist, other gases are, including water vapor, carbon dioxide, and methane. Without its greenhouse atmosphere, Earth's temperature would plummet to well below freezing. ....
   How the Greenhouse Effect Works.
   Greenhouse gases allow sunlight to pass through the atmosphere and heat Earth, but they interact with the loss of heat from the land and ocean, redirecting some of the heat back to the surface.
   1. Earth absorbs solar energy and heats up
   2. Like all warm objects, Earth begins to radiate heat.
   Earth radiates heat, which is absorbed by the atmosphere
   3. Heat radiating from Earth encounters greenhouse gas molecules in the atmosphere, and is absorbed. The atmosphere warms; as a result, it too radiates heat. Some of this heat is radiated out into space, but the rest is radiated back to Earth's surface. This extra energy warms Earth to higher temperatures. When averaged over several years, the energy radiated into space very nearly balances the solar energy absorbed by Earth. Currently, however, Earth is radiating slightly less heat into space than it is receiving from the Sun, because of the recent addition of greenhouse gases to the atmosphere. Consequently, the planet is warming.
   Earth's atmosphere radiates more heat to the atmosphere than it gets from the Sun because of greenhouse gases.
   *Mann, Michael E.; Kump, Lee R. (2008). Dire predictions: understanding global warming. DK. pp. 22–23. ISBN 978-0-7566-3995-2.
10. Visible sunlight penetrates easily through the air and warms the Earth’s surface. When the surface emits invisible infrared heat radiation, this radiation too easily penetrates the main gases of the air. But as Tyndall found, even a trace of CO2 or water vapor, no more than it took to fill a bottle in his laboratory, is almost opaque to heat radiation. Thus a good part of the radiation that rises from the surface is absorbed by these gases in the middle levels of the atmosphere. Its energy transfers into the air itself rather than escaping directly into space. Not only is the air thus warmed, but also some of the energy trapped there is radiated back to the surface, warming it further. Weart: Simple Models of Climate Change
11. Beginning with work by Joseph Fourier in the 1820s, scientists had understood that gases in the atmosphere might trap the heat received from the Sun. As Fourier put it, energy in the form of visible light from the Sun easily penetrates the atmosphere to reach the surface and heat it up, but heat cannot so easily escape back into space. For the air absorbs invisible heat rays (“infrared radiation”) rising from the surface. The warmed air radiates some of the energy back down to the surface, helping it stay warm. This was the effect that would later be called, by an inaccurate analogy, the "greenhouse effect."Weart: The Carbon Dioxide Greenhouse Effect

Proposals:

I suggest that editors sign "~~~~" their respective proposals.

1. The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without this atmosphere.

   Radiatively active gases (i.e., greenhouse gases) in a planet's atmosphere radiate energy in all directions. Part of this radiation is directed towards the surface, thus warming it. Similarly, aerosols have radiatively active effects. The intensity of downward radiation – that is, the strength of the greenhouse effect – depends on the amount of greenhouse gases and aerosols that the atmosphere contains. The temperature rises until the intensity of upward radiation from the surface, thus cooling it, balances the downward energy flow.
   . . version as of 7 January 2022

2. The greenhouse effect is the process in which a planet's atmosphere, when warmed, emits thermal radiation which warms the planet's surface to a temperature above what it would be without this atmosphere. Sunlight passing unhindered through the atmosphere heats the surface, which then emits the energy as thermal radiation. This warms greenhouse gases (and clouds) in the atmosphere, which radiate energy in all directions. Part of this radiation goes down to the surface, warming it. The temperature rises until a higher layer radiates to space as much energy as arrives from the sun, balancing the energy flow.
   . . dave souza, talk 16:48, 10 January 2022 (UTC)
3. In the greenhouse effect, the energy of light from a planet's sun heats its surface, which emits the energy towards space as heat that gets absorbed by air and spreads in all directions, warming the planet's surface to a higher temperature than it would have reached without the air.
   Sunlight mostly passes unhindered through Earth's atmosphere and heats the surface. The warmed surface puts out radiant heat absorbed by parts of the atmosphere which warm and radiate heat in all directions, so heat going downwards raises the temperature of the surface. About a third of sunlight gets reflected into space, only 1% of the atmosphere actively absorbs and emits radiant heat, mainly greenhouse gases and clouds. The effect of water vapour varies with temperature, so even a small change in other greenhouse gases causes significant climate change.
   . . dave souza, talk 12:04, 11 January 2022 (UTC) tweaked 13:01, 11 January 2022 (UTC), rethought in simple terms 11:23, 15 January 2022 (UTC))
4. (Not overly techy, as Femke suggested; and with fewer explanatory tangents) The greenhouse effect is a process that occurs when energy from a planet's sun goes through its atmosphere and warms the planet's surface, but the atmosphere prevents the heat from returning directly to space, resulting in a warmer planet. Light arriving from our Sun passes through Earth's atmosphere and warms its surface. The warmed surface then radiates heat, which is absorbed by greenhouse gases such as carbon dioxide. Without the natural greenhouse effect, Earth's average temperature would be well below freezing. Current human-caused increases in greenhouse gases trap greater amounts of heat, causing the Earth to grow warmer over time.
   
