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![]() | Climate change feedbacks is currently an Earth sciences good article nominee. Nominated by InformationToKnowledge ( talk) at 18:28, 8 June 2024 (UTC) Anyone who has not contributed significantly to (or nominated) this article may review it according to the good article criteria to decide whether or not to list it as a good article. To start the review process, click start review and save the page. (See here for the good article instructions.) Short description: Feedback related to climate change |
Cleaned up some refs and code, switched some to LDR, others to {{ Cite doi}}. We're using the latest AFAIK. Some references I think could be improved. For example, #2 from the University of Texas are lecture notes, and #4 is about planetary science in general—not really focused on climate change feedback. [1] ChyranandChloe ( talk)
The "Negative feedbacks" section of the graphic has been re-worked in new Version 5 (05:54, 20 July 2023). — RCraig09 ( talk) 06:01, 20 July 2023 (UTC)
@ Sjsmith757, InformationToKnowledge, Dtetta, and Femke: Requesting concise input on what wording to include in this diagram. There may be some subtleties on what different sources define as a climate feedback per se (versus a parallel process), but let's define concisely what to include in the diagram with minimal theoretical digressions if possible. Specific wording is key at this point, keeping in mind space limitations in the graphic. — RCraig09 ( talk) 21:50, 21 July 2023 (UTC)
Please answer inline within each topic, so we can keep discussions separate. I've implemented (late 22 July) many of the above suggestions (exceptions discussed as follows). I'll post a new version if more time passes without further comment below.
<tspan>
element, which is suspected of involvement in ongoing SVG font rendering problems (software bug in Wikimedia projects). "Carbon dioxide" is also less jargony. —
RCraig09 (
talk) 04:09, 23 July 2023 (UTC)I do think that a feedback analysis of the links in Al Gore (2006). An inconvenient truth: the planetary emergency of global warming and what we can do about it. would be a useful contribution and i guess i agree that File:Gore inconvenient truth loops.png isn't high quality, so i've put it in the article about the book itself. i'd hoped that somebody might improve the image as it's a useful contribution to understanding the ultimately negative consequences of human population growth and technological development. if you know of anyone who'd like to pursue this, please let me know. Lee De Cola ( talk) 13:52, 19 July 2023 (UTC)
Actually I regard the graphic's main point as that most of the important feedbacks to humans are negative and will reduce their numbers during this century, and we are seeing this playing out now. I think I'll post a similar graphic with page numbers on the AN INCONVENIENT TRUTH page, and see who reacts. Lee De Cola ( talk) 18:27, 19 July 2023 (UTC)
References
:26
was invoked but never defined (see the
help page).I've just done some work on the lead:
This blackbody radiation or Planck response has been identified as "the most fundamental feedback in the climate system"- do we need to provide both those terms or would one be sufficient? Are they the same thing? EMsmile ( talk) 21:47, 23 January 2024 (UTC)
@ Bikesrcool: WP:ONEDOWN is a general principle that I think editors in the climate change area intuitively follow, as we know we are communicating with the general public. Separately, I think the formulation itself is so similar to the early textual description, that a formulation doesn't really add anything more to the reader's knowledge. For these reasons, a "Mathematical formulation" section is not appropriate so early--and prominently--in the article. If it's retained in the article, I definitely think it should be moved down, before "See also" because all previous sections are meant for a lay audience and their likely concerns. I hope you'll consider these constructive remarks. — RCraig09 ( talk) 04:54, 19 August 2023 (UTC)
We aren't talking about a singular feedback. Even in our definitional sentence we begin by saying "Climate change feedbacks...". Sorry if this has been covered before, but it reads weird in the general climate change article as well, where climate forces are all plural except feedbacks. We have "aerosols", "clouds", "greenhouse gases", and then "climate change feedback". Any objection to doing a simple rename to this article? Efbrazil ( talk) 15:49, 9 February 2024 (UTC)
I am trying to improve the reading ease of the lead but this sentence really baffles me, it seems messed up: These are
arctic methane release from
thawing permafrost, peat bogs and hydrates, abrupt increases in
atmospheric methane, decomposition, peat decomposition, rainforest drying,
forest fires,
desertification.
Seems like a messy list. Also, the paragraph in the lead about positive feedbacks (currently the second one) should line up better with the graphic on the right. I suggest to use the same ordering, and ensure the most important one is first (?).
EMsmile (
talk) 23:10, 15 March 2024 (UTC)
References
WG1AR5_TS_FINAL
was invoked but never defined (see the
help page).Quotation taken from top of page 978 AR6 WGI Chapter7 (and see table 7.10 at bottom of same page): "It is virtually certain that the net climate feedback is negative, primarily due to the Planck temperature response, indicating that climate acts to stabilize in response to radiative forcing imposed to the system. Supported by the level of confidence associated with the individual feedbacks, it is also virtually certain that the sum of the non-Planck feedbacks is positive. Based on Table 7.10 these climate feedbacks amplify the Planck temperature response by about 2.8 [1.9 to 5.9] times."
Likewise quoting from page 96 AR6 WGI Technical Summary (and see accompanying figure TS.17): "The combined effect of all known radiative feedbacks (physical, biogeophysical, and non-CO2 biogeochemical) is to amplify the base climate response (in the absence of feedbacks), also known as the Planck temperature response (virtually certain). Combining these feedbacks with the Planck response, the net climate feedback parameter is assessed to be –1.16 [–1.81 to –0.51] W m –2 °C –1 , which is slightly less negative than that inferred from the overall ECS assessment."
Could a simplified version of the Chapter 7 quotation replace the one now at the end of the lead?: It is virtually certain that the net climate feedback is currently negative and thus stabilizes climate over time, primarily due to Earth's blackbody radiation response. It is also virtually certain that the sum of all other feedbacks is positive and causes amplification of global warming. Bikesrcool ( talk) 05:54, 14 April 2024 (UTC)
Carbon cycle feedbacks are negative as carbon uptake increases when atmospheric concentrations increase. However, higher temperatures and saturation of carbon sinks will decrease that effect.(perhaps an example could help to clarify this? Sounds very abstract like this.).
The last sentence was a clear run on sentence with bad readability. The Planck response is not a feedback and the IPCC explicitly says feedbacks will increase for the remainder of the century. Feedbacks are not "primarily estimated through models". The lead that was there was arrived at through extensive discussion- go slow on edits or open talk discussion please.
