Talk:History of climate change science

Wiki Education Foundation-supported course assignment

This article was the subject of a Wiki Education Foundation-supported course assignment, between 19 January 2021 and 7 May 2021. Further details are available on the course page. Student editor(s): Rchlanne00.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 23:35, 16 January 2022 (UTC)

Content re-used in sandbox

A paragraph from this article is also temporarily used in a sandbox article in the Toronto Conference.Oceanflynn (talk) 03:25, 10 December 2020 (UTC)

Review article in The Guardian

Editors active in this article may want to incorporate content from this Guardian article:
<ref name=Guardian_20210705>{{cite news |last1=Bell |first1=Alice |title=Sixty years of climate change warnings: the signs that were missed (and ignored) |url=https://www.theguardian.com/science/2021/jul/05/sixty-years-of-climate-change-warnings-the-signs-that-were-missed-and-ignored |work=The Guardian |date=5 July 2021 |archive-url=https://web.archive.org/web/20210709022437/https://www.theguardian.com/science/2021/jul/05/sixty-years-of-climate-change-warnings-the-signs-that-were-missed-and-ignored |archive-date=9 July 2021 |url-status=live }}</ref>

References

—RCraig09 (talk) 19:58, 9 July 2021 (UTC)

Central discussion thread for associated List articles like "2022 in Climate change"

Greetings folks, I was pinged to an article improvement discussion in user talk and chose to answer here as a good central location per WP:MULTI since what I have to raise touches on our whole series of (Year) in climate change articles. I won't mind if someone moves this to WikiProject talk.

• Re background, I stopped by 2022 in climate change the other day. I found that the list had been initially created by User:RCraig09 and for inclusion criteria I found the naked word "notable", without any explanation what it means. About 10 years back climate eds and climate deniers had quite a time getting consensus over the now AFD'd List of scientists opposing the mainstream scientific assessment of climate change. I helped make sense of the storm by helping develope List criteria, and one thing we did was to actually explain the wikipedia meaning of the word. When I arrived at the climate list, I assumed the word meant notable and was not a mere WP:WEASELWORD. Remembering the solve we came up with way back when I applied it to the 2022 climate change list[1] As far as I'm concerned, I didn't change the standard a whit.... it already said "notable" when I got there. RCraig09 reverted and changed from the naked "notable to the naked "significant". Their edit sum said Changed old "notable" (which has a specific definition within Wikipedia) to "significant" (intended in its lay meaning). . . . Having their own WP article is MUCH too high a bar![2]

• Re List procedure.... Within just the last few days, due to a flap at List of coups and coup attempts I learned about Template:List criteria. I don't know how long it has been around, or how mandatory its use is considered to be, but I found it to be very wisely crafted and recommend its use. There are at least two required parameters

A. Text that articulates the agreed inclusion criteria

B. A link to wherever interested eds formed the consensus about (A)

I find the template to be an awesome idea since it helps laser focus team development and documentation of such criteria, and that will go a long way to ensure there's a minimum of drama when unknown WP:CIR-challenged trouble makers potentially pop up in the future. I don't think I knew about this template five days ago when I made the reverts on the climate list. If I had, I almost certainly would have shared this info then.

• Re Text for the listcrit template.... Frankly I don't care, provided they are measurable criteria. I noticed the proposed guidelines use the undefined adjective "important" instead. Without defining them so they are tools for measuring and assessing items for inclusion, they're just WP:WEASELWORDS and that means the list is inherently created by a subjective "well, yeah.... OKAY". See WP:NOTINDISCRIMINATE. I believe ya'll have good subective judgment on this stuff, but I think the template requires a more objective standard.

• Thanks for caring. What I'm caring most about right now is the Jan 6 hearings and stuff, so that's where I'll be focusing my attention. Carry on!

