Talk:Greenhouse gas

Natural and anthropogenic

As someone trying to understand a little about greenhouse gases - there is a table showing Natural and anthropogenic gas ppm in the atmosphere and rediative forcing. However, the table doesn't contain water vapour which seems to be the major component of greenhouse gas. It would be useful to include this so the relevance and importance of the other gases can be understood. —Preceding unsigned comment added by 210.193.162.198 (talk) 04:52, 29 June 2009 (UTC)

Shouldn't a section titled "natural and anthropogenic sources" has some tables comparing these two sources? See http://www.geocraft.com/WVFossils/greenhouse_data.html for examples, though there may be more recent or better tables elsewhere. JesseChisholm (talk) 00:04, 20 July 2010 (UTC)

Portrayal of anthropogenic global warming theory as fact

I'm not familiar with how this whole thing works, so apologies in advance if I do something stupid.

Wikipedia articles in general have been an excellent resource, but I'm a little concerned with an apparent bias of the greenhouse gas one. The line that I find most disturbing is:

"Human activities since the start of the industrial era around 1750 have increased the levels of greenhouse gases in the atmosphere."

This seems no more than a mere parroting of what we have been hearing on TV, and certainly not worthy of being encyclopedic content. Given that no evidence exists to support such a direct statement, I made a few edits to present the information in a more neutral manner (along with minor corrections) which were rejected. May I ask why? —Preceding unsigned comment added by 96.236.8.229 (talk) 04:56, 14 January 2010 (UTC)

You're right to point out that the statement as it stood in the article was unsupported, less correct to claim that there is no scientific support for the statement. I've added a link to this FAQ at the US government's Carbon Dioxide Information Analysis Center. --TS 22:58, 23 February 2010 (UTC)

Good reference. Go to link in the answer to the second question. Then read footnote 4. You'll see that this US government source uses a totally different way of describing "atmospheric lifetime" from the way this article defines the term. Not only does it describe the use of a short impulse function, it describes decay as a physicist would, with an exponential and a one over e decay time. Obviously there are individuals who have some understanding of the subject, unlike the editors who wrote the sections of this article that refer to atmospheric lifetime. blackcloak (talk) 07:17, 24 February 2010 (UTC)

Methane

In a recent edit, WMC removed an EPA reference that stated

Methane is over 20 times more effective in trapping heat in the atmosphere than carbon dioxide (CO2) over a 100-year period

and replaced the text with

methane is about eighty times stronger greenhouse gas than carbon dioxide

with the following explanatory note

twenty is over 100 y (GWP) not instantaneous. eight is obviously wrong - I think 80 is most likely

The methane article says that methane has a

global warming potential of 72 (calculated over a period of 20 years) or 25 (for a time period of 100 years).

which does not appear to be supported by the provided reference (IPCC).

At any rate, please restore the EPA reference and value, or provide an appropriate reference for the "80 times stronger". Either way, the methane page also needs to be fixed. Q Science (talk) 08:07, 27 April 2010 (UTC)

Yes. The point is that we're talking about the direct radiative forcing in this place, not the time-integrated GWP. Because methane decays faster than CO2, its instantaneous radiative forcing (per molecule) is higher relative to CO2 than its long-term GWP William M. Connolley (talk) 08:39, 27 April 2010 (UTC)

Good point. However, the provided reference only links to an abstract that does not provide the value. Have you verified that the full reference supports "80"? Your edit comment implies that you haven't. Q Science (talk) 05:22, 28 April 2010 (UTC)

No I haven't. I'm guessing. It is consistent with the 72 over 20 years though - whatever the number is, it should be a little higher than that William M. Connolley (talk) 09:26, 28 April 2010 (UTC)

You might like to look at WP:OR and WP:SYNTH. Perhaps we can come up with a form of words which is directly supported by the source. Stephen B Streater (talk) 10:22, 28 April 2010 (UTC)

Rewrite of section on emissions

I've rewritten the section on GHG emissions. I felt that the previous revision did not offer a suitably broad coverage of the topic:

1. It concentrated on particular time periods for measuring emissions,
2. The global coverage was inadequate
3. There wasn't sufficient information presented on cumulative emissions
4. There was a bias towards discussing emissions in China and the US.

