Billy, you always have encouraged people to think, Now I encourage you to do some thinking: Statement: In essence, the amount of downwelling radiation of CO2 versus escaping radiation is solely depending on the emitting altitude expressed in IR optical depth counts above and below that emitting altitude (at the surface about 30 feet as far as I recall). As CO2 increases both optical depths above and below the emitting altitude are affected equally, which means that it does not affect the ratio in downwelling and escaping radiation. So the basic question is, what the emitting altitude is doing, which is almost completely dependent on the vertical density of water vapor.
It is a very complex question - I can only offer a few comments: First thing to note is that the run-away to "Venus like" hot state of Earth will not be due to CO2 alone. This is obvious as I think it true that the atmospheric CO2 concentrations have been about 10 fold greater than they are today and Earth is not now trapped in the hot Venus like stable state. You are surely correct to focus on the water vapor, even if CH4 concentration are enormously increased from their current almost zero levels. I think Earth can only switch to that hot seterile state if the Methane is being releasted faster than it is being destroyed, so it too is accumulating in the atmosphere. It is at least 10 times more important, molecule by molecule than CO2 (The Forbes article of my link states 23 times more important, but this too is a complex separate question which depends up the density of excited states, the radition field it is absorbing in etc. and both of these depend upon the relatively local temperature.) Second point of complexity is that there is not one "emitting altitude" altitude as you seem to believe. The effective emitting altitude will differ for each of the radiative transition permitted. The stronger absorption bands will have a different emitting altitude form the weaker bands. What happens is that IR photons will be absorbed at one level and in a dense atmosphere may often not just reradiate this energy, but shair it with other molecules, not even of the same type!, via collsions. We are not talking about solids radiating black body continium here nor isolated molecular radiators but something inbetween. Another way to summarize this is to observer that molecule species has it own sprecrum of absorption bands and every absorption band of each type will have a different physicsl length associated with "one optical depth." Thus I have no idea what the radiative distribution vs. altitiude will be and further more the micro-scopic collisonal transport and the gross convective transport of energy will be enormously complex also. The gross convective transport will at least be simpler than it currently is near the surface of the Earth with H2O now exisiting in two states with 540 callories/ per gram separating them. That is to say once the temperature is greater than the local presure controlled boiling point of water there are no clouds of water droplets at that altiude. So Third complexity (and very important thermal transport factor) is that there is no rain at that altitude. Rain is a very efficient mover of thermal energy as anyone who has seen hail surely knows. I expect that the surface region of the atmosphere will be come "rain free," but I am just guessing on my intuition. One could do better if they were to look up the steam tables and see how the proessure and boiling point of water are related at high pressure. I expect that it will be continuously raining at some higher altitudes. This falling rain evaporating as it falls into hot lower layers will help cool them but make the temperature vs altitude profile more complex to model than if only radiative and convective trans port of energy were active. In spite of all of the above complexity, I do however think that the energy transport (but not the photon distributions) will be in equlibrium (which we can assume) be the SAME net upward loss rate at all levels. Thus, without actual analysis, here is what I guess: Initially as the CH4 begins to make a significant contribution to the IR absorption, the surface air temperature will increase. This will increase the rate of ocean evaporations and reduce the rate of cloud formation, near the surface but not much change the effect of clouds on the net energy flux, both IR escape and the solar to surface flux. However the increased H2O vapor will be a feed-back to increase the CH4 release more, which in turn will increase the H2O released by the oceans more etc. This is not necessarily a disaster for life on Earth as just because positive feed-back does exist, does not mean it leads to a run-away thermal switch to the hot Venus like state of Earth. This positive feed-back is in fact now in progress. The methane release rates have been measured and definitely are increasing. The critical question is: Is the loop gain increasing? Or worse: Is it already greater than unity? I do not think anyone knows the answer to either question. Nor do I think it can be accurately answered by models due to the extreme complexity (only part of which I have mentioned above.). If it is already greater than unity, then the Earth will become sterile and there is nothing we can now do to stop that. If, however it is still less than unity, but growing, we must try to keep it from reaching unity. In view of mankind's ignorance, I think it very prudent to stop de-sequestering petroleum as rapidly as possible. Again let me state that it is not the CO2 build up by its self that is troubling. It is the complex ill understood dynamics of the entire atmospheric system and especially the scary possibility that the RATE of CO2 release is causing a RATE of methane release in excess of natural processes that remove it. (oxidize it mainly). SUMMARY: take no comfort in the fact that the concentration of CO2 has been much higher in the past - it is the RATE of increase that may be the problem. In closing let me ask someone to look up and tell what is the water boiling temperature at the highest pressure published in steam tables? I expect that there is a real danger that the surface pressure will exceed whatever any boiler has achieved, and that the surface temperature and pressure of the Earth will be significantly higher when only half of the oceans have been evaporated and cannot fall back as rain. I could be wrong on this as I do not know how half of the ocean mass compares to the present atmospheric mass but that should be easy for someone skilled in search to find also. As some of the ocean mass will escape in to space, probably the hottest surface temperature will be when about half of the ocean water mass is in the atmosphere. Then the surface pressure will be higher by the ratio of that half ocean mass to the current atmospheric mass. I am just guessing that pressure is greater than any ever achieved in any boiler.