   17:50, 11 Jan, revised 18:04, 13 Jan; 18:07, 15 Jan; 21:20, 26 Jan RCraig09; (edit #4 as requested dave souza, talk 14:26, 28 January 2022 (UTC)); revised 17:44, 28 Jan, 19:53, 29 Jan and —RCraig09 (talk) 19:32, 30 January 2022 (UTC), edits to cover static result pre-industrial, dave souza, talk 06:40, 30 January 2022 (UTC) modified 10:20
5. In the greenhouse effect, light from a sun heats a planet's surface, but something in the atmosphere makes it harder for the heat to escape to space, so the planet is warmer than it would have been without this effect. Earth's atmosphere is transparent to sunlight (including visible light and UV light) from the extremely hot Sun. The warmed surface emits radiant heat, nearly all of which is absorbed by Greenhouse gases such as carbon dioxide (CO₂), though they are only a tiny proportion of the atmosphere. They heat up, warm the atmosphere, and emit radiant heat in all directions, keeping Earth warmer. Changes to the amount of greenhouse gases can cause climate change, such as global heating from human caused greenhouse gas emissions.
   . . . dave souza, talk 18:02, 26 January 2022 (UTC), rethought 14:15, 28 January 2022 (UTC)
6. ___
7. ___

Discussion:

• AR6 definition in body of article and above includes aerosols and clouds. But definition of "radiative effect" on page AVII-48 of AR6 glossary mentions clouds, aerosols and greenhouse effect separately by saying: "Examples include the aerosol-radiation interactions, cloud radiative effect, and greenhouse effect." So are aerosols and clouds in scope of this article or not? Chidgk1 (talk) 19:28, 10 January 2022 (UTC)

clouds and aerosols have other radiative effects beside the greenhouse effect. For instance, clouds reflect sunlight. So they are in scope,but sources typically don't emphasise them. Femke (talk) 19:39, 10 January 2022 (UTC)

• The current version is better, thanks. But heat makes all gas molecules with three or more atoms vibrate and rotate faster is awkward, not very comprehensible, and not quite true - see "details" section. What it wants is something about "radiatively active" gases and a note that most of the atmosphere isn't William M. Connolley (talk) 09:12, 11 January 2022 (UTC)

Thanks, I've modified it taking these points on board, and put a copy here (#3) which can be compared with #1 the 2021 version, and #2 which modified that. Please edit or suggest improvements.. . dave souza, talk 12:12, 11 January 2022 (UTC)

• I think we must sacrifice exhaustive technical completeness in the initial description for an encyclopedia directed to the general public. Also, as Femke suggested, a 15-year old should be able to understand it readily. My proposal (#4) avoids mention of radiation, thermal radiation, radiative energy, radiatively active effects, lower frequency radiant heat, intensity of upward radiation, downward energy flow, energy flow, ... and elaborations like the effect of aerosols and clouds. Of course I'm open to changes that don't conflict with readability. —RCraig09 (talk) 18:07, 11 January 2022 (UTC)

Unfortunately "prevents some of the heat reflected from the surface from escaping into space" and "gases heated by the Earth" are wrong: the central point is that heat absorbed in the surface is emitted as IR, not "reflected", and for a balanced energy budget it all has to escape into space: the surface and atmosphere warms until that happens. I've seen "re-radiate" criticised as confusing or misleading.
Can look again at splitting the paragraph into a simplistic first sentence, then the bit after "More specifically" becomes a more technical paragraph suitable for 17 year olds. Please note, the wording "radiant heat" was selected as I think most 15-year olds will have heard of radiant heaters, and can look at one to help to understand it. . . dave souza, talk 18:35, 11 January 2022 (UTC)

Hmmm. I'll ponder, and revise accordingly. I want to avoid a mountain of different proposals. —RCraig09 (talk) 22:02, 11 January 2022 (UTC)

@Dave souza: I've revised Proposal 4 per your extremely helpful 11 Jan comments. If you have small changes to Proposal 4 that would bring it to your ~full approval, feel free to make them directly to Proposal 4's text (and add your "~~~~" signature to the end). I'm still strongly in favor of a non-techy intro, with minimal explanatory tangents (energy budget, etc.). —RCraig09 (talk) 18:04, 13 January 2022 (UTC)