NewsAndEventsGuy (talk) 00:27, 21 June 2022 (UTC)

PS 2022_in_science has the same problem.NewsAndEventsGuy (talk) 00:48, 21 June 2022 (UTC)

I frankly can't follow a solid purpose or line of reasoning underlying the foregoing post, or why a non-list "History of..." article is juxtaposed with a "(year) in CC" list article. Inclusion criteria focus ~always on "encyclopedic content", which inherently requires judgment on the part of editors, as does each and every edit each and every day. Re list articles, WP:LISTCRIT recites "While notability is often a criterion for inclusion in overview lists of a broad subject, it may be too stringent for narrower lists; one of the functions of many lists on Wikipedia is providing an avenue for the retention of encyclopedic information that does not warrant separate articles,...", and it's thus against this policy for User NaEG to require that each item in a list article be notable enough to warrant its own Wikipedia article. If anyone else can decode a genuine overarching issue here, please weigh in. —RCraig09 (talk) 01:43, 21 June 2022 (UTC)

Since I've already told you more than once I'm not requiring WP:Notability to be the standard, your persistent untrue assertion that I am is best not done any more lest it drift into complainable territory. And since I answered you, and told you I am not going to be working here, please don't suck me back in ok? NewsAndEventsGuy (talk) 02:05, 21 June 2022 (UTC)

diff showing Notability "requirement". —RCraig09 (talk) 04:03, 21 June 2022 (UTC)

PS Oh yeah... I thought this made sense because your proposed "guidelines" explain the purpose to provide a research tool for historians who presumably interested in the topic of this article, and it made little sense to have a meta discussion on the 2022 year list when it will presumably apply to the whole series. NewsAndEventsGuy (talk) 02:09, 21 June 2022 (UTC)

"this made sense"? "My"(?) proposed "guidelines"? "meta discussion"? "whole series"? Maybe you should wait until you have a clear, concise expression of what you want people people to respond to, before continuing here. —RCraig09 (talk) 04:03, 21 June 2022 (UTC)

(A) Your approach encourages me to consider AFD for lack of adequate list criteria. Chill'ax, I'm not the enemy here

(B) Instead of bickering my way, why not try to get help from interested folks to look for concrete criteria without including formal WP:NOTABILITY or WP:WEASELWORD "significant"? Until you just deal with that, being pissed at me won't help.

(C) The challenge seems like one that might apply to many other topics and a lot of uninvolved eds might help develope ideas, so one way to seek such help would be with a brainstorming question at the village pump, something like, "seeking help articulating actionable list criteria that does not rely on Wiki's notability standard?" I'd think several other list editors might be interested

NewsAndEventsGuy (talk) 10:37, 21 June 2022 (UTC)

Oops, above where I said WP:WEASELWORD I guess the section of "words to watch" I really meant to link is WP:PEACOCK. Notice that "notable" without a definition is listed as an example. "Significant" is not explicitly listed but seems like a synonym that belongs there. NewsAndEventsGuy (talk) 13:17, 21 June 2022 (UTC)

Is CO2 a pollutant and when did it become one?

The last paragraph of this article refers to “aerosols and other pollution” but seems to suggest that they are different from “humanity's production of greenhouse gases”. If that’s a statement that greenhouse gasses are not pollutants then a citation would surely be useful, and so I added a tag. The question of whether they’re pollutants, in a scientific sense, seems important.

I would like to suggest that this article address whether a current consensus of scientists consider greenhouse gasses to be pollutants, and if so when they became pollutants in the scientific (not legal) sense. Assuming that they are pollutants, they must have become pollutants at some point in time, by reason of doing more harm than good to the atmosphere. When did that happen? I note that in smaller quantities they were probably beneficial to the climate. For example, Joseph Sternberg wrote this in 2006:

“ Urgent steps are needed to limit the rapid growth of CO2 in the atmosphere, which can be expected to have serious consequences such as an increase in the sea level. But preventing another ice age is also an important objective. It may well be that the intense worldwide exploitation of fossil fuel resources came just in time to provide a way to warm the Earth enough to delay, for a long time, the occurrence of another ice age. ”

Sternberg, Joseph. “Preventing Another Ice Age”, Eos Transactions American Geophysical Union Vol. 87, p. 539 (November 2006).

