Talk:Greenhouse gas

Misleading statement in intro

Re: "However, an excess of greenhouse gases can raise the temperature of a planet to lethal levels, as on Venus where the 96.5% carbon dioxide (CO2) atmosphere results in surface temperatures of about 467 °C (872 °F)."

The sentence above states that the CO2 in the atmosphere of Venus is responsible for the high temperature. This most certainly is false. Venus can not serve as a reference point in the discussion on the effect of atmospheric CO2 on atmospheric temperatures. blackcloak (talk) 04:50, 1 June 2008 (UTC)

This most certainly is false. - is it? William M. Connolley (talk) 18:32, 1 June 2008 (UTC)

Remove all the CO2 from the atmosphere of Venus and the temperature would still be lethal (which I'll define as above 100°C). No simulation/calculation necessary. blackcloak (talk) 04:39, 10 June 2008 (UTC)

Are you sure? The atmosphere is 96% CO2. Radiative balance at 0.71 AU with no atmosphere is only 30°C (assuming albedo similar to Earth). The remaining Venusian atmosphere (mostly N2) would provide some enhancement, but it is unlikely that Venus without CO2 would average above 50 C. Extremophile bacteria have been observed all the way up to 121 C. Hence, other factors not withstanding, known organisms could survive the temperature on the surface of Venus if there was no CO2. Dragons flight (talk) 05:08, 10 June 2008 (UTC)

I'm pretty sure you can convince yourself, if you're willing to do (and believe) the calculations. I didn't feel I had to do the calculation, but I'll guide you through a process if you'll do the work and enter it here. To get started, go to the black body article and compute the temperature of Venus following the procedure shown for the Earth. Show your assumptions (specifically the Sun's temperature), calculations and results. Then we'll take the next step if you get the right answer. (Regarding my use of the word believe above, I tend to think your biases will prevent you from accepting the premises and results of this process. But I'll take you as far as you are willing to go.) Deal, or no deal? blackcloak (talk) 07:20, 26 June 2008 (UTC)

I already did the calculation and reported my result. If you disagree then you should show your work rather than asking me to walk you through it. Which, incidentally, I am disinclined to do when you throw around personal attacks. Dragons flight (talk) 07:43, 26 June 2008 (UTC)

I wouldn't have bothered to write if I felt you were close enough to the right answer. I actually don't think you are interested in the right answer at this point. Suggesting you are biased is not a personal attack, it is a statement of my opinion regarding how open you are to delving into the details of a fairly complicated process, based on what you've written, here and elsewhere. Obviously I didn't really expect you to take up the challenge. And accusing me of throwing around personal attacks is a gross exaggeration, and itself a personal attack. blackcloak (talk) 07:26, 2 July 2008 (UTC)

1366 W/m^2 * (1 AU / 0.71 AU)^2 * ( 1 / 4 ) * ( 0.7 albedo ) = ( 5.67e-8 W/m^2/K^4 ) T^4

=> T = 302 K = 29 C.

I've done the calculation (twice now), you are the one unwilling to provide any math to back up your blind assertions. Dragons flight (talk) 07:40, 2 July 2008 (UTC)

If this is going to go anywhere, it looks like we'll have to find a way around WMC. http://en.wikipedia.org/w/index.php?title=Talk:Greenhouse_gas&oldid=234730667 blackcloak (talk) 04:17, 31 August 2008 (UTC)

The main cause of the high surface temperature on Venus is the the massive atmosphere, more than 90 times the Earth's. The lapse rate on both planets is very similar. On Venus the distance to the surface is greater so the temperature is correspondingly greater [[1]]--Damorbel (talk) 18:48, 9 October 2008 (UTC)

I'm not sure how to fix this

re: "It is not possible to state that a certain gas causes a certain percentage of the greenhouse effect, because the influences of the various gases are not additive. (The higher ends of the ranges quoted are for the gas alone; the lower ends, for the gas counting overlaps.)[3][4] "