@RCraig09:, thanks. I'd already begun a rethink in the simples possible terms, so have now reviewed it and inserted it here in place of #3. See what you think, and make changes where you feel it would be an improvement. In the first paragraph I've used "air" as a non-techy word for atmosphere, change that if you think the latter term works better. I've left out the energy budget as that's currently discussed [badly] in the next paragraph, which is a better place. I've mentioned sunlight reflecting as that's shown prominently in the adjacent picture. . . dave souza, talk 08:18, 15 January 2022 (UTC)

Thank you again, @Dave souza: I think Proposal 3 is an improvement, and I've adopted some of that content into my twice-revised Proposal 4. I see the importance of explaining how GHGs radiate in all directions, so I've reluctantly added some length to Proposal 4 for that purpose. I want to avoid comparisons ("than it would have reached without the air") that aren't absolutely necessary. I think that quantifications ("a third", "1%") are distracting to non-technical people, and should go lower in the lede or article body. (I think "atmosphere" is non-techy, though I've substituted "air" when appropriate.) Separately, I'm aware there's some vagueness about the definition of GHG (vs water vapor, vs particulates, etc), but for the first paragraph I'm leaving Proposal 4 to refer to GHGs only. — 18:07, 15 Jan . . Strikeout added —RCraig09 (talk) 23:32, 18 January 2022 (UTC)

• Quick comment about suggestion 4: not technically correct. Basically all heat is captured by the air, re-emitted, and captured again and so forth (about 10 times iirc) The fact that the last layer is colder than the surface causes the GHE. Femke (talk) 18:41, 15 January 2022 (UTC)

I designed my 15 Jan revision to Proposal 4, to avoid the problem you describe.

I think Proposal 4 communicates best with our predominantly non-techy readers. Feel free to make minor wording changes (e.g., possibly eliminating "more effective") to bring it closer to what consensus desires. (P.S. Where'd everybody go?) —RCraig09 (talk) 23:32, 18 January 2022 (UTC)

I agree with this, i.e. proposal 4, deleting "more effective". –Pakbelang (talk) 00:31, 20 January 2022 (UTC)

Having looked at more sources, intend to greatly simplify 3 – some minor word changes could help 4 a bit: "captures some of that energy" implies it doesn't get out and is less simple than "absorbs that energy" – if you're standing in front of a fire, you absorb radiant heat and warm up, which is the main point. "Some of the air's heat-capturing elements" is a vague way of saying "radiates heat, which is absorbed by greenhouse gases and clouds, warming the atmosphere and the surface." No need to name gases in this paragraph. Note that "ground" leaves out sea surface. Omitting "The greenhouse gases radiate heat in all directions, and the heat that is radiated downward warms the Earth's surface" leaves out the central definition of the greenhouse effect from several sources, but I'm inclined to think that can go in the second paragraph looking at the sources again, worth trying to rephrase this. The last sentence misses the point that temperatures have been stable, any change in greenhouse gases can cause climate change (whether up or down) but current increases are causing warming. Hope to add sources and edit alternatives next week, am time-limited just now. Noting modifications in 4 is already getting messy . . dave souza, talk 10:31, 20 January 2022 (UTC) strike part, add rethink . 12:00, 20 January 2022 (UTC)

— Sorry, for an intro paragraph for a lay audience, I'm still finding Proposal 3 has too many techy digressions and detailed tangents: ● Quantification (1%, "a third"). ● Unnecessary detailed digressions/tangents (clouds; water vapor especially as relates to changing with temperature). ● Reference to climate change which is the eventual, indirect result of GH Effect (compare to Proposal 4's directly "causing the earth to grow warmer"). Being recited in many references doesn't clear it for inclusion in this opening paragraph for a lay audience.

— I'm definitely open to wording improvements to Proposal 4 (specific suggested changes are more useful here than critiques). But in all events I think we must keep the intro paragraph simple, simple, simple. That said, I do think mentioning carbon dioxide and methane helps to clarify the mysterious term, "greenhouse gas", for the lay reader. —RCraig09 (talk) 18:12, 23 January 2022 (UTC)

Simples. Mann and Kump point towards simpler terminology, both they and Henson's The Rough Guide to Climate Change cover the difference to greenhouses before explaining how the GE works, and that's useful for the lay audience these books are aimed at. More detailed topics for the next paragraph include "causing the earth to grow warmer" which is climate change as global warming: the primary point is that the GE stabilises higher temp than no GE. Agree with including CO₂ as a common example, methane is more complicated and less significant than water vapour, so intend to cover these further into the lead. . . Work in progress. . . dave souza, talk 18:32, 26 January 2022 (UTC)

Methane is a much more powerful GHG per molecule, though less powerful overall, than CO2.

