The title here should strike a familiar theme for most readers. Climate forcings do not just include CO2 (other greenhouse gases, aerosols, land use, the sun, the orbit and volcanoes all contribute), and the impact of human emissions often has non-climatic effects on biology and ecosystems.
First up last week was a call from Michael Prather and colleagues that the production of a previously neglected greenhouse gas (NF3) was increasing and could become a significant radiative forcing. This paper was basically an update of calculations done for the IPCC combined with new information about the production of this non-Kyoto gas.
Most of the media stories that picked this up focused on the use of this gas in a particular manufacturing process – flat screen TVs. Thus the headlines almost all read something like “Flat-screen TVs cause global warming”! (see here, here, here etc.). Unfortunately, very few of the headline writers read the small print.
NF3 is indeed a more powerful greenhouse gas than CO2 (as are methane, CFCs and SF6 etc.), but because it is much less prevalent, the net radiative forcing (as with other Kyoto gases) is much smaller. Unfortunately, no-one has any measures of the concentration of NF3 in the atmosphere. This is likely to be increasing, since production has stepped up rapidly in recent years, but the amount of gas that escapes to the air is unknown. Manufacturers claim that it is only a very small percentage – but historically such claims have not always been very reliable. However, it is almost certain that NF3 has not caused a significant amount of global warming (yet).
The one issue that many stories did get wrong was in the comparison with coal. Prather’s paper compared the effect of the entire global production of NF3 being released into the atmosphere with the CO2 impact of one coal-fired power station. Since that is the maximum estimate of the current effect, and only matches a single power-station, the subtlety of the comparison got a little lost on the way to “Flat screen TVs ‘worse than coal’” story….
Needless to say, no-one should be throwing away their flat screen TVs because of this (it’s not in the use of the TV that causes a problem), but manufacturers will likely need to step up monitoring of NF3 leakage or switch to an alternative process which some have already done.
The second story getting some attention, is the ocean acidification issue. As we’ve discussed previously, the increased take up in the oceans of human-released CO2 is rapidly increasing the acidity (lowering the pH) of the oceans, making it more difficult for many carbonate-producing organisms to produce calcite or aragonite. These organisms include corals, coccolithophores, foraminfera, shell fish etc.
Both of these issues are relevant to the ongoing climate change discussion and it’s good to see the media picking up (albeit imperfectly) on these ancillary discussions. But as with the “North Pole” lightning rod discussed last week, there always needs to be a hook before something gets wide press (the ‘tyranny of the news peg’ as ably described by Andy Revkin). In the first case, there was a link to a popular consumer item and in the second, there has been a concerted effort to get the ocean acidification issue higher up the agenda.
The fact of the matter is that most of what goes on in the sciences is completely (and usually correctly) well below the radar of the public at large. But when there are discoveries and issues that do have public policy ramifications, getting the public to pay attention often requires finding just these kinds of resonances. Now if there was only a way to make sure the story underneath was accurate….
P.S., stumbled into this while looking up NF3. Discover Magazine does the really stupid about this general topic: http://blogs.discovermagazine.com/betterplanet/category/air-pollution/
[Response: very odd. – gavin]
In response to Richard (143),
While I appreciate the complexities involved with turbulence modeling, I don’t think that it is necessary to understand microscale turbulence features to say something about global climate change. There are many instances where one can predict macroscopic behavior without detailed knowledge of what’s happening on a microscopic scale: for years, chemical engineers have predicted heat flow in pipes containing turbulent fluids; rheology of metals can be predicted without tracking the movement of every dislocation in the material; and electrical flow in conductors can be measured without tracking the tortuous path of electrons in the crystalline lattice.
I am not trying to say that turbulence modeling has no place in climate models. I think that it could improve regional forecasts of GCMs. However, it is important to remember that turbulence is responsible for the redistribution of heat in the Earth’s troposphere and hydrosphere only; large-scale turbulent flow does not exist within the stratosphere. Since global climate models rely on radiation laws for transfer of heat to outer space and for absorption of heat from the Sun, incorporating turbulence models will have little effect on the resulting global temperature. Regional temperatures may be somewhat different, however.