This is the comparison of the two versions.
Current wording | The reverted paragraphs |
---|---|
....The main positive feedback is that warming increases the amount of atmospheric water vapor, which is a powerful greenhouse gas.[5] Another positive feedback is the loss of reflective snow and ice cover. Positive carbon cycle feedbacks occur when organic matter burns or decays, releasing CO2 back into the atmosphere. Loss of organic matter can happen through rainforest drying, forest fires, and desertification. Methane can also be released into the atmosphere by thawing permafrost.
The main cooling effect is called the Planck response, which comes from the Stefan–Boltzmann law. It states that the total energy radiated per unit surface area per unit time is directly proportional to the fourth power of the black body's temperature. The carbon cycle acts a negative feedback as it absorbs more than half of CO2 emissions every year. Atmospheric CO2 gets absorbed into rocks and into plants. It also gets dissolved in the ocean where it leads to ocean acidification. There are several types feedbacks: physical feedbacks, biological feedbacks and carbon cycle feedbacks. Calculations can give different results depending on the time frame and location that is used. Carbon cycle feedbacks are negative, which means that as atmospheric concentrations increase, carbon uptake also increases. However, higher temperatures and saturation of carbon sinks decrease that negative feedback effect. Overall feedbacks are expected to trend in a positive direction for the near future, though the Planck response will become increasingly negative as the planet warms.[6]: 94–95 There is no threat of a runaway greenhouse effect from current climate change. |
....Feedbacks are generally divided into purely physical and partially biological (i.e. biogeophysical and biogeochemical.) The former include cloud feedback, ice-albedo feedback, Planck response feedback as well as the lapse rate and water vapor feedbacks. The latter mostly consist of feedbacks associated with the carbon sinks and the carbon cycle. Sometimes, feedbacks associated with the ice sheets are treated separately from either, because it takes multiple centuries before they become apparent, whereas the others have a substantial role within decades. Feedback strengths and relationships are primarily estimated through global climate models, with their estimates calibrated against observational data whenever possible. "Fine-scale" modelling devoted to specific processes also exists, and has been used more widely starting from 2010s.
The overall sum of climate feedbacks is negative, meaning that they make the warming slower than it would be otherwise. It also means that runaway greenhouse effect effectively cannot occur due to anthropogenic climate change. This is largely because of the Planck rate negative feedback, which is several times larger than any other singular feedback. Additionally, the carbon cycle already absorbs a little over half of annual CO2 emissions, and its ability to do so scales almost in proportion to emissions. However, as the warming increases, it amplifies positive feedbacks - like the ice-albedo feedback and soil carbon feedback, or the various feedbacks which increase atmospheric methane concentrations - more than the negative ones, so the warming is slowed less than it would have been at a cooler initial state. |
Now...
and the IPCC explicitly says feedbacks will increase for the remainder of the century.
- Which is exactly what the last sentence was meant to say - the one which you concluded lacked readability.
The IPCC also explicitly says that the sum of all feedbacks is negative, yet as already pointed out by Bikesarecool above, this is not currently mentioned at all. And speaking of things which were explicitly mentioned by the IPCC...
Feedbacks are not "primarily estimated through models".
- Wanna bet?
Up until AR5, process understanding and quantification of feedback mechanisms were based primarily on global climate models. Since AR5, the scientific community has undertaken a wealth of alternative approaches, including observational and fine-scale modelling approaches.
- AR6, WG1, CH7, 967
The Planck response is not a feedback
- and this is where the discussion above gets really confusing. So, Bikesarecool has already provided an IPCC quote where it is considered a feedback. If necessary, I can provide another. EDIT: There it is.
The Planck response represents the additional thermal or longwave (LW) emission to space arising from vertically uniform warming of the surface and the atmosphere. The Planck response αP, often called the Planck
feedback, plays a fundamental stabilizing role in Earth’s climate and has a value that is strongly negative: a warmer planet radiates more energy to space.
- AR6, WG1, CH7, 968
Yet, apparently, the discussion so far has opted to believe that the IPCC as a whole has made a mistake, based on...Femke's individual opinion and an Annual Reviews article from 2009? Sure, this here
It is also worth mentioning that what even counts as a feedback depends on the definition of the reference system. For example, the Stefan-Boltzman relation is often described as a negative climate feedback acting to regulate temperature anomalies. In fact, for a blackbody planet, which is the simplest imaginable reference system for the climate that is still meaningful, the Stefan-Boltzman relation is part of the reference system and therefore not a feedback at all. These are not semantic or esoteric issues—the quantitative intercomparison of different feedbacks can be done only when the reference system is defined and held constant
Is interesting. Should this, written by just one professor, be given credence over the wording of the world's premier scientific body, over a decade later? I doubt it. Moreover, here is something else from the earlier discussion: (quote template keeps bugging out here, for some reason.)
"Also, it occurs to me that if feedbacks that included the Planck response as a feedback were net positive, then we could be talking about a runaway greenhouse effect, which nobody is predicting. Is that correct, or does a positive feedback value just mean warming would be amplified? Maybe a feedback value of over 1.0 = runaway greenhouse effect?..."
I believe that (the bolded part) actually is the case? I would quote myself from a discussion we had here last year ( now archived):
According to the leading expert on climate feedback loops and tipping points, Dr. Adam Armstrong McKay (the lead author of last year's Science assessment of tipping points):
"Outgoing longwave radiation acts as the main major negative feedback, as hot things radiate more heat away. Positive feedbacks do not inevitably lead to runaway warming, as negative feedbacks will eventually counter them – if there were no negative feedbacks Earth would have become as hot as Venus long ago."
So, it probably shouldn't matter given the opinion of the IPCC alone, but the lead author of this paper we cite very extensively, and almost certainly one of the top 5 experts on the subject worldwide, also happens to describe the Planck response/blackbody radiation as a feedback. Are we going to argue against this too? (Trivia: I think he and Femke might be at the same research institution, so there is conceivably a chance they could talk this over in person?) InformationToKnowledge ( talk) 12:34, 15 May 2024 (UTC)
What's interesting for the lead is whether the climate response to a linear increase in greenhouse gas emissions going forward is going to accelerate or decelerate, or whether the geographic locations of amplified warming will change at all.- I have already answered this question in the lead of Causes of climate change (which apparently wasn't read very closely by anyone here?)
