A couple of months ago, we discussed a short paper by Matthews and Weaver on the ‘climate change commitment’ – how much change are we going to see purely because of previous emissions. In my write up, I contrasted the results in M&W (assuming zero CO2 emissions from now on) with a constant concentration scenario (roughly equivalent to an immediate cut of 70% in CO2 emissions), however, as a few people pointed out in the comments, this exclusive focus on CO2 is a little artificial.
I have elsewhere been a big advocate of paying attention to the multi-faceted nature of the anthropogenic emissions (including aerosols and radiatively and chemically active short-lived species), both because that gives a more useful assessment of what it is that we are doing that drives climate change, and also because it is vital information for judging the effectiveness of any proposed policy for a suite of public issues (climate, air pollution, public health etc.). Thus, I shouldn’t have neglected to include these other factors in discussions of the climate change commitment.
Luckily, some estimates do exist in the literature of what happens if we ceased all human emissions of climatically important factors. One such estimate is from Hare and Meinshausen (2006), whose results are illustrated here:
The curve (1) is the result for zero emissions of all of the anthropogenic inputs (in this case, CO2, CH4, N2O, CFCs, SO2, CO, VOCs and NOx). The conclusion is that, in the absence of any human emissions, the expectation would be for quite a sharp warming with elevated temperatures lasting almost until 2050. The reason is that the reflective aerosols (sulphates) decrease in abundance very quickly and so their cooling effect is removed faster than the warming impact of the well-mixed GHGs disappears.
This calculation is done with a somewhat simplified model, and so it might be a little different with a more state-of-the-art ESM (for instance, including more aerosol species like black carbon and a more complete interaction between the chemistry and aerosol species), but the basic result is likely to be robust.
Obviously, this is not a realistic scenario for anything that could really happen, but it does illustrate a couple of points that are relevant for policy. Firstly, the full emissions profile of any particular activity or sector needs to be considered – exclusively focusing on CO2 might give a misleading picture of the climate impact. Secondly, timescales are important. The shorter the time horizon, the larger the impact of short-lived species (aerosols, ozone, etc.). However, the short-lived species provide both warming and cooling effects and the balance between them will vary depending on the activity. Good initial targets for policy measures to reduce emissions might therefore be those where both the short and long-lived components increase warming.
491 Chuck Kutscher: I wouldn’t mind another lecture on that subject either. Especially the part where there is a 1000 year delay and then more CO2 comes out of the ground or somewhere. The somewhere is unclear.
What I do have is the ice cube in the glass of water thing. The oceans take a long time to heat up and then the polar ice including Greenland and Antarctica melt. After that, the temperature goes up because there is no more cold reservoir. So the whole thing takes how many years to get to 2 degrees C warming? Then it takes 100,000 years before it cools back off?
Comment by Ray Ladbury — 12 June 2010 @ 4:02 PM
Thank you Ray. I think you’ve hit the nail on the head. It’s a great reason why the U.S. Constitution was such a very big step in the idea of governments. It wasn’t based on fear, and not on religion as so many were. It was based on individual rights, and the government being a caretaker so to speak for those individuals that couldn’t do that for themselves. I’m not for big government, but I couldn’t defend the country as an individual, so I like to have a military to do so. I can’t guard the Gulf of Mexico from oil spills, but I would like the government to do so. I was against the Patriot Act, but I find a majority against government intrusion seem to find that intrusion against individual rights okay. I can’t speak for anyone here, but why is that kind of intrusion, (and not to speak badly) when it was a few thousand people okay to give up liberty and freedom when there is possibly thousands more if not millions on the line just in this country. We lose more than 10 times that from automobile accidents each year, but I doubt anyone would be willing to give up individual freedoms to protect them (not to the degree of the Patriot Act).
I know we cannot attribute single weather events to climate, but things are pretty consistent with what has been predicted by the science and models as of late.
Actually, Mr. Ladbury, it was onerous regulation, particularly in land useage, that led to the first Bolshevik revolts. The Tsar moved too slowly to undo them – by the time they started taking effect, the people had enough.
