Talk:Carbon dioxide/Archive 3

Archive 1

Archive 2

Archive 3

Archive 4

Plants

I've added some info about the effects of increased Co2 on plants. It's quite a controversial topic so please feel free to add any other views that there might be. Smartse (talk) 16:10, 26 April 2009 (UTC)

Not my area, but your addition looks reasonable. The source to Bellamy in the Mail is dodgy; someone like the Idso's would be better William M. Connolley (talk) 19:12, 26 April 2009 (UTC)

I included the Bellamy story because it used to be (and still is for some) an acceptable idea to suggest that climate change will be averted by plants growing faster. Unfortunately it's not the case. It's a common argument that climate change deniers use so I thought including it wasn't so stupid. Thanks for the comments. What/who is Idso? Smartse (talk) 19:24, 26 April 2009 (UTC)

imo the current wording is *extremely* biased, the CO2 increases plant growth is treated as opinion then the Co2 decreases plant growth is nearly fact. Logically, if the world used to have 5x and 20x as much co2, and co2 is now a trace gas, a claim of more co2 means less plant growth unqualified is wrong (otherwise co2 would have spun out of control millions of years ago). As far as food production goes, warms tends to generate more rain overall (though weather patterns may change) and warmth, rain and co2 all boost plant growth by themselves (easily shown in greenhouses), on downside soil fertility may go down if too warm. "Such views are too simplistic" Weasel words imo as the rebuttals are also too simplistic. Eg if China and India can increase rice production several times by breeding rice, obviously plants may adapt to pressures in relatively short periods of time like 20-50 years. —Preceding unsigned comment added by 174.3.145.178 (talk) 16:13, 18 November 2009 (UTC)

Thanks for your comment, I don't quite understand where you read that "Co2 decreases plant growth" because it isn't in the article. Did you mean something different? I agree that the current text isn't perfect but the refs I used where from a lecture I had about the effects of CO2 increases. Bascially no one really knows what will happen but it is definitely the case that the idea of CO2 fertilisation is way too simplistic. If you are unhappy with the wording can you suggest some alternatives? You'll have to add them below as IP users can't edit the article. Does anyone else have any thoughts/comments?

The logic overall is CO2 leads to more acidy conditions which reduces plant growth and CO2 leads to warmth which leads to less fertile soil on one hand, verses CO2 directly boosts plant growth, warmth directly boosts plant growth and warmth/energy should lead to overall more rain (though change in local weather) and rain leads to more plant growth (and acid can be neutralised with lime or similar). There have been studies that found the growth in urban areas with more warmth and CO2 had *drastically* more growth than nearby rural ones. I would have to find good articles to bring these out as otherwise will likely get editted out as claimed not "good source"/independent research. —Preceding unsigned comment added by 174.3.145.178 (talk) 19:34, 26 November 2009 (UTC)

Any mentions in this article should be directly related to the effect of CO₂ on growth rather than indirect effects of increased CO₂ (like climate change). I've not heard that CO₂ acidifies the soil, are you sure you aren't confusing this with acid rain caused by sulphur dioxide emissions? You are correct that any additions would need to be properly cited and come from reliable sources, if you can find links to the studies I'd be interested to read them. Smartse (talk) 20:35, 26 November 2009 (UTC)

The direct effect of atmospheric CO2 on soil acidity most likely is extremely small. See e.g., here for readable discussion of influences on soil acidity. I think what you really want is something like FACE. Short Brigade Harvester Boris (talk) 22:01, 26 November 2009 (UTC)

Heat Capacity

This page really does require an accurate heat capacity. Carbon Dioxide is so common that its page really requires a heat capacity. —Preceding unsigned comment added by 72.208.248.210 (talk) 13:03, 27 April 2009 (UTC)

I'm not too familiar with SHC but this page [1] seems to say that it changes with temperature?! If anyone does find a single figure can you put it on Carbon_dioxide_(data_page)? Thanks Smartse (talk) 13:11, 27 April 2009 (UTC)

Questions: FutureGen and similiar operations to store CO2 underground

Just like with ash retention ponds from power plants that store heavy metal ash from burning coal, it seems hard to believe that a major leak would not occur. But there seems too much money involved for people to ask questions. 1)I have two questions: what would be a killing zone for each year of storage at 1 million metric tons per year of released CO2? 2) Would bacteria or other micro-organism be able to reduce C02 to CO making it more deadly? 71.127.17.39 (talk) 01:56, 31 May 2009 (UTC)

You've mistaken this for an internet newsgroup. It is a page for discussion improvements to this article William M. Connolley (talk) 19:53, 31 May 2009 (UTC)

Atmospheric Graph Is Misleading

The graph of atmospheric CO2 is quite misleading. It seems that CO2 has gone up by 10x or more, when it really has increased by only 25%. The graph should start at zero, not 310 ppm. Check out How to Lie with Statistics, by Darrell Huff. —Preceding unsigned comment added by 173.79.114.81 (talk) 02:43, 29 June 2009 (UTC)

It's showing the raw data collected in Hawaii. CO₂ was at 310ppm when these measurements started and it therefore makes sense to start there. Although you could claim it is "lying" graphs look a lot better like this than when they have acres of blank space. As a side, by your reasoning shouldn't any graph of temperature start at absolute zero? Smartse (talk) 13:56, 29 June 2009 (UTC)

Invalid Citation (19)

Citation number 19 is being used as a citation for the statement(Emphasis mine):

Due to human activities such as the combustion of fossil fuels and deforestation, the concentration of atmospheric carbon dioxide has increased by about 35% since the beginning of the age of industrialization.

HOWEVER, if you actually go to the citation in question, it is an article that makes this conclusion without demonstrating any proof (Again, Emphasis mine):

"Atmospheric CO2 levels have increased from about 315 ppm in 1958 to 378 ppm at the end of 2004, which means human activities have increased the concentration of atmospheric CO2 by 100 ppm or 36 percent.

While I'm sure that the NOAA (A government agency, with a vested interest in obtaining funding) wouldn't deliberately engage in sloppy research, A citation for the statement, with proof, is still required. I see no demonstration in the cited article that the increase in CO2 since 1958 is solely due to human activity, or any quantification of human-generated CO2 versus natural sources.

Also, the last time I checked, 378 minus 315 was NOT 100. If the article can't even get simple subtraction right, I don't think it can be relied on to be accurate in other areas.

I would also point out that the age of industrialization began around 1830, NOT 1958 - the article doesn't even refer to the same Time Period the Wiki article is trying to cite.

Extraordinary claims require extraordinary proof, and simply SAYING that human activities have caused something doesn't make it so. Redwood Elf (talk) 19:25, 30 June 2009 (UTC)

Later in the cited article you will find the statement Scientific measurements of levels of CO2 contained in cylinders of ice, called ice cores, indicate that the pre-industrial carbon dioxide level was 278 ppm. That level did not vary more than 7 ppm during the 800 years between 1000 and 1800 A.D. Also, I find it curious that you apparently interpret the year 1958 as the beginning of the industrial era; perhaps you meant something else. Short Brigade Harvester Boris (talk) 19:51, 30 June 2009 (UTC)

I was not the one interpreting 1958 as the start of the industrial era, the ARTICLE is (See the quoted text above, where Wikipedia's article says the words "age of industrialization." I am presuming that this is meant to refer to the industrial era, or the time from the industrial revolution onward. I am saying it was NOT 1958. Please READ the objectioned-to section of the article before jumping to conclusions. Redwood Elf (talk) 00:49, 1 July 2009 (UTC)

This isn't an extraordinary claim, it's mainstream science. Isotope ratio mass spectrometry shows that all this extra CO₂ is of photosynthetic origin (must be due to fossil fuel burning) - there'll be loads of books on this. Ben (talk) 21:19, 30 June 2009 (UTC)

perhaps you could point out how, exactly, Isotope ratio mass spectrometry proves the origin of simple carbon dioxide molecules as "human generated"? I suspect that it can't. Redwood Elf (talk) 21:06, 10 July 2009 (UTC)

Science never "proves" anything in the strictly mathematical/logical sense. Fossil carbon has a different ratio between C14 (essentially none), C13 (very little) and C12 than atmospheric carbon. We can observe a shift in these isotopes in atmospheric CO2 that corresponds very well to the known use of fossil fuels (and corresponding release of CO2 with the isotope ratios of fossil carbon). There is no other plausible explanation for this phenomenon, in particularly because we also see a decrease in atmospheric oxygen that agrees with fossil fuel burning. --Stephan Schulz (talk) 21:24, 10 July 2009 (UTC)

Mainstream to whom? Al Gore's movie doesn't count, sorry. Wikipedia requires VERIFIABLE information, and The only thing verifiable about this reference is that even the basic math they are using is incorrect. Even within this small paragraph, they claim that 378 minus 315 is 100. I think anyone with a calculator can disprove that. Just for fun, pull up your calculator function (the thingie under your start>accessories folder will do just fine if you're on windows) and hit the following keys: 3 7 8 - 3 1 5 = unless I miss my guess, you're NOT looking at the number 100. Then, to determine the percentage increase from the original number, press the following keys: / 3 1 5 * 1 0 0 That will get you a number that is NOT 35 - that is the percentage increase, using THEIR OWN NUMBERS. I get 20%.

Now just getting 20% there doesn't finish your homework, oh no! Now try to PROVE, using actual scientific methods, that every single percentage point of that is man-caused. You can't. The conclusion emerges, Ex Nihilo, like Minerva from the forehead of Jupiter. Redwood Elf (talk) 00:49, 1 July 2009 (UTC)

Yup. More at Talk:Global_warming/FAQ#Can.27t_the_presently_high_levels_of_CO2_be_an_effect_of_warming_rather_than_a_cause.2C_as_they_may_have_been_in_the_past.3F_Can.27t_the_CO2_be_produced_by_volcanic_eruptions_or_the_oceans.3F Short Brigade Harvester Boris (talk) 21:39, 30 June 2009 (UTC)

To quote ref 19 in full:

Scientific measurements of levels of CO2 contained in cylinders of ice, called ice cores, indicate that the pre-industrial carbon dioxide level was 278 ppm. That level did not vary more than 7 ppm during the 800 years between 1000 and 1800 A.D.

Atmospheric CO2 levels have increased from about 315 ppm in 1958 to 378 ppm at the end of 2004, which means human activities have increased the concentration of atmospheric CO2 by 100 ppm or 36 percent.

