Wikipedia:Reference desk/Archives/Science/2022 December 21

= December 21 =

"Venusiforming" Venusforming Veneriforming the Earth
First, apologies for the bad Latin in the question (I'd appreciate knowing what the word should be, although I guess that's more a matter for the language desk). More seriously, I notice that different points of view are listed in Runaway greenhouse effect on whether it's theoretically possible to turn Earth today into a facsimile of Venus: what's the latest opinion on whether it's possible for us to release enough CO2 to do so at current technology levels? And if not, could it be done by maxing out industrial production of much more potent greenhouse gases like CF4 or SF6? (Asking purely out of curiosity, and certainly not for any Venusian friends.) Double sharp (talk) 08:26, 21 December 2022 (UTC)
 * Cytherean actually talks about this, theoretically, it would be Cytheriforming but almost no one would know the term, so I'd stay with Venusiforming.Naraht (talk) 09:01, 21 December 2022 (UTC)
 * Why the i? Assuming that terra in terraforming is nominative (but is it?), then venusforming would do nicely. Something like veneriforming (i from dative case, but then it would have to be terraeforming, I guess) would also sound good. --Wrongfilter (talk) 09:25, 21 December 2022 (UTC)
 * Great, "Venusforming" it is then! :) Double sharp (talk) 12:29, 21 December 2022 (UTC)
 * These constructions are usually formed from the accusative (example "Jovian" from the accusative Jovem, not the nominative Iuppiter: the final -m tends to disappear in Romance languages).  So if you were going to do it that way "venereform" would be more logical. 2A00:23C4:570A:601:E1F1:B501:4B61:3168 (talk) 12:57, 21 December 2022 (UTC)
 * In forming such Greek or Latin-based scientific composite terms, usually the first part is based on the stem of the component. The stem of Terra is Terra- and that of Venus is Veneri-. For other planets, the stem of Mercurius is Mercuri-, that of Mars is Marti-, and that of Jupiter is Jovi-. --Lambiam 16:54, 21 December 2022 (UTC)
 * OK. I hope I don't have to change the title a third time! :) Double sharp (talk) 16:58, 21 December 2022 (UTC)
 * While the direct effect of "us" releasing CO2 in the atmosphere is (per John Houghton) unlikely to create conditions resembling Venus, there are indirect effects for which we have no good models backed by scientific consensus to base worst-case assessments on. The indirect effect of permafrost thawing, which may engender positive feedback, may more than double the greenhouse gases in the atmosphere, not only for CO2 but even more so for methane, a more potent greenhouse gas. --Lambiam 16:41, 21 December 2022 (UTC)
 * The article says that 2013 calculations suggest you'd need ten times as much CO2 as the direct effect would give you to cause a runaway greenhouse: would there be enough methane released to compensate, as a rough order-of-magnitude estimate? And what if we started emitting tetrafluoromethane as well, seeing as it's about four orders of magnitude better as a greenhouse gas – would we be able to make enough? Double sharp (talk) 16:47, 21 December 2022 (UTC)
 * One difference is that Venus has a very weak magnetosphere, and so the solar winds break apart water in the atmosphere, and strip it away. Card Zero  (talk) 16:51, 21 December 2022 (UTC)
 * Well, I didn't intend to ask about turning off Earth's magnetic field – just about creating a runaway greenhouse, since that's probably the most well-known feature of Venus. :) Since we can retain water vapour in our atmosphere, and that's also a greenhouse gas, that should make this task easier. Double sharp (talk) 16:54, 21 December 2022 (UTC)
 * This is a side-track, but there are albedo, the hydrological cycle and global dimming to consider. I mean, water vapor forms clouds which tend to reflect radiation into space, and then the amount that the atmosphere can hold is limited since it returns the ground as rain, so its function as a greenhouse gas is qualified by these effects. Card Zero  (talk) 17:42, 21 December 2022 (UTC)
 * There are also other effects. Above a certain rise in temperature, there will not only be a massive die-off of the fauna, but also of the flora. The decomposing biomass will release huge amounts of CO2. --Lambiam 17:16, 21 December 2022 (UTC)
 * @Lambiam: That's not quite right.  In the first declension the accusative ends in -am, in the second in -um, and in the third in -em.   Both Mercury and Mars are second declension - Venus is third, which is how we get the word venereal.   The stem of Jupiter is not jovi-, it's jove-, which is why the poetic name of the planet is Jove.   The adjective "jovial" comes from the adjectival form jovialis.   The nominative of Mars is Martius and it declines similarly to Mercurius, Saturnus and Neptunius, giving us martial, mercurial, saturnine and Neptunian.   They are not comparable - you cannot argue the form Veneriform from them.   The stem is Vener-, to which the case endings are added. 2A00:23C4:570A:601:9065:CFB9:73C7:6751 (talk) 20:07, 21 December 2022 (UTC)
 * That is not quite right. I indeed simplified a bit by declaring Veneri- to be the stem, but in general an epenthetic -i- is inserted when a third-declension consonant stem would otherwise be followed by a consonant, as in flor- (the stem of flos) + -genus = florigenus, and in leg- (the stem of lex) + -fer = legifer; compare also the adjective veneriform, meaning "having the form of a Venus clam". This is not a golden rule, though; the Latin stem of Iuppiter is actually the consonant stem Iov-; hence Iuppiter < Iov- + pater, and not *Iovipiter. But in later coinage, we see the -i- inserted, as in jovicentric. Furthermore, the nominative of the Latin proper noun Mars for both the god and the planet is Mars. The Latin proper noun Martius refers to the month of March. --Lambiam 11:04, 22 December 2022 (UTC)
 * Mars, Martis is third declension (consonant stem; the third declension also includes i-stems, such as adjectives in –alis). —Tamfang (talk) 20:14, 24 December 2022 (UTC)
 * There's enough carbon around to get us to 7000 ppm, which sounds like a bignum, but for 10s of millions of years mammals coped with (or more exactly, thrived in) 2000 ppm, and 7000 is only two doublings of that. However i see some idiot is proposing turning water vapor (aka clouds) over the oceans into drinking water. This will lower earth's albedo and so increase the amount of downwelling heat flux. Greglocock (talk) 20:46, 21 December 2022 (UTC)