When we look past the revolution and into the Soviet Union, over regulation stifled not only personal freedoms but the economy as well.
Do we need to discuss the Cultural Revolution in China?
The EPA has stated they will go after the largest emitters of GHG’s first, as the administrative system cannot handle the flood of permits that would be required on every industry and home, but starting in 2016 the paperwork hurdles should be solved and they can address every GHG emission source.
http://www.epa.gov/NSR/documents/20100413final.pdf
“A. Does this action apply to me?
Entities affected by this action include sources in all sectors of the economy, including commercial and residential sources. Entities potentially affected by this action also include states, local permitting authorities, and tribal authorities.”
(emphasis mine)
Remember, the head of the EPA is appointed based on political merit. And every four years (if not sooner) there is a chance he will be changed, based solely on political expediency and agenda of the Executive.
Do you really want to leave the problems of GHG emissions in the hands of a political appointee who can at will change climate policy for the nation with oversight after the fact? In all possibilities of Presidental election outcomes?
Norman (494)
1) You need to better carefully distinguish between the incoming solar energy and the outgoing terrestrial energy. Water vapor does absorb solar radiation, but its effect is about 5 to 10 times less as a feedback component than its longwave impact.
2) Both water vapor and CO2 absorb over a wide range of wavelengths, not just at one particular wavelength (which would generate no greenhouse effect). Even as the centers are completely opaque, there’s always more absorption waiting out in the “wings” of the spectral bands.
3) See A saturated Gassy Argument written a few years ago at RC for a discussion of saturation, as well as greater context into the role of the temperature structure of the atmosphere (also Part 2 linked inside, and I have a somewhat more detailed discussion here…anything much more and you’ll have to hunt down a good textbook on the subject). Even in the opaque case it is still possible to increase the temperature with more greenhouse gases by making the planet radiate primarily from colder layers.
Norman #494, you have to look at the full spectrum. Yes, the centre of the band is saturated, but the flanks are not, and these will move outward when CO2 is added.
Play with David Archer’s modtran simulator to see for yourself. Enlightening.
http://forecast.uchicago.edu/Projects/modtran.doc.html
“nearly all the radiation is totally absorbed before it reaches the ground. Would more Water vapor and CO2 cause more absorption at this wavelength?”
Yes. There would be more absorption at that wavelength because there is more of the absorbing gas at higher levels. This absorbs the wavelength and therefore there is more absorption taking place.
Your other error is thinking that the main IR flux is coming down.
It’s going out, not coming down.
“This doesn’t make sense to me. Anthropogenic greenhouse gases create a transient, not steady-state, heat transfer problem.”
Well the non-steady-state is a transient feature, but what feature of the gas is caused by its production from anthropogenic causes makes the IR absorption effect of that gas transient?
“I, too, doubt the EPA would actually be so draconian in the control of CO2. But make no mistake, it’s possible”
It’s also very unlikely, to the case of astronomically high probabilities against happening.
It’s also possible that the EPA regulation is a NECESSARY element of avoiding catastrophe. Since the EPA are a part of the elected US government and the effects of CO2 are not reversed by a popular pole, this is an extremely likely proposition.
Isn’t it far more possible that NOT allowing EPA to regulate would allow companies to continue to pollute?
Isn’t that EXACTLY why the EPA were set up, and the examples of pollution without hooting is EXACTLY what happens even WITH regulation but no enforcement?
“can you give an estimate of the minimal amount of fossil fuels we are supposed to burn per year,”
nil.
Who said anything about BURNING it???
You’re fixated like a pyromaniac.
494 : Norman. The radiation is actually continuously absorbed and reemitted at the wavelengths where the atmosphere is optically thick. Rather than “absorbed’, you should think it as “thermalized” since the final result is to set the specific intensity of radiation at the local temperature of the absorbing medium (more precisely : at the excitation temperature of the relevant degree of freedom, i.e. here the vibration of GHG molecules).