The biggest factor on how much heat (green house effect) an atmosphere can hold is directly related to atmospheric weight or mass amount present. This correlates with pressure at the land/air interface. Venus needs less atmosphere (and some spin) to make it habitable while Mars needs at least double of what Earth has to make it habitable. Please Register or Log in to view the hidden image!
Billy, The biggest difference with Venus is that there is zero convection out there. The atmosphere is unconditionally stable. This makes that almost all IR radiation from the surface returns and cannot escape. On Earth we do have convection, raising the effective emission altitude of IR to mid throposphere levels, then other effects take place. I just wrote this to another club:
To Andre: I must say I admire your courage even to attempt any model, but considering the complexity, even only those I specifically mentioned in my post, I think it is not predictive of what will happen or what conditions will be. However, I encourage you to keep at it as at least you can learn the relative importance of these various energy transport mechanisms by ignoring some to permit analysis of one. I certainly agree that Earth is not the "simple case" Venus is because Earth does have convection and it is very important part of the overall thermal transport picture. I also directly mentioned in my post the fact that falling rain and hail is an efficient way to move "cold" down. Do you know if there is any rain high up in the atmosphere of Venus? Or is that atmosphere free from this complexity in its thermal transport also? Perhaps if no H2O rain there is some SO2 rain at some altitude? I certainly mentioned the fact that rising moist air masses have a very significant internal heat source in the 540 calories /gram of water vapor condensed and also noted that this will probably not play any role near the surface as it does now in "thunder head" clouds rising quickly (really a type of "Taylor instability" that feeds on its self) to even 35,000 feet. - (I was slightly bumped around by some on my last trip to the US from Brazil.) The reason why I think at the surface this convection may be much weaker or even possibly absent as on Venus is that I do not expect that the temperature will be low enough for near surface water vapor to condense, even though the boiling point will be much higher than 100C due to the huge pressure. I am too lazy to look up the information that is available in steam tables boiler designers use. I.e. as I stated in the prior post: "The gross convective transport may at least be simpler than it currently is near the surface of the Earth with H2O now existing in two states with 540 calories/ per gram separating them. That is to say once the temperature is greater than the local pressure controlled boiling point of water there are no clouds of water droplets at that altitude." Thus I am not ignoring the convective transport at all. If anyone is it is you in your only radiative transport model. Again I do not mean this as any criticism -at least you are willing to simplify and be quantative whereas I just guess not even WAGs sometimes. Keep at it. Your approach is better.
Well they haven't landed a robot on Venus yet - that's a guess. Yes a sudden Methane expulsion is going to be catastrophic for us. But not the Earth, and she's been through it before, probably multiple times. People need to realize, it's not about saving the "planet", it's about saving ourselves. The earth has been able to do far worse things than we can do (excepting perhaps letting off nukes in the fucking atmosphere, let's give the Americans and the Russians BIG GOLD stars for that bullshit). We need to do our usual thing that has gotten us this far. We adapt. Are we going to be able to control a natural occurrence(methane expulsion). No! We can't even control ourselves from making the air fucking disgusting in the big cities. That's the crux right there. You can ban the most heinous radioactives, but you cannot put a lid on carbon's. People do not give a shit that child athsma is at a rediculous level in some places, they sure as hell won't give up their job on the oil rigs so somewhere else it will stay 4deg C cooler. So we need to start planning for these kinds of things, even if they are 1000 years off, it will eventually happen. There will be a huge disaster at some point and the majority of us will be dead. We need to at least have some way to make 1-10% or more survive an extinction event. Otherwise, we are just spinning our goddam wheels here on planet earth and waiting for species death.