Likewise, as early as 1908, Svante Arrhenius realized that CO2 emissions could be beneficial:

“ By the influence of the increasing percentage of carbonic acid in the atmosphere, we may hope to enjoy ages with more equable and better climates, especially as regards the colder regions of the earth, ages when the earth will bring forth much more abundant crops than at present, for the benefit of rapidly propagating mankind. ”

But at some point in time, they became excessive and started doing more harm than good, thus turning into pollutants. When was that? And when countries like China say the West has polluted the atmosphere with greenhouse gasses more than China has done, it would be interesting to know whether China is counting greenhouse gas emission before they became pollutants.

By the way, I’m not asking when scientists realized that greenhouse gasses are pollutants. I’m asking when scientists currently believe they became pollutants.

Anythingyouwant (talk) 13:41, 26 July 2022 (UTC)

As per WP:MULTI I am just pointing out for house keeping reasons that there was a discussion about it here: https://en.wikipedia.org/wiki/Talk:Climate_change#When_CO2_emissions_became_pollution (If you're unsure in future which article this would belong to, then consider asking at WikiProject Climate Change: https://en.wikipedia.org/wiki/Wikipedia_talk:WikiProject_Climate_change); I see now that that one has already been archived, so all good. I think your question is mainly a philosophical one. Perhaps it's been addressed at Climate change scenario. Basically, CO2 became "too much" and hence a pollution when it started to have effects such as increasing global temperature or ocean acidification. We noticed it perhaps in the 60s but it started much earlier. So wasn't it a pollutant already back then when we started burning coal and other fossil fuels? Just that for a while the Earth system was able to accommodation this additional CO2 in the atmosphere? (by the way, interestingly, the article on greenhouse gas emissions only deals with the harmful, anthropogenic emissions, not with "natural emissions"; might be a discussion worth having on that article's talk page). Anyway if you find some good reliable sources on this, it could be interesting to add it, I guess. Or it's just a philosophical question, I am not sure. EMsmile (talk) 11:31, 27 July 2022 (UTC)

Thanks very much for the reply. If no one shows up here with more answers/guidance then I may try to find some reliable sources on this issue. I put a “citation needed” tag at the last paragraph of this article because it’s clearly implying that CO2 is not a pollutant. Solving the riddle about “if and when” it became a pollutant has many practical implications, and I already mentioned a primary one: western industrialized countries probably cannot be blamed or held liable for emissions that occurred before CO2 became a pollutant. Thanks again. Anythingyouwant (talk) 11:42, 27 July 2022 (UTC)

This is rather a complex conversation, at a simple level the last paragraph is about other pollutants, and shouldn't be read as saying CO₂ isn't a pollutant. Air pollution "is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials." Weart cites the 1965 report to LBJ for "pollution", and Without attempting to say anything specific, they remarked dryly that the resulting changes "could be deleterious from the point of view of human beings." The report has an appendix on the topic by Revelle, Broecker and Keeling, first section headed "Carbon Dioxide From Fossil Fuels—The Invisible Pollutant". It's politically topical: Regulation of greenhouse gases under the Clean Air Act and now The Supreme Court has curtailed EPA's power to regulate carbon pollution – and sent a warning to other regulators – other sources call it emissions. . . dave souza, talk 17:23, 3 August 2022 (UTC)

Thanks for your reply, User:dave souza, I’ve clarified the last paragraph of this article accordingly. Regarding the question of when CO2 became a pollutant, as I said above, “I’m not asking when scientists realized that greenhouse gasses are pollutants. I’m asking when scientists currently believe they became pollutants.” As I understand the polluter pays principle, polluters are typically responsible and liable for their pollution regardless of whether it was knowing or intentional. So, according to current scientific standards and definitions of what pollution means, when in history did CO2 become a pollutant? Whatever that date is, there would seem to be no way to hold prior emissions against the emitters, or to claim now (as China does) that they are entitled to cumulatively emit just as much CO2 as other countries have cumulatively emitted. Anythingyouwant (talk) 19:23, 3 August 2022 (UTC)

When did light become a pollutant? These are social questions, entitlement and legal liability is another can of worms. You seem to be asking for an answer in physics to social questions. It'd probably be reasonable to say the effects began to kick in around 1900, became evident so that "by 2001 almost all the major likely impacts of the climate changes caused by human activities... were roughly understood on the global scale", and "By 2010 a world-wide increase in record-breaking and devastating heat waves, droughts and floods had convinced many insurance companies and ordinary citizens that something unprecedented was happening to the weather." Liability and responsibility is a social and moral question. Like lead pipes, the polluter pays principle tends to be ignored, denied, or evaded. . . dave souza, talk 20:34, 3 August 2022 (UTC)