The warming from the greenhouse effect has a logarithmic relationship with the concentration of greenhouse gases. This means that every additional fraction of CO2 and the other greenhouse gases in the atmosphere has a slightly smaller warming effect than the fractions before it as the total concentration increases. However, only around half of CO2 emissions continually reside in the atmosphere in the first place, as the other half is quickly absorbed by carbon sinks in the land and oceans.
As the warming from CO2 increases, carbon sinks absorb a smaller fraction of total emissions, while the "fast" climate change feedbacks amplify greenhouse gas warming. Thus, both effects are considered to each other out, and the warming from each unit of CO2 emitted by humans increases temperature in linear proportion to the total amount of emissions.
As cumulative emissions increase, weakening land and ocean carbon sinks increase the airborne fraction of CO2 emissions (see Figure 5.25), but each unit increase in atmospheric CO2 has a smaller effect on global temperature owing to the logarithmic relationship between CO2 and its radiative forcing (Matthews et al., 2009; Etminan et al., 2016). At high values of cumulative emissions, some models simulate less warming per unit CO2 emitted, suggesting that the saturation of CO2 radiative forcing becomes more important than the effect of weakened carbon sinks (Herrington and Zickfeld, 2014; Leduc et al., 2015). The behaviour of carbon sinks at high emissions levels remains uncertain, as models used to assess the limits of the TCRE show a large spread in net land carbon balance (Section 5.4.5), and most estimates did not include the effect of permafrost carbon feedbacks (Sections 5.5.1.2.3 and 5.4). The latter would tend to further increase the airborne fraction at high cumulative emissions levels, and could therefore extend the window of linearity to higher total amounts of emissions (MacDougall et al., 2015). Leduc et al. (2016) suggested further that a declining strength of snow and sea ice feedbacks in a warmer world would also contribute to a smaller TCRE at high amounts of cumulative emissions. However, Tokarska et al. (2016) suggested that a large decrease in TCRE for high cumulative emissions is only associated with some EMICs; in the four ESMs analysed in their study, the TCRE remained approximately constant up to 5000 PgC, owing to stronger declines in the efficiency of ocean heat uptake in ESMs compared to EMICs.
Overall, there is high agreement between multiple lines of evidence (robust evidence) resulting in high confidence that TCRE remains constant for the domain of increasing cumulative CO2 emissions until at least 1500 PgC, with medium confidence of it remaining constant up to 3000 PgC because of less agreement across available lines of evidence.- AR6, WG1, CH5, 746
Let me know if you disagree and I can dig up some IPCC talk that reflects the alternate view that backs what Femke said.- Please do. Having said that, this is secondary to the question at the top of this section - about the direction of the net sum of feedbacks. As you might have noticed, I included another prominent reference which says that the net feedback is negative, but I don't know if this is going to make a difference. If some editors here already find the IPCC text "ambiguous", would a single paper on top of it (even from Nature Geoscience) matter? Would 3, 5, or 10 more matter?
As for saying feedbacks are "primarily estimated through models": The issue is that's wording that climate deniers use.Hmm, my primary impression to date has been the opposite - stupid claims on various social media that "[feedback which has been known for many decades] isn't in the models and so there'll "actually" be this much more warming than what the IPCC says." I noticed that the individual feedback sub-sections already had little "This feedback is in the models" disclaimers (which I tried to rework into stronger and more specific sentences), so at least some editors are clearly aware of this issue. I wonder if anyone else wants to weigh in? InformationToKnowledge ( talk) 02:43, 16 May 2024 (UTC)
The last sentence was a clear run on sentence with bad readability.
However, as the warming increases, it amplifies positive feedbacks - like the ice-albedo feedback and soil carbon feedback, or the various feedbacks which increase atmospheric methane concentrations - more than the negative ones, so the warming is slowed less than it would have been at a cooler initial state.
The overall sum of all climate feedbacks is negative, meaning that, for a warming climate, the warming is slower than it would be otherwise. This due to the strongly negative Planck radiative rate feedback, which is several times larger than any other singular feedback. In estimates where Planck rate response is described as part of the baseline climate system, the net sum of feedbacks is positive, but its stabilizing effect is still assumed implicitly.
Long-term feedbacks associated with ice sheets (Section 7.4.2.6) are relevant primarily after several centuries or more."Primarily after" is a much stronger wording than "can take". InformationToKnowledge ( talk) 19:31, 28 May 2024 (UTC)
The IPCC says that the feedback parameter, i.e. Planck + feedbacks, is negative (assuming you use their sign convention). The IPCC is also declarative that the net effect of the actual radiative feedbacks is amplifying in
Chapter 7 (page 926). They say: The combined effect of all known radiative feedbacks (physical, biogeophysical, and non-CO2 biogeochemical) is to amplify the base climate response, also known as the Planck temperature response (virtually certain)
. If there is consensus among editors here to use a convention that Planck is a feedback, we need to use a different source than the IPCC, or only cite page 96, where they say something different to the rest of the report in the caption. All the other page numbers contradict what we now say.
—Femke 🐦 (
talk) 21:23, 28 May 2024 (UTC)
The IPCC is also declarative that the net effect of the actual radiative feedbacks is amplifying in Chapter 7 (page 926).Really?
Radiative feedbacks, particularly from clouds, are expected to become less negative (more amplifying) on multi-decadal time scales as the spatial pattern of surface warming evolves, leading to an ECS that is higher than was inferred in AR5 based on warming over the instrumental record.- Same page
They say- Yes, and Chapter 7's primary author already said that this text applies when feedbacks are treated as a modification of the base temperature change, but not when they are described as changes in radiative forcing. He also literally used the phrase "Planck feedback".
Saying when feedback effects become apparent is very different from saying when the feedbacks will have their primary effect.- OK, then don't say "become apparent" (yes, I was the one who first used it) and write what their text actually intended to convey instead.
We could adapt this image to a compressed form that is good for smartphones / thumbnails: https://www.ipcc.ch/report/ar6/wg1/downloads/figures/IPCC_AR6_WGI_TS_Figure_17.png
Chart (b) of that image can be cut as the content is already represented in chart (a) and isn't very consequential. The naming is a torture though, so I'd rename the item from "Biophysical and non-CO2 biogeochemical" to the somewhat simpler "Non-CO2 biological".
It's annoying that they have "total" for climate system feedbacks but do not provide a total for carbon cycle feedbacks. I'd just leave out "total" as a result.
Charts (a) and (c) could then be combined as the x axis is the same.