This is not exactly a “warming” but rather a slowing of the heat transfer, much like insulating the walls of your house. It produces an “absorption line” from outside because the last surface of emission is as a higher altitude and thus normally cooler (although an inversion of temperature profile could produce an emission line like in solar corona). But if you increase the concentration of GHG and wait for enough a long time until a new equilibrium value is reached, there is no net “absorption of heat” by the atmosphere – the temperature keeps steady and no net heat is absorbed, it is only transmitted more slowly. But, for a given effective temperature outside the atmosphere, the temperature gradient is higher and the ground temperature is also higher.
”
#448 flxble
“Yes, it is possible to have gains in GDP and reductions in FF use.”
You won’t find any post of mine where I’m denying that.””
Shit.
I need *another* keyboard.
Gullible, there are REAMS of posts where you state CATEGORICALLY that reducing Fossil Fuel use means reduction in GDP.
“The EPA is not going to make a regulation like that. — Edward Greisch
Did you get a secret message from EPA or something?”
Did YOU, Roddie?
“3. Do you have children? ‘Nuff said.”
If you DO have children, why?
The average length of a generational family is 5 generations, IIRC. Not everyone survives to bear children. Not everyone dies with children to carry on the name. And the average distance forward to the last child on the branch to reach that state is 5 generations.
So why have children?
Hope.
But it seems that some people hope that they get all the wonga they can now, and screw the future.
Rod B 489: BPL (478), you just can’t deal with the elephant in the room, can you? Evidently your “spurious regression” and “autocorrelation in the residuals” told you it’s not there!
BPL: In your dreams, Rod. Go read the articles Ray cited and see how they did it.
Norman,
Because IR absorption takes place at all levels, and it is not saturated the lower the pressure. Radiation from the ground gets stopped soon, yes. But of radiation from the level stopping it, a little gets through to the next level up–and more from that level gets through to the next level, and so on. Adding more CO2 always increases absorption somewhere, because the upper levels of the atmosphere are always at low pressure. Check it out:
http://BartonPaulLevenson.com/Saturation.html
494
Norman says:
12 June 2010 at 9:06 PM
“I am still working on the theories behind AGW. I believe it is Barton Paul Levenson who worked out equations to show how CO2 Band saturation will not take place…more CO2 will continue to continue warming.”
BPL’s equations are not correct. And it is also incorrect to state that more CO2 will produce more warming at the same rate (it will not due to the logarithmic nature of infrared absorption at greater concentration).
Show us precisely where BPL’s equations are incorrect.
Chris Colose #504,
I read through the RealClimate link you attached to your post. Not sure I am buying this argument yet (although I might). Mars has 30 times the CO2 as Earth but has no warming from it. The high thin layers are too thin to warm from the ground based radiation to warm them enough to emit radiation back down (I would think if this argument was valid then you should be able to use Mars as a example to show how much warming thin layers provide, my reading has shown Mars has no greenhouse warming from its atmopshere…these readings could be wrong).
[Response: Not true. Mars has a greenhouse effect from CO2 but it is relatively small because of the low atmospheric pressure and the lack of any feedbacks via water vapour or clouds. – gavin]
1)My point was that the empirical tested radiation is almost completely absorbed coming in from the sun. Outgoing radiation would work exactly in the same way. If there is evidence a band can be fully absorbed it does not matter the radiation direction.
[Response: The frequencies of incoming radiation and outgoing radiation do not overlap to any relevant extent and so the complete absorption of high energy solar UV by ozone in the stratosphere has got absolutely nothing with absorption of 14 um upwelling long-wave by CO2. – gavin]
2)How far can the wings spread? You can look at IR spectrum of 100% CO2 and the band is so wide and that is it. The wings would not expand past the 100% point unless there was higher pressure.