On point 1, the previous revision was rather arbitrary in its coverage of time periods. Things were mixed together and I felt that they would be better presented in separate categories. The new revision has information on emissions over the 1970-2004 time period, as well as the 1990-present. I've kept some info from the previous revision on measurements since 2000.

On point 2, it doesn't make sense to concentrate only on China, the US, and the UK. The subject needs to be explained from a global perspective. I've attempted to do this in a short a space as possible. I've put in a link to the article on Kyoto Protocol and government action. This article more comprehensively describes emissions and climate policies in a wide number of countries.

Point 3: I've added info on cumulative emissions from the IEA.

Point 4: This is related to point 2. Emissions in these countries are important, but it is biased only to discuss emissions within the context of comparing emissions between these two countries. This is a rather arbitrary thing to do. The US and China are important emitters, but that does not mean that this article should concentrate so much on their actions. A global perspective should look at the issue in broader terms, e.g., Annex I v. non-Annex I, developed versus developing. For this article, these kind of groupings are more appropriate since they include a far larger number of countries. The Kyoto article I referred to previously offers a broader description of emissions in various countries. Enescot (talk) 12:56, 22 May 2010 (UTC)

Units

The table "Relative CO2 emission from various fuels" should be in SI-units. —Preceding unsigned comment added by ArnaudContet (talk • contribs) 16:00, 24 May 2010 (UTC)

Add Category:Emissions reduction ?

Add Category:Emissions reduction ? 99.37.85.55 (talk) 18:07, 25 May 2010 (UTC)

Inconsistent radiative forcing figures.

Radiative forcing figures for CO2 are inconsistent across article. They were probably counted with:

P = 3.35*ln(1 + 1.2*C + 0.005*C^2 + 0.0000014*C^3)

where C is CO2 in parts per million and P is radiative forcing

...but something wrong happened while updated. If I'm right this numbers should be:

For 280->387 ppm: 1.79 W/m^2 (instead of 1.46 in section "Natural and anthropogenic", "current level" updated but radiative forcing not?)

For 280->365 ppm: 1.46 W/m^2 (that's right - section "Greenhouse gas emissions")

For 280->383 ppm: 1.73 W/m^2 (instead of 1.53 in section "Greenhouse gas emissions", typo? "5" instead of "7"?) —Preceding unsigned comment added by 89.246.67.228 (talk) 13:33, 31 May 2010 (UTC)

This is what I found (Please expand and correct as appropriate.)

CO2 change	Article	Reference	Computed	Reference
278 -> 365	1.46	1.46	1.46	[IPCC - ref 41 in main document]
280 -> 384.8	none	1.66	1.76	[ref 42 in main document]
280 -> 383	1.53	none	1.73	none
280 -> 387	1.46	none	1.79	none

Since computing values instead of using those in the references is considered WP:OR, I don't think it is correct to change the values, but it is a good idea to add a column with the computed values and to delete all values that do not have references. Q Science (talk) 23:25, 31 May 2010 (UTC)

Statistics by industry

It would be very illuminating to have statistics showing what percentage of each major greenhouse gas come from each industry. For example, a 2006 U.N. report claims that more global warming is caused by livestock than transportation: [1] -- Beland (talk) 15:18, 5 July 2010 (UTC)

fossil fuels

The statement which makes fossil fuels the villain is not adequately referenced. The current statement says: "The burning of fossil fuels since the beginning of the industrial revolution has substantially increased the levels of carbon dioxide in the atmosphere." Reference [5] is to a Q & A of the Carbon Dioxide Information Analysis Center (CDIAC). CDIAC only estimates carbon dioxide from fossil fuels and from no other source. The reference which CDIAC gives for their conclusion is an article by Richard A. Houghton on Land Use Changes. Land Use Changes do not prove anything about fossil fuel.

The alleged need for all carbon dioxide control and greenhouse gas regulation is the control of fossil fuels. For this reason, the allegation that fossil fuel is the culprit needs to have overwhelming understandable scientific references. It does not have that. Obviously, there is a reason for such omissions.