It takes a remarkable degree of shortsightedness to miss-interpret this as Elf does. --Stephan Schulz (talk) 06:38, 1 July 2009 (UTC)

But he put it in bold and CAPITAL LETTERS and even BOLD CAPITAL LETTERS. You just don't understand "proof by vehement assertion," STEPHAN. Short Brigade Harvester Boris (talk) 12:40, 1 July 2009 (UTC)

You are assuming what you are attempting to prove. Sorry, but science doesn't work like that. Just because humans exist doesn't mean that every change in everything on the planet is man-caused. I have yet to see any proof one way or the other. Martian icecaps have been decreasing during the same time period, and that doesn't mean that human activity on Earth is causing that, does it? CO2 goes up and down continuously, it is NEVER a constant, and there are literally millions of factors that affect it. Singling out "human activity" as the sole cause, simply because humans exist, is disingenuous. It is perfectly acceptable to highlight the offending portion of the text to point out its inaccuracy, however much you might wish to ignore it. Redwood Elf (talk) 21:00, 10 July 2009 (UTC)

(Also, Boris is lying. I used no capital leters whatsoever in the quoted text. The bolded text is exactly as it appeared in the original documentation.) Redwood Elf (talk) 21:02, 10 July 2009 (UTC)

May I suggest that you look up a few lines to your text reading "I was not the one interpreting 1958 as the start of the industrial era, the ARTICLE is" and then withdraw your personal attack and apologize profundly? --Stephan Schulz (talk) 21:28, 10 July 2009 (UTC)

I am lying. Short Brigade Harvester Boris (talk) 22:10, 10 July 2009 (UTC)

I think I'll stick with what pretty much every single scientist thinks! Smartse (talk) 22:39, 10 July 2009 (UTC)

In the Earth's atmosphere

Shouldn’t this section cite total CO2 emitted by all natural sources and man made sources, volcanoes are not the only source of natures CO2 emissions especially in this era of low volcanic activity.

secondly what is the annual CO2 tonnage that cycles through the carbon cycle in nature, isn’t this sort of data critical to get a realistic perspective on CO2 and the 0.04% of the atmosphere that CO2 represents ? —Preceding unsigned comment added by 76.70.189.103 (talk) 17:17, 12 July 2009 (UTC)

To William M. Connolley who reverted the statement The total mass of atmospheric carbon dioxide is 3.0×1015 kg (3,000 gigatonnes) or 0.04% of the atmosphere. "(rv: rm dupl: we've already said its 385 ppmv) " The general public who reads these wiki pages would have no idea what 385 ppmv means, they would know what 0.04 % is. —Preceding unsigned comment added by 76.70.189.103 (talk) 17:23, 12 July 2009 (UTC)

re: “It is estimated that volcanoes release about 130-230 million tonnes (145-255 million tons) of CO2 into the atmosphere each year. This is about a factor of 1000 smaller than the sum of the other natural sources and about factor of about 100 smaller than the sources from human activity.” This puts natural sources of CO2 somewhere in the range of 130,000 to 230,000 million tonnes of CO2, that’s just looks like a rough guess.

The last sentence is impossible to decipher “Emissions of CO2 by human activities are currently more than 130 times greater than the quantity emitted by volcanoes, amounting to about 27 billion tonnes per year.” , the number don’t jive with previously stated numbers. Is the 27 billion tonnes volcanic CO2 emissions or human CO2 emissions?

Can't the Natural CO2 emissions from all sources be stated along with Man Made CO2 emissions in a plain simple method without requiring the reader to interpret what these numbers are in relation to other factors and numbers ? It seems these other factors and numbers are present to further someone’s POV regarding climate politics and obfuscate what should be easily stated! —Preceding unsigned comment added by 76.67.246.160 (talk) 04:26, 11 March 2010 (UTC)

New ideas

Could someone put a table that lists the top ten cities that have the most CO2 in their atmosphere? That would be really helpful--LouisSS13 (talk) 18:25, 15 July 2009 (UTC)

Beer

I am absolutely astounded that this article makes no reference to the fact that CO2 is used to serve just about every draught (draft) beer on the planet apart from British Real Ale. This is a huge industry involving just about every pub, bar or restaurant in the world that serves beer on tap. Rectified. (see Drinks) --MichaelGG (talk) 07:47, 24 August 2009 (UTC)

Protecting

Maybe this article should be semi-protected, considering that just about every third edit is vandalism. --The High Fin Sperm Whale (talk) 19:47, 27 October 2009 (UTC)

Agreed and protected. Materialscientist (talk) 00:36, 31 October 2009 (UTC)

CO2 + H2khjuehgfjsducujsdhir f[[aes[8fdyhas;ljfcjifuhxcjfvaisf[ d hfawe'flks[oiuxhflvaspd faodi[ghds/ov a[dsujfoadsld oWH ]\][KIIJJUHNJNNBGGTRDSDCYRDYKIXETJRHYGVHKJHJGYUGYUBHJ Bnmvbhyu ycgjjhivgyi gvtyu vgtyu g F gt 6c78 ftf87 ft7 ft7 f ⇌ H2CO3

There still is a significant vandalism on the front page which I cannot fix. Apparently protecting the article from vandalism has protected the current vandalism. From the history it has been there for a long time. At least a month so far. User drew.r.hawkins 15:05, 10 December 2009 (UTC)

amount exhaled

Typically the gas we exhale is about 4% to 5% carbon dioxide and 4% to 5% less oxygen than was inhaled.

This amounts to about 100 times (1, pg. 42) of the background carbon dioxide in the air we breathe, or over 35,000 ppm. Now, this appears to represent somewhat of a dilemma with the alleged toxicity of CO2 mentioned in the main article on account of the following:

Since the tidal volume (volume of air an individual is normally breathing in and out) is about 0.5 liters (2) and the functional residual capacity (amount of air that stays in the lungs during normal breathing) is about 2.4 liters (2), then it appears that during normal breathing the CO2 concentration in the lungs must be in excess of 29,000 ppm (say, 2.4 liters at 35,000 ppm CO2 plus 0.5 liters at 380 ppm CO2 total 2.9 liters at 29,031 ppm).

Refs: (1): Fundamentals of Industrial Hygiene, 4th Edition, by B. Plog, J. Niland and P. Quinlan, National Safety Council 1996. (2): http://en.wikipedia.org/wiki/Lung_volumes

Mipedia4 (talk) 15:36, 28 May 2010 (UTC) Breathing produces approximately 2.3 pounds (1 kg) of carbon dioxide per day per person. [2]

The above were at the end of the Carbon dioxide#Human physiology section. I removed the first uncited and ambiguous statement (5% of what?). Breathing makes similar uncited claims. I think it should mean 5% by volume of the inhaled air.

• 1. The EPA claims the average human exhales 1 kilogram of carbon dioxide per day.
• 2. Lung volumes claims males have a tidal volume of 500 ml and breathe from 9 to 20 times a minute.
• 3. Oxygen#Biological role claims "An adult human in rest inhales 1.8 to 2.4 grams of oxygen per minute." citing [3] which has neither 1.8 nor 2.4 but instead "For humans, the normal volume is 6-8 liters per minute, and under stress, 20 liters per minute."
• air at sea level has 21% oxygen by volume, density about 1.292 g/L at 0 C and about 1.2 g/L at 20 C
• at sea level and 0 C, density of oxygen is 1.429 g/L, nitrogen 1.251 g/L and carbon dioxide 1.977 g/L.
• From 2., a male would exchange from 6.48 to 14.4 cubic metres of air daily. (0.5 litres * 9 * 60 * 24 to 0.5 litres * 20 * 60 * 24.) 6.48 cubic metres of air at 20 C masses 7.776 kg.
• 4. At 9 breaths a minute a male would exchange 1.36 cubic metres of oxygen (21% of 6.48) which would mass 1.75 kg (simplifying).
• 5. At 20 breaths a minute a male would exchange 3.02 cubic metres of oxygen (21% of 14.4) which would mass 3.9 kg.
• 0.57 kg of oxygen (atomic weight 16) could generate up to 1 kg of carbon dioxide (atomic weight 28).
• From 1. and 4.: 0.57 kg O2 converted / 1.75 kg O2 inhaled is 0.33 which means a whole third of the oxygen inhaled in each breath is respired to CO2 (must be too high or else CPR).
• Or, from 1. and 5.: 0.57 kg O2 converted / 3.9 kg O2 inhaled means about 15% of the oxygen inhaled in each breath is respired to CO2.
• 1.75 kg of oxygen consumed daily is 1.2 grams per minute
• 3.02 kg of oxygen consumed daily is 2.1 grams per minute (consistent with 3.)
• 6 litres of air masses 7.2 grams of which about 1.8 grams is oxygen
• 8 litres of air masses 9.6 grams of which about 2.4 grams is oxygen
• 1. and 4. mean 33% of the oxygen, or 0.33*0.21 of the air, or 6.9% by volume.
• 1. and 5. mean 15% of the oxygen, or 0.15*0.21 of the air, or 3% by volume.
• 5% of 1.8 grams is 0.09 grams which would generate 0.09*(28/16) = 0.1575 grams of carbon dioxide per minute or 0.226 kg per day, which contradicts source 1.
• 20% of 1.8 grams is 0.36 grams which would generate 0.36*(28/16) = 0.63 grams of carbon dioxide per minute or 0.907 kg per day (close to source 1 above). 20% of 21% is 4%. If 2.4 grams is used then 5%.

A possible phrasing to avoid the percentages could be (replace 5 with whatever sources can support):

Typically the gas we exhale differs from the gas inhaled, by volume, by about 5 parts per hundred more carbon dioxide and 5 parts per hundred less oxygen.

-84user (talk) 22:28, 25 November 2009 (UTC)

EPA deems it a health hazard

The EPA has declared that carbon dioxide is a health hazard as of today. Perhaps the article should be updated to better reflect the hazardous nature of CO2?EPA Issues Carbon-Emissions Rule, Giving Obama Copenhagen Tool This page will get a bit of traffic soon...165.230.83.183 (talk) 19:35, 7 December 2009 (UTC)

Us Govt agencies do not have a good record in the recent past: why should we believe the latest message from the EPA, when it flies in the face of CO2's biological roles on the planet? Peterlewis (talk) 20:41, 7 December 2009 (UTC)

Error

There is an error under "In the Earth's Atmosphere". The earlier part says that volcanoes account for 1/1000th of human output. The later part within the same section says 1/100th. Based on the figures provided the later is true -- the later also has a source whereas the former does not. Thanks 72.220.81.40 (talk) 04:16, 14 December 2009 (UTC)

What exactly is a problem? 100 apparently refers to humans and 1000 to nature. Materialscientist (talk) 04:20, 14 December 2009 (UTC)

Canaries

It is suggested that canaries in mines were used to detect CO2. I don't think this is right as far as I know, the canaries were used to detect carbon monoxide, methane and low oxygen. Am I right? if so can this be edited out/corrected? Cheers MarkC (talk) 11:23, 20 December 2009 (UTC)

Chemical determinations of CO2?

Long before IR methods were developed, many scientists had measured and published CO2 levels in air using a variety of chemical methods which were quite sensitive. As a student 30 years ago, I was told in my text books that CO2 was 0.03-0.04% and these values must have come from the literature. While these values seem somewhat higher than more recent ice core values, I suspect the ice cores cannot be corrected for a loss of CO2 which is likely to be due to algal growth and maybe increasing pressure effects on C02 solubility in the ice? How about some discussion of the extensive historical literature on direct CO2 measurements? Cheers MarkC (talk) 11:55, 20 December 2009 (UTC)

You might want to read http://www.realclimate.org/index.php/archives/2007/05/beck-to-the-future/ for some problems with the early chemical measurements (summary: they don't tell you anything useful about average CO2 levels). CO2 preservation in ice has been extensively studied; Greenland cores need correction, Antarctic ones don't (you don't get a lot of algae growing in pure snow at -60 oC, for example :-) William M. Connolley (talk) 11:05, 3 January 2010 (UTC)

Article probation

Please note that, by a decision of the Wikipedia community, this article and others relating to climate change (broadly construed) has been placed under article probation. Editors making disruptive edits may be blocked temporarily from editing the encyclopedia, or subject to other administrative remedies, according to standards that may be higher than elsewhere on Wikipedia. Please see Wikipedia:General sanctions/Climate change probation for full information and to review the decision. -- ChrisO (talk) 03:01, 2 January 2010 (UTC)

The IAP statement on ocean acidity

On June 1, 2009, the InterAcademy Panel on International Issues (IAP) released a statement on ocean acidification, signed by 70 of the 104 IAP members (i.e., mainly, academies of sciences from various countries). Should this be quoted in the section Carbon dioxide#In the oceans?