Martin Vermeer #505,
Thanks for the link to the program. My problem with these is they are models. I am looking for solid empirical data (actual measurements) to prove or disprove the AGW hypothesis. I have read they are measuring downwelling Longwave radiation. But when I read through the articles they are actually just models. I am not against computer models and simulations but I am old school science. I need actual measurements to go with models. When I was taking Chemistry in College (many years ago), the textbooks would have graphs of the theoretical mathematical description of some interaction but then they would have the empirical actual tested interaction. The model theory would usually be fairly close but not exact. I am just trying to find some empirical data to support the claims and not more models (useful as they are). If the measurement shows near complete absorption of incoming IR (so that the addition of more water vapor or CO2 will have little impact) why would I believe a model or math calculations that show it does not do this?
Barton Paul Levenson #515,
Thanks for the link to your calculations. I am going to really work on understanding what you have come up with. Thanks.
CFU :”Gullible, there are REAMS of posts where you state CATEGORICALLY that reducing Fossil Fuel use means reduction in GDP.”
Again, CFU, my name is Gilles, and persistent provocation doesn’t help thinking you’re able to argue rationally. And probably causes more harm to the cause you pretend to defend than you think.
There isn’t any post where I claimed that reducing FF intensity is impossible – I just said first that it was limited , and that above some rate of decline, keeping a GDP growth would be impossible (implying of course that a ZERO, or even very low, consumption would destroy the industrial civilization – NOT “the” civilization, nor mankind of course). And second that even if we knew how to reduce FF intensity, there is nothing that would prevent to allow more people to use them (more cars, more big houses, more travels..) , increasing more GDP, instead of reducing the net amount of FF. That is , it wouldn’t change the bell shape of FF consumption , it would just improve how we use them – but a CO2 molecule has of course no idea of how it was produced and which economic use we had with it.
Richard Steckis #516,
I have been finding the same thing in my research on the topic. What I am really looking for is some empirical data to prove or disprove the non saturation effect.
I have an idea for a test (similar to the Angstrom one). Get the long tube and fill it with CO2 and other gases N2 and O2 and water vapor. Run a lot of tests with various concentrations and record the data. Put the whole thing in a radiation shielded testing device. Have a IR detector behind a shielded IR source and measure the backradiation. Get actual measurements to go with the model. Measure how much IR returns to the source of the emission with various gas concentrations. That is why I like science so much, it is not faith based. Empirical data collected in Newton’s day is as valid today as then. Does anyone have experimental data on this backradiation amount to prove the hypothesis?
Norman #519,
Sorry, I missed that you were looking at incoming Solar radiation. This is the wrong place to look for understanding the greenhouse effect. You need to look at outgoing thermal infrared.
About observations, they exist, I have seen them. From satellites looking down back in the 1970’s and recently. And from radiometers looking up at the sky. (And from Samuel Langley looking at the Moon!) Someone else may dig up the links for you…
Furry 500: I do keep firmly fixed in my mind that you’re a science fiction writer when I respond to you.
BPL: Furry advances the argument, BPL is an SF writer, therefore his argument cannot be taken seriously. Since this is directed at the arguer rather than the argument, it is a classic example of the ad hominem fallacy. You cannot take what Obama says seriously because he is a Democrat. You cannot take McCain seriously because he is a Republican. This falls under the larger class of “fallacies of distraction.” Anything but engage on the actual argument–usually because the person providing the ad hominem is weak on the ability to legitimately refute the argument in question.
Gilles 510: if you increase the concentration of GHG and wait for enough a long time until a new equilibrium value is reached, there is no net “absorption of heat” by the atmosphere
BPL: Wrong. Absorption by the atmosphere will be higher than previously.
RS 517: BPL’s equations are not correct.
BPL: They’re not “my” equations. They’re basic radiation physics. Want references?
Norman wrote: “What I am really looking for is some empirical data to prove or disprove the non saturation effect.
I have an idea for a test (similar to the Angstrom one). Get the long tube and fill it with CO2 and other gases N2 and O2 and water vapor. ”
Hmm. So you think that this isn’t a model? Very strange. This is your model atmosphere and your model atmosphere will most likely result in saturation unless you use a very long tube. I gotta tell you, It sounds to me like saturation is the result that you’re trying to find since you’re describing an experiment that is rigged to yield saturation. I would suggest that if you want to try to disprove established science that step 1 is: understand the established science that you want to disprove. Otherwise you’re just one more wanking blog “scientist”.