I'm not sure how to fix this up, since the quote is trying to qualify the foregoing data ranges, but you all might chew on the fact that any average warming has a net amplified effect of introducing more water vapor into the atmosphere, which if the article is correct introduces one hell of a positive feedback factor into the system. If the point made above about only high altitude water vapor being an effective greenhouse gas, then the article is misleading and inaccurate. That's a distinction and clarification which needs multiple cites, imho. Further, IIRC from Science Channel or NatGeo documentaries, hurricanes today are up about 150% in average strength from about two decades ago (perhaps was just one), which isn't showing up yet in gross numbers of higher category hurricane's simply because the scale is logarithmic—and are further expected to go on gaining relative strength and numbers. Which ties in well with the aforesaid positive feedback. More storms and worse storms.

Another documentary tidbit that caught my attention was the distribution of temperature increase is not uniform, but skewed significantly into the high latitudes... so a few tenths of a degree of mean temperature increase planet wide shows as a significantly higher—and I'm talking significant orders of magnitude here—temperatures in the arctic and antarctic regions. IIRC, the (NOAA ?) expert discussing that used a half-degree Fahrenheit increase in global mean temperature translating to nearly 100 times that (43 degrees, iirc) in the arctic average temperatures which he tied into both the observed increases in glacial surface waters, glacier retreats and shrinkages, and glacier advancing speeds.

Lastly, I'd like to reemphasize the points made several times above about heavily weighted verbiage such as "lethal concentrations" vis a vis Venus' atmosphere, et al. Certainly some mention of experts believing Venus is so hot because of the high percentage of atmospheric CO₂ is appropriate, but the TONE it creates couched as it is now is patently unacceptable. The point on the preponderance of the article really being focused on Carbon dioxide also needs addressed... particularly in light of the percentage claims of water vapor being a predominate percentage contributor to greenhouse effects. Some better state of balance and coverage, not to say consistency is needed. Best wishes // FrankB 08:09, 28 July 2008 (UTC)

Water vapor concentrations in the atmosphere rising due to hotter global climate introduce a negative feedback and a positive feedback simultaneously, that have to be considered as two independent effects. H20 molecules re-emit IR radiation, this is true, but clouds are opaque, so they also increase the Albido of the Earth's surface. Hot by night, Cold by day I suppose :P, which of these is dominant integrated over 24 hours is context sensitive, hence your mention of only high altitude water increasing temperatures. —Preceding unsigned comment added by 121.44.161.120 (talk) 15:46, 18 August 2008 (UTC)

Atmospheric lifetime

"It is the net concentration changes of the various greenhouse gases by all sources and sinks that determines atmospheric lifetime, not just the removal processes". Why is this considered for the CO2 but not for the H2O, for which gas it is taken into account the removal time of about 10-12 days? —Preceding unsigned comment added by 189.71.57.224 (talk) 20:02, 6 August 2008 (UTC)

It is, actually -- see e.g., Trenberth (1998), Climatic Change, 39, 667-694. Short Brigade Harvester Boris (talk) 18:09, 17 August 2008 (UTC)

Be careful with this reference. It is listed as a Viewpoint, which suggests that it is an opinion piece, and has not been peer reviewed. The text is only available for purchase and not readily available to the average joe. Here is what you might want to consider. There are about 30 molecules of H2O in the atmosphere for every molecule of CO2. A large amount of water moves into the atmosphere (evaporation, hot water vapor emissions) and out (rain) in relatively short periods of time. Liquid H2O forms readily in the atmosphere and falls because it is denser than air. The removal of CO2 from the atmosphere occurs through a different process- that of disolving in rain and the surface of the oceans, and at much lower rates, through photosysthesis. When dissolved in water, it occurs only at the concentration of about 1 molecule of CO2 for every 3000 molecules of H2O. The reservoir of CO2 in the oceans is about 50 to 100 times larger than the reservoir of CO2 in the atmosphere. Another key fact to keep in mind is that every carbon atom that oxidizes (combustion or aerobic decomposition) creates a molecule of water, much of that entering the atmosphere along with the CO2. blackcloak (talk) 19:09, 2 September 2008 (UTC)