OK, all this seems to mean that we probably couldn't do it just with CO2, but secondary effects might push it over. A Scientific American article suggests we need 30,000 ppm CO2 to do that.

So, what about my follow-up – could we seal our own runaway-greenhouse doom by trying to lock carbon up as CF4? Presumably we'd need three to four orders of magnitude less per its greenhouse warming potential, but could we engage in fluorocarbon production at that scale? Double sharp (talk) 03:25, 22 December 2022 (UTC)
 * OK, tetrafluoromethane can be made by directly fluorinating carbon according to Ullmann's encyclopedia. Our Fluorine article says that "At least 17,000 metric tons of fluorine are produced each year"; even assuming we react all that with carbon, and making just the order-of-magnitude assumption that one ton of CF4 is about as bad as 10,000 tons of CO2, this does not appear to be enough by several orders of magnitude (still). I am not sure if the 17,000 tons figure refers only to elemental fluorine, though. (Well, terraforming is a massive endeavour anyway, so it stands to reason that the same is true of Veneriforming!)
 * (The idea behind the question was proposals to use perfluorinated gases to terraform Mars.) Double sharp (talk) 12:04, 22 December 2022 (UTC)
 * 5.6 million tonnes of fluorite ore were extracted in 1989, which was apparently the peak. Converting 100% of it to CF4 (assuming fluorine is the limiting reagent), this still seems to be about three orders of magnitude too little. (It results in 3.15E9 kg of CF4; the atmosphere has mass 5.15E18 kg, and 1 ppm CF4 should be in the right order-of-magnitude ballpark to think about doing this – 3% CO2 would do it, and CF4 is about four orders of magnitude more potent.) Admittedly this is only one year's worth of ore, so dumping CF4 into the atmosphere for about a millennium should do the trick. Double sharp (talk) 13:19, 22 December 2022 (UTC)
 * Estimate a lower bound by finding the amount of gold that's been harvested (some over 5,000 years ago but mostly in the last century or so), dividing by (all-time harvest plus the amount of gold in the crust), then multiplying that by the amount of fluorine in the crust? Sagittarian Milky Way (talk) 05:09, 23 December 2022 (UTC)
 * Estimates on the amount of gold that's ever been harvested are mostly around 200,000 tonnes = 2E8 kg. According to Abundance of elements in Earth's crust (which lists abundances by mass fraction), the continental crust (whose mass is about 2E22 kg) is 4 ppb gold (which amounts to 8E13 kg). So we have extracted about 2.5E−6 of what we theoretically could.
 * As for fluorine, the crust is 585 ppm fluorine by mass (obviously in compounds), which amounts to about 1E19 kg. This could get us 2E19 kg of tetrafluoromethane, which is actually more than the atmosphere of Earth. If we extract about 2.5E−6 of that, we would release 5E13 kg of tetrafluoromethane, which should be enough (based on previous posts) to create a runaway greenhouse effect.
 * Or we could more sensibly dump all that tetrafluoromethane on Mars. Double sharp (talk) 09:26, 23 December 2022 (UTC)
 * Wrongfilter assumes that terra- in "terraforming" is nominative.  Of course it's not, and (s)he suggests that forming these compounds from the dative would "sound good."   No reason given, but following the reasoning of Lambiam, which (s)he says is "simplified", (a euphemism for "false"  — Preceding unsigned comment added by 2A00:23C4:570A:601:5D0:A90E:78A9:D5ED (talk) 19:11, 30 December 2022 (UTC)