@Dave souza: I'm not sure which terminology your references use that's simpler, but I've simplified Proposal 4 even more. I'm not married to methane but would prefer to keep her in the picture (see diagram at right). Re Proposal 5 (which is diverging discussion rather than converging it): In the opening paragraph I think it's slightly too much detail to explain which direction heat is re-radiated, especially since it's not just the "surface" that's involved in global warming, but the entire lower atmosphere as well. I'm against opening an article with a diversion to a flawed analogy. Is there a minor revision to Proposal 4 that would bring your OK? —RCraig09 (talk) 21:20, 26 January 2022 (UTC)

@RCraig09:, Weart covers methane: "Tyndall immediately went on to study other gases, finding that carbon dioxide gas (CO2) and water vapor in particular also block heat radiation. Tyndall figured that besides water and CO2, "an almost inappreciable mixture of any of the stronger hydrocarbon vapors" would affect the climate. But there was far more water vapor circulating, and although CO2 was only a few parts in ten thousand in the Earth's atmosphere, that was still much more than other gases. There is so little of Tyndall's "hydrocarbon vapors" in the atmosphere that the most important of them, methane, was not detected there until 1948."
Have rethought Proposal 5 while still covering points in Proposal 4. The flawed analogy is in the title, which is why authors cover that early, but have removed it from the proposal for this opening paragraph.
Have made some minor changes to Proposal 4 as suggested, think the most important is that "trap the heat" means "heat cannot so easily escape back into space". If standing in front of a fire, you'd absorb the heat or soak up the heat, not trap it. (offtopic: tourist asks kilted Scot at breakfast room fireplace "is that your Ayrshire bacon?", he replies "Naw, just warmin' ma haunds".) . . .dave souza, talk 14:48, 28 January 2022 (UTC)

— Sorry, I wasn't asking for an historical explanation of terms; I was actually trying to converge the discussion. Most of your changes to Proposal #4 are OK, though I made some reversions re: ● "nearly all" the heat being absorbed (not true of general definition), ● minor wording change ("Most light..."), ● heat "redirected to warm earth" (unnecessary "extra step", and repetitive of ensuing sentence). Both "captured" or "trapped" are accurate, since that heat doesn't escape to space.

I'm trying to converge the discussion to a final result. I think Proposal 5, even by itself, isn't converging. Proposal 5 has descriptive issues ("something in the atmosphere", "harder... to escape", "extremely hot" sun, etc) and unnecessary techy diversions ("visible light", "tiny proportion of the atmosphere", "emitting heat in all directions", mentioning ordinary Climate Variability and Change, human GHG emissions, etc) inappropriate for an intro paragraph on GHE for lay readers. I think Proposal 4 is converging and we should finalize it with small refinements. —RCraig09 (talk) 17:44, 28 January 2022 (UTC)

Thanks for moving a bit forward, however I think Proposal 4 has serious issues and it's at best premature to focus on "converging" and "finalize it with small refinements". Don't mind editing it to explore areas for discussion, but my edits are not endorsement of it as "finalized". What's needed is working towards consensus on the basics to be covered, and finding the best wording to convey these basics to lay readers. On points discussed:

● Weart wasn't for "historical explanation of terms", but for expert views of a physicist and educator, specifically the point that methane is relatively minor overall, regardless of its power per molecule, thanks for leaving that gas out.
● "nearly all" the heat being absorbed "(not true of general definition)" – fair point, but equally your wording as restored "some of the heat" is not general either: isn't "all of the heat" absorbed on Venus?
● "Most light from our Sun passes freely through Earth's atmosphere to warm it" is really "most of the light arriving from the sun", since about half the light reaching Earth is reflected, and some (infrared?) light is absorbed on the way in.
● heat "redirected to warm earth" – for this lay reader, the absorbed heat being emitted in all directions and effectively redirected to warm Earth is essential to understanding.
● "Both "captured" or "trapped" are accurate, since that heat doesn't escape to space" – the energy received from the Sun, transformed into radiant heat, does eventually escape to space, as it did in the stable warmed situation prior to industrial global warming. If the last point can't be conveyed in this opening paragraph, better to leave "Increasing amounts of greenhouse gases ..." etc. to a later paragraph.
Will think about edits. . . dave souza, talk 19:00, 29 January 2022 (UTC)