IMHO, the statement does not in itself contain much more information than those already quoted in the section. The outspoken idea with this and other IAP statements is rather to exhibit clear scientific community consensi, in matters the academies judge of importance and calling for action. In this case, the statement explicitly aimed at influensing the agenda of the forthcoming Copenhagen summit in December 2009. JoergenB (talk) 22:13, 10 February 2010 (UTC)

Volcanoes are a factor of 1000 less than other sources?

From the page: "Up to 40% of the gas emitted by some volcanoes during subaerial eruptions is carbon dioxide.[24] It is estimated that volcanoes release about 130-230 million tonnes (145-255 million tons) of CO2 into the atmosphere each year. This is about a factor of 1000 smaller than the sum of the other natural sources and about factor of about 100 smaller than the sources from human activity."

Just what are these other natural sources? Biological decay? If that is what they are, then they need to be explained there, at least in summary. SkoreKeep (talk) 06:19, 25 February 2010 (UTC)

Instability of carbonic acid

Intro, para 5 claims:

It is the anhydride of carbonic acid, an acid which is unstable and is known to exist only in aqueous solution.

But Carbonic acid claims that it has been manufactured in pure samples, and been characterized by infrared spectroscopy... I don't know how to rewrite the sentence in para 5, but it is not only known to exist in aqueous solution, but also in pure form, although the manufacturing process is a little unexpected. Rursus dixit. (^mbork³!) 13:08, 4 April 2010 (UTC)

I rewrote claiming it cannot be concentrated from aqueus solution, but must be produced by irradiated from CO2/H2O mixes in vacuum. Rursus dixit. (^mbork³!) 13:29, 4 April 2010 (UTC)

Photosynthesis vs respiration

There seems to be a slo-mo argument about this going on in the article. Let's be clear (and maybe clarify the wording in the article so as not to confuse the non-specialist readers). Plants absorb CO₂ during photosynthesis but the self-same plants emit CO₂ during respiration while they are alive. When fully grown there has been a net absorption of CO₂. During decay or burning, all of the absorbed carbon can be re-emitted again, so that in the end there has been no net effect after the plant (or tree) is destroyed. This is unlike animals: at the end of our life and decay, we will have left a net conversion of O₂ to CO₂ behind, due to all the physical work we have done. A climax forest represents a huge fixation of carbon from the air, but if you chop it all down and burn it, that effect is completely negated - plants do not leave behind a net conversion of CO₂ to O₂ after they have disappeared or been destroyed. This is, unless things get buried and eventually turn into fossil fuels, or eaten by shelled animals and turned into carbonate rocks, of course. Do I have all that right? --Nigelj (talk) 10:47, 12 June 2010 (UTC)

Pest control - bedbugs

Uses introductory paragraph now concludes, High concentrations of carbon dioxide can also be used to kill pests. Liquid carbon dioxide released from a pressurized container into the atmosphere could freeze insects and their eggs on contact, which may kill them. An enterprise in Secaucus, New Jersey, claims success in killing bedbugs.

Stern Environmental Group, LLC. "NYC bed bug exterminator". Advertisement. Retrieved 6 Sep 2010. We now are providing bed bug extermination with the new treatment from Europe called Cryonite®.

CTS Technologies. "Cryonite®". Advertisement. Retrieved 6 Sep 2010. The initial idea for this unique method of pest control - elemination of insects and their eggs through freezing instead of poison - was concieved by Per-Åke Hallberg, M.Sc, and biologist Bertil Eliasson, B.Sc, in 1996. Cryonite® is covered by extensive patent protection and the company owns all the intellectual property related to the technology.

--Pawyilee (talk) 10:25, 6 September 2010 (UTC)

Yep, supported only by ads with typos, but wadda expect of Swedes and Jerseys? Still, the only reason I wound up on the bedbug article was because BBC broadcast about them swarming NYC, and a guy freezing them out with CO2, who has more business than he can handle but can't find anyone with smarts enough to handle the equipment who'll work for what he's willing to pay. Wound up here trying to find what's so hard about it, and how does it differ from fighting a fire. Goggling further, I found a bedbug sufferers' blog with a discussion archived for anyone who wants to see it: freeze them dead.

I won't bother further with it as I'm 12 time zones from NYC, don't have a CO2 extinguisher to play with, and anyway figure using one on mosquitoes swarming me would be as effective as using one on forest fires. --Pawyilee (talk) 13:04, 7 September 2010 (UTC)

Greenhouses

Greenhouses do not "replenish" consumed CO2. They increase it -- usually to a level of about 1000 to 1200 ppm, several times the atmospheric level. The recently inserted text is inaccurate. Fell Gleaming^talk 20:23, 21 September 2010 (UTC)

That's not what the source you cited said: "In a tightly closed greenhouse there can be very little fresh air infiltration and CO2 levels can become limiting, thus limiting plant growth. In the winter, many large commercial greenhouses provide supplemental CO2 to stimulate plant growth." --Nigelj (talk) 20:33, 21 September 2010 (UTC)

The statement "CO₂ increases plant growth" is a major simplification. As explained in the best of the three sources you referenced ([4]) this effect is only transitory and after a short time, plants adapt to the increased CO₂ and grow at the same rate. References about this need to be from academic journals, the references you've used fo not go into sufficient detail to explain the enormous complexity of this subject. If you'd like to improve the photosynthesis section I can find some suitable papers for you and email them to you. I've been meaning to get round to improving it myself but have plenty of other things to do. I really don't think that the mention of greenhouses in the lead is relevant either - it's only a small use of CO₂ and would be better off in the greenhouse article or in the section on photosynthesis linked above. Smartse (talk) 20:52, 21 September 2010 (UTC)

Eh? You are severely misrepresenting that source. Just beyond the bit you cite says; "Idso et al. (1991[IKA91]) grew orange trees in Arizona, at about twice the present concentration. Tree growth nearly tripled, and increases in growth and in photosynthetic rates continue unabated. ". Furthermore, the one study they do cite where increased growth tapered off was from a 1987 experience. The same researcher (D. Tissue) reproduced the research in 1995, and concluded the opposite. See the paper here: [5].

Finally, you're ignoring the most important point. This isn't random theory. Greenhouses have been performing CO2 enrichment for decades. There's an entire industry built around it. It's not a "minor use" of CO2, its one of the primary uses of the industrial gas. See: [6] Fell Gleaming^talk 21:03, 21 September 2010 (UTC)

OK, now you are edit warring over this. At that level of discourse, then I will have to agree with Smartse's take on your addition: What you are wanting to add to the lead is not well enough sourced (the new sources you add talk about exact specifics like "plants in their juvenile phase" etc). The situation over artificially enhanced CO2 in plant growth is too controversial and complex, and what you want to say so prominently is an oversimplification of it. In this form it needs to go from the lead. Please don't edit war. --Nigelj (talk) 20:46, 21 September 2010 (UTC)

Nigel, its not an oversimplification. Google "co2 enrichment" and you'll see an entire industry built up around increasing CO2 levels in to boost greenhouse plant growth. If you don't like the text, suggest an alternative than answers your objections. Fell Gleaming^talk 20:48, 21 September 2010 (UTC)

Try googling "free air carbon enrichment" - then you will see why it is an oversimplification. Smartse (talk) 20:55, 21 September 2010 (UTC)

I agree that "more co2 => more growth" is an over simplification, but I also agree that greenhouses boost co2 to increase growth (because they *aren't* nutrient or water limited). I've tried to tweak the wording to solve this. _{Previous unsigned comment added by William M. Connolley at 22:23, 21 September 2010}

So that would be a Use of CO₂ so could be mentioned in that section. WMC - this is already mentioned in the relevant section of photosynthesis - I'm not sure it is important enough to be mentioned in the lead, especially as it could give the misleading impression that more CO₂ = faster growth. I've already removed this twice, so won't be again as edit warring gets us nowhere. Smartse (talk) 21:49, 21 September 2010 (UTC)

I don't have a strong opinion on where it should be. I've tried trimming it down - we don't really need to say (in the lede) that they use higher levels of Co2, and that they use multiples of Co2. Mostly, I was trying to solve what seemed to be you talking past each other. I don't think it is disputed that greenhouses uses elevated Co2 to increase growth, of that Idso's trees didn't show a response. What is disputed is whether this applies out in the real world, which is why the original version "co2 increases growth, greenhouses also use co2 to inc growth" was bad William M. Connolley (talk) 22:12, 21 September 2010 (UTC)

Coatracking

The article goes into excessive detail about potential affects of ocean acidification. This has little to no relevance to an article on CO2 the gas. It should more properly be in one of the climate change articles. Fell Gleaming^talk 20:23, 21 September 2010 (UTC)

A very large part of the earth's surface is ocean. An article on CO₂ can't ignore the effect of the gas on the oceans, and the brief list of research projects just shows the (quite appropriate) importance that is being placed on this by the scientific community. --Nigelj (talk) 20:35, 21 September 2010 (UTC)

What's ocean acidification got to do with climate change?! They are both caused by CO₂ emissions, but other than that are unrelated. Smartse (talk) 20:43, 21 September 2010 (UTC)

Sure, the effect of CO2 on the ocean is important. But you're two steps further from that...the effects of Step #1 on acidification, and from that the postulated effects of acidification on various sea creatures. That has nothing whatsoever to do with CO2. It's a climate change issue. Fell Gleaming^talk 20:44, 21 September 2010 (UTC)

Can you clarify this? It does not seem logically consistent as written. Short Brigade Harvester Boris (talk) 20:57, 21 September 2010 (UTC)

Which part did you not understand? The effects of acidification on sea creatures is not relevant to an article on CO2 the chemical compound. Fell Gleaming^talk 21:04, 21 September 2010 (UTC)

Why on Earth not? You are aware of the fact that the "acid" in question is carbonic acid, H2CO3, or, in other words, the solution of CO2 in water? And again, while this is an effect of CO2, it has fairly little to do with climate change, except via indirect effects. --Stephan Schulz (talk) 21:34, 21 September 2010 (UTC)

Carbon fixation and photosynthesis

I'm not happy with the paragraph about these under Carbon dioxide#Role in photosynthesis. I had a start at it this morning, and I see that Smartse did some more later. Here are the remaining issues:

• Carbon fixation is more general, not more specific, than photosynthesis as it includes calcification.
• During photosynthesis, we cannot say that free oxygen is released from the decomposition of water, as in 6CO₂ + 6H
  ₂O -> C
  ₆H
  ₁₂O
  ₆ + 6O
  ₂, we cannot say that all the oxygen atoms came from the water and not from the CO₂.
• The production of ATP by photophosphorylation has almost nothing to do with the later role of ATP, NADPH etc in photosynthetic fixation of carbon, which is what this paragraph is about. Introducing it in such proton-and-electron detail adds nothing to an article on CO₂, especially since we are totally ignoring calcification, which is far more relevant.
• While the Calvin cycle is the part of photosynthesis that involves CO₂, and so is the part in which we are interested here, launching straight into 3-phosphoglycerate and metabolism is not the best way to introduce it or the light-independent reactions, as can be seen from the ledes and texts of the relevant articles.