John E. Pearson #527,
Not sure you understand what I am getting at. The empirical evidence (measured radtiation that does not make it to the surface, a chart I linked to) suggests that incoming radiation will be absrobed to near extinction and additions of either water vapor or CO2 will not change this. So why would outgoing radiation change it?
I don’t think you understand what I mean by “model”. Model in the terminology I am using it is a computer simulation of real events. I think this is okay as a useful tool but it is not empirical data. Modeling the atmposphere to test it is not the same type, you are gathering actual measured values. I am not interested in determining saturation in the test I describe. I am interested in the back radiation flow. Not just a tube, maybe a series of tubes that can have various pressures (made of nonabsorbing material like certain plastics or halite).
Would the far end of the configuration (tube with very low pressure and few molecules density) be able to absorb and emit enough radiation to make it to the source of emission? Could it be detected. In this set up you could double the CO2 in the far end and see what type of effect it has on back radiation.
My problem is I can’t find the established science for the theory. I find computer models and simulations. No real experiment data or tests. I do understand the reported science, the upper fringes of the atmposphere will react to more CO2 by being more absorbive to IR radiation. I just would like some empirical measurements to go with it and I have a hard time finding any.
gavin,
Thank you for taking time to respond to my questions above. My point on the absorption of incoming radiation is that there is enough water vapor and Carobn dioxide to prevent solar IR incoming radiation from making it to the surface. Around 1400 nm wavelength. Additions of water vapor or Carbon Dioxide will not change this. Why would outgoing radiation behave any different in the atmosphere? If the incoming is mostly absorbed where any addition would not have much effect, why would the outgoing behave different?
[Response: But this nothing whatsoever to do with the greenhouse effect and actually has nothing much to do with CO2 either. 1400nm is a water vapour absorption line, not one for CO2. The absorption in bands relevant for emitted IR are not saturated. – gavin]
Re 522 Norman – Maybe not the kind of test you’re looking for, but you could consider what the satellite measured spectra of OLR (outgoing LW radiation (LW = infrared longer than ~ 4 microns, shorter wavelengths are included in SW radiation))) look like (graphed against black body radiation spectra for various temperatures). You can infer a saturation** taking place near 15 microns (CO2 band peak) and in some other places (water vapor), and maybe in some places (**the highest cloud tops), but you can also see that regions where the amount of radiation coming up could be further reduced. Very importantly, you can see that the OLR slopes downward from saturation into unsaturated parts of the spectrum. Knowing what contributes to the optical thickness both in the sloped regions (sloped relative to brightness temperature) and in broader unsaturated regions, it follows that increasing those things (at least if those things are well mixed, or otherwise, raising them up to higher colder levels, such as with clouds) must result in a decrease in OLR. (until temperature changes in response). The slope in brightness temperature on either side of the CO2 peak is also associated with CO2, and increasing the concentration of CO2 brings points on those sloped part of OLR graph closer to saturation, reducing the OLR in those places; it also lifts up (actually, depresses, if OLR brightness temperature is graphed upward positive – it may be thought of as ‘lifting up’ because the source of OLR is spatially lifted up from the surface and through the atmosphere)) more slope farther out from the center of the band as CO2 optical thickness starts to become significant there (based on the known shape of the CO2 absorption band)
Of course, if I’m not mistaken, the changes in OLR have actually been measured (right? I keep forgetting…).
** OLR can start to increase again when the optical thickness increases so much that the OLR starts to come significantly from the upper stratosphere. (In order to understand the effect on climate, one must consider the changes in upward and downward LW radiation over vertical distances. The forcing at the tropopause level after stratospheric adjustment is a key value.) Because the source of OLR from gases distributed from the troposphere through the stratosphere (including water vapor, although the concentration as a fraction of air drops ‘precipitously’ (pun intended) with height, it is still present in the stratosphere) is never concentrated just in the coldest levels, the brightness temperature of OLR will not actually reach all the way down to the minimum temperature in the vertical column. However, at wavelengths where the stratosphere is essentially transparent, very high clouds could bring the OLR brightness temperature closer to that minimum (offhand, I don’t know how close this can be.)