#152 Thank you for your comments Jeff you have made some interesting points.
In the case of heat flow in pipes the models tend to be okay as long as the pipes are smooth and straight and the heating is homogeneous (because that is the same problem the models were calibrated for).
As soon as you make the pipes more complicated such as putting bends in them you suddenly find all the models giving different answers.
If you want to know any detail about the heat transfer fluctuations at the pipe walls you even have difficulty knowing what’s going on with the smooth straight pipe.
Macro scale solutions for macro scale problems can be found only under very controlled environments where the forcing and boundaries are all known and well defined. (But even then the micro scale can sometimes encroach on the macro scale e.g. thermal fatigue failure)
It is okay to separate the macro from the micro scales in turbulence until you realise that transfers really do exist from the small scales to the large scales.
I really don’t know enough to estimate how important turbulence is in the sun/atmosphere/ocean system.
Maybe it can just be ignored? Are the mass transfer processes in any way linked to the mixing processes and hence the radiation balance?
In response to Jeff(152)
I think Richard has his point. If I understand GCMs, they contain radiation, dynamic prozesses, surface processes, chemistry and everything as a function of time and space. So the minimal model contains a system of coupled non-linear differential equations.
If you have such a system of coupled non-linear differential equations it is in general, as I understand it, very difficult to deduct straightforward relations between cause and effect. This is valid for measurements as well as for simulations. And to make predictions within the framework of the Navier-Stokes equation is still part of the millennium problems in mathematics.
Actually, if an easy model as you suggest would suffice, it would make me nervous .
Guenter (152),
I did not mean to imply that a simple model involving only radiative processes would be effective for determining global temperatures. My point was that incorporating turbulence in models would not change the TOA radiative flux, which is the primary driver of climate change. The Navier-Stokes equation is certainly important for characterizing fluid dynamics in the troposphere, but it becomes less relevant as one moves higher in the atmosphere, where mass decreases exponentially. On the other hand, the NS equation can have an impact on feedbacks in climate models. Regional heat transport can affect albedo, cloud cover, etc., which will affect global temperatures. However, I am skeptical that incorporating complex turbulence models in GCMs will have a first-order effect on global temperature. You would have to convince me that by incorporating turbulence in models, the feedbacks would be significantly altered. Considering that current GCMs do a reasonably good job of forecasts and hindcasts, incorporating and validating turbulence effects in GCMs would take a lot of work. However, I would be THRILLED if anyone in the turbulence field thought the problem interesting enough (and tractable) to pursue such a model.
Jeff #155:
But isn’t precisely the problem of cloud formation and aerosols the current greatest remaining feedback uncertainty in climate modelling, and relatively intractable precisely due to being turbulent chaotic processes? IMHO Richard put his finger on a sore spot. Though I am not nearly as pessimistic as the text he quotes — the models are doing remarkably well, perhaps due to the combined effects of ensemble averaging and studying global or large-area bulk quantities.
The post on Ed Lorentz and chaos theory not so long ago here on RC would appear worth a re-read.
Discover Magazine blog on NF3
Journalists should have a better understanding of the issues by now. Ethanol production from biomass is not a solution to global warming, but it is a partial solution to the energy supply problem as fossil fuels are phased out (the others are solar and wind).
The three basic lines of evidence (paleoclimate, climate models, and real-time data) all support the notion that fossil fuel-sourced CO2 is having a large and persistent influence on global climate. International organizations are going to have to come to terms with this – carbon dioxide emissions are not the issue, fossil fuel use is. CO2 emissions have historically been balanced against CO2 uptake, which is why CO2 varied so little over the past few million years. By pulling hundreds of billions of tons of carbon out of multimillion-year old fossil fuel deposits, we’ve increased the size of the active carbon pool. The planet is warming, and the two major culprits are fossil fuel use and extensive deforestation. Thus, the solution is to halt the combustion of fossil hydrocarbons (bury your plastic in a landfill – that’s the right approach!), and halt deforestation (especially tropical deforestation).