@Dave souza: I'm flexible as to exact wording, of course. Observations: ● It's speculative that Venus captures 100.0000% of the heat, so "some of the heat..." is safe wording, ● "most light arriving from the sun..." is OK with me (now changed) ● "redirection...etc" is an "extra step" necessary for deeper understanding but not in the intro paragraph for lay readers ● not "all" heat eventually escapes to space ● conversely, the greenhouse effect on Earth that most incoming readers are seeking, does involve the effect of the "growing warmer over time", and is thus crucial. I think Proposal 4 is both concise and appropriately detailed. 19:53, 29 Jan . . . . Eighty-six of the most beautiful words ever written! —RCraig09 (talk) 19:57, 29 January 2022 (UTC)

@RCraig09:, in my reading, some of the heat..." implies only a little, so unquantified is safe wording. It strikes me that the defining characteristic of greenhouse gases is that they absorb and emit heat. They don't prevent heat from [eventually] going out, but they do mean it doesn't go freely, and the result is a raised temperature (not rising temperature, which is interim). Have made changes with the aim of allowing a subsequent paragraph to cover the redirecting effect. . . dave souza, talk 07:01, 30 January 2022 (UTC)

@Dave souza: I know there may be an ambiguity over the extent of the definition of Greenhouse "effect". 19:59, 29 Jan... On second thought, the exact definition of GHE isn't an issue: we're only talking about where to include a particular sentence (about "growing warmer over time"). —RCraig09 (talk) 23:30, 29 January 2022 (UTC)

Thanks, have boldly made 3 edits to cover static result pre-industrial, and greenhouse gases emitting heat, so the paragraph is more universal, subsequent paragraphs to give detail. .. dave souza, talk 07:01, 30 January 2022 (UTC) – after a little copyediting, think this is getting closer. . . dave souza, talk 12:20, 30 January 2022 (UTC)

I love, love, love the joining of "natural GHE" and "...growing warmer over time"; it's well worth the few extra words required. I think the passages limited to GHE on Earth are ready for publication. However, I think the first sentence—GHE not limited to Earth—can use some fine tuning (e.g., "interacting" seems suboptimal, "resulting in a higher temperature" is vague as to where and I think may be omitted). We'll have to think some more. —RCraig09 (talk) 17:04, 30 January 2022 (UTC)

@RCraig09: – Thanks! Interacting avoids getting into absorb / emit / redistribute heat cycle, don't have an alternative wording to hand. Have changed "resulting in a higher temperature" to "with the result that the temperature of the planet is increased", we want to be clear that temp doesn't continue to go up without limit. Could be the temp of the planet's surface, assuming it has one. . . dave souza, talk 18:25, 30 January 2022 (UTC)

@Dave souza: I've just noticed the opening paragraph of the main Climate change article. I can't remember the detailed history, but due to high levels of editor attention it probably has met consensus at some time in the past. The current version recites "Greenhouse gases are transparent to sunlight, allowing it through to heat the Earth's surface. When the Earth emits that heat as infrared radiation the gases absorb it, trapping the heat near the Earth's surface." —RCraig09 (talk) 17:53, 30 January 2022 (UTC)

Noticed that too, but "the heat" isn't [all] trapped, indeed about as much [heat] energy goes out as comes in from the Sun, and increased heat goes all the way up to "an altitude of roughly 5-6 kilometers [where] the concentration of greenhouse gases in the overlying atmosphere is so small that heat can radiate freely to space."[1] Once we've got this intro together, we can look again at that article. . . dave souza, talk 18:25, 30 January 2022 (UTC)

Details are in my edit comment, but I've made changes trying to avoid various issues we have perceived. I suggest we continue refining Proposal #4 directly, as I think it's more efficient than longer descriptions here. 19:35, 30 Jan ... The issue maybe needing explanation is that we don't need to include the "extra step" of GHGs radiating heat it just absorbed; that step is implied. —RCraig09 (talk) 19:39, 30 January 2022 (UTC)

Agree, have made a few minor copyedits, mainly to avoid suggesting light does things "to" warm the earth, it doesn't act purposefully. Leaving the first paragraph alone but using some ideas which came up in these discussions, I've edited the rest of the lead to follow on from the new intro. . . dave souza, talk 15:10, 31 January 2022 (UTC)

I think we're ready to WP:BOLDly insert into the article, subject to any other editors' comments or suggestions that come along soon. Our collective goal in the intro paragraph should be to present GHE in layman's terms, while being broad but technically correct. —RCraig09 (talk) 16:56, 31 January 2022 (UTC)

Boldly implemented. Added cite to the NASA budget source, left Smit in place but think it's too techy. dave souza, talk 07:40, 3 February 2022 (UTC)