Not true. C+O2 >> CO2, and not a molecule of water anywhere to be seen. Plantsurfer (talk) 19:19, 2 September 2008 (UTC)

Yes, true. In a carbon chain there are approximately two hydrogen atoms associated with each carbon atom (oil hydrocarbon, organic molecule). When the carbon atom is oxidized, the two hydrogen atoms attach to an O atom to form H20. For carbon alone (even coal has some hydrogen) you're right. Remember most CO2 entering the atmosphere (high 90s in percent) is by natural causes, and is accompanied by the H2O, though much of that H2O is probably traped by soil or water. blackcloak (talk) 02:24, 3 September 2008 (UTC)

Discussion on WHY certiain gases have more impact than others.

I'd love to make a request if somebody has the time.

The discussion on why N2 and O2 are NOT greenhouse gases is more informative than the discussion on why CO2, H2O, methane, etc. ARE! The wikipedia article on "Greenhouse effect" has a nice discussion on this topic, but the link is placed fairly out of context, in a sentence about the direction of re-emitted IR energy.

alternatively, I had to click on 'homonuclear diatomic molecule' that was describing chemicals that specifically aren't greenhouse gases just to get a rough explanation of the energy levels associated with translational/rotational/vibrational motion. Then I had to work backwards and assume that a similar process means that greenhouse gases would respond to the wavelengths emitted by the Earth due to its temperature because they have 3 or more atoms in their molecular structure leading to the ability to emit photons via vibrational motion (vs. rotational or translational). Also, the link to "dipole moment" leads to a disambiguation page leading to topics ranging from the distribution of charge within an electron, to the polarity of chemical bonds!

All of this is unacceptable, communicating subtle concepts cannot be so clumsy or open to (mis)interpretation. Notice that the paragraph referencing N2 and O2 refers to concepts only introduced in the article on "Greenhouse effect" and not the current article "Greenhouse Gas".

Another gripe I have with the article is that it mentions that methane is not a significant contributor to greenhouse effect because of its low concentration, but there was no mention that the reason WHY methane has low concentration is because it tends to be less stable than CO2, and breaks down into CO2 after 100 years (off the top of my head). There is currently not enough information given to the reader! should I logically deduce that if CO2 has roughly 2-3x more greenhouse impact than methane but 1/25th the impact per-molecule, then the net release of CO2 into the atmosphere is 50-70 times more than methane released each year?

Also, "It was recognized in the early 20th century that the known major greenhouse gases in the atmosphere caused the earth's temperature to be higher than it would have been without the greenhouse gases." - IMO a link to the article on the "Faint young sun paradox" would be particularly enlightening for those new to the concept of atmospheric insulation.

Unfortunately, I don't have the wiki skills to neaten this up myself. If somebody could follow this up? I assume it's a simple matter for more experienced members of the community.

121.44.161.120 (talk) 15:28, 18 August 2008 (UTC)David Meister - University student, undergrad Physics/Earth Sciences.

edit: my bad, I just found the section on "removal from the atmosphere", so the removal of methane is mentioned, but not until 3 sections after it is mentioned that methane has less effect than CO2. Is this some limitation of the wiki rules in creating articles? or are writers just that disorganized that they can't create a link to something further down in the same article?

121.44.161.120 (talk) 15:35, 18 August 2008 (UTC) David Meister

Hi David Meister. Your criticisms of the article are valid, but what you should realise is that this is a work in progress by a bunch of people who don't have too much free time, snd one of the rules of the game is that if you don't like what you see here you don't just criticise it but actively work to improve it. The article, and Wikipedia generally, needs people like you with a critical eye and specialist knowledge of a subject to make an input. Please register and help us! Plantsurfer (talk) 08:58, 31 August 2008 (UTC)