That results in some secondary problems, like a lack of energy supplies and building materials. That’s where the economically viable technical solutions come into play. These are based on reliance on sunlight, wind and photosynthesis as basic sources of energy and raw materials. Replacing existing fossil fuel infrastructure with renewables will cost will require a redirection of perhaps 40% of the world’s economic activity (that’s the current share that energy takes up). Some leading industrialized countries (Japan and Germany, mainly) are following this strategy, while others (the U.S., Australia, and the members of OPEC) are mostly dedicated (for obvious, if short-sighted, economic reasons) to pursuing the status quo.
That’s all been known for some time, though. For something a bit more interesting, look at the following graph of waper vapour increases over the oceans, 1988-2003: http://www.cgd.ucar.edu/Images/fig11.jpg
The trend is +1.28% per decade – a slow but steady increase. Also note the large pulse of water vapour into the atmosphere during the 1997-1998 El Nino, followed by the return to the normal. A “skeptic” would look at the period from 1998-2000 as proof that global warming was over; an “alarmist” would take the period 1996-1998 as proof that global warming was rapidly accelerating, and a scientist would look at the entire dataset and draw conclusions from that. That conclusion is pretty well summed up in the 4th IPCC – we’ll have catastrophic results under business as usual scenarios within a hundred years, and significant climate changes are unavoidable even with drastic and immediate action.
NF3 is just one of the high GWP gases
http://www.epa.gov/highgwp/
Small concentrations but very potent. None of these are getting much play in the media. Maybe NF3 made it into the news cycle because it has to do with TV’s and that makes it a great story somehow?
Re #56 myself:
correction/clarification. It is not the chaoticness that is the problem, it is the necessity to include a huge range of scales for physical realism, from droplets through cloud systems to the size of the Earth. This is obviously computationally impossible, but if it were, the resulting model would still be chaotic. But with photorealistic cloud etc. feedbacks…
(BTW thank you RC for banning the use of text-only browsers like lynx. What the about visually impaired?)
[Response: There is an audio challenge for those who can’t see the captcha, but I don’t see a way for lynx users to have this work. I’m open to suggestions to fix this. – gavin]
Please allow me to post some recent worrying data here, on which I haven’t seen press coverage:
In 2007, global emissions of carbon dioxide (CO2) from fossil fuel use and cement production increased by 3.1%, which is less than the 3.5% increase in 2006. The emissions from China, with an emission increase of about 8%, accounted for two thirds of this global increase. Smaller contributions were made by India, the USA and the Russian Federation, in contrast to the European Union (EU-15), where a relatively warm winter and high fuel prices led to a 2% decrease in CO2 emissions. The increase in emissions, in 2007, of about 800 million metric tons of CO2, was mainly due to a 4.5% increase in global coal consumption, to which China contributed by more than 70%. At present, CO2 emissions per person from China, EU-15 and the USA come to about 5, 9 and 19 tonnes of CO2, respectively. In the 1990-2007 period, total CO2 emissions related to the use of global fossil fuel and cement production increased by about 34%.
These figures are based on a preliminary estimate by the Netherlands Environmental Assessment Agency (PBL), using recently published BP (British Petroleum) energy data and cement production data for 2007.
Re John P. Reisman (158) …“Maybe NF3 made it into the news cycle because it has to do with TV’s and that makes it a great story somehow?”
No.
“…a previously neglected greenhouse gas (NF3).” (Second sentence of the article). The other gasses you mentioned are all discussed by the IPCC and covered at Kyoto.
“At present, CO2 emissions per person from China, EU-15 and the USA come to about 5, 9 and 19 tonnes of CO2, respectively.”
I shudder to think about what the world would be like if everyone equaled the USA’s 19 tonnes per person.
Except that doesn’t seem at all possible. I’m not sure if peak oil is a problem or a solution.