Also, I'm not sure we should have the jargony "planck" in there, so maybe add a parenthetical explanation saying (thermal radiation).
Finally, there's the discussion up above that we should account for, namely that planck response is not technically a feedback and that the carbon cycle is part of the climate system. So that leaves something like this:
Title: Factors influencing climate sensitivity
Rows, where "Radiative feedbacks" and "Carbon cycle feedbacks" would just be headers with no data:
Planck (thermal radiation)
Radiative feedbacks
Carbon cycle feedbacks
Finally, for the X axis label, simply have 2 arrows pointing off center that say "Negative feedback" and "Positive feedback", like the top of the IPCC chart does. I don't see a point in articulating "Climate feedback parameter (WM-2 C-1)" and the numbers as those will mean nothing to people. The caption and graphic description can get into all that. The real point of the graphic is to highlight the major factors to consider. Efbrazil ( talk) 23:33, 20 May 2024 (UTC)
— Version 1 is uploaded 22 May. The different processes are all very techy and need external explanation, making it unsuitable for a lead graphic in a layman's encyclopedia article. I've de-emphasized the confidence intervals for a similar reason.
— Graphically, I can now see how I could compress the actual chart area horizontally a bit (the large blue and read areas), so the font-height-to-image-width ratio is larger (see
), though that would make the graphic occupy more vertical space in articles for a predetermined pixel width. Since that change involves a non-trivial amount of work, I will wait until any substantive issues are resolved.
— I've just downloaded the Wikipedia app. The above flowchart is definitely readable in landscape orientation on my 2.5x4-inch screen, even moreso if the viewers spread their fingertips. —
RCraig09 (
talk) 16:03, 22 May 2024 (UTC)
Snow cover loss and ice shelf melt- A reminder of what an ice shelf actually is. On a global scale, the surface area of all ice shelves is absolutely tiny, and I never saw any paper bother to single them out for any radiative effect. Presumably you meant to write ice sheet, but that is also incorrect, since practically all the melting to date had occurred on their margins - Greenland's surface did get darker, but not enough for a meaningful global impact. Virtually all the albedo feedback to date is from the sea ice loss followed by snow cover. As a bonus, writing
Snow cover and sea ice declineshould allow you to reduce it to two lines, not three. (Planck box staying at three will visually highlight its importance.)
Thawing permafrost releases methane into the air- Permafrost emits a lot more CO2 than methane - by an order of magnitude or thereabouts. It is only the difference in GWP which (probably) makes warming from methane larger - and even then, it's a 70%/30% ratio at most. I am guessing you decided to omit CO2 emissions from positive feedbacks because they are far outweighed by absorption? (In which case, this could still warrant a small * note at the bottom.)
Thawing permafrost and warming wetlands release methane? (
Warming permafrost and wetlands release methaneif you can't fit it into two lines otherwise.) I think we can trust our readers to fill in the blanks and not have to specify "in the air" on this one.
Clouds become thinner and reflect less sunlight. To balance it, the negative feedback side could describe lapse rate as
more heat is lost at higher altitudes. This shouldn't add too much space to the graphic, and will make it far more accurate. InformationToKnowledge ( talk) 11:28, 31 May 2024 (UTC)
Thanks Craig! Very glad you like it!
Regarding CO2 feedbacks, there are really 2. There's the CO2 response to more CO2 in the air, which is a strongly negative feedback and the first feedback listed above. It's what the IPCC carbon feedback chart calls "Land response to more CO2" and "Ocean response to more CO2" (which I aggregated). That's not part of global warming, it's simply an artifact of more CO2 in the air (the planet has consistently absorbed a steady percentage of annual emissions, instead of a fixed amount of emissions, which has been very helpful in limiting climate change). On the flip side, the positive feedback is that global warming is reducing the ability of the planet to absorb CO2, which is the last feedback in the version of the chart I created, and that's the one that includes wildfires, drought, and so on. Make sense?
I'm not sure what you mean by "group the blue boxes". Did you mean moving the "More CO2 absorbed" label down? I want that directly beneath emissions and above global warming, for the reasoning above.
These are the changes I made:
Let me know what you think, and thanks again for the encouragement! Efbrazil ( talk) 23:45, 7 June 2024 (UTC)
I believe we need to say what qualifies as a climate change feedback in the definition section. After all, we just burned through a lot of time discussing that exact issue up above on this talk page, and it seems critical to define the scope of climate change feedbacks in an article on climate change feedbacks. Here is what I added to the beginning of the definition section, which is my best attempt to condense the discussion above:
InformationToKnowledge reverted it with this comment: Not an improvement. I doubt this will make sense to readers who have not read the talk page, and it doesn't make sense to feature this early in the article. Either place a shorter version in the Planck section itself, or omit it entirely.
I disagree strongly on the placement issue. We are in the definition section and this is critical for defining the topic of the article. I can see the argument that this might be hard for someone new to understand at first, but I think it is best to be precise here at the expense of accessibility. Perhaps someone can come up with better wording. Anyone else care to comment, particularly RCraig09 and Femke? Efbrazil ( talk) 18:08, 14 June 2024 (UTC)
References
I find this sentence too difficult to read. It contains an enumeration of 4 things. Why not split it into two? I mean this sentence: Physical feedbacks include increased
water vapor from evaporation, altered
cloud distribution, decreased
surface reflectivity as snow and ice cover diminishes, and an amplification of the
rate at which atmospheric temperature falls with rising altitude.
. My proposal was two sentences each with two feedbacks: Physical feedbacks include increased
water vapor from evaporation as well as altered
cloud distribution. Another two physical feedbacks are decreased
surface reflectivity (albedo) as snow and ice cover diminishes, and an amplification of the
rate at which atmospheric temperature falls with rising altitude.
. I think this is a valid way of splitting a long sentence in two. Efbrazil reverted this with the explanation "To split a sentence you must have separate subjects for each sentence.". I don't think this is true. Who says so? I've seen long sentences with long enumerations split in similar ways before. - Can you think of other ways of making this sentence easier to read?