I'm going to start a rewrite of this paragraph, based on summarising much clearer text (and references) from the detailed articles that already exist. Comments and further clarifications welcome. --Nigelj (talk) 16:00, 11 November 2010 (UTC)

Thanks for posting about this. Photosynthesis (Pss) is horribly complicated so summing it up in such a short paragraph is pretty tricky.

• As I said in the edit summary, it is correct to say that CO₂ is removed by pss, but more specifically by carbon fixation, because there are both light-dependent and light-independent reactions involved in pss. Light doesn't have anything to do with the removal of CO₂ from the atmosphere - rubisco does that relying on chemicals produced by the light dependent reactions.
• The O2 does come from water and not CO₂ - see Oxygen_evolution#Biochemical_reaction. CO₂ + 6H
  ₂O -> C
  ₆H
  ₁₂O
  ₆ + 6O
  ₂ is a lovely equation, but a massive oversimplification.
• I'm a bit confused by this - ppplation created the ATP + NADPH required for CO₂ to be fixed. This section is about pss and not calcification (It'd be great if someone could add details of that to the article).
• 3-PGA should probably be hatted to something like "a simple sugar". I think it's important to link the Calvin cycle with molecules that the layman might have heard of.

I'll keep an eye on it and help where I can. SmartSE (talk) 16:47, 11 November 2010 (UTC)

You have done an excellent work at #Photosynthesis_and_carbon_fixation, and now it turns out that the section seriously competes with Carbon fixation. Since Carbon dioxide is already a very long page, what do you think about keeping this section only with the minimum content and move the rest to the main Carbon fixation article? I can help but I'm no expert in this topic.--Qgil (talk) 21:56, 11 April 2011 (UTC)

Second paragraph clarification

Currently the second paragraph reads as follows:

Carbon dioxide is used by plants during photosynthesis to make sugars, which may either be consumed in respiration or used as the raw material to produce other organic compounds needed for plant growth and development. It is emitted during respiration by plants, and by all animals, fungi and microorganisms that depend either directly or indirectly on plants for food. It is thus a major component of the carbon cycle. Carbon dioxide is generated as a by-product of the combustion of fossil fuels or the burning of vegetable matter, among other chemical processes. Amounts of carbon dioxide are emitted from volcanoes and other geothermal processes such as hot springs and geysers and by the dissolution of carbonates in crustal rocks.

I suggest for brevity:

As part of the carbon cycle known as photosynthesis, plants, algae, and cyanobacteria absorb carbon dioxide, sunlight, and water to produce energy for themselves and oxygen as a waste product. By contrast, during respiration they emit carbon dioxide, as do all other living things that depend either directly or indirectly on plants for food. Carbon dioxide is also generated as a by-product of combustion; emitted from volcanoes, hot springs, and geysers; and freed from carbonate rocks by dissolution. —Preceding unsigned comment added by BruceSwanson (talk • contribs) 01:10, 6 December 2010 (UTC)

Methanedione and Dioxidocarbon

I have never come across either of these terms, but I am not an expert. I just want to remind the parties involved (Plasmic Physics and Shinkolobwe) about WP:BRD and not to edit war in the article, but to discuss. I would also like to remind Plasmic Physics that the WP:BURDEN of proof lies with those who add and restore material, so, unlike their recent edit summary, adding a term requires references, not its removal. --Nigelj (talk) 09:58, 20 December 2010 (UTC)

Thank you very much for your reaction. I also never came across either of these terms. However, I can understand how the IUPAC nomenclature rules were used to derive them. Dioxidocarbon although not an elegant term is probably in line with the IUPAC Red Book for the nomenclature of inorganic compounds. Methanedione is clearly an exaggeration arising from a carbo-centric terminology which is poorly applicable to inorganic compounds. <br\> In fact, I just followed the way already open by Dirac66 when he discovered that Methanidylidyneoxidanium (No, You Do Not Dream, someone imagined such a term for CO!!!) was used as Systematic Name for carbon monoxide and I immediately went to the carbon dioxide page to see if it was also not plagued with the same problem. I deleted a name that no real chemist would ever use because complex organic nomenclature rules do not apply to simple inorganic molecules. There is a common source for "Methanedione" and this incredible "Methanidylidyneoxidanium": both have been added by the user Plasmic Physics who has a long history of misguided names. A priori, I whish to assume his good faith, but unfortunately he shows a particular obstinacy for choosing intricate and misleading terms which make no sense and disturb the readers. These last months most of edits of Plasmic Physics have been highly disruptive or with a very low added value. Other editors have continuously to corral him and to canalize his work, but most often without success. This poses a serious concern for the categorisation of chemical compounds and the nomenclature names presented in chemboxes. More discussion on the talk page of the project chemical and on the talk page of Plasmic Physics. Many contributors are tired to have to discuss so many poor edits with him, but at least since a few weeks, he starts to answer to our multiple requests of discussion, what was previously not the case. Best regards, Shinkolobwe (talk) 22:30, 22 December 2010 (UTC)

Is the math conversion correct?

The following is pasted from the article: "3.16×10(raised to)15 kg (about 3,000 gigatonnes)"

It may be late in the day, but for me 3.16×10(raised to)15 kg becomes 3,000,000 gigatonnes. This is of course under the presumption that giga is the same as billion, which it is (about) in computer science. — Preceding unsigned comment added by 80.216.200.189 (talk) 13:19, 16 June 2011 (UTC)

You loose the more zeros by going from kg to tonnes (one metric ton is exactly 1000 kg, other ones vary a bit). --Stephan Schulz (talk) 13:26, 16 June 2011 (UTC)

In the Earth's atmosphere

Emissions of CO2 by human activities are currently more than 130 times greater than the quantity emitted by volcanoes, amounting to about 27 billion tonnes per year. This is referenced with http://volcanoes.usgs.gov/Hazards/What/VolGas/volgas.html Which says, Volcanoes release more than 130 million tonnes of CO2 into the atmosphere every year.

This reference has been misquoted. — Preceding unsigned comment added by 202.172.118.38 (talk) 10:13, 8 October 2011 (UTC)

I found this too, but I don't know how to change it. I will try. May God have mercy on us all...Mancockmike (talk) 21:09, 25 January 2012 (UTC)

It was just the wrong link. I've re-added it, using http://volcanoes.usgs.gov/hazards/gas/climate.php William M. Connolley (talk) 21:21, 25 January 2012 (UTC)

Carbon Dioxide - Emissive constants

First waveband 2.64 - 2.84 Microns Emissivity 4.9 1/ft. atm Second waveband 4.13 -4.46 microns Emissivity 550.0 1/ft atm Third waveband 13.0 -17.0 microns Emissivity 24.0 1/ft atm

Source Heat Transfer Notes by Boelter, Cherry, Johnson & Martinelli. Published by University of Californis Press. 1948

The third waveband is the one responsible for the 'Greenhouse' effect. This effect commences at a temperature of -51.7 degrees C. Hence, when the radiated sky temperature exceeds -51.7 C, radiation from the earth is to either dust or free moisture in the atmosphere. — Preceding unsigned comment added by 78.149.85.65 (talk) 14:29, 1 November 2011 (UTC)

'Solar fuel' section

This section was added in this edit by Nepomuk 3 (talk · contribs) with the comment, "Moved section from article Carbon dioxide removal to this section". The section is badly written and badly formatted, using an unexplained soup of TLAs. It is sourced to the website of a German company with the same name, that appears to be looking for venture capital.[7] I think this is spam that should be deleted rather than improved. Is this in fact a recognised use of CO₂, or do other editors agree it should go for now until the technology picks up? --Nigelj (talk) 19:31, 1 November 2011 (UTC)

Ref errors, beyond my knowledge to fix

Folks, We need some one with editing and knowledge of advance references to fix reference #68 and #69. I looked at them and I fear I will just mess them up more. Jack --Jackehammond (talk) 05:33, 22 November 2011 (UTC)

They are simply absent (nothing to fix), thus asked the editor who added them. Thanks for the note. Materialscientist (talk) 05:47, 22 November 2011 (UTC)

In the Earth's atmosphere

This section stated that CO2 levels had increased by 35% "since the beginning of the industrial age". But the reference is on the Keeling Curve which measured temperatures only from 1955 and states that the levels have risen 36% since 1958. I've modified the blurb appropriately. — Preceding unsigned comment added by Manawyddan (talk • contribs) 23:11, 10 January 2012 (UTC)

The source states:

Atmospheric CO2 levels have increased from about 315 ppm in 1958 to 378 ppm at the end of 2004, which means human activities have increased the concentration of atmospheric CO2 by 100 ppm or 36 percent.

But the 36% part is talking about the percentage increase since the industrial revolution, not between 1958 an 2004. Using figures from today we can calculate that it's actually a 40% increase now: ((392-280)/280)*100 = 40% . Can we update this based on WP:CALC or not? SmartSE (talk) 23:30, 10 January 2012 (UTC)

Okay. Re-reading your article, I see your point on the "pre-industrial age" part. But I don't think updating the calculations is "simple math" since the information comes from two different sources. I'm personally bothered that the NOAA article combines (with out saying so) data from the Keeling data with data from some unnamed source. This is fine by the rules of Wikipedia, but adding to this a calculation based on a THIRD unassociated measurement moves this article from Wikipedia to being a research article on metadata. Manawyddan (talk)

IR absorption and re-emission

"Carbon dioxide is a greenhouse gas as it transmits visible light but absorbs strongly in the infrared and near-infrared, before slowly re-emitting before slowly re-emitting at the same wavelength as what was absorbed."

This is unreferenced and is vague. What does "before slowly re-emitting" mean? That the absorbed energy is re-emitted over some period, presumably. Does "slowly" mean over a period of microseconds? Or over a period of weeks?

Sorry I don't have the expertise to make any improvements myself. — Preceding unsigned comment added by 86.215.75.133 (talk) 23:21, 16 February 2012 (UTC)

Concerns about references in Toxicity section

In the toxicity section, there is reliance on:

• InspectAPedia - I'm not familiar with this source. I looked in RSN and don't see any discussion. While I see that entries have some references included, I don't know that this qualifies as a Reliable Source. Has this been discussed? If not it should be, as the article makes health and safety related claims which deserve special attention to ensure they are accurate.
• "Marine Notice: Carbon Dioxide: Health Hazard". Australian Maritime Safety Authority. I'm not familiar with this, not have I located it online. I did find [this] containing a reference to a 2003 document "Carbon dioxide - health hazards" with the note under Action "no longer required" so, we ought to follow up to see whether the reference needs updating.
• Occupational Safety and Health Administration. Chemical Sampling Information: Carbon Dioxide. This link is used to support the statement "NIOSH also states that carbon dioxide concentrations exceeding 4% are immediately dangerous to life and health" but I don't see anything at the link to support this.

I have no doubt that elevated levels of CO₂ are a health risk, but if we are to report this, we owe it to readers to do so accurately, and with references that support the claims.--SPhilbrick(Talk) 21:59, 24 February 2012 (UTC)

Exact mass

The infobox gives an exact mass. Carbon dioxide, per se, doesn't have an exact mass. Various isotope combinations have an exact mass (e.g. C14 O16 O16 has an exact mass), but this exact mass is given without respect to any particular isotope combination. It should be clarified or removed.Ordinary Person (talk) 04:17, 3 April 2012 (UTC)

Yes, I agree with you. The implicit meaning is "exact mass of the most abundant isotopic species", i.e. C12 O16 O16 for this molecule. But this may not be clear to all readers, and it is too long to put explicitly into the infobox, which would require modifying the template file anyway. So I think the best solution is just to remove this datum. It is less useful than the molar mass, except for practitioners of high-resolution mass spectrometry. I will remove it.