I’ve put up a longer post with links about why the Prather and Hsu paper should be withdrawn and the authors drawn and quartered. The only semi-reasonable thing is that there should be a watching brief on NF3 concentrations. It should only be put onto the controls list if concentrations grow to the point where they can be measured. Right now the forcing is below 0.001 W/m2.
Joseph, #163:
Problem is that peak oil means that although demand is going up, we can’t pump it out any faster.
That doesn’t mean production is going down, just that it can’t go up quick enough to meet demand.
I don’t think “peak oil” is a solution.
Re #163, its certainly not possible with fossil fuels but globally solar engine could be harvested to yield some serious amounts of energy if required to do so. Globally we can power the earth with solar. Once installed we can power all our cars etc from electricity from this source plus wind and other places. We just need globalisation to mean that for everything.
re. #142
Gavin-Thank you for the response.
Tyndall (1865) is not available either at my library or at Borders.
Neither is Arrhenius(1896). My understanding is that Arrhenius conclusions on CO2 were based on numerical calculations.
While it is true that climate and climate change due to any forcing is horrenously complicated, with multiple feedbacks, it would seem that at least somewhere, someone would have a controlled, isolated experiment to measure the effect of varying CO2 concentrations on temeperature changes from incident radiation. While far from a perfect model an order of magnitude figure regarding the relation between CO2 levels and temperature, in the climatically important range, would then be available. After all it is known with other relations such as CO2 solubility as a function of temperature.
Perhaps this stuff is in some high school or college chemistry text but I do not know of it and have not seen it. There are enough posters, with a lot of knowledge, on these threads that you would think that someone would know of such an experimentally determined relation.
Robert Stenson in 167 wrote:
Since you are asking for a “controlled” experiment, you need to control for the emissivity of the surface that is absorbing the radiation, the absolute humidity, the pressure, the temperature, etc..
However, you are asking specifically about carbon dioxide and how it will affect radiation. So perhaps we should ask for the spectral emissivity of carbon dioxide — which is also its absorptivity — assuming local thermodynamic equilibrium conditions under which Kirchoff’s Law applies — at roughly atmospheric pressures of 20 mb and above.
Here are some posts which show how the spectral emissivity of carbon dioxide varies according to temperature and pressure — and which point you to an online tool where you can create your own graphs:
Temperature
Wednesday, July 04, 2007
http://rabett.blogspot.com/2007/07/temperature-anonymice-gave-eli-new.html
Pressure broadening
Thursday, July 05, 2007
http://rabett.blogspot.com/2007/07/pressure-broadening-eli-has-been-happy.html
High Pressure Limit. . . .
Sunday, July 08, 2007
http://rabett.blogspot.com/2007/07/high-pressure-limit.html
Incidentally, the spectral properties of carbon dioxide essentially fall right out of quantum mechanics — although you should mix in some quantum statistical mechanics for good measure as you are not dealing with molecules in isolation, but collisions, bending, etc. where for example, a temporary magnetic diapole may result in some minimal absorption of infrared radiation even by non-greenhouse gases such as oxygen.
*
For more of the history and physics, please check out:
A Saturated Gassy Argument
26 June 2007
https://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument
Part II: What Ångström didn’t know
26 June 2007
https://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument-part-ii/
#167 Robert Stentson
In general
John Tyndall’s Research on Trace Gases and Climate
http://www.tyndall.ac.uk/general/history/JTyndall_biog_doc.pdf
This might be the Tyndall(1865) Gsvin referred to “On Radiation: The “Rede” Lecture” on google books
http://books.google.com/books?hl=en&id=RT9-bP9p9zQC&dq=Tyndall+(1865)&printsec=frontcover&source=web&ots=hEJ5uRThUW&sig=5MF9_3kTsaWkGnO_WSQDGQBs2Fw&sa=X&oi=book_result&resnum=2&ct=result
It might not be the same work Gavin refers to, but it does discuss the absorption of heat by CO2 and basic experiments showing it.
Re: #167 (Robert Stenson)
You’ll find a lot of information about “classic” papers in climate science, including links to full-text articles, at this site.