[connection restored]) Double Sharp introduces a new word - Veneriform .  Lambiam doubles down, claiming that "in general an epenthetic -i- is inserted when a third-declension consonant stem would otherwise be followed by a consonant."   There follow a number of "examples", none of which appear in the English dictionary.   It has been pointed out that words of this type are not back-formations using a non-existent rule but are formed from actual Latin words, e.g. "jovial" from jovialis and words from Latin florifer.   The rule has always been that words are formed from the accusative stem, not least because the plural is formed by simply adding -s to make a word identical to the Latin plural.   Thus Latin florem gives Port. flores ("flowers"), while Latin artem gives Port. arte, artes, artefacto ("art", "arts", "artefact").   Page five of this morning's Daily Telegraph contains the sentence

"He was named on a sign next to the cane when it was displayed at Bramshill Police Staff College, whereupon the artefact was feared lost."

Using Lambiam's "rule" the word would be spelled artifact, a monstrosity we can do without. — Preceding unsigned comment added by 89.243.13.100 (talk) 21:03, 30 December 2022 (UTC)

Effects of a Mutation to reactivate L-gulonolactone oxidase? (Vitamin C producer)
L-gulonolactone oxidase is the last step in the Enzymatic sequence which produces Vitamin C in the large majority of Mammal Species. It has been lost in humans (and the rest of the dry nosed apes), some bats etc. If a person was born in the last 20 years where that gene had mutated *back* to properly generate the enzyme (the mutation back and forth has apparently occurred in the history of some bird species) would it be obvious to the person, their family, medical professionals? I *guess* it would be obvious in the event that if everyone in down was coming down with scurvy and this person didn't, but otherwise? Naraht (talk) 17:27, 21 December 2022 (UTC)
 * I do not think that any simple mutation can reactivate this (pseudo)gene as it has decayed significantly. Ruslik_ Zero 19:39, 21 December 2022 (UTC)
 * I would think that as well, but given that there have been loss and regain in bird evolution, I'd like to get a feeling for how "decay" is measured. Do we know that there would be a stretch of (say) 18 amino acids that would need to be in a specific order (and thus 54 ACGT) and we know that of the 54 have two missing and one changed?Naraht (talk) 15:30, 22 December 2022 (UTC)
 * What would be the point? It would die out again. Um..., unless people altogether give up on eating greens and fruit. Is our motto to be - the future is not green, the future is junk food :-) NadVolum (talk) 12:52, 23 December 2022 (UTC)
 * Not asking what the point would be, humans iun the 20th century are in situations where it generally isn't *needed*, I'm asking what the medical effects would be for such an individual (including detectablitiy).Naraht (talk) 04:24, 24 December 2022 (UTC)
 * If it was produced in reasonable amounts I doubt it would be noticed. None of the chemicals involved has bad effects. If too much then they'd suffer from the usual effects of too much vitamin C but that's quite a lot, only real fans of Pauling do that but I suppose it would be possible if we suddenly got the ability to produce it. There may be a good reason why producing it has a cost that is worth avoiding and the usual explanation that it was lost because it was not necessary due to its abundance is only part of the story. NadVolum (talk) 10:34, 24 December 2022 (UTC)
 * Reading Vitamin C megadosage, wasn't Pauling's idea based on the inactivation of GULO being an error, and thus advocating taking as much vitamin C as would be made if the enzyme were active? If so, then the results should be similar to those of taking vitamin C megadoses.
 * The idea is quite fun to fantasise about in the Age of Sail context, though. Double sharp (talk) 16:59, 24 December 2022 (UTC)