Greenhouse gases are the cause of climate change

I agree with Dave souza. I think it's more a matter of lexical characterization than scientific substance. Most instances of the string "pollut" in this article don't refer to greenhouse gases anyway. If there is any issue with usage, it can be changed through ordinary editing of particular passages. —RCraig09 (talk) 21:09, 3 August 2022 (UTC)

I don’t agree that the title of this section is a social rather than scientific question. Chemical pollutants are a type of chemical contaminant, i.e. chemical contaminants that cause measurable harm, especially harm to living things. Scientists are in the business of taking measurements, so it’s at least partly a scientific question. And the answer has huge implications. If nations like China and India are entitled to cumulatively pollute the atmosphere just as much as other nations (as some of their leaders claim), then we have to figure out how much the other nations have cumulatively “polluted”. It may not be an easy thing to measure, but perhaps climate scientists have tried to do so. I’d like to find out. Anyway, thanks for the discussion, and I’ll look into this some more on my own. Anythingyouwant (talk) 21:56, 3 August 2022 (UTC)

Wait. The entire "Discovery of other climate changing factors" section should be deleted. The first paragraph is basic Tyndall / greenhouse effect which is covered earlier and doesn't even have to do with "Other climate changing factors". The second paragraph is a near duplicate of a paragraph in the "... 1980–1988" section. The third paragraph is unsourced editor WP:SYNTHESIS. As a whole, the three paragraphs don't even achieve a description of "Discovery of other climate changing factors" like that shown in the graphic at right. And it's what gives rise to this discussion about what is really a characterization of CO2 rather than its actual physical properties. This section should be deleted, yes? —RCraig09 (talk) 02:38, 4 August 2022 (UTC)

There’s certainly some repetitive overlap in the last section. But be careful, because it also mentions some stuff not mentioned previously, like coal gas, permafrost, and nitrous oxide. Anythingyouwant (talk) 19:41, 4 August 2022 (UTC)

Coal gas and nitrous oxide are greenhouse gases, and melting permafrost releases methane which is a greenhouse gas. These items do not fit the section title's "other climate changing factors". I will delete that entire section now. If someone finds any meaningful content along these lines (unlikely, since it's GHGs that cause climate change), they should start from scratch. —RCraig09 (talk) 20:32, 4 August 2022 (UTC)

Per WP:Preserve, I don’t think the proper test is whether items such as the ones I mentioned fit within the section’s title, but instead whether they would belong anywhere in the finished article: “As long as any of the facts or ideas added to an article would belong in the ‘finished’ article, they should be retained if they meet the three article content retention policies: Neutral point of view (which does not mean no point of view), Verifiability, and No original research.” That said, I don’t care about this much, I just came here to talk about the history of when CO2 became a pollutant, i.e. when the first measurable harm to humans or other living things happened due to CO2 emissions by humans. Anythingyouwant (talk) 00:41, 5 August 2022 (UTC)

@ Anythingyouwant, your definition is begging the question – see Pollutant, noting Pollutant#Fund pollutants "do not cause damage to the environment unless the emission rate exceeds the receiving environment's absorptive capacity (e.g. carbon dioxide .... )". Thus, human caused pollution is now known to have happened by 1900. The timeline notes relevant points, by 1972 measurable harm to humans was occurring, but "the rise in dust pollution worked in the opposite direction from the rise in CO₂, so nobody could say whether there would be cooling or warming".[3][4]
Re "just came here to talk about the history", WP:NOTFORUM, but this has led to article improvements, the 1970s shift looks worth a mention, and the timeline suggests directions for further work. Thanks, . dave souza, talk 08:54, 5 August 2022 (UTC)

Of course, when I said that I came here to talk about when CO2 became a pollutant, I meant that I came here to talk about that rather than coal dust or other items, not that I wasn’t interested in article improvements related to what I came here to talk about. My very first sentence at this talk page questioned the accuracy of this article’s last paragraph, to which I added a “citation needed” tag. Anyway, I’ll look into the matter about “fund pollutants”, thanks for pointing that out. Anythingyouwant (talk) 18:01, 5 August 2022 (UTC)