Of course the same criticism applies to the "exact mass" values given for other molecules in Wikipedia. So we really should remove exact mass from the Infobox template for molecules. Does anyone know how to do that? Dirac66 (talk) 01:47, 4 April 2012 (UTC)

Join discussion here. Materialscientist (talk) 01:51, 4 April 2012 (UTC)

Reduce length of lede

The lede is 7 paragraphs. It should be about 3.129.2.129.220 (talk) 13:33, 21 April 2012 (UTC)

Removing paragraphs doesn't really make it shorter, you are cutting information away from the article.--iGeMiNix 19:41, 21 April 2012 (UTC)

We can shorten the intro by moving some paragraphs down into other sections instead of deleting them. For the paragraphs which 129.2.129.220 tried to remove, we could move a) the first two (As of November 2011 ... and Before the advent ...) to the section In the earth's atmosphere; b) the paragraph about phases (CO2 has no liquid state ...) to Physical properties; and c) the paragraph CO2 is an asphyxiant gas ... to somewhere in Biological role. Dirac66 (talk) 23:19, 21 April 2012 (UTC)

Dirac66, sounds like a good idea.129.2.129.220 (talk) 15:56, 22 April 2012 (UTC)

OK, done. There have been no other opinions for 6 weeks so I have gone ahead. I have not actually removed anything, except for one sentence about phase transitions in Physical properties which duplicated a paragraph moved from the lede. Dirac66 (talk) 14:31, 3 June 2012 (UTC)

I don't like having all mention of GHE/GW/Co2 in the earths atmos removed from the lede William M. Connolley (talk) 17:05, 4 June 2012 (UTC)

The WP:LEDE should summarise the article. The main sections of the article are currently:

1. Chemical and physical properties
2. History
3. Isolation and production
4. Uses
5. In the Earth's atmosphere
6. In the oceans
7. Biological role

We need a sentence or two about each of these sections. --Nigelj (talk) 17:37, 4 June 2012 (UTC)

I have now added mentions of CO₂ in the atmosphere and in the oceans. I agree that these two topics should be mentioned in the lead because they are of very general interest. At the same time I moved the paragraph about Henry's law (for the hydration equilibrium) from the lead to the section In aqueous solution, so the total length of the lead is about the same. Dirac66 (talk) 19:19, 4 June 2012 (UTC)

Carbonic acid Ka values incorrect

The Ka values for carbonic acid seem to be incorrect on the carbon dioxide page. They do not match the same values on the carbonic acid page. — Preceding unsigned comment added by 158.121.194.135 (talk) 15:40, 24 April 2012 (UTC)

good catch. You are referring to the first pKa. The value in the table for carbon dioxide and carbonic acid match, but in the text for carbon dioxide the values do not match. There are two ways of calculating the first pKa, depending whether one includes the dissolved CO2 into the H2CO3 concentration or just considers only [H2CO3]. I dont have the time to puruse this issue now, but some reconciling would be a good idea. --Smokefoot (talk) 17:15, 24 April 2012 (UTC)

I have now (6 months later) inserted this explanation of the difference between the two values of K_a1.Dirac66 (talk) 01:33, 20 October 2012 (UTC)

Source of carbon dioxide

The lede states "Carbon dioxide is produced by combustion of coal or hydrocarbons, the fermentation of sugars in beer and winemaking, by animal respiration of all animals." This is an undeniable modern fact, but fails to explain what the source of carbon dioxide has been for the 2-3 billion pre-industrial years in which life arose and has thrived on earth. What were the primary pre-industrial sources of CO2?? Plantsurfer (talk) 02:15, 22 December 2012 (UTC)

Find a source. Probably you could add respiration of plants and animals, fires (burning of plant material), yeast fermentation of plant material, and such things. Not sure which were biggest. Dicklyon (talk) 02:44, 22 December 2012 (UTC)

Yes, those biological sources do produce CO2 but only return to the atmosphere the amounts they have already extracted from it, so do not constitute a primary source. They are simply turning it over. In fact, considering that oil, coal and peat etc are fossil carbon of biological origin it is obvious that biota are not returning all of their carbon to the atmosphere after use - huge quantities of CO2, much more than the atmosphere has contained at any time since at least the Silurian, were buried in the form of limestone and organic carbon, yet sufficient has always remained to sustain biological life. So my question should perhaps be what are the non-biological sources of carbon dioxide. Dissolution of limestone doesn't count since that is again recycling carbonate of biological origin.Plantsurfer (talk) 11:04, 22 December 2012 (UTC)

Like everything else, carbon was present in the solar nebula from which Earth formed. Due to heating during the early epochs of solar system formation, much of it formed simple chain molecules and aromatics with the abundant hydrogen. During planet formation, this material was brought to Earth by carbonaceous chondrites (roughly 1% carbon by weight) and similar objects. Heating during meteor impacts, or later via volcanism, caused this carbon to be released from the rocks, often in the form of CO2. In the earliest epochs of Earth's existence, the atmosphere may have had over 3000 times as much CO2 as it does today. That primordial CO2 is the source of most of the carbon that ultimately entered the biosphere. A small amount of primordial carbon is probably still being released by volcanoes, but most of the CO2 associated with volcanoes today is likely to be recycled organic material that got subducted into volcanic areas. Dragons flight (talk) 17:22, 23 December 2012 (UTC)

It would be nice to have WP:SECONDARY sources on prebiotic CO2 levels and sources thereof. Our opinions dont matter very much. Interesting topic.--Smokefoot (talk) 17:41, 23 December 2012 (UTC)

Agreed. So why isn't such information included in the article? As it is, the article is launching into discussion of anthropogenic sources before presenting the background and historical context. I don't in any way wish to diminish the importance of CO2 as a driver of climate change but the historical perspective is vitally important. Plantsurfer (talk) 22:52, 23 December 2012 (UTC)

Probably because the ancient history is less relevant than what's happening in relatively modern times? Still, feel free to add it, with sources. Dicklyon (talk) 04:57, 24 December 2012 (UTC)

Also this is a general article on CO2 and more information is found at the main article linked at the top of the section. Check out Carbon dioxide in Earth's atmosphere#Past variation. Dirac66 (talk) 20:02, 24 December 2012 (UTC)

The boiling point and melting point are switched

I don't know how to switch them back. If you look at any government source they're switched, and that makes more sense anyway. — Preceding unsigned comment added by 67.161.106.164 (talk) 03:30, 27 February 2013 (UTC)

See File:Carbon dioxide pressure-temperature phase diagram.svg. At ambient pressure, there is no liquid, thus no melting or boiling, only sublimation. The triple point (high pressure) is both a melting point and a boiling point. Our standard chembox template is not suited for sublimating solids; though the current values are roughly correct with the remarks given there. Materialscientist (talk) 04:01, 27 February 2013 (UTC)

The chembox template needs two extra entries - one for (normal) sublimation point and one for triple point. The infobox of this article now describes the normal sublimation point as the "melting point", and the triple point as the "boiling point". The infobox for acetylene (which also sublimes at 1 atm) does the opposite and describes the triple point as the "melting point" and the normal sublimation point as the "boiling point", as per a discussion last year at Talk:Acetylene#Melting point, boiling point, triple point, sublimation! Both ways are misleading so rather than debate which article has a "less incorrect" infobox, I think we need to revise the template and describe the values correctly. However modifying a template requires an administrator, so Materialscientist would you consider doing this? Dirac66 (talk) 04:00, 28 February 2013 (UTC)

Mistakes in the Uses Section

The section reads: Inert gas It is one of the most commonly used compressed gases for pneumatic (pressurized gas) systems in portable pressure tools. Carbon dioxide also finds use as an atmosphere for welding, although in the welding arc, it reacts to oxidize most metals. Use in the automotive industry is common despite significant evidence that welds made in carbon dioxide are more brittle than those made in more inert atmospheres, and that such weld joints deteriorate over time because of the formation of carbonic acid. It is used as a welding gas primarily because it is much less expensive than more inert gases such as argon or helium. When used for MIG welding, CO2 use is sometimes referred to as MAG welding, for Metal Active Gas, as CO2 can react at these high temperatures. It tends to produce a hotter puddle than truly inert atmospheres, improving the flow characteristics. Although, this may be due to atmospheric reactions occurring at the puddle site. This is usually the opposite of the desired effect when welding, as it tends to embrittle the site, but may not be a problem for general mild steel welding, where ultimate ductility is not a major concern. It is used in many consumer products that require pressurized gas because it is inexpensive and nonflammable, and because it undergoes a phase transition from gas to liquid at room temperature at an attainable pressure of approximately 60 bar (870 psi, 59 atm), allowing far more carbon dioxide to fit in a given container than otherwise would. Life jackets often contain canisters of pressured carbon dioxide for quick inflation. Aluminum capsules of CO2 are also sold as supplies of compressed gas for airguns, paintball markers, inflating bicycle tires, and for making carbonated water. Rapid vaporization of liquid carbon dioxide is used for blasting in coal mines. High concentrations of carbon dioxide can also be used to kill pests. Liquid carbon dioxide is used in supercritical drying of some food products and technological materials, in the preparation of specimens for scanning electron microscopy and in the decaffeination of coffee beans.

The sentence at the beginning of the second paragraph reads "and because it undergoes a phase transition from gas to liquid at room temperature at an attainable pressure of approximately 60 bar (870 psi, 59 atm), allowing far more carbon dioxide to fit in a given container than otherwise would." This would lead the reader to believe that the propellant carbon dioxide occurs in a liquid or super critical liquid phase. In fact, the typical aerosol can could not contain liquid carbon dioxide due to the extreme pressure necessary to keep it in the liquid form (about 1070 psi at common temperatures). At these pressures and temperatures, it would actually be in the supercritical fluid phase.

Also, the phrase "undergoes a phase transition from gas to liquid at room temperature" has problems too. What it is stating would require pressure, and seems to be backwards. It would undergo a liquid to gas phase transition at room temperature, but for the aforementioned pressure issue, the can would not contain liquid carbon dioxide. — Preceding unsigned comment added by SL1358 (talk • contribs) 17:32, 8 April 2013 (UTC)

Large-scale changes

I reverted this edit. The edit summary said that covalent double bonds were more specific than covalent bonds, but the edit itself was on a much larger scale than this. It was difficult to track each part of the changes made, but I decided simply to revert the lot when I found the following:

... a particularly swift reduction occurring 49 million years ago. coccolithophore algae, coralline algae, foraminifera, Human activities such as the combustion of fossil fuels and deforestation...