Re #167 Robert Stenson:
Arrhenius is scanned and on line, link inside:
http://www.globalwarmingart.com/wiki/Image:Arrhenius_pdf
Tyndall apparently not, but a description of his measurements is:
http://www.tyndall.ac.uk/general/history/JTyndall_biog_doc.pdf
Current knowledge of greenhouse gas spectra is much improved. Play with it at:
http://geosci.uchicago.edu/~archer/cgimodels/radiation.html
HTH
# 167
Robert try reading Spencer’s Brief History (it’s on-line):
http://www.aip.org/history/climate/co2.htm#Callendar
Here’s a snippet
Then you could read through this:
https://www.realclimate.org/index.php?p=456
It might give you some links
PS. I *love* your thinly veiled assertion that the emperor has no clothes…it’s classic!!
Robert,
There is paper in The Quarterly Journal of the Royal Meteorological Society vol 67 p. 263 (1941) by G.S. Callendar entitled “Infra-red Absorption by Carbon Dioxide, with special reference to atmospheric radiation”. It summarises the experimental results up until that date.
There is also this site which contains the latest information on spectral lines in the atmosphere.
HTH,
Cheers, Alastair.
Timothy Chase, a quicky clarification: I didn’t think diatomic molecules like O2 could ever have a magnetic dipole… can they?
Rod B,
I think they can:
http://www.nature.com/nature/journal/v212/n5057/abs/212066b0.html
The National Geographic Channel aired the first part of a new documentary this evening, Earth: The Biography(previews can be seen at http://channel.nationalgeographic.com/series/earth-the-biography). The series is narrated by Dr. Ian Stewart, a senior lecturer in geodynamics at the University of Plymouth’s School of Earth, Ocean and Environmental Sciences.
The first episode was Volcanoes, and near the end of the show, Dr. Stewart discusses the snowball earth hypothesis and the (alleged) importance of volcanic CO2 emissions in re-warming the earth around 630 million years ago (you can view this segment at http://channel.nationalgeographic.com/channel/videos/player.html?channel=1797&category=31120&title=05511_00).
Although Stewart hints that the planet might not have been completely frozen, he doesn’t clearly explain is that it would have taken millions of years for atmospheric CO2 to reach a level sufficient to cause greenhouse warming, and he doesn’t mention any other greenhouse gases; according to a Wikipedia article on snowball earth(http://en.wikipedia.org/wiki/Snowball_Earth), CO2 and methane are thought to have risen over a period of 4-30 million years. I was surprised to see no mention of water vapor playing a role.
As AGW skeptics and deniers like to claim that volcanoes are the major source of atmospheric CO2, they are likely to seize on Dr. Stewart’s explanation of post-snowball earth warming by volcanic emissions of CO2 to bolster their argument.
Perhaps one of the RC moderators could comment on the snowball earth-CO2 warming hypothesis and its relevance (or lack of relevance) to current warming?
Chuck Booth wrote in 176:
Volcanoes did play a role in four out of five of the major extinctions, I believe. The one I am most familiar with (which is to say not very much) is the Permian-Triassic extinction, brought on by a supervolcano in Siberia which erupted for approximately a million years, laying waste to a huge forest and releasing huge quantities of methane from shallow deposits along the continental plate. The major waves of extinction took place during the first 15,000 years — if I remember correctly.
I am not sure that the AGW skeptics would want to remind people of this, but if they do, it underscores the fact that changes in carbon dioxide levels have in fact preceded changes in temperature. And it doesn’t do them much good — unless they can point to a supervolcano that is currently active. Additionally, we do have levels of oxygen falling in tandem with the rise of carbon dioxide — which is a smoking tailpipe of combustion.
Rod B asked in 174:
Not even a transient electric diapole (unlike carbon dioxide), but a magnetic diapole?…
Observations of the Magnetic Dipole Rotation Spectrum of Oxygen
H. A. GEBBIE, W. J. BURROUGHS, J. A. ROBB & G. R. BIRD
Nature 212, 66 – 67 (01 October 1966)
http://www.nature.com/nature/journal/v212/n5057/abs/212066b0.html
PS
Sorry, Paul, didn’t see your response — and we picked the same article, too!