EMsmile (
talk) 21:58, 17 June 2024 (UTC)
Physical feedbacks include increased water vapor from evaporation, altered cloud distribution, and decreased surface reflectivity as snow and ice cover diminish. Additionally, there is an amplification of the rate at which atmospheric temperature falls with rising altitude.EMsmile ( talk) 21:58, 17 June 2024 (UTC)
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![]() | Climate change feedbacks is currently an Earth sciences good article nominee. Nominated by InformationToKnowledge ( talk) at 18:28, 8 June 2024 (UTC) Anyone who has not contributed significantly to (or nominated) this article may review it according to the good article criteria to decide whether or not to list it as a good article. To start the review process, click start review and save the page. (See here for the good article instructions.) Short description: Feedback related to climate change |
Cleaned up some refs and code, switched some to LDR, others to {{ Cite doi}}. We're using the latest AFAIK. Some references I think could be improved. For example, #2 from the University of Texas are lecture notes, and #4 is about planetary science in general—not really focused on climate change feedback. [1] ChyranandChloe ( talk)
The "Negative feedbacks" section of the graphic has been re-worked in new Version 5 (05:54, 20 July 2023). — RCraig09 ( talk) 06:01, 20 July 2023 (UTC)
@ Sjsmith757, InformationToKnowledge, Dtetta, and Femke: Requesting concise input on what wording to include in this diagram. There may be some subtleties on what different sources define as a climate feedback per se (versus a parallel process), but let's define concisely what to include in the diagram with minimal theoretical digressions if possible. Specific wording is key at this point, keeping in mind space limitations in the graphic. — RCraig09 ( talk) 21:50, 21 July 2023 (UTC)
Please answer inline within each topic, so we can keep discussions separate. I've implemented (late 22 July) many of the above suggestions (exceptions discussed as follows). I'll post a new version if more time passes without further comment below.
<tspan>
element, which is suspected of involvement in ongoing SVG font rendering problems (software bug in Wikimedia projects). "Carbon dioxide" is also less jargony. —
RCraig09 (
talk) 04:09, 23 July 2023 (UTC)I do think that a feedback analysis of the links in Al Gore (2006). An inconvenient truth: the planetary emergency of global warming and what we can do about it. would be a useful contribution and i guess i agree that File:Gore inconvenient truth loops.png isn't high quality, so i've put it in the article about the book itself. i'd hoped that somebody might improve the image as it's a useful contribution to understanding the ultimately negative consequences of human population growth and technological development. if you know of anyone who'd like to pursue this, please let me know. Lee De Cola ( talk) 13:52, 19 July 2023 (UTC)
Actually I regard the graphic's main point as that most of the important feedbacks to humans are negative and will reduce their numbers during this century, and we are seeing this playing out now. I think I'll post a similar graphic with page numbers on the AN INCONVENIENT TRUTH page, and see who reacts. Lee De Cola ( talk) 18:27, 19 July 2023 (UTC)
References
:26
was invoked but never defined (see the
help page).I've just done some work on the lead:
This blackbody radiation or Planck response has been identified as "the most fundamental feedback in the climate system"- do we need to provide both those terms or would one be sufficient? Are they the same thing? EMsmile ( talk) 21:47, 23 January 2024 (UTC)
@ Bikesrcool: WP:ONEDOWN is a general principle that I think editors in the climate change area intuitively follow, as we know we are communicating with the general public. Separately, I think the formulation itself is so similar to the early textual description, that a formulation doesn't really add anything more to the reader's knowledge. For these reasons, a "Mathematical formulation" section is not appropriate so early--and prominently--in the article. If it's retained in the article, I definitely think it should be moved down, before "See also" because all previous sections are meant for a lay audience and their likely concerns. I hope you'll consider these constructive remarks. — RCraig09 ( talk) 04:54, 19 August 2023 (UTC)
We aren't talking about a singular feedback. Even in our definitional sentence we begin by saying "Climate change feedbacks...". Sorry if this has been covered before, but it reads weird in the general climate change article as well, where climate forces are all plural except feedbacks. We have "aerosols", "clouds", "greenhouse gases", and then "climate change feedback". Any objection to doing a simple rename to this article? Efbrazil ( talk) 15:49, 9 February 2024 (UTC)
I am trying to improve the reading ease of the lead but this sentence really baffles me, it seems messed up: These are
arctic methane release from
thawing permafrost, peat bogs and hydrates, abrupt increases in
atmospheric methane, decomposition, peat decomposition, rainforest drying,
forest fires,
desertification.
Seems like a messy list. Also, the paragraph in the lead about positive feedbacks (currently the second one) should line up better with the graphic on the right. I suggest to use the same ordering, and ensure the most important one is first (?).
EMsmile (
talk) 23:10, 15 March 2024 (UTC)
References
WG1AR5_TS_FINAL
was invoked but never defined (see the
help page).Quotation taken from top of page 978 AR6 WGI Chapter7 (and see table 7.10 at bottom of same page): "It is virtually certain that the net climate feedback is negative, primarily due to the Planck temperature response, indicating that climate acts to stabilize in response to radiative forcing imposed to the system. Supported by the level of confidence associated with the individual feedbacks, it is also virtually certain that the sum of the non-Planck feedbacks is positive. Based on Table 7.10 these climate feedbacks amplify the Planck temperature response by about 2.8 [1.9 to 5.9] times."
Likewise quoting from page 96 AR6 WGI Technical Summary (and see accompanying figure TS.17): "The combined effect of all known radiative feedbacks (physical, biogeophysical, and non-CO2 biogeochemical) is to amplify the base climate response (in the absence of feedbacks), also known as the Planck temperature response (virtually certain). Combining these feedbacks with the Planck response, the net climate feedback parameter is assessed to be –1.16 [–1.81 to –0.51] W m –2 °C –1 , which is slightly less negative than that inferred from the overall ECS assessment."
Could a simplified version of the Chapter 7 quotation replace the one now at the end of the lead?: It is virtually certain that the net climate feedback is currently negative and thus stabilizes climate over time, primarily due to Earth's blackbody radiation response. It is also virtually certain that the sum of all other feedbacks is positive and causes amplification of global warming. Bikesrcool ( talk) 05:54, 14 April 2024 (UTC)
Carbon cycle feedbacks are negative as carbon uptake increases when atmospheric concentrations increase. However, higher temperatures and saturation of carbon sinks will decrease that effect.(perhaps an example could help to clarify this? Sounds very abstract like this.).
The last sentence was a clear run on sentence with bad readability. The Planck response is not a feedback and the IPCC explicitly says feedbacks will increase for the remainder of the century. Feedbacks are not "primarily estimated through models". The lead that was there was arrived at through extensive discussion- go slow on edits or open talk discussion please.