I’m going to mosey on over to the pollutant talk page to discuss “fund pollutants”, of course for the purpose of clarifying and improving what that article says. Anythingyouwant (talk) 18:33, 5 August 2022 (UTC)

The difference between a conventionally conceived "pollutant" like the element lead, versus atmospheric CO2, is that (a) lead directly causes harm (b) whereas CO2 only harms indirectly through the greenhouse effect. The CO2 itself is innocent! This distinction is in addition to subtler distinctions like exceeding a concentration level in fund pollutants. That's why I don't think the term pollutant has much purpose in a climate change discussion, beyond what a few politicians might make of it. It's a lexical characterization and not a true physical quality of the CO2 itself. —RCraig09 (talk) 21:19, 5 August 2022 (UTC)

Surely you wouldn’t deny that Earth’s atmosphere has an “assimilative capacity” with respect to various substances, and so it seems perfectly legitimate to ask when its assimilation capacity was reached with respect to CO2. This is a matter of environmental science, not law or politics. And I’m getting pretty darn curious when it was in history that the CO2 assimilative capacity was reached. Anythingyouwant (talk) 21:25, 5 August 2022 (UTC)

It seems that your application of "assimilative capacity" leads to a binary (yes/no) decision. But for climate change, CO2 concentration causes a non-binary quantity of global warming, with non-binary effects, which affect one species or another or one nation or another to different degrees. Such CO2 concentrations vacillated between ~140 and ~280 parts per million for at least 800,000 years, until it blasted off to ~420ppm in recent decades. There was and will be no particular threshold at which "assimilative capacity was reached" and (if I understand your use of the terms) no particular instant in history when CO2 became a "pollutant". Different politicians will say CO2 became a "pollutant" in 1850 versus 1980 versus never. —RCraig09 (talk) 22:32, 5 August 2022 (UTC)

I am going to study up on Assimilative_capacity#Atmosphere. Thanks for the discussion. Anythingyouwant (talk) 23:09, 5 August 2022 (UTC)

Merge Scientific consensus on climate change into here?

The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section. A summary of the conclusions reached follows.

The result of this discussion was no consensus. Chidgk1 (talk) 19:03, 10 November 2023 (UTC)

---

I propose to merge the bloated Scientific consensus on climate change into here. Obviously the consensus is not going to change, and it might be more likely future editors will condense and summarize the content if it is here. Chidgk1 (talk) 13:36, 8 November 2023 (UTC)

• Oppose (Unless I'm misunderstanding your reasoning) the two topics don't seem to overlap very much. Merging the two articles would make the result even more bloated. —RCraig09 (talk) 17:38, 8 November 2023 (UTC)
• Mild oppose. We had a related discussion about that here: https://en.wikipedia.org/wiki/Wikipedia_talk:WikiProject_Climate_change#Update_Scientific_consensus_on_climate_change_with_IPCC_AR6. We might be better off to revisit that discussion and try to bring it to a consensus? EMsmile (talk) 18:33, 8 November 2023 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Adding info on stuff that turned out to be wrong?

I am wondering if we should move some content from elsewhere to here to show how the science developed and sometimes got it wrong at first and things were later corrected? Basically, some of the content that is current here: Global warming controversy#Debates around details in the science. These are things that were perhaps hotly debated by scientists for a while in the past but which are now regarded as settled and to be wrong (in hindsight) or insignificant. One example is the Iris hypothesis, I guess. Others are around sunspot activity, Antarctica cooling controversy and alike. NB it would be important not to create new overlap with other articles. EMsmile (talk) 14:31, 21 November 2023 (UTC)

Sounds sensible to me although I would find it too boring to do myself Chidgk1 (talk) 14:40, 21 November 2023 (UTC)

I think that disproven theories should only be included in /* History of ___ */ (sub)sections. If no such (sub)sections exist, then I would omit the content about disproven theories. This ensures that past misunderstandings do not undercut present knowledge, giving credibility to denialists. —RCraig09 (talk) 18:00, 21 November 2023 (UTC)