Re #176 Chuck Bboth: pretty good video, that.
The problem I see is that it indeed seems to claim that it was volcanic CO2 that ended the snowball episode, and in a trivial sense that is true. The full story is that on Earth, on a time scale of hundreds of thousands of years, there is an equilibrium between these volcanic processes, and the absorbtion of CO2 back into the Earth’s crust by rock weathering and deposition of carbonates. It is the latter processes that came to an abrupt stop under the global glaciation: no rain, no rivers, little exposed rock, no plant roots opening it.
Water vapour was correctly left out of it: at Snowball Earth temperatures, it is virtually absent, and plays no role in coming out of it either.
If anybody wants to turn this into denialist propaganda, point out the difference in time scales: sub-century for AGW as against geological time scales for volcanism/weathering. Currently humans are releasing two orders of magnitude more CO2 than the world’s volcanoes combined, and it was no different back then. It was the slow, slow build-up in the absence of weathering that melted the snowball.
Of the possible relevance to current warming, it could be that it demonstrates that there were conditions in the past where total feedback was (due to albedo) over 100%. Both the glaciation and the deglaciation were “runaway”, due to ice sheets below 45 degs latitude. This particular runaway isn’t going to happen now, but the Earth system isn’t quite as self-regulating as some folks wish to think.
HTH
Re # 180 Martin Vermeer:
Thanks for your response.
That I knew.
I was assuming that as the earth warmed, the water vapor pressure in the atmosphere would increase, and act as a feedback to increase temp further. What am I missing here?
Paul (175), thanks, this was interesting. I’m not terribly versed in this, but in link’s summary hypothesis suggesting (showing evidence of) O2 rotation absorption, they talk of O2’s “permanent magnetic dipole” I can’t visualize how a diatomic molecule with identical atoms can possibly have a dipole, even if it’s one vibration DoF gets excited. Do you have any insight?
Timothy, I’m not sure if it should be electric or magnetic dipole. Electric makes more intuitive sense to me, but the link said “magnetic” dipole. ??
Martin, et al. In the slow but millions of years long release of CO2 way back then, why wouldn’t the CO2 have been absorbed out of the atmosphere into earth and carbonaceous rock (which I understand is far and away the largest carbon store), mitigating the temperature increase?
Chuck Booth (181) — Nothing. Once there was open ocean (and it is not clear that ‘snowball earth’ was ever completely covered with ice) then water vapor plays a role.
Rod B asked in 183:
Google Search: oxygen “magnetic dipole”
Result #9:
Rotational Lines of Molecular Oxygen
http://www.iras.ucalgary.ca/~volk/oxygen.html
Rod writes:
It is. There’s a dynamic balance between weathering, which removes CO2, and volcanism/metamorphism, which adds it. Weathering goes up with temperature, drawing out more CO2 when it’s hotter, and when it’s colder, weathering decreases and CO2 builds up. This “carbonate-silicate cycle” keeps Earth habitable over the long run. It has failed a couple of times when we’ve had “snowball Earth” conditions.
Chuck (#181):
That it will come too late to make a difference. The glaciation and the deglaciation are both “flip-flops” between two stable climate states, the snowball state and the “normal” one, which are some 60 degs apart for the same CO2 concentration. What happens in the deglaciation is that, as soon as equatorial temperatures rise above zero over a large enough area, a runaway deglaciation driven by albedo starts, and doesn’t stop until the Earth is not only ice free, but a super-tropical hothouse from pole to pole. The transition is very fast, mere centuries.
It takes a lot of CO2 to melt a snowball… we’re talking thousands of ppmv here. And at the point where the runaway starts most of the Earth is still frozen over and “aquaeous vapour” still well out of the game. But it gets its sweet revenge in the hothouse phase!