If we try, it should be a well insulated boat and able to float in moltant lead as there may be such lakes on the surface. Earth is farther from the sun so that will never happen here. - Earth can boil away most of the oceans into space if the atmospheric blanket get IR absorbing enough. But it will be mainly water vapor, not CO2 nor CH4 that is dominating the absorption of IR trying to leave Earth.
Actually we do know more about the surface of Venus than that of earth, which hides all the ocean for us. The key word is Magellan. No moltant lead seas, only extinct volcanoes, lava streams, coronae, and many unexplained features, suggesting an even much hotter past. Combine that with the loss of spin and there may be a completely different story for Venus. And yes the Russians have made several landings on Venus, decades ago.
To Andre: Thanks for the information and correction. I long ago had read that the surfact temp of Venus was higher than the melting point of lead so simply concluded from this that there could be "lead lakes" on Venus. Perhaps the surface temp is now thought to be lower than lead's MP? I went to your sites but did not quickly see surfact temp data. Anyway thanks again for correcting me.
you're welcome. I did Venus for a study case and linked the heat to a sudden breaking of the rotational spin by an inner core going wild against the mantle due to different precession cycles. This would have happened especially in the "Chaotic Zone" http://www.imcce.fr/Equipes/ASD/preprints/prep.2003/th2002_laskar.pdf The Venus resurfacing would have been cause by extreme friction heat between core and mantle when the Planet grinded to a halt. This would have ignited all the carbon and would have reduced all the limestone, producing CO2, which lead to the disappearance of the oxygen and the dense CO2 atmosphere. There is something to think about. Anyway, the short answer: average 470 degrees Celsius, the variation is only in the elevation, the lower the hotter, not in the lattitude. The poles are just as warm
This is exactly what one should expect if the atmosphere is at least two optical depths thick and convection is absent. (More on that soon). Imagine that some spot on surface, "C," (for Cooler) were cooler than others. It would radiatel less and have an net gain of thermal radiation from the "others" which are hotter. (This is true regardless of what the absorption coefficient at "C" is, assuming it is non zero, of course.) Via the atmosphere if direct line of sight is prohibited. If convetion is absent, one can think of the surface as being inside an oven which has (or rapidly will achieve by the above radiative transfer abolishment of any spot like "C") uniform loss thru all parts of the "walls." If there were some convection, it too would tend to transport more energy to the atmosphere from spots near spot "C" than spot "C" would convectively send to the atmosphere above "C." Thus, from the atmosphere near and above "C" the atmospheric radiation into "C" would also be bring spot "C" up to the average global surface temperature. Once the entire surface has the same temperature, the thermal gradient must be the same at least up to the level where the assumption that there are two or more optical depths covering that altitude is invalid. In this lower "oven-interior" zone with ONLY vertical thermal gradients, there can be not convection as for convection to exist some sections of the atmosphere must be going down while others are going up, but with the same, purely vertical, thermal gradients this is impossible, unless there is something going on on the surface to disturb the spherical uniforimity, such as a volcano or hot lava flow from the interior. If Earth should get (OR ALREADY HAVE Please Register or Log in to view the hidden image! ) greater than unity thermal feed-back loop gain, then I strongly suspect the above logic applies to some surface contacting lower zone of Earth also. I.e. after the oceans have boiled away, say half having escape into space and half remaining as a thick, mainly water steam, atmosphere in at least the lower altitudes, there will be so much IR absorption by H2O molecules at altitudes below the "at least two optical depths" above still altitude that this will be true to quite a high altitude.* Thus I expect, that should Earth enter this cooler version of Venus stable state, the lower levels of the Hot Earth's atmosphere will, like Venus, be stable and have only a vertical thermal gradient. Surely at some higher altitude, with lower presures and temperatures it will be possible for the steam to condense. At that altitude rain will form and fall, which evaporates completely well before reaching the surface. I will use LRA to designate the Lowest Rain Altitude (Where 99.9% of the rain has converted back to steam). Above LRA, there will be convection as the falling rain will cool the atmosphere below it causing it to contract and thus increasint the rain fall there - I.e. the rain will cause growing instabilities, which in turn will dirve convetion. I think this is somewhat resembles what happens in the sun, but of course rain is not the cause of the convection zone of the sun. I.e. the deeper layers are convection free, spherically symetric and have only radiative transport of energy (neglecting the very much samller non-convective thermal conduction). ----------------- *One thing Humans can take credit for, it they get to some other location than Earth and if Earth does switch to the hot stable (Venus like) state is that we cleanded up most of the mess we earlier had left in low Earth orbit. - I.e. low Earth orbit altitudes will have many orders of magnitude higher atmospheric density and all the wrenches the astronauts droppped etc. will rapidly spiral down an burn up; However, the objects in geostationary orbit may seem very primative to the first aliens to find them, but at least they will know that life did originate around a star other than their own. -somethink we can only speculate about. Now that is what I call "spreading knowledge!" Please Register or Log in to view the hidden image!