This is the comparison of the two versions.
Current wording | The reverted paragraphs |
---|---|
....The main positive feedback is that warming increases the amount of atmospheric water vapor, which is a powerful greenhouse gas.[5] Another positive feedback is the loss of reflective snow and ice cover. Positive carbon cycle feedbacks occur when organic matter burns or decays, releasing CO2 back into the atmosphere. Loss of organic matter can happen through rainforest drying, forest fires, and desertification. Methane can also be released into the atmosphere by thawing permafrost.
The main cooling effect is called the Planck response, which comes from the Stefan–Boltzmann law. It states that the total energy radiated per unit surface area per unit time is directly proportional to the fourth power of the black body's temperature. The carbon cycle acts a negative feedback as it absorbs more than half of CO2 emissions every year. Atmospheric CO2 gets absorbed into rocks and into plants. It also gets dissolved in the ocean where it leads to ocean acidification. There are several types feedbacks: physical feedbacks, biological feedbacks and carbon cycle feedbacks. Calculations can give different results depending on the time frame and location that is used. Carbon cycle feedbacks are negative, which means that as atmospheric concentrations increase, carbon uptake also increases. However, higher temperatures and saturation of carbon sinks decrease that negative feedback effect. Overall feedbacks are expected to trend in a positive direction for the near future, though the Planck response will become increasingly negative as the planet warms.[6]: 94–95 There is no threat of a runaway greenhouse effect from current climate change. |
....Feedbacks are generally divided into purely physical and partially biological (i.e. biogeophysical and biogeochemical.) The former include cloud feedback, ice-albedo feedback, Planck response feedback as well as the lapse rate and water vapor feedbacks. The latter mostly consist of feedbacks associated with the carbon sinks and the carbon cycle. Sometimes, feedbacks associated with the ice sheets are treated separately from either, because it takes multiple centuries before they become apparent, whereas the others have a substantial role within decades. Feedback strengths and relationships are primarily estimated through global climate models, with their estimates calibrated against observational data whenever possible. "Fine-scale" modelling devoted to specific processes also exists, and has been used more widely starting from 2010s.
The overall sum of climate feedbacks is negative, meaning that they make the warming slower than it would be otherwise. It also means that runaway greenhouse effect effectively cannot occur due to anthropogenic climate change. This is largely because of the Planck rate negative feedback, which is several times larger than any other singular feedback. Additionally, the carbon cycle already absorbs a little over half of annual CO2 emissions, and its ability to do so scales almost in proportion to emissions. However, as the warming increases, it amplifies positive feedbacks - like the ice-albedo feedback and soil carbon feedback, or the various feedbacks which increase atmospheric methane concentrations - more than the negative ones, so the warming is slowed less than it would have been at a cooler initial state. |
Now...
and the IPCC explicitly says feedbacks will increase for the remainder of the century.
- Which is exactly what the last sentence was meant to say - the one which you concluded lacked readability.
The IPCC also explicitly says that the sum of all feedbacks is negative, yet as already pointed out by Bikesarecool above, this is not currently mentioned at all. And speaking of things which were explicitly mentioned by the IPCC...
Feedbacks are not "primarily estimated through models".
- Wanna bet?
Up until AR5, process understanding and quantification of feedback mechanisms were based primarily on global climate models. Since AR5, the scientific community has undertaken a wealth of alternative approaches, including observational and fine-scale modelling approaches.
- AR6, WG1, CH7, 967
The Planck response is not a feedback
- and this is where the discussion above gets really confusing. So, Bikesarecool has already provided an IPCC quote where it is considered a feedback. If necessary, I can provide another. EDIT: There it is.
The Planck response represents the additional thermal or longwave (LW) emission to space arising from vertically uniform warming of the surface and the atmosphere. The Planck response αP, often called the Planck
feedback, plays a fundamental stabilizing role in Earth’s climate and has a value that is strongly negative: a warmer planet radiates more energy to space.
- AR6, WG1, CH7, 968
Yet, apparently, the discussion so far has opted to believe that the IPCC as a whole has made a mistake, based on...Femke's individual opinion and an Annual Reviews article from 2009? Sure, this here
It is also worth mentioning that what even counts as a feedback depends on the definition of the reference system. For example, the Stefan-Boltzman relation is often described as a negative climate feedback acting to regulate temperature anomalies. In fact, for a blackbody planet, which is the simplest imaginable reference system for the climate that is still meaningful, the Stefan-Boltzman relation is part of the reference system and therefore not a feedback at all. These are not semantic or esoteric issues—the quantitative intercomparison of different feedbacks can be done only when the reference system is defined and held constant
Is interesting. Should this, written by just one professor, be given credence over the wording of the world's premier scientific body, over a decade later? I doubt it. Moreover, here is something else from the earlier discussion: (quote template keeps bugging out here, for some reason.)
"Also, it occurs to me that if feedbacks that included the Planck response as a feedback were net positive, then we could be talking about a runaway greenhouse effect, which nobody is predicting. Is that correct, or does a positive feedback value just mean warming would be amplified? Maybe a feedback value of over 1.0 = runaway greenhouse effect?..."
I believe that (the bolded part) actually is the case? I would quote myself from a discussion we had here last year ( now archived):
According to the leading expert on climate feedback loops and tipping points, Dr. Adam Armstrong McKay (the lead author of last year's Science assessment of tipping points):
"Outgoing longwave radiation acts as the main major negative feedback, as hot things radiate more heat away. Positive feedbacks do not inevitably lead to runaway warming, as negative feedbacks will eventually counter them – if there were no negative feedbacks Earth would have become as hot as Venus long ago."
So, it probably shouldn't matter given the opinion of the IPCC alone, but the lead author of this paper we cite very extensively, and almost certainly one of the top 5 experts on the subject worldwide, also happens to describe the Planck response/blackbody radiation as a feedback. Are we going to argue against this too? (Trivia: I think he and Femke might be at the same research institution, so there is conceivably a chance they could talk this over in person?) InformationToKnowledge ( talk) 12:34, 15 May 2024 (UTC)
What's interesting for the lead is whether the climate response to a linear increase in greenhouse gas emissions going forward is going to accelerate or decelerate, or whether the geographic locations of amplified warming will change at all.- I have already answered this question in the lead of Causes of climate change (which apparently wasn't read very closely by anyone here?)