Rod (#184):
But Rod, that reaction requires running water! It works this way, that the rain “leaches” basic substances out of the rock and carries them to sea, where the “carbonic acid” is also dissolved. No rain, no rivers… just ice as far as the eye can see, under an ever-blue, cloudless sky.
(Are you aware BTW of the theory that the current succession of ice ages (modulated by Milankovic) was triggered by the rise of the Himalayas?)
Timothy (186), re O2 rotation. Thanks. Very interesting
BPL (187) and Martin (188), Thanks for the insight. Makes sense. Except some of Martin’s I didn’t fully follow: You mentioned the water leaching carbon out of the rocks (and delivering it to the ocean). I understand that process but am not sure the connection with rock absorbing carbon, not giving it up…?
No, I haven’t heard of the Himalayas effect on ice ages. Sounds intriguing and a little mind boggling! I’ll have to go investigate it.
Thanks to Martin, Tim, and David for setting me straight on CO2 warming of snowball (or slushball) earth. The remaining episodes of Earth: The Biography, on the origin of the atmosphere and the history of the oceans, look very interesting. As always with National Geographic productions, the graphics, animations, etc are outstanding. And its nice to have a narrator who’s a scientist, as opposed to a television or film celebrity.
Re # 186 Tim C and others: Oxygen as a magnetic dipole
If I’m not mistaken, this property of oxygen is the basis for measuring O2 concentration in air using a paramagnetic oxygen analyzer (e.g., http://www.aoi-corp.com/additional_information/oxygen_sensor_types)
(Sorry for veering off topic.)
Rod B (#190):
Not carbon, Rod, but rather, basic compounds like CaO which reacts with acidic CO2 to produce CaCO3, calcium carbonate, then deposited as sediment. (It’s more complicated than that, but that’s the idea.)
http://www.snowballearth.org/
Want to thank posters #168, 169, 170, 171, 172, and 173. for their comments. Working my way through the material and there is a lot of it.
Specific comment first to Timothy on #168:
Was not trying to replicate the atmospheric humidity and other potentially confounding factors in my “controlled” experiment but was trying to isolate the effects of CO2 concentration changes and its contribution alone to temperature changes from incident radiation that mimics the solar spectrum.
Went to the articles that you provided and came across that very neat spectralcalc. Had fun trying different scenarios.
However, the following comments/questions arose:
1) If CO2 is opaque to earthly reradiation then it is also opaque to incident radiation of the same wave number. Analogous somewhat to cloud cover which traps warming radiation at night but provides cooling umbrella coverage during the day.
2) What % of the incident radiation that caues warming whether primarily or secondarily thru reradiation is blocked by CO2 at the climatically important concentrations and how does that compare quantitatively to the energy that is reflected or reradiated from earth. In another words what is the energy balance sheet in the important CO2 absorption range.
3) My original question was related to temperature changes with changing CO2 concentrations and I am not sure how to take the spectral analysis and determine that.
4) It appears that my original “experimental” setup question is not valid since it was taking atmospheric gases with 380ppm of CO2 and was not considering the total number of CO2 molecules that would be encountered on a sun to earth trip. However, I am not sure that taking the number of CO2 molecules that would be encountered and stuffing them in a 1.25 or 2.5m tube at 1000 mbar replicates the situation either and as far as I know that is the way the experimental absoption setup is structured.
Robert, did you try the ‘Start Here’ link at the top of the page, and the first link under Science on the right side? You’re asking very basic, frequently answered questions that you may feel better about answering for yourself, since you can read the references and get a better idea of the weight of the evidence.
This may help. Remember the energy/wavelength relationship.
http://en.wikipedia.org/wiki/Image:Solar_Spectrum.png
> opaque
beware that word, it will confuse you. It absorbs and emits infrared (handing the energy off to surrounding molecules or, if emitted near the top of the atmosphere, having a good chance of losing it into space).
You’ll find this notional horse reduced to horseburger in several long threads here.
In response to Robert Stenson’s comment 193
First, I should let you know that I am not a climatologist or even a physics student. Just a coder in an unrelated industry. But I have hung around for a little bit — so I will help where I can.