The application of mathematics to measurements of optical properties of materials to predict the effects of materials is really quite straightforward (there can be a lot of number crunching, but the principles are crystal clear).
“BPL: Wrong. Absorption by the atmosphere will be higher than previously.
”
Again, all absorbed photons are reemitted, since the line is saturated, and the amount of radiation contained in the absorption line doesn’t change when the radiation escapes the atmosphere. Only the radiative thermal conductivity decreases, so the temperature gradient is higher. It is much like the effective thickness of the atmosphere would have increased, since photons travel a longer distance (they are more often scattered) before escaping.
Rod B wrote: “SecularAnimist (463) et al, the only reasonable regulation is that which is very precise and very focused with very specific and explicit boundaries and objectives attached — as written by the legislature. Regulation that is broad and general is always a recipe for fascism heading for tyranny on its way to totalitarianism, which is why legislatures in democratic republics hardly ever (never?) do that — it would in effect turn over the legislative powers to the regulators.”
Rod, in the real world of the USA where I live, the legislature does not write precise and explicit regulations. That task is performed by the regulatory agencies pursuant to regulatory authority given to the agencies by legislation which establishes “broad and general” regulatory frameworks to be implemented with specific and detailed regulations by the agencies.
There is a very specific, well-defined process by which an agency drafts regulations, makes them available for public comment and review, revises the regulations, and then eventually publishes the final regulations.
And as is the case throughout the structure and function of the US government, the Executive branch power of the regulatory agencies is “checked and balanced” by the other two branches of government, since such regulations can be and often are challenged in court, and can be overturned by subsequent legislation.
Your comment indicates you have no knowledge of how this actually works in reality. Instead, you toss out a bunch of ill-informed generalities and outlandish, cartoonish bumper-sticker stereotypes about “fascism” and “tyranny” and “totalitarianism”. Really, that has got to be one of the silliest comments you have ever posted here.
At least you are not calling the EPA a “non-governmental agency” and claiming that limiting CO2 emissions will give the EPA the power to “regulate churches”, like Republican Senator Scott Brown, I’ll grant you that. But your comment is nearly that silly.
Re Norman – the greenhouse effect refers to the effects of the optical properties of the atmosphere for LW radiation. Absorption of solar radiation by the atmosphere does have effects but they are not the same thing. Absorption above the tropopause will** have a cooling effect on the troposphere+surface (negative forcing at the tropopause level). Absorption below that level affects the surface energy budget but doesn’t** have an effect on the tropopause level forcing. **EXCEPT that any increase in absorption could decrease the albedo (atmospheric absorption can intercept photons before they would have been reflected/scattered back to space, or after they have been reflected/scattered, preventing their escape.)
The Earth’s surface and atmosphere emit essentially no SW radiation (wavelengths dominated by solar radiation). In contrast, depending on optical properties, both the surface and the atmosphere and any layer thereof (except where absorption is nearly absent), can emit significant amounts of LW radiation. If the opacity is large, radiation emitted by the top layer of the atmosphere might not reach the surface, but radiation emitted by the lowest layer will reach the surface. Saturation is reached when farther compression of the ’emission weighting function’ (a description of where radiation reaching some location is being emitted) can no longer significantly change the brightness temperature. This doesn’t happen everywhere at the same time; it depends on how temperature varies relative to optical thickness, and aside from lapse rate (temperature variation with height) changes over height, optical thickness per unit air mass path (much less geometric distance) is not constant – there is the matter of line broadenning and line strength changes, but also, very importantly for clouds and water vapor (and ozone), the concentration of the material that is absorbing and emitting radiation is highly variable. Water vapor in particular is much more abundant near the surface than in the upper troposphere or stratosphere. Thus, at least for wavelengths dominated by water vapor (and aside from clouds), LW flux aturation at the surface will tend to be reached long before saturation at the tropopause or at the top of the atmosphere. Furthermore, it is possible absorption by the whole atmosphere can approach 100 % without saturating the fluxes at some levels (consider the room for farther change in LW flux both at the surface, tropopause, and top of the atmosphere, when a mid-tropospheric cloud layer blocks nearly 100 % of radiation).