I don't fully understand what you mean, RCraig09. Could you give an example of what to include and what not to include? E.g. for Iris hypothesis and for Antarctica cooling controversy? I think if we describe the history of climate change science, this could also include stuff that ended up being a dead end or dead horse, not just the things that turned out to be right. Compare with the article Miasma theory which also describes an abandoned theory. EMsmile (talk) 09:32, 22 November 2023 (UTC)

I think that discredited theories should only be included in "History of..." sections; I realize this entire article is a "History of..." article, so practically nothing should be excluded here. However, any discredited theories should be mentioned only in the context of their being discredited. My 18:00 21 Nov comment mainly applied to other articles. —RCraig09 (talk) 17:32, 22 November 2023 (UTC)

I've started a section for this now, called "Discredited theories and reconciled apparent discrepancies" (title too long? Split into two?). I think this is useful and I have started to fill it by moving content from Global warming controversy to here which I think is an elegant solution to some of our problems with Global warming controversy. EMsmile (talk) 12:39, 4 December 2023 (UTC)

A basic principle is that content must be notable enough, and must be pertinent to the particular article. Here, a discredited theory should be included only if the discredited theory was notable. These additions, especially the transclusions, bloat the article and give WP:UNDUE weight to wrong theories and accusations. The two desktop-screenfulls (!) of that section give the impression that mainstream science has been fighting a defensive battle. Just because something was in another article that is being phased out, does not mean that all of its content must be moved somewhere else—it can simply be omitted (or at most, radically shortened). —RCraig09 (talk) 15:11, 4 December 2023 (UTC)

Sure, it can be shortened. Any editor is welcome to do so (carefully, please). This is not so easy to do though but I am happy for someone who knows this stuff better than I do to shorten and condense it. However, the current article size is only 38 kB (even after my additions). So the article does not yet suffer from being overly large (unlike the one called climate change denial which is 79 kB now which I really think ought to be shortened. Your argument on the talk page there was "But I think this topic is still important enough, and the article viewed enough, to warrant a "long" article".)

The Iris hypothesis was certainly notable. It has its own Wikipedia article and a number of scientific papers that were arguing about it. This is not "denial type" stuff but real science that sometimes barks up the wrong tree. As the article was so far, it made it seem a bit like it was a very simple straight forward path from knowing nothing to knowing everything about climate change.

I think it's useful to also chronicle some of the discussions and confusions (of course not when it's wacko type stuff; but this stuff that I added was in peer reviewed journal articles so I think it was serious research, even if proven wrong later). And I disagree with this statement "give the impression that mainstream science has been fighting a defensive battle". The article is about the history of scientific discovery, it's not the scientific consensus on climate change article. So it should be a good chronicle/archive and can explain some of the issues that scientists faced and what they discussed with each other. I highly recommend the memoirs of Kevin Trenberth which I used as a source for the Iris hypothesis article today. EMsmile (talk) 21:23, 4 December 2023 (UTC)

Removed most of a very long quote

There was a huge amount of text in a long quote which I think is not adding value. I've selected only one paragraph to remain. Here is the quote that I removed (in bold the part that I decided to keep (still too long?)):

++++++++++

Previous advocacy of an atmospheric hypothesis, – The general doctrine that the glacial periods may have been due to a change in the atmospheric content of carbon dioxide is not new. It was urged by Tyndall a half-century ago and has been urged by others since. Recently it has been very effectively advocated by Dr. Arrhenius, who has taken a great step in advance of his predecessors in reducing his conclusions to definite quantitative terms deduced from observational data. .. The functions of carbon dioxide. – By the investigations of Tyndall, Lecher and Pretner, Keller, Roentgen, and Arrhenius, it has been shown that the carbon dioxide and water vapor of the atmosphere have remarkable power of absorbing and temporarily retaining heat rays, while the oxygen, nitrogen, and argon of the atmosphere possess this power in a feeble degree only. It follows that the effect of the carbon dioxide and water vapor is to blanket the earth with a thermally absorbent envelope. .. The general results assignable to a greatly increased or a greatly reduced quantity of atmospheric carbon dioxide and water may be summarized as follows:

*a. An increase, by causing a larger absorption of the sun's radiant energy, raises the average temperature, while a reduction lowers it. The estimate of Dr. Arrhenius, based upon an elaborate mathematical discussion of the observations of Professor Langley, is that an increase of the carbon dioxide to the amount of two or three times the present content would elevate the average temperature 8° or 9 °C. and would bring on a mild climate analogous to that which prevailed in the Middle Tertiary age. On the other hand, a reduction of the quantity of carbon dioxide in the atmosphere to an amount ranging from 55 to 62 per cent, of the present content, would reduce the average temperature 4 or 5 C, which would bring on a glaciation comparable to that of the Pleistocene period.

*b. A second effect of increase and decrease in the amount of atmospheric carbon dioxide is the equalization, on the one hand, of surface temperatures, or their differentiation on the other. The temperature of the surface of the earth varies with latitude, altitude, the distribution of land and water, day and night, the seasons, and some other elements that may here be neglected. It is postulated that an increase in the thermal absorption of the atmosphere equalizes the temperature, and tends to eliminate the variations attendant on these contingencies. Conversely, a reduction of thermal atmospheric absorption tends to intensify all of these variations. A secondary effect of intensification of differences of temperature is an increase of atmospheric movements in the effort to restore equilibrium. Increased atmospheric movements, which are necessarily convectional, carry the warmer air to the surface of the atmosphere, and facilitate the discharge of the heat and thus intensify the primary effect. ...

In the case of the outgoing rays, which are absorbed in much larger proportions than the incoming rays because they are more largely long-wave rays, the tables of Arrhenius show that the absorption is augmented by increase of carbonic acid in greater proportions in high latitudes than in low; for example, the increase of temperature for three times the present content of carbonic acid is 21.5 per cent, greater between 60° and 70° N. latitude than at the equator.

It now becomes necessary to assign agencies capable of removing carbon dioxide from the atmosphere at a rate sufficiently above the normal rate of supply, at certain times, to produce glaciation; and on the other hand, capable of restoring it to the atmosphere at certain other times in sufficient amounts to produce mild climates.

When the temperature is rising after a glacial episode, dissociation is promoted, and the ocean gives forth its carbon dioxide at an increased rate, and thereby assists in accelerating the amelioration of climate.

A study of the life of the geological periods seems to indicate that there were very notable fluctuations in the total mass of living matter. To be sure there was a reciprocal relation between the life of the land and that of the sea, so that when the latter was extended upon the continental platforms and greatly augmented, the former was contracted, but notwithstanding this it seems clear that the sum of life activity fluctuated notably during the ages. It is believed that on the whole it was greatest at the periods of sea extension and mild climates, and least at the times of disruption and climatic intensification. This factor then acted antithetically to the carbonic acid freeing previously noted, and, so far as it went, tended to offset its effects.

In periods of sea extension and of land reduction (base-level periods in particular), the habitat of shallow water lime-secreting life is concurrently extended, giving to the agencies that set carbon dioxide free accelerated activity, which is further aided by the consequent rising temperature which reduces the absorptive power of the ocean and increases dissociation. At the same time, the area of the land being diminished, a low consumption of carbon dioxide both in original decomposition of the silicates and in the solution of the limestones and dolomites obtains.

Thus the reciprocating agencies again conjoin, but now to increase the carbon dioxide of the air. These are the great and essential factors. They are modified by several subordinate agencies already mentioned, but the quantitative effect of these is thought to be quite insufficient to prevent very notable fluctuations in the atmospheric constitution.

As a result, it is postulated that geological history has been accentuated by an alternation of climatic episodes embracing, on the one hand, periods of mild, equable, moist climate nearly uniform for the whole globe; and on the other, periods when there were extremes of aridity and precipitation, and of heat and cold; these last denoted by deposits of salt and gypsum, of subaerial conglomerates, of red sandstones and shales, of arkose deposits, and occasionally by glaciation in low latitudes.

The term "greenhouse effect" for this warming was introduced by Nils Gustaf Ekholm in 1901. EMsmile (talk) 08:01, 19 December 2023 (UTC)

References

EMsmile (talk) 08:01, 19 December 2023 (UTC)