The CDIAC conclusion appears to be nothing more than an assumption since its land use reference is not evidence of its truth. It is not supported by peer-reviewed scientific studies of the many sources of carbon dioxide emissions. —Preceding unsigned comment added by 24.27.16.34 (talk) 19:53, 27 July 2010 (UTC)

See [2] read up to and including the paragraph which starts "What about the land biosphere?" You may need to read it a few times to absorb it, I did (no pun with "absorb" here) ..in essence they can measure the net effect of both deforestation (which would increase CO2) and absorption of CO2 in the biosphere...basically by doing some "Accounting" with + and - for CO2 among oceans, atmosphere, and biosphere. This accounting shows that the extra CO2 in the atmosphere did not come from the biosphere, which actually lost 15±9 PgC net. This loss is a combination of the loss from deforestation of 24±12 PgC, and additional land uptake of 39±18 PgC in response to elevated CO2 and climate changes...but in net 15 PgC give or take, was added, So in net, CO2 at higher levels in the atmosphere did not come from the biosphere.(by comparison, fossil fuel burning was 117±5 PgC..these numbers are not annual but for the period 1980-1999) In any case CO2 at higher levels in the atmosphere did not come from the biosphere..or did it come from the oceans losing CO2 since oceans gained CO2..[a little more analysis can then match fossil fuel burning minus extra taken up by oceans and biosphere with the level of increase we measure in the atmosphere..but that's a step beyond your question, which was merely, can we rule out that the biosphere including deforestation, is the cause of the huge [3] increase in CO2, and the answer is, yes, we can] --Harel (talk) 01:23, 19 August 2010 (UTC)

Opening sentence too vague

I'm not sure about the opening sentence of the article, "Greenhouse gases are gases in an atmosphere that absorb and emit radiation within the thermal infrared range." There is more to distinguish a greenhouse gas than that it simply "absorb[s] and emit[s] radiation within the thermal infrared range". As the diagram in the lead makes clear (as do any number of textbooks), a greenhouse gas is one that is relatively transparent to high temperature (high frequency) IR, but relatively opaque to lower temperature (lower frequency) IR. Then it produces the differential effect of letting the high-temperature solar radiation in, but interfering with some of it's loss back into space at the lower temperatures of the planet and its atmosphere. How to summarise this into one clear opening sentence? It has to be longer, with more information in it than the current sentence. How about, "Greenhouse gases are gases in an atmosphere that selectively absorb and re-emit radiation more readily within the infrared region that is equivalent to the planet's surface temperature than they do for higher temperatures."? With suitable links to other articles about infrared and maybe black-body temperature, this would be clearer, IMHO. --Nigelj (talk) 12:05, 23 August 2010 (UTC)

The opening summary is fine. If you want more details, please place them in the appropriate section. Also, "re-emit" is a common error. Even if no energy is absorbed at a given frequency, a greenhouse gas will still emit energy because of its current temperature. If fact, both water vapor and CO2 tend to emit more energy than they absorb because they are also heated by direct contact with the surface. Q Science (talk) 18:49, 23 August 2010 (UTC)

Well, the current summary includes hypothetical gases that absorb radiation right across the thermal infrared range, and those that might be opaque at high frequency IR and transparent at lower ones. Neither of these would be greenhouse gases. --Nigelj (talk) 21:31, 23 August 2010 (UTC)

Actually, it mentions 5 real gases by name. (The main article mentions several more.) It also says "thermal infrared range" which I interpret to mean "not" the high frequency range. However, that is not clarified in the body of the article, and I agree with you that it should be. Q Science (talk) 23:06, 23 August 2010 (UTC)

First Diagram

The first diagram shows solar radiation at 343 watts per sqm. Should not this be 1366 (or something similar)? See Wikip Solar Radiation Page - http://en.wikipedia.org/wiki/Solar_radiation#Solar_constant.

Why the discrepancy? If there is an explanation this should be stated. Oversite22 (talk) 01:38, 16 September 2010 (UTC)

The continuous TOA (Top of Atmosphere) value is 4 times larger than the average seen at the surface because the planet rotates. Q Science (talk) 02:22, 16 September 2010 (UTC)

The area of intercepted solar radiation is pi*r², the area of the planet's surface is 4pi*r², so the ratio is 1/4.

On the subject of diagrams, can we not find a better diagram than http://en.wikipedia.org/wiki/File:Atmospheric_Transmission.png? See the comments: http://en.wikipedia.org/wiki/File_talk:Atmospheric_Transmission.png Something like http://acd.ucar.edu/textbook/ch15/fig3.jpg would be much more relevant for explaining how GHGs work. 88.152.128.36 (talk) 09:20, 28 September 2010 (UTC)