Methane lifetime is more like 10y than 100, as you've just found. Its also not insignificant, just samller than CO2. Different molecules radiative properties: having just looked, it seems to me that the discussion of why N2 and O2 aren't, pretty well explains why the others are. The table also shows that CO2 has increased by 100x more than methane, which answers another of your questions, I think. So I think you're complaining that the info is in the wrong order William M. Connolley (talk) 13:46, 31 August 2008 (UTC)

36%

I have been looking for an alternative source for that figure for a bit, I saw many websites(i.e all of them) giving the 'usual' figures between roughly 60 and roughly 70%, but none I think strong enough to stand up to the rigors I expect certain users would put them through, I realise that this is a very touchy subject for some of you so I'd prefer to find a 'big' source...does the IPCC give out some simple pie-chart type thing for this? I doubt it somehow...

The current 36% figure I reckon does the article no good at all in the eyes of a mildly educated reader, as they're likely to have the same reaction I did when I read it i.e '36%? What bollocks.'....looking at the current source used it appears to be gotten as the result of someone playing with theoretical numbers too much; the nonsense of it can be seen if you examine another result of the juggling on that page...that if water vapour were the only greenhouse effect causing thing in the sky (not even including clouds), the greenhouse effect would be 66% of what it is now....does anyone have a suggestion for a more widely accepted source?92.5.78.172 (talk) 17:10, 5 September 2008 (UTC)

Sorry guv you're not making a lot of sense. You don't like the numbers, based on... something; but you have no alternative reliable sources to propose. I guess you could try reading IPCC yourself, though I don't recall seeing it in there William M. Connolley (talk) 20:34, 5 September 2008 (UTC)

Off the top of my head, Kiehl and Trenberth (1997, BAMS) is one source. It's right (ah, just a sec...) here. They give figures of 60% for H2O, 26% for CO2, 8% for O3 as clear sky contributions which are in reasonable agreement with the Wikipedia article given accounting for overlap etc. (NB they use the term "radiative forcing" in a different sense from climate change discussions.) There are other sources out there that probably differ a few percent one way or the other. Basil "Basil" Fawlty (talk) 03:23, 6 September 2008 (UTC)

Thanks Basil. I think you misunderstand me William, I 'don't like the number(s) based on' the fact that 36% is completely different to all the figures I've ever seen given for this. I saw many alternative sources (90% of which giving numbers between 60 and 70% with a few outside by a % or 2, and the other 10% giving that 95% figure the skeptics love), but I didn't think any of them would be accepted by, when it comes down to it, you. You are rather well known, even outside wikipedia, for controlling any and all articles into which the message that human beings are causing global warming can be inserted with great zeal. I'm sure you're aware that 60-70% is the more accepted figure, but I'm equally sure that I would not be wrong thinking that you're the one who chose to use the 36-66 figure from that source, and that you have a reason for doing so, therefore I asked if anyone had any 'extra strong' sources, preferably IPCC. I did try searching the IPCC site, but didn't find anything either....

I would suggest that not even the author of the article cited now meant that 36% should be taken as a serious answer to the question 'how much of the greenhouse effect is caused by H2O?', and perhaps Basils source would be better. 92.2.214.57 (talk) 18:30, 6 September 2008 (UTC)

I'll be glad to discuss radiative forcing and literature references but your personal swipes at William are way out of line. Focus on content and not on personalities, please. Basil "Basil" Fawlty (talk) 20:10, 6 September 2008 (UTC)

Nothing intended as a 'personal swipe' I was merely stating the well known fact that William is the controller of global warming relatied articles, and explaining that I did see alternative sources, but none I felt would be strong enough to meet with his approval to override a source (which I assume) he had previously chosen 92.2.214.57 (talk) 21:15, 6 September 2008 (UTC)

Looking at what I wrote I'm hard pressed to see what the 'personal swipe' was, possibly the word zeal carries some undesirable connotations....but either way, if I did offend I apologise. 92.0.46.200 (talk) 02:43, 7 September 2008 (UTC)