The warming from the greenhouse effect has a logarithmic relationship with the concentration of greenhouse gases. This means that every additional fraction of CO2 and the other greenhouse gases in the atmosphere has a slightly smaller warming effect than the fractions before it as the total concentration increases. However, only around half of CO2 emissions continually reside in the atmosphere in the first place, as the other half is quickly absorbed by carbon sinks in the land and oceans.
As the warming from CO2 increases, carbon sinks absorb a smaller fraction of total emissions, while the "fast" climate change feedbacks amplify greenhouse gas warming. Thus, both effects are considered to each other out, and the warming from each unit of CO2 emitted by humans increases temperature in linear proportion to the total amount of emissions.
As cumulative emissions increase, weakening land and ocean carbon sinks increase the airborne fraction of CO2 emissions (see Figure 5.25), but each unit increase in atmospheric CO2 has a smaller effect on global temperature owing to the logarithmic relationship between CO2 and its radiative forcing (Matthews et al., 2009; Etminan et al., 2016). At high values of cumulative emissions, some models simulate less warming per unit CO2 emitted, suggesting that the saturation of CO2 radiative forcing becomes more important than the effect of weakened carbon sinks (Herrington and Zickfeld, 2014; Leduc et al., 2015). The behaviour of carbon sinks at high emissions levels remains uncertain, as models used to assess the limits of the TCRE show a large spread in net land carbon balance (Section 5.4.5), and most estimates did not include the effect of permafrost carbon feedbacks (Sections 5.5.1.2.3 and 5.4). The latter would tend to further increase the airborne fraction at high cumulative emissions levels, and could therefore extend the window of linearity to higher total amounts of emissions (MacDougall et al., 2015). Leduc et al. (2016) suggested further that a declining strength of snow and sea ice feedbacks in a warmer world would also contribute to a smaller TCRE at high amounts of cumulative emissions. However, Tokarska et al. (2016) suggested that a large decrease in TCRE for high cumulative emissions is only associated with some EMICs; in the four ESMs analysed in their study, the TCRE remained approximately constant up to 5000 PgC, owing to stronger declines in the efficiency of ocean heat uptake in ESMs compared to EMICs.
Overall, there is high agreement between multiple lines of evidence (robust evidence) resulting in high confidence that TCRE remains constant for the domain of increasing cumulative CO2 emissions until at least 1500 PgC, with medium confidence of it remaining constant up to 3000 PgC because of less agreement across available lines of evidence.- AR6, WG1, CH5, 746
Let me know if you disagree and I can dig up some IPCC talk that reflects the alternate view that backs what Femke said.- Please do. Having said that, this is secondary to the question at the top of this section - about the direction of the net sum of feedbacks. As you might have noticed, I included another prominent reference which says that the net feedback is negative, but I don't know if this is going to make a difference. If some editors here already find the IPCC text "ambiguous", would a single paper on top of it (even from Nature Geoscience) matter? Would 3, 5, or 10 more matter?
As for saying feedbacks are "primarily estimated through models": The issue is that's wording that climate deniers use.Hmm, my primary impression to date has been the opposite - stupid claims on various social media that "[feedback which has been known for many decades] isn't in the models and so there'll "actually" be this much more warming than what the IPCC says." I noticed that the individual feedback sub-sections already had little "This feedback is in the models" disclaimers (which I tried to rework into stronger and more specific sentences), so at least some editors are clearly aware of this issue. I wonder if anyone else wants to weigh in? InformationToKnowledge ( talk) 02:43, 16 May 2024 (UTC)
The last sentence was a clear run on sentence with bad readability.
However, as the warming increases, it amplifies positive feedbacks - like the ice-albedo feedback and soil carbon feedback, or the various feedbacks which increase atmospheric methane concentrations - more than the negative ones, so the warming is slowed less than it would have been at a cooler initial state.
The overall sum of all climate feedbacks is negative, meaning that, for a warming climate, the warming is slower than it would be otherwise. This due to the strongly negative Planck radiative rate feedback, which is several times larger than any other singular feedback. In estimates where Planck rate response is described as part of the baseline climate system, the net sum of feedbacks is positive, but its stabilizing effect is still assumed implicitly.
Long-term feedbacks associated with ice sheets (Section 7.4.2.6) are relevant primarily after several centuries or more."Primarily after" is a much stronger wording than "can take". InformationToKnowledge ( talk) 19:31, 28 May 2024 (UTC)
The IPCC says that the feedback parameter, i.e. Planck + feedbacks, is negative (assuming you use their sign convention). The IPCC is also declarative that the net effect of the actual radiative feedbacks is amplifying in
Chapter 7 (page 926). They say: The combined effect of all known radiative feedbacks (physical, biogeophysical, and non-CO2 biogeochemical) is to amplify the base climate response, also known as the Planck temperature response (virtually certain)
. If there is consensus among editors here to use a convention that Planck is a feedback, we need to use a different source than the IPCC, or only cite page 96, where they say something different to the rest of the report in the caption. All the other page numbers contradict what we now say.
—Femke 🐦 (
talk) 21:23, 28 May 2024 (UTC)
The IPCC is also declarative that the net effect of the actual radiative feedbacks is amplifying in Chapter 7 (page 926).Really?
Radiative feedbacks, particularly from clouds, are expected to become less negative (more amplifying) on multi-decadal time scales as the spatial pattern of surface warming evolves, leading to an ECS that is higher than was inferred in AR5 based on warming over the instrumental record.- Same page
They say- Yes, and Chapter 7's primary author already said that this text applies when feedbacks are treated as a modification of the base temperature change, but not when they are described as changes in radiative forcing. He also literally used the phrase "Planck feedback".
Saying when feedback effects become apparent is very different from saying when the feedbacks will have their primary effect.- OK, then don't say "become apparent" (yes, I was the one who first used it) and write what their text actually intended to convey instead.
We could adapt this image to a compressed form that is good for smartphones / thumbnails: https://www.ipcc.ch/report/ar6/wg1/downloads/figures/IPCC_AR6_WGI_TS_Figure_17.png
Chart (b) of that image can be cut as the content is already represented in chart (a) and isn't very consequential. The naming is a torture though, so I'd rename the item from "Biophysical and non-CO2 biogeochemical" to the somewhat simpler "Non-CO2 biological".
It's annoying that they have "total" for climate system feedbacks but do not provide a total for carbon cycle feedbacks. I'd just leave out "total" as a result.
Charts (a) and (c) could then be combined as the x axis is the same.