528: Norman, your comments indicate that do not you understand the basic science at all. I would suggest you learn the basic science that you are hoping to disprove. As far as your imaginary experiments not being “a model” how do you figure that they aren’t? You’d like to take the results of laboratory experiments and draw conclusions about planetary atmospheres. That is modeling.
Norman #519 (cc: Martin #523, Patrick #530),
On the first day of Christmas, BPL gave to us a nice reference list on the observed spectra of outgoing longwave radiation. Better than a partridge in a pear tree.
Norman, I think others have set you off on a good starting path, so just a few more words. I also suggest David Archer’s MODTRAN model (accessible from the saturated gassy argument link) to play around with different CO2 concentrations and see the changes to the transmission curve on the screen.
There is still a large difference between the IR energy coming in from the sun and outgoing IR energy from the Earth to space where CO2 strongly absorbs (this spectrum can be further decomposed into the near and far IR). Understanding the spectral selectivity is crucial to understanding the greenhouse effect. Greenhouse gases are not grey gases which make the atmosphere opaque throughout the whole spectrum. CO2 makes our current atmosphere opaque between 14 and 16 um and partially so some distance away from those edges. For now you can think of the outgoing energy from the Earth as all that is relevant to this picture. See the image http://www.sundogpublishing.com/fig7-6.pdf [PDF file] and note the individual contributions of CO2, CH4, H2O ,etc. The total transmission at the bottom is obtained by multiplying the individual transmittances for each constituent. If you play around with Archer’s model, you will see that at the 15 um band even the stratosphere is strongly absorbing (and thus virtually no transmittance since absorption = 1-transmittance, where transmittance = exp(- optical depth) in a non-scattering atmosphere). Near the edges the absorption is present but not as strong. As you add more CO2 you fill up more and more of the absorption that can place in the wings, continuing to decrease the area under the Planck curve and decreasing the planetary emissivity for a given temperature. Note that even on Venus which is some 90 bars of CO2 the whole atmosphere is not completely saturated, although here the “thinning and cooling” component of Ray Pierrehumbert’s post is relevant. Suppose you outgas some pulse of H2O (which does not condense on that planet). You can still make the temperature warmer in an optically thick atmosphere by adding more greenhouse effect to the upper layers which are thin and not well absorbing.
A suite of models in the IPCC AR4 gives a radiative forcing due to a doubling of pre-industrial levels of CO2 between 3.39 and 4.06 W/m2 (Forster and Taylor, 2006) and LBL codes of ~3.7 W/m2 (Myhre et al 1998) which is valid across a wide range of doublings under Earth-like conditions. This all takes into account “saturation” effects and the log dependence between the reduction in outgoing radiation and concentration.
Anonymous Coward (497),
The banning of a number of hugely popular narcotics was done through constitutional legislation with very specific procedures and limits.
Frank Giger (503),
Looks like I was wrong. The EPA is not limiting itself to transportation (“mobile” sources) in its CO2 enforcement.
CFU (508),
Police states are always formed out of some perceived necessity. The EPA is not an elected body.
[Response: OK, let’s veer this discussion back onto the relevant science. This is too far afield and has gone on too long–Jim]
The police aren’t an elected body either.
~~~Scary~~~~!
Gullible rewrites what he wrote earlier when he “re states” his position.
“Oh, did I say that I never said that GHG emissions meant reduced GDP? I meant I never said something else. Oooh, look! Ponies!!!”.
Gullible thinks we are all as gullible as he.