You don't have to accept Basil's characterization of your comments. I certainly don't. What you have to understand is that manipulative editors (and no, I am not singling out Basil) bring out the personal attack (I presume a swipe is one small step down from a bonifide passes-the-wiki-test attack.) claim with far too little provocation in order to gain a psychological advantage. Please be aware of the mind games being played. You are not some grunt to be controlled by power freaks. Say what you have to say unapologetically, never direct malicious comments at an individual, and point not the finger at the person but at the content/logic of their contributions. Chances are, you'll generate more heat as you get closer to the truth. blackcloak (talk) 06:39, 9 September 2008 (UTC)

Have you considered getting a sidekick with dagger in their name? :)

Does anyone object to me replacing the blog (I think it's a blog, looked like one) figures with Basils source? 92.3.162.247 (talk) 15:16, 10 September 2008 (UTC)

Yes William M. Connolley (talk) 15:47, 10 September 2008 (UTC)

Note that both 36% and 60% are correct, because there are two ways to look at the problem:

1. Start with no greenhouse gases and add water vapor. Compare the LW flux with just water vapor to the LW flux with all greenhouse gases. This gives the 60% figure.
2. Start with all of the greenhouse gases and remove the water vapor. Compare the LW flux with all greenhouse gases except water vapor to the LW flux with all greenhouse gases. This gives the 36% figure.

There are several reasons for the difference, the most obvious being that there is overlap in the absorption spectra of the gases. In other words, in the second approach the other greenhouse gases absorb some of the radiation that would have been absorbed by water vapor so that the apparent effect of water vapor is smaller. The upshot is that we can't say one number is right and the other is wrong. It just depends on how we approach the problem. As our article states: It is not possible to state that a certain gas causes a certain percentage of the greenhouse effect, because the influences of the various gases are not additive. (The higher ends of the ranges quoted are for the gas alone; the lower ends, for the gas counting overlaps.) Short Brigade Harvester Boris (talk) 16:14, 10 September 2008 (UTC)

water vapor and hydrogen fuel cell use

First I should say that I am not a scientist, and most of the technical stuff in the article are unintelligible to me, so any responses need to be really basic.

I've actually been waiting since the moon flights for someone to get the idea of using hydrogen fuel cells for cars, but, now that they're apparently the next big thing, I'm getting worried. The article says that water vapor "accounts for the largest percentage of the greenhouse effect", yet asserts that "human activity does not directly affect water vapor concentrations except at local scales (for example, near irrigated fields)." But what happens when millions of hydrogen fuel cell vehicles start adding water vapor to the atmosphere?

Harriet 71.188.232.210 (talk) 16:48, 14 September 2008 (UTC)

The short answer is that the extra water will rain back out, and that it's not much water anyway compared to the enormous fluxes in the natural system. (The number of liters in just a day's rainfall are staggering if you work them out.) The long answer is, well, longer... Short Brigade Harvester Boris (talk) 19:10, 14 September 2008 (UTC)

Thanks Boris;
Can you tell me where I can find a long answer understandable to a layman? Since the article mentions local effects, I still envision permanent rain clouds hovering over big cities,(only partially a joke),or stifling humidity at ground level.(Just stand in an alley with a bunch of air conditioners going.) I can still remember coming down from the mountains back in the late sixties, and seeing a smudge of pollution hanging over the road as it snaked across the the desert towards Vegas, (or was it Reno?) Maybe we'll have linear storms.;o).

If techno-fixes are still being brought to us by the same outrageously irresponsible mindset that built nuclear power plants, I'm definitely skeptical of easy assurances. These folks thought it was OK to build the plants before figuring out what to do with waste products that will be radioactive for thousands of years longer into the future than all human history. I hope more foresight goes in to the development of hydrogen fuel cells.

I suppose the extra water vapor could have a favorable effect, as well: clouds raising the earth's albedo, vapor dimming the sun, or more, and better, water-from-air tech for the dry areas.

In any case, I find it hard to believe that the emissions from, not millions, of course, but billions of vehicles, plus probable other power uses, can actually have a negligible effect.
Thanks for your patience. ...Harriet 71.188.232.210 (talk) 21:54, 15 September 2008 (UTC)