Also, I'm not sure we should have the jargony "planck" in there, so maybe add a parenthetical explanation saying (thermal radiation).
Finally, there's the discussion up above that we should account for, namely that planck response is not technically a feedback and that the carbon cycle is part of the climate system. So that leaves something like this:
Title: Factors influencing climate sensitivity
Rows, where "Radiative feedbacks" and "Carbon cycle feedbacks" would just be headers with no data:
Planck (thermal radiation)
Radiative feedbacks
Carbon cycle feedbacks
Finally, for the X axis label, simply have 2 arrows pointing off center that say "Negative feedback" and "Positive feedback", like the top of the IPCC chart does. I don't see a point in articulating "Climate feedback parameter (WM-2 C-1)" and the numbers as those will mean nothing to people. The caption and graphic description can get into all that. The real point of the graphic is to highlight the major factors to consider. Efbrazil ( talk) 23:33, 20 May 2024 (UTC)
— Version 1 is uploaded 22 May. The different processes are all very techy and need external explanation, making it unsuitable for a lead graphic in a layman's encyclopedia article. I've de-emphasized the confidence intervals for a similar reason.
— Graphically, I can now see how I could compress the actual chart area horizontally a bit (the large blue and read areas), so the font-height-to-image-width ratio is larger (see
), though that would make the graphic occupy more vertical space in articles for a predetermined pixel width. Since that change involves a non-trivial amount of work, I will wait until any substantive issues are resolved.
— I've just downloaded the Wikipedia app. The above flowchart is definitely readable in landscape orientation on my 2.5x4-inch screen, even moreso if the viewers spread their fingertips. —
RCraig09 (
talk) 16:03, 22 May 2024 (UTC)
Snow cover loss and ice shelf melt- A reminder of what an ice shelf actually is. On a global scale, the surface area of all ice shelves is absolutely tiny, and I never saw any paper bother to single them out for any radiative effect. Presumably you meant to write ice sheet, but that is also incorrect, since practically all the melting to date had occurred on their margins - Greenland's surface did get darker, but not enough for a meaningful global impact. Virtually all the albedo feedback to date is from the sea ice loss followed by snow cover. As a bonus, writing
Snow cover and sea ice declineshould allow you to reduce it to two lines, not three. (Planck box staying at three will visually highlight its importance.)
Thawing permafrost releases methane into the air- Permafrost emits a lot more CO2 than methane - by an order of magnitude or thereabouts. It is only the difference in GWP which (probably) makes warming from methane larger - and even then, it's a 70%/30% ratio at most. I am guessing you decided to omit CO2 emissions from positive feedbacks because they are far outweighed by absorption? (In which case, this could still warrant a small * note at the bottom.)
Thawing permafrost and warming wetlands release methane? (
Warming permafrost and wetlands release methaneif you can't fit it into two lines otherwise.) I think we can trust our readers to fill in the blanks and not have to specify "in the air" on this one.
Clouds become thinner and reflect less sunlight. To balance it, the negative feedback side could describe lapse rate as
more heat is lost at higher altitudes. This shouldn't add too much space to the graphic, and will make it far more accurate. InformationToKnowledge ( talk) 11:28, 31 May 2024 (UTC)
Thanks Craig! Very glad you like it!
Regarding CO2 feedbacks, there are really 2. There's the CO2 response to more CO2 in the air, which is a strongly negative feedback and the first feedback listed above. It's what the IPCC carbon feedback chart calls "Land response to more CO2" and "Ocean response to more CO2" (which I aggregated). That's not part of global warming, it's simply an artifact of more CO2 in the air (the planet has consistently absorbed a steady percentage of annual emissions, instead of a fixed amount of emissions, which has been very helpful in limiting climate change). On the flip side, the positive feedback is that global warming is reducing the ability of the planet to absorb CO2, which is the last feedback in the version of the chart I created, and that's the one that includes wildfires, drought, and so on. Make sense?
I'm not sure what you mean by "group the blue boxes". Did you mean moving the "More CO2 absorbed" label down? I want that directly beneath emissions and above global warming, for the reasoning above.
These are the changes I made:
Let me know what you think, and thanks again for the encouragement! Efbrazil ( talk) 23:45, 7 June 2024 (UTC)
I believe we need to say what qualifies as a climate change feedback in the definition section. After all, we just burned through a lot of time discussing that exact issue up above on this talk page, and it seems critical to define the scope of climate change feedbacks in an article on climate change feedbacks. Here is what I added to the beginning of the definition section, which is my best attempt to condense the discussion above:
InformationToKnowledge reverted it with this comment: Not an improvement. I doubt this will make sense to readers who have not read the talk page, and it doesn't make sense to feature this early in the article. Either place a shorter version in the Planck section itself, or omit it entirely.
I disagree strongly on the placement issue. We are in the definition section and this is critical for defining the topic of the article. I can see the argument that this might be hard for someone new to understand at first, but I think it is best to be precise here at the expense of accessibility. Perhaps someone can come up with better wording. Anyone else care to comment, particularly RCraig09 and Femke? Efbrazil ( talk) 18:08, 14 June 2024 (UTC)
References
I find this sentence too difficult to read. It contains an enumeration of 4 things. Why not split it into two? I mean this sentence: Physical feedbacks include increased
water vapor from evaporation, altered
cloud distribution, decreased
surface reflectivity as snow and ice cover diminishes, and an amplification of the
rate at which atmospheric temperature falls with rising altitude.
. My proposal was two sentences each with two feedbacks: Physical feedbacks include increased
water vapor from evaporation as well as altered
cloud distribution. Another two physical feedbacks are decreased
surface reflectivity (albedo) as snow and ice cover diminishes, and an amplification of the
rate at which atmospheric temperature falls with rising altitude.
. I think this is a valid way of splitting a long sentence in two. Efbrazil reverted this with the explanation "To split a sentence you must have separate subjects for each sentence.". I don't think this is true. Who says so? I've seen long sentences with long enumerations split in similar ways before. - Can you think of other ways of making this sentence easier to read?
EMsmile (
talk) 21:58, 17 June 2024 (UTC)
Physical feedbacks include increased water vapor from evaporation, altered cloud distribution, and decreased surface reflectivity as snow and ice cover diminish. Additionally, there is an amplification of the rate at which atmospheric temperature falls with rising altitude.EMsmile ( talk) 21:58, 17 June 2024 (UTC)