The possibility carbon from man capable of harming the world doesn't exist. Big corporate smoke stacks might be another story. But pollution and global warming are two separate events. Humans are not doing the stuff that warms the earth. The warming is caused by underwater volcanoes for temporary shift of some sort that they always go through after many hundreds of thousands of years as a natural process. Humans aren't responsible ! Case dismissed.
Any evidence of these under water volcanoes? or just your fantasy? If they are not noted by observers, how do they cause the CO2 in air to increase. Nearly all who are informed think the ocean is removing CO2 from the air. Do you have some "special knowledge" all others lack? Please Register or Log in to view the hidden image!
Mechanism of the planet "grinding to a halt" against the angular momentum of its mantle and core? Does it have anything to do with whatever causes the greater CO2 heat trapping at lower altitudes to lead to net cooling there ? I was informed that had something to do with convection, but the details escaped me.
No not "special knowledge". Hardly my fantasy. Need not take that tone. Please Register or Log in to view the hidden image! right back a ya. As this remains unproven either way... Then how and why does everyone be so eager to adopt the theory about the CO2 in the air actually even increasing? And how their fellow man be the culprit. :fart: Must a some control freak who came up these theories. Some who agree: Indiadaily.com - Underwater volcanoes increasing global warming ... Feb 26, 2006 ... Global warming on massive rise due to an exponential rise in underwater volcanoes. The hot methane underwater can cause temperature of the ...http://www.indiadaily.com/editorial/7146.asp
I agree under water volcanoes are real, and given that Earth's surface in more than half water covered, probably more common that those on land. However, much of the gas they release will be absorbed in the water instead of releasted to the air. Those that do vent to the surface do add to the GHG problem and may release CH4, but the CH4/ water hydrates are much more serious potential problem, imho.
You have got to be kidding!!!! Anyone who uses the India Daily as a source of information immeditely puts their own credibility at GREAT risk!! That rag is well-known worldwide to be little more than gargabe and sensationalism at it's worst. For example, just take a look on that same page at the headlines for additional articles they have. Two of which are good indicators of the kind of trash they regularly publish: "Extraterrestial Influence on Human Minds" and "Super acceleration and deceleration of time inside a black hole singularity provide propulsion for advanced extraterrestrial UFOs". What nonsense!!!!!!!!!!!!!!!!!!!!!!!!!!!:bugeye:
If the atmosphere were to expand in reaction to warming, thus cooling itself, I wonder how much of an additional increase in cooling radiation would occur at the outer layer ?
quick answer to your quick question: it does exist, it just isn't a problem. Its perfectly normal. the same global warming that is going on here is also going on on mars. I'm pretty sure a few landrovers didn't do that to the environment.
But Nietzsche, there is a difference. In the past these changes were natural, now it is man-made. What you are saying is equivalent to saying that it's ok to tackle a kid and then say: "It's no problem that I tackled him and that he's now bleeding. His wounds will heal. I know so because he tripped a couple of times before and his wounds always healed."