— (Refs removed here for clarity)

Perhaps, considering that this is a long-standing and mature article, if the IP editor wants to make wholesale changes, they should discuss here what these are, get consensus that each change will actually improve the article, and then make them one at a time - each with an edit summary that actually describes the individual edit. --Nigelj (talk) 20:19, 29 July 2013 (UTC)

I suspect the real culprit here is Visual Editor, which sometimes mangles large files and makes large-scale changes unintended by the user. This happened to me 2 days ago with another article, though I caught the problem myself and reverted my own edit. So I will use Edit Source (which does not do such things) to restore the minor change described in the edit summary by 174.19.179.127 which seems constructive, and ignore the other changes. Dirac66 (talk) 00:49, 30 July 2013 (UTC)

Human physiology CO2 produced per year

The article cites (from a broken link) that 290g of carbon comes from the approx 1 kg of CO2 produced per day. I am doubtful that a person ingests 290g of carbon in a daily diet, so a percentage of this CO2 is likely inhaled from the air and exhaled without being absorbed, can we find a more substantial (and working) source for the 290g? — Preceding unsigned comment added by 74.88.5.252 (talk) 07:26, 13 August 2013 (UTC)

The air we breathe in has about 400 ppm = 0.04% of CO2. The air we breathe out has about 4% CO2. So the effect of atmospheric CO2 on exhaled CO2 is 1%. For the accuracy of number we use here, that is negligible. So yes, we eat about 290 grams of carbon a day (actually, probably a lot more, since we also lose carbon in other ways). The most common elements in our food are hydrogen, oxygen and carbon. The hydrogen has very little mass, and there is not very much oxygen (otherwise we could not use it as food, which basically oxidises is further). If you eat a pound of cookies, that should be about 290g of carbon. Similarly for a pound of butter (which is less than 20% water). Veggies and meat have more water, but then the weight of foodstuff one consumes on average is a lot more than 290 g. Sorry, I could not find a better source - the EPA does not seem to have this tidbit in its FAQ anymore. This is a good back-of-the-envelope computation, but not a RS. --Stephan Schulz (talk) 08:05, 13 August 2013 (UTC)

Density of liquid at 1 atm?

What's the density of liquid CO2 at 1 atm? 770 kg/m3 (liquid at 56 atm and 20 °C) is not helpful.
~ender 2013-09-29 22:14:PM MST — Preceding unsigned comment added by 174.17.43.160 (talk)

It's not liquid at 1 atm. It goes directly from gas to solid and vice versa. So your question has no answer. --Stephan Schulz (talk) 07:56, 30 September 2013 (UTC)

Not so highly nonmetallic oxide

Carbon dioxide is often characterised as "well soluble in water", but it is in fact, in standard condictions, rather poorly soluble. 1.45 g/L at 25 °C, 100 kPa - it is weak solubility (1,45 g/kg of water, 0,145g/mL of water). Hydrogen chloride is a good example of a gas which is well soluble in water: 82.3 g/100 mL (0 °C), 72.0 g/100 mL (20 °C), 56.1 g/100 mL (60 °C). Main oxides of the elements with similar level of metallicity (on "carbon diagonal") to carbon are more soluble or much easier react with water: phosphorus trioxide, phosphorus pentoxide, selenium dioxide (38.4 g/100 mL (20 °C), 39.5 g/100 ml (25 °C), 82.5 g/100 mL (65 °C)), selenium trioxide, iodine pentoxide (187 g/100 ml). Even some oxides of typical metalloids are more soluble: boron trioxide (22 g/L), arsenic trioxide (20 g/L (25 °C)). Carbon monoxide has really low solubility in water (27.6 mg/1 L (25 °C)).

Low sublimaton point is not due to especially high nonmetallicity of carbon, because if we compare sublimation point of arsenic trioxide (738 K) to molecular mass of its monomer (about 195, carbon dioxide only 44), we can see that quotient (sublimation point in K/ molecular mass) is higher for carbon dioxide (in comparison with trioxides of sulfur (boiling point ca. 45 C) and selenium (boiling point ca. 165 C) also). In addition, if carbon dioxide was not so volatile (especially if it was similar to silicon dioxide at normal pressures), carbon could not be soo good element to life.

79.185.135.200 (talk) 22:34, 25 October 2013 (UTC)

Misleading statement in opening paragraph

As Wikipedia articles are supposed to be impartial I would suggest an edit to the following statement, "Burning of carbon-based fuels since the industrial revolution has rapidly increased concentrations of atmospheric carbon dioxide, increasing the rate of global warming and causing anthropogenic climate change." It has not yet been conclusively proven that a rise in man-made CO2 'causes' global warming. This statement has the potential to be both biased and misleading. Rabbit78 (talk) 19:39, 21 October 2013 (UTC) Rabbit78

There are a number of sources presented in this and other articles with regards to carbon dioxide's role in global warming. Can you present a reliable, contrary source. --OuroborosCobra (talk) 20:12, 21 October 2013 (UTC)

ADD: A number of years ago, Wiki write ups on CO2 gas stated clearly that CO2 gas was a "minimal greenhouse gas component" and is a trace component in the earth's atmosphere at 0.035%. CO2 gas was not listed as a greenhouse gas in engineering or environmental literature all through the 60s, 70s, 80s, etc., until the current EPA Admin decreed CO2 as a Greenhouse Gas per se. EPA's decree was politically motivated to be sure. The dominant green house gases in earth's atmosphere are water vapor and methane gas. It is clear from reading Wiki on CO2 gas that it has now become polluted with PC intentions. CO2 levels were hundreds of times higher in earth's history and the oceans did not boil. CO2 gas emissions from the Ocean (which is the leading source of CO2 compared to the miniscule CO2 production by mankind per se Ref: UN Panel report original form with bar charts) are emitted 4-600 years after the Solar Flare activity of the Sun. In short, Solar Flare activity causes major releases of CO2 as opposed to mankind and CO2 is a response to the call of solar activity. This logic becomes more clear when one ponders just why did the ice age Only 14,000 years ago that formed the Great lakes in north America melt due to "global warming"? There was no mankind or industry emitting CO2 as compared to today. My references come from my MS/PhD studies in environmental engineering. [User Nature4U2] [User Nature4U2] — Preceding unsigned comment added by Nature4U2 (talk • contribs) 00:33, 16 December 2013 (UTC)

I also want to know why this is included " Carbon dioxide is an important greenhouse gas, absorbing heat radiation from Earth's surface which otherwise would leave the atmosphere" How is it defined as a greenhouse gas and what is its percentage in the air (I recall somewhere around 0.011 percent) and what is its ability as a "greenhouse" gas compared to water vapor? I may have already stated on one of my websites but I will state here as well: if a beach ball represents the size of this planet, all the humans on it would occupy about the same space as something around the order of hundred to thousands of amoebas - now consider what effect humans really have on this planet. It's so much junk science to be talking about carbon footprints when plants require carbon dioxide to live - perhaps the effort is made to get CO2 down to nothing to cause the human race to be extinct, but of course that couldn't happen because of the enormous natural source of CO2 being produced without any human activity. This article like so many on wiki are heavily slanted towards OBFUSCATION, just like how this site refuses to show the real NEGATIVE 10% GDP growth for the United States upon proper accounting with the actual inflation rate and percentage of the GDP due to the federal deficit to be able to prop up the GDP - wiki is thus into propaganda. Thomas_Blankenhorn (talk) 07:04, 20 January 2014 (UTC)

Semi-protected edit request on 10 April 2014

This article mentions methane as being heavier than air. Methane has a relative density of 0.55. 143.238.66.140 (talk) 03:22, 10 April 2014 (UTC)

Corrected, thanks. Materialscientist (talk) 03:49, 10 April 2014 (UTC)

Semi-protected edit request on 16 February 2014

Simple change request concerning the line stating: ″Carbon dioxide is a greenhouse gas as it is transparent to visible light but absorbs strongly in the infrared and near-infrared, before slowly re-emitting the infrared at the same wavelength as what was absorbed″. CO2 does not absorb strongly in infrared or near-infrared because of its weak dipole structure (only a few vibration modes can absorb the electromagnetic radiation). Therefore CO2 has a very narrow absorption band. A more important correction is basic physics on how it re-emits infrared radiation. It is thermal radiation from molecular collisions (causing dipole movements of the molecules that produce the radiation). Thus that re-radiation is black-body radiation - all wavelengths centered on the average temperature of the gas. This is an important correction. I forgot to add what the line should become: ″Carbon dioxide, because of its molecular structure, absorbs infrared radiation in only a few narrow bands and is thus a weak greenhouse gas. As for all the gases, that absorbed energy heats the gas and is re-radiated as thermal radiation (broad spectrum radiation caused by the molecular collisions).″ — Preceding unsigned comment added by 184.6.25.121 (talk) 15:06, 16 February 2014 (UTC) Thanks, mark riggle - markriggle@alumni.rice.edu 184.6.25.121 (talk) 14:45, 16 February 2014 (UTC)

I partly agree. It is true that absorbs strongly is overstated on a per-molecule basis; I would say instead that it absorbs in two vibrational bands (as already stated in the Structure and bonding section). And I think you are write about the thermal radiation. However I oppose referring to a weak greenhouse gas, as this may suggest (to some readers) that it is unimportant. In fact as explained at Greenhouse gas, environmental importance depends not only on molecular characteristics but on abundance, so that CO2 is the second most important greenhouse gas (after H2O) despite having a lower global warming potential than many larger molecules. There is also the fact that the bending vibrational frequency at 667 cm-1 is close to the peak of the Earth's thermal emission spectrum.

So I would instead suggest the following revision -

″Carbon dioxide is a greenhouse gas as it is transparent to incoming visible light from the sun but absorbs outgoing infrared radiation from the ground at its vibrational frequencies (see Structure and bonding above). As for all gases, the absorbed energy heats the gas and is re-radiated as thermal radiation (broad spectrum radiation caused by molecular collisions).″ What do you think of this text? Dirac66 (talk) 00:24, 18 February 2014 (UTC)

I'll risk showing my ignorance here but "As for all gases, the absorbed energy heats the gas and is re-radiated as thermal radiation (broad spectrum radiation caused by molecular collisions)″ sounds wrong to me. The radiation isn't "caused" by molecular collisions - energy is redistributed by same. But more than that: surely (and here I'm open to correction) it doesn't radiate as a block body? Like any other gas, it can only radiate in its lines? William M. Connolley (talk) 09:49, 18 February 2014 (UTC)

Good points, thanks. The term thermal radiation is incorrect for a gas. There are two separate processes: redistribution of energy by collisions which heat the gas, and radiative emission at allowed line frequencies. The thermal redistribution is more relevant for the greenhouse effect which is the subject of this paragraph. With this in mind, the second sentence should be revised too. How about this -

″Carbon dioxide is a greenhouse gas as it is transparent to incoming visible light from the sun but absorbs outgoing infrared radiation from the ground at its vibrational frequencies (see Structure and bonding above). As for all gases, the absorbed energy can be (partly?) redistributed by molecular collisions which heat the gas." Dirac66 (talk) 23:23, 18 February 2014 (UTC)

OK, but I'm still missing the point of "redistributed by molecular collisions which heat the gas". What difference does this make? The energy still "needs" to get (eventually) re-emitted as radiation at some point. The GHG's are sitting in a sea of O2 and N2, and so the thermal redistribution moves the energy into these too, but that's irrelevant as they can't re-radiate it (no?) because they don't have any lines at "thermal" energies William M. Connolley (talk) 12:11, 19 February 2014 (UTC)

The point is that this is the molecular mechanism responsible for GHG atmospheric heating. The energy is not all re-emitted as radiation into space. Some of it is transferred to O2 and N2 as you say, so that makes our atmosphere warmer. At least if the rate of absorption of energy is faster than the rate of radiative emission, which seems to be the case in recent decades. Dirac66 (talk) 18:08, 19 February 2014 (UTC)

No further comments so I have gone ahead. In the final version I changed which heat the gas to which heat the atmosphere, since as pointed out by William Connolley the O2 and N2 are heated too.Dirac66 (talk) 02:04, 26 April 2014 (UTC)