Your “questions” 1, 3 and 4 (or 1 for that matter) aren’t exactly questions. However, I will focus on 1 and 2.
You wrote:
True, but largely irrelevant. Carbon dioxide is almost entirely transparent to sunlight — including the infrared. You can see this here:
Solar Radiation Spectrum
http://www.globalwarmingart.com/wiki/Image:Solar_Spectrum_png
… and here:
Atmospheric Transmission
http://www.globalwarmingart.com/wiki/Image:Atmospheric_Transmission_png
… and in the first diagram the amount of energy which gets absorbed then re-emitted to space without making it to the surface would be roughly proportional to that small section of yellow directly above “CO2” to the far right. Of course it wouldn’t be exactly equal proportional to it as some energy is getting absorbed by other atmospheric constituents, transmitted via collisions, then radiated by CO2 and other molecules. However, to a first approximation, CO2 is simply transparent to solar radiation and opaque only to certain parts of the earth’s thermal radiation.
You wrote:
It wouldn’t make sense really to break carbon dioxide out this way. Radiation which gets absorbed by a given carbon dioxide molecule will typically be lost due to collisions with other atmospheric constituents. Above an atmospheric pressure of 20 mb, a molecule will typically suffer a million collisions or more over the half-life of an excited state. However, this is a quantum excitation, and as such excited molecules will have no memory of how long they have been in an excited state, and thus so long as a certain percentage are in an excited state at any given time, a certain percentage will undergo spontaneous decay over any given period of time. This applies as much to water vapour and methane as it does to carbon dioxide — where each atmospheric constituent will be exchanging energy with other atmospheric constituents.
As such, if you are interested in what is taking place in the atmosphere itself, what you need to do is model it — including this interaction. The following is a fair representation of the results:
The Energy Balance and Natural Climate Variations
http://www.cara.psu.edu/climate/climatechangeprimer-pr4.asp
In net, carbon dioxide is responsible for 1/10 to 1/4 of the greenhouse effect — depending upon how you calculate it, e.g., by removing all other atmospheric constituents and seeing what is left of the greenhouse effect, or by removing it and seeing what of the greenhouse effect is left when you have only the other atmsopheric constituents.
PS to my response to Robert Stenson
The following might interest you:
NASA AIRS Mid-Tropospheric (8km) Carbon Dioxide
http://www-airs.jpl.nasa.gov/Products/CarbonDioxide/
The image is carbon dioxide at 8 km. You will notice the plumes rising off the heavily populated east and west coast of the United States. What is being measured is the infrared radiation being absorbed and then reemitted by carbon dioxide at a particular wavelength — 15 μm, I believe. The thicker the carbon dioxide, the more opaque the atmosphere becomes to the infrared radiation in that channel. So in essence, you are seeing CO2’s enhanced greenhouse effect in action when you look at that photo.
re
#194,195
Hank
I used the term opaque in the sense of no tansmission ie 100% absorption of a specific wavelength as indicated in the spectrum charts on Spectralcalc . Realize that there is reradiation and also that the top of the column will be more likely to radiate into space.
The original question as to the availability of a CO2 temperature curve and the responses to that request is what has led me off into the deep weeds. I have no desire to review 200 posts. I thought the original question was fairly straight forward and that an answer would be readily forthcoming. Apparently not.
In any case it is dinner time and we are having horseburger.
Re: Robert #198
As you go up, you go through the well mixed CO2. At some height, you’re no longer 100% opaque (because the number of CO2 molecules left going up isn’t enough).
But, if you increase the amount of CO2, the amount you have from any height to the edge of the atmosphere increases too. So the height at which 100% opacity increases.
Now, when you insulate something like, say a loft or hot water tank, as you add another layer, you increase the insulating properties.
Does this seem to be familiar?
Remember ‘absorbed’ doesn’t mean soaked up and held permanently, taken out of play. That’s one word around which confusion often arises. The infrared from the surface is slowed down by more interactions but eventually does leave the planet.