One reason why I didn’t bother linking is that in his travels across his own mind he won’t read anything and won’t admit anything and change what he has to admit to if all else fails.
What about REAL necessities? World War 2, for example. Or Cholera epidemics. Or, indeed, the catastrophes that have hit San Francisco at the turn of last century and Florida more recently?
“A. Where? Where? and … Where?”
A: Pump water uphill. Spin flywheels.
A: Pump water uphill. Spin flywheels.
A: Pump water uphill. Spin flywheels.
These are not exhaustive suggestions.
“…it’s a technical problem …”
I think we already know how water retains energy when pumped up hills. There is not a lot in the way of technical problem facing us there.
Don’t worry your pretty little head: engineers have answered your problem here.
BPL @ 524:
I asked if you knew how an electric grid works, not if you know what an ad hominem fallacy is.
I also acknowledged many posts prior that pointing out that you’re a SciFi writer =is= an ad hominem attack, however, I do it to point out that you’re … a science fiction writer and that you DO NOT have a clue how electric grids work.
Where are these storage things? Where are the transmission lines between those non-existent storage things and grid? What is the rated capacity of these non-existent transmission lines? How does the capacity of these turbines compare to synchronous reserves? Non-synchronous reserves? What are the expected up and down wind ramps from the turbines? Have you heard of wind ramps before today? What is the nature of the wind and how predictable is it? How do demand-following generators work? How much demand-response load is available? Is that load capable of both up and down regulation?
Answer those, then your assertion that being a science fiction writer qualifies you to make wild, inaccurate, and utterly useless statements might just be valid.
And no secret, magic, non-existent, science fiction technologies in your responses. Just demonstrate that if you had to manage an electric grid, you could actually do so.
SecularAnimist (532),
I guess you read very little of the US Code or State Laws.
I can’t recall from the cited EPA document if religious structures are explicitly listed. But residences are, so I would guess churches will be covered, too. There’s nothing Constitutional that says churches don’t have to obey the law (as a rule).
I dunno if anyone read the recent National Geo Magazine about Water, but one of the topics was the third pole. I think everyone can agree that sea level rising and ice melting isn’t good for any of us, but lets consider people who would never use this website…people in thrid world countries that are walking hours just to find water. I have a feeling that climate change has a much more drastic effect on them, just a feeling though…
Any thoughts?
Mike
http://www.gbb.org/doubleyourleads/
Norman, if you are referring to papers referenced here, and think this it is only “model”, then I think you need to read more closely. The methodology is use MODEL to calculate what spectrum filtered for water would look like given our understanding of GHG physics. Then you MEASURE the actual radiation spectrum, filter it for water and compare. That is using empirical data to verify a model result.
Furry 544 tries to dazzle ’em with the excrement of the male bovine:
” you’re … a science fiction writer and that you DO NOT have a clue how electric grids work.
Where are these storage things? Where are the transmission lines between those non-existent storage things and grid? What is the rated capacity of these non-existent transmission lines? How does the capacity of these turbines compare to synchronous reserves? Non-synchronous reserves? What are the expected up and down wind ramps from the turbines? Have you heard of wind ramps before today? What is the nature of the wind and how predictable is it? How do demand-following generators work? How much demand-response load is available? Is that load capable of both up and down regulation?”
BPL: Right, Furry. No fossil or nuclear or solar plant ever stored energy. It’s just science fiction.
Yet you’d have us believe you’re an expert on electrical utilities.
You think pumped hydro is something I made up? You don’t think any real power plants already use it?
Google is your friend, Furry.
Furry: “Where are these storage things”
They seem to be nearly everywhere, even Texass – shouldn’t be hard to pair some up with wind turbines.
Gilles says “Again, all absorbed photons are reemitted,…”
BZZZZZZZZZ!!!!!
Oh dear, Gilles, but thank you for playing. See the problem with this answer is that the absorption takes place mainly in portions of the atmosphere that are cooler than the regions of emission, so rather than emitting another photon, most of the excited CO2 relaxes collisionally. It’s called the greenhouse effect. Look it up.