I think that there is more to this than the article now states. Much of the greenhouse CO₂ is fairly high in the atmosphere. Global warming is normally considered to be the warming of the global average surface temperature. Therefore, re-radiation of absorbed heat is important, not just the conduction of heat locally in the atmosphere to where it was absorbed by CO₂. I would therefore slightly alter the existing last sentence of the paragraph, and add one more sentence: "As for any gas, the absorbed energy is redistributed by molecular collisions which heat the atmosphere, and it is then re-radiated in all directions including downwards. Thus some of the Earth's outgoing radiant heat is trapped in the atmosphere and transferred back towards the planet surface." --Nigelj (talk) 08:23, 26 April 2014 (UTC)

You can make this change yourself if you wish. The original requester above was unregistered (as he was identified by a number) and could not edit a semiprotected article, so he made the request on this talk page instead. However you are registered so can edit the article yourself. Dirac66 (talk) 17:00, 26 April 2014 (UTC)

thin crust

The lead states "It is emitted from volcanoes, hot springs, geysers and other places where the earth's crust is thin . . ". Is it a valid generalization that these geological features occur where the crust is thin? Isn't it the case that continental volcanoes occur above subduction zones, where crustal thicknesses are locally increased rather than decreased? Plantsurfer (talk) 21:52, 23 June 2014 (UTC)

Whether its valid or not, its use in this context seems a little gratuitous and should go away. It's enough to talk about these geothermal and volcanic sources, without straying from the CO2 topic to start talking lithosphere structure. NewsAndEventsGuy (talk) 22:41, 23 June 2014 (UTC)

Clarification needed

"Carbon dioxide differential above outdoor levels at steady state conditions (when the occupancy and ventilation system operation are sufficiently long that CO₂ concentration has stabilized) are sometimes used to estimate ventilation rates per person." A truly horrendous sentence. What does it mean in everyday English? Please, someone edit it and put it out of its misery. Also, it is going to need a source. Plantsurfer (talk) 20:03, 24 June 2014 (UTC)

The revision history of the article shows that this sentence was inserted on 7 Feb 2010 by Schoenl, whose entire contribution to Wikipedia consists of 3 edits on CO₂ within 30 minutes. So this is an inactive editor who is unlikely to reply.

The previous version of the sentence (prior to Schoenl's edits) was "Carbon dioxide ppm levels (CDPL) are a surrogate for measuring indoor pollutants that may cause occupants to grow drowsy, get headaches, or function at lower activity levels". This seems a clearer sentence at least, so perhaps we should think about reinserting it in place of what we now have. However it was unsourced also, and I know little about toxicity, so I will leave for others to decide whether it was correct. Dirac66 (talk) 21:09, 24 June 2014 (UTC)

Overly indexed formulae

User:Valeg96 has added additional indexes in formulae. For example:

Fe
₂O
_3(s)+ 3 CO
_(g)→ 2 Fe
_(s)+ 3 CO
_2(g)

instead of

Fe
₂O
₃+ 3 CO → 2 Fe + 3 CO
₂

In my view this only muddles them up, without adding any useful information. I am considering reverting. −Woodstone (talk) 07:44, 9 October 2014 (UTC)

User:Woodstone Personally speaking, I think they should be kept, as it helps the reader focus and understand the reaction going on without reading all the descriptions before. It is way quicker to copy on a piece of paper the reaction with the indexes than

"Iron is reduced from its oxides with coke in a blast furnace, producing pig iron and carbon dioxide:".

Anyway, I think we should aim to completeness, and these equations are rather short, so it's not really that confusing. By the way, thank you for talking about this openly and not reverting without a single word :) Valeg96 (talk) 11:34, 9 October 2014 (UTC)

The usual style in Wiki-chemistry articles is to omit these symbols. Professional journals and textbooks rarely use them. They are mainly featured by students proudly displaying their knowledge but these symbols encumber an already difficult subject, making it more complicated to understand. Now one must know the chemistry and the states. And finally, these symbols are often wrongly used, implying conditions that are untrue. For example the neutralization of carbonates can give CO₂(g) but it also can give a solution of CO₂. Implying that such reactions only give gaseous CO₂ is incorrect. --Smokefoot (talk) 13:18, 9 October 2014 (UTC)

I agree that those (s) and (g) indicators should be removed. They complicate more than enlighten, so their net value is negative. ~Amatulić (talk) 19:01, 9 October 2014 (UTC)

I agree with Valeg96 that these symbols should be retained here. Professional chemistry journals are written for professional chemists who know the phases of common substances. Wikipedia articles on the other hand should consider readers who are beginners in chemistry. This article was consulted in the last 30 days almost 140 000 times (see Page view statistics on the Revision history page), so it is quite possible that an appreciable number of readers may not know that Fe₂O₃ is solid and CO is a gas. Dirac66 (talk) 20:52, 11 October 2014 (UTC)

Um. I and all my acquaintances at age 6, knew that rust is sold and carbon dioxide is gas. This isn't esoteric knowledge available only to scientists.

Also, a layman will likely not understand what those {s) and (g) indexes mean, so the argument that these indexes actually add clarity makes no sense. ~Amatulić (talk) 21:23, 11 October 2014 (UTC)

Respectfully responding to Dirac:

• "Professional chemistry journals are written for professional chemists who know the phases of common substances...." what about beginning textbooks? They are not written for pro's (I need to check to see whether they support my case!)
• "This article was consulted in the last 30 days almost 140 000 times" how the number of hits is relevant? These are not votes.
• Finally, indices are often wrong (or overly restrictive) as I point out above - CO₂ forms whether it is gaseous or otherwise in these cases.--Smokefoot (talk) 22:16, 11 October 2014 (UTC)

• First point: I have checked my two first-year university textbooks and they do include the phases, but not as subscripts. R.H.Petrucci, W.S.Harwood and F.G.Herring General Chemistry (8th ed. Prentice-Hall 2002, p.962) write Fe₂O₃(s) + 3CO(g) → 2Fe(l) + 3CO₂(g). As do K.W.Whitten, K.D.Gailey and R.E.Davis General Chemistry (4th ed. Saunders 1992, p.844), except that they add + heat at the end. So it seems at least some authors of beginning textbooks think that phase information is useful to students.
• Second point: The number of hits shows that there are a large number of readers (allowing for multiple hits, perhaps 140 000 divided by x, where x is between and 1 and 10), so it is reasonable to assume that this includes an important number of non-expert readers. No, they didn't vote by participating in this discussion, but some might still find the information useful.
• Third point: Yes, we must be careful to write the correct phase. I had assumed that the Fe(s) now in the article is correct, but my two sources above both write Fe(l) at blast furnace temperatures. And sometimes we should point out that the phase can vary, as for your example of CO₂(g) and CO₂(aq). I don't think this is a reason to omit the information entirely. Dirac66 (talk) 23:51, 11 October 2014 (UTC)

Inconsistent pressure units

Under "Physical properties", the narrative talks about the triple and critical points using units of atm and MPa, and suggests "see phase diagram", which uses bar. Is there some good reason to use three different pressure units in one discussion? It seems to me this just confuses people. Gwideman (talk) 07:14, 15 November 2014 (UTC)

The use of multiple units is a consequence of multiple authorship, since different editors have different ideas about which units to use. The temperature values in the same paragraph are more consistent: all three temperatures are given first in °C which is the most familiar unit for most (non-American) readers, and alternate scales (°F and K) for one value are in parentheses. I think we should do the same for pressure: express all values in atm first as the most familiar and meaningful unit, with perhaps some values in kPa in parentheses.

The diagram is a special problem because changing it would require redrawing the image file. However the legend can be changed easily, so we can just a note at the end to say that 1 bar = 0.987 atm. Dirac66 (talk) 01:51, 16 November 2014 (UTC)

Primary sources of CO2

The lead states "Its presence in the atmosphere comes primarily from three sources: it is a byproduct of animal respiration, it is a product of the combustion of materials with carbon in them, and it is a byproduct of natural decomposition of organic material by microorganisms like bacteria and fungi." This is incorrect. The sources specified are parts of the terrestrial biosphere, just one of the components of the global carbon cycle, many of which are very much larger reservoirs. Plantsurfer 00:22, 27 April 2015 (UTC)

Density Error

The liqid density is listed as 770 kg/m3 (liquid at 56 atm and -20 °C). I have several reference that this is way too low. Engineering toolbox lists 1032 kg/m3 for saturated CO2 and Airliquide gives 1256 kg/m3 at -20°C and 20 bar and Airproducts lists 1017 kg/m3. Does anyone have a definative value, as I am sure the given one is wrong.Stainless316 (talk) 09:50, 6 November 2015 (UTC)

Density

OK, I am going with the Air products one of 1017kg/m3 - I have seen similar densities at the saturation point.Stainless316 (talk) 15:21, 9 November 2015 (UTC)

Final change

I looked it up in CRC "Rubber Book" - quite an old copy. That gave 1101 at -37°C. I looked at CO2 data page, and that gives very similar figure. I have seen quite a few MSDS sheets giving 0.8g/mL, and I wonder if they have got this figure from here.Stainless316 (talk) 16:04, 9 November 2015 (UTC)

PPM

There is mention somewhere of atmospheric PPM values, and two different numbers are given, one for volume and one for mass. PPM is a dimensionless ratio of amount, and it's pretty unclear what these numbers signify. — Preceding unsigned comment added by 82.169.42.228 (talk) 08:40, 27 April 2015 (UTC)

Hmm. I take your point, but in the lede, we once specify "by volume". This usage is, as far as I can tell, universal in the article and sources (some sources use molar fraction, but for gases that's close enough to not matter for the levels of precision we have here). Spelling it out every time would be annoying, I think. An suggestion on how to improve the article? — Preceding unsigned comment added by Stephan Schulz (talk • contribs) 10:02, 27 April 2015

"PPM is a dimensionless ratio of amount..." So is percent, but we talk of alcohol % by volume all the time (well, some of us more than others). I don't think this is a problem.Stainless316 (talk) 11:46, 10 November 2015 (UTC)

NASA-TV/ustream (11/12/2015@12noon/et/usa) - "Global warming-related" News Briefing.

IF Interested => NASA-TV/ustream and/or NASA-Audio (Thursday, November 12, 2015@12noon/et/usa) - NASA will detail the Role of Carbon on the Future Climate of the Earth - in any case - Enjoy! :) Drbogdan (talk) 14:19, 10 November 2015 (UTC)

• BRIEF Followup - REPLAY LINK (Audio; 66:01) => http://www.ustream.tv/recorded/77531778 - Enjoy! :) Drbogdan (talk) 19:43, 12 November 2015 (UTC)
• SUMMARY (and possible addition to article) (see below) - Comments Welcome - Enjoy! :) Drbogdan (talk) 13:06, 14 November 2015 (UTC)

NASA scientists report that human-made carbon dioxide (CO₂) continues to increase above levels not seen in hundreds of thousands of years: currently, about half of the carbon dioxide released from the burning of fossil fuels remains in the atmosphere and is not absorbed by vegetation and the oceans.

Carbon dioxide in Earth's atmosphere if half of global-warming emissions are not absorbed.
(NASA simulation; November 9, 2015)

References

natural sources of CO2

The natural sources listed include volcanoes, hot springs, geysers. What about aerobic organisms and planets during respiration, weathering of limestone? I think those should be included.

2620:101:F000:700:15DC:C74D:3BDC:20DA (talk) 18:01, 14 January 2016 (UTC)

It is stated there. Weathering of limestone is stated as (CO₂) is freed from carbonate rocks by dissolution in water and acids. Photosynthetic organisms (inc. plants) is discussed in the next paragraph and aerobic oranisms (inc animals) in the third. Jim1138 (talk) 11:10, 15 January 2016 (UTC)

Missing and Inaccurate Values for State Transition Temperatures

In the Properties section, this page is currently missing the entry for the Boiling point for CO2, and the current value in the Melting point has the value Boiling should have. For whatever reason, Google's automatic response for CO2 Boiling and Melting temperatures are reversed, and I believe this to be at least partially caused by the mixed up/missing data on this page.

I wanted to make sure the editors of this page were made aware of this error, that's all.

Pdfitzgerald (talk) 03:13, 20 January 2016 (UTC)

@Pdfitzgerald: At atmospheric pressure, CO₂ sublimes; it is not liquid at any temperature. Liquid carbon dioxide forms only at pressures above 5.1 atm (about 75 PSI). See the section under Carbon dioxide#Physical properties. Jim1138 (talk) 07:56, 20 January 2016 (UTC)

Jim1138 is correct. I would add that since CO₂ cannot be liquid at 1 atm, it has no normal (meaning at 1 atm) boiling point or melting point. This is why no (normal) boiling point is listed and the normal sublimation point is listed instead. Similarly there is no normal melting point and the triple point is listed instead, although it is listed in the Infobox with the parameter Melting point because the Infobox Template does not yet have Triple point as a parameter. Dirac66 (talk) 18:37, 23 January 2016 (UTC)

@Jim1138: @Dirac66:Interesting. Good to know that the problem I observed was not actually a problem. Thanks for replying. Pdfitzgerald (talk) 22:31, 24 January 2016 (UTC)

Carbon Dioxide

Why can't CO2 be disrupted chemically. Hydrolysis separates Hydrogen & Oxygen. Is there no catalyst over which CO2 could be passed with heat, electrical discharge or something similar? Is anyone looking? — Preceding unsigned comment added by 86.163.142.232 (talk) 16:42, 20 July 2016 (UTC)

What? There are many reactions you can do with CO2. Just straight away, one that "fits" your requirements in the Bosch reaction, one of many reactions that can be done with CO2, and yes, others are under investigation. It can also be used in methanol production. --OuroborosCobra (talk) 17:37, 20 July 2016 (UTC)

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Methane - mentioning greenhouse gas potential

@Carlos Danger: I see no useful purpose of mentioning methane as you have done here and here. Its mention belongs in other articles such as Greenhouse gas. Not here. Jim1138 (talk) 08:18, 21 December 2016 (UTC)

Semi-protected edit request on 27 April 2017

Wikiplschecksources (talk) 23:07, 27 April 2017 (UTC)

Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format. Murph9000 (talk) 23:12, 27 April 2017 (UTC)

Atmospheric carbon dioxide is vital to life on Earth

The statement "Atmospheric carbon dioxide is vital to life on Earth" is incorrect. Humans get their carbon from food and plants get some of their carbon from the soil, not from atmospheric CO2. Brian Everlasting (talk) 18:59, 29 April 2017 (UTC)

The point is that carbon dioxide is the primary source of carbon for life on earth. Whether heterotrophic organisms eat it or not is irrelevant. Their source of carbon in the food they eat is carbon dioxide fixed by autotrophic organisms. Plantsurfer 19:09, 29 April 2017 (UTC)

Is CO2 odorless?

There is currently an edit war following a video by Thunderf00t https://www.youtube.com/watch?v=qF7qJ1K4VOk The video claims that CO2 has a sharp, acidic odor. This is due to the formation of acid when CO2 reacts with water, so we might argue that it is not CO2 itself that we smell. Safety data sheets list CO2 as odorless or having "no odor warning properties" so I think we should keep the "odorless" label and maybe explain the reason of the acidic smell somewhere else.

--2A01:CB1C:8DC:7300:85C7:A731:B090:DFF (talk) 21:39, 26 April 2017 (UTC)

If it generates a smell when it reacts with your nose, by definition it must have an odour, right? I think 'odour' refers to the sensation, not the chemical process that leads to it. Illiteration (talk) 22:06, 26 April 2017 (UTC)

It really should be specified. Whether or not it has an odor is entirely dependent on the concentration. Pure CO2 has a sharp smell but levels that will asphyxiate someone don't. — Preceding unsigned comment added by 96.253.22.191 (talk) 22:37, 26 April 2017 (UTC)

I just noticed, the article already mentioned this: "At low concentrations, the gas is odorless. At higher concentrations it has a sharp, acidic odor." Is it normal in the field of chemistry to refer to a chemical as odourless if it has no smell at normal concentrations? Illiteration (talk) 23:34, 26 April 2017 (UTC)

It depends. At low enough concentrations, hydrogen sulfide is odorless. At 100%, it might have a smell but no one is alive to report it. Carbôn dioxide may or may not be odorless at normal concentrations, but from our point of view it is odorless - we are used to it. If you stick your head into a dry ice chest, it has an odor.JSR (talk) 00:41, 27 April 2017 (UTC)

At this point the odor question is still hypothetical. The video doesn't really use a conclusive test. There's semantics involved as to what actually constitutes an odor as well as gas concentration being relevant. Until these issues can be resolved by high sigma testing and linguistic/practical verification as to if an odor is specifically an olfactory sense or a more general term I feel it is premature to edit the article and it should be left as "odorless".79.68.125.23 (talk) 01:29, 27 April 2017 (UTC)

Comment Wikipedia goes by what wp:reliable sources state. One MSDS http://www.uigi.com/MSDS_gaseous_CO2.html - Carbon Dioxide gas is colorless. At low concentrations, the gas is odorless. At higher concentrations it has a sharp, acidic odor. It will act as an asphyxiant and an irritant. Please use RS. Our opinions here are irrelevant. Jim1138 (talk) 05:03, 27 April 2017 (UTC)

Right now the article uses two asterisks to point the reader to another section of the article within the first sentence. I don't think that's a good flow for the article; I think the details of the smell should be mentioned in the lead section of the article. To do this, we should probably remove any mention of the odour/lack thereof from the first few sentences and put it later on in the lead section, so we can spend more than a few words explaining it.

And to get the facts straight, from what I've gathered, CO2 has no smell in regular, low concentrations. In order for there to be enough for you to smell, it would already have to be past the point where you'd asphyxiate (from lack of oxygen?), unless you take it in short bursts like Thunderf00t did. Does anyone disagree with that? Illiteration (talk) 15:50, 27 April 2017 (UTC)

There is no more edit war, at least not from IPs. DMacks, I went a step further and semi-protected it; I hope you don't mind. Drmies (talk) 18:16, 27 April 2017 (UTC)

Good idea. DMacks (talk) 19:25, 28 April 2017 (UTC)

Well, the article says it's both odorless and acidic with no explanation as to why the confusion, so maybe you mods should stop blindly reverting changes and lock it into a state that has some sense of credibility.— Preceding unsigned comment added by 174.233.137.8 (talk • contribs) 18:39 27 April 2017 (UTC)

Reliable source needed Does anyone have access to a wp:reliable source on the odor threshold of CO₂? It appears that if you detect the "sharp, acidic" odor/sensation, you will quickly asphyxiate. But, you would not get this sensation/odor at lower, but still hazardous-to-lethal levels. A good reference should probably be added to the three mentions of odor. Possible sources for which I do not have sufficient access to:

• Ruth, Jon H. (4 Jun 2010) [1986]. "Odor Thresholds and Irritation Levels of Several Chemical Substances: A Review". 47 (3). American Industrial Hygiene Association Journal: A-142–A-151. Retrieved 27 April 2017. {{cite journal}}: Cite journal requires |journal= (help)
• Cheremisinoff, Nicholas P. (1999). Handbook of Industrial Toxicology and Hazardous Materials. CRC Press. ISBN 9780824719357.
• Universal Industrial Gasses gives a detailed list of effects at various concentrations and At low concentrations, the gas is odorless. At higher concentrations it has a sharp, acidic odor. It will act as an asphyxiant and an irritant. Also, discusses other effects.

Many MSDSs just state "odorless", some state 'high level sharp/acidic'. With a citation, perhaps the infobox should be changed to "No odor<br>High concentrations:<br>sharp; acidic".

What should be mentioned about of "odor" and its importance in the article? Probably not what you would smell if you inhaled a 100% gas or snort the material. A chemist, for instance may want to know if a chemical would have an odor below a dangerous level. Example: per Phosgene#Safety does have an odor, but its detection level is about four times its hazard level. This MSDS states Odour: Initially, musty hay, then the sense of smell is deadened. Hydrogen sulfide at high/lethal levels quickly deadens the sense of smell. Odor threshold detection can be complicated. Jim1138 (talk) 21:24, 27 April 2017 (UTC)

I think the problem (other than finding sources) is that it's hard to summarise the points of its odour in just a few words. Right now the infobox says "Low concentrations: Odorless", "High concentrations: Sharp, acidic", which is redundant because everything is odourless in low enough concentrations. I stick by my earlier suggestion of making no mention in the first few sentences to keep the beginning clean, and then go into detail on the odour later on in the lead section. Illiteration (talk) 21:42, 30 April 2017 (UTC)

@Illiteration: That's what the RS states. We need non-wp:original research. Jim1138 (talk) 23:40, 30 April 2017 (UTC)

• Ryanharmany added odor info from an MSDS and a citation. American English per top of page. I copied the odor info and reused ref to Chembox. Jim1138 (talk) 23:43, 28 April 2017 (UTC)

"No smell in low [enough] concentration" is true of every single substance in the world, it's almost tautological. I'm not sure I see the logic in bothering to write that. Even for safety reasons, knowing that isn't going to help you much until you get some symptom that IS noticeable, namely feeling yourself suffocate in this case, at which point it is a bit redundant whether there's a smell isn't it? — Preceding unsigned comment added by 64.180.192.224 (talk) 23:23, 12 May 2017 (UTC)

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The article appears to be using a reputable, but otherwise fake citation to support a claim.

An article used as citation doesn't support sentence where cited. That article simply cites another article as proof, which cites another, etc. The citation should be deleted, and another should be found.

"The concentration of carbon dioxide has risen due to human activities." [57]

Citation #57, Li, Anthony HF. "Hopes of Limiting Global Warming? China and the Paris Agreement on Climate Change." China Perspectives 1 (2016):49. — Preceding unsigned comment added by 68.54.0.181 (talk) 06:01, 15 July 2017 (UTC)

The best citations are WP:secondary citations in WP:reliable sources, not WP:primary ones. What exactly do you see as fake about the citation? Dmcq (talk) 13:03, 15 July 2017 (UTC)

It is a weird ref though. Why not use the obvious, IPCC? William M. Connolley (talk) 19:31, 15 July 2017 (UTC)

I was wondering what exactly they were looking for, the IPCC also references lots of other references. Did they want one particular study instead? Would they consider the IPCC a secondary source? Dmcq (talk) 14:33, 16 July 2017 (UTC)

Density

The intro gives th value of density as "about 60% higher than that of air (1.225 g/L)" This information is confusing, as the number in parentheses can be understood as the density of Carbon dioxide. --Jidu Boite (talk) 08:17, 20 July 2017 (UTC)

And I think that the density of CO₂ is the value that should be reported, since that chemical is the article-topic, rather than air, if a density value is reported. But for the intro, why do we need the specific value at all? WP:LEDE says we should summarize the main ideas, and a comparitive statement without the underlying data is sufficient in my opinion. DMacks (talk) 05:27, 21 July 2017 (UTC)