|
Post by glc on Aug 2, 2009 18:17:50 GMT
ignoring glc's complete lack of any experimental data...
1. What do you think the motivation was for Arrenhuis and Tyndall more than a century ago. 2. Do you not think that the fact that the results from radiative transfer equations agree with measured emission spectra is fairly persuasive. 3. Laboratory experiments are able to measure the amount of light absorption through CO2. Why do you imagine CO2 would behave differently in the atmosphere.
I have no idea how long this trend will continue, but it sure looks a lot bleaker for the proponents of a "tipping point" with respect to Arctic sea iced this year.
Considering the models predicted we wouldn't reach current ice extent levels until ~2050 this is a somewhat puzzling statement.
|
|
|
Post by nautonnier on Aug 2, 2009 18:47:21 GMT
So "basically convection just shifts energy around"? You are either being unnaturally glib or ignorant. Convection transports heat upward from the surface to the tropopause huge amounts of heat that are NOT radiation. The heat transported by convection of warm air and by state change of water is not intercepted by any green house gas and bypasses the most dense levels of the atmosphere in which most of the CO2 is to be found. Not only that but the input radiation is reduced by the SAME convection due to albedo being raised as water vapor and droplets turn to ice crystals in the upper troposphere.
It is of course true that heat can only leave the Earth at the TOA by radiation. Your last sentence says it all. The only way that earth's climate system cools is by radiation. It is by radiation alone that the climate is regulated. The earth receives ~235 w/m2 from the sun and emits ~235 w/m2 at TOA. I'm just wondering how many more ways there are to say the pretty much the same thing. The main point is that an increase in greenhouse gases will reduce the amount of outgoing radiation Do you agree with this? As far as the rest of your post is concerned you are simply describing well understood climatological processes. Yes the input radiation is reduced by the albedo. That's why average incoming radiation is ~235 w/m2 and not ~342 w/m2. So what? What's your point? I know this. I know that the surface is cooled by convection and evaporation. Again you use these obvious facts in what I can only assume is an attempt to give an appearance of complexity and confusion. You state that "The heat transported by convection of warm air and by state change of water is not intercepted by any green house gas and bypasses the most dense levels of the atmosphere in which most of the CO2 is to be found."There is some truth in this but again it is misleading. Earth's emission spectra shows the radiation emitted to space at different wavelengths. It's quirte clear that a significant proportion is emitted in the CO2 band at much higher (and drier & colder) altitudes. It doesn't bypass CO2 in the way you claim. Emission from CO2 is dominant in the upper troposphere. The additon of CO2 will increase the concentration at higher levels. This will result in an increase in the average height at which emittance takes place. PLEASE TRY TO FOLLOW THIS BIT. If radiation is emitted from a higher level - it will be emitted from a colder level. If it is emitted from a colder level the amount of energy emitted will be lower . This is a consequence of the Stefan Boltzmann Law (i.e. E is proportional to T 4). In order to maintain equilibrium (incoming=outgoing) the atmosphere must warm. How much depends on the increase in thickness of the abosrbing layer. Now back to your convection/latent heat stuff. If the addition of CO2 either directly or indirectly changes the albedo (or some other factor), then this would be considered a feedback. This is a separate issue which is not considered in the equations I cited to calculate the primary change in forcing. As for other bits of your post. I don't think you've though through your proposed "experiment". Either that or I haven't read it properly. Whatever, we have plenty of evidence of the greenhouse effect from emission spectra measured by satellites. One step at a time (and this is not really an ice issue). "Your last sentence says it all. The only way that earth's climate system cools is by radiation. It is by radiation alone that the climate is regulated. The earth receives ~235 w/m2 from the sun and emits ~235 w/m2 at TOA. I'm just wondering how many more ways there are to say the pretty much the same thing. The main point is that an increase in greenhouse gases will reduce the amount of outgoing radiation
Do you agree with this? "You are avoiding the issue by oversimplification. I do not see a black and white issue that you see. I see a system that can respond by bypassing much of the ghg (a point you acknowledge as 'having some truth in it'). I also see a system that can increase its albedo reflecting away much of the input energy. So a simple radiation model of the atmosphere is extremely imprecise. You cannot define the TOA surface area - so how can you define 235Wm -2 ? So yes - it appears that the only way input energy can leave the Earth is as radiation. But the INPUT can be moderated by atmospheric processes. The atmosphere has shrunk considerably so the number of square meters is "The additon of CO2 will increase the concentration at higher levels. This will result in an increase in the average height at which emittance takes place. PLEASE TRY TO FOLLOW THIS BIT. If radiation is emitted from a higher level - it will be emitted from a colder level. If it is emitted from a colder level the amount of energy emitted will be lower . This is a consequence of the Stefan Boltzmann Law (i.e. E is proportional to T4). "The radiation blind spot. PLEASE TRY TO FOLLOW THIS BIT Water droplets being carried to the tropopause freeze and give up energy outside the CO 2 band - they are actually at a higher temperature than the surrounding air as they radiate to cool down to that level. The radiation may be at a level where the normal OAT is ~ -50C but the water is only just freezing. That is that heat energy can get to the tropopause not as radiation and radiate at a temperature that is well above what would be expected in an ICAN adiabatic lapse rate. This becomes especially true if the surface temperatures and humidity are high leading to an unstable atmosphere such as in the tropics. At the same time the ice crystals start reflecting out the inbound short wave radiation. I am sorry but I deal with REAL atmospheres not imaginary stationary ones. Your arbitrary splitting of the behavior of the atmosphere into inputs and feedbacks is fine - but REMEMBER TO ADD IN THE FEEDBACK when you calculate - so you say the input radiation is ~235 w/m2 but this is not true if a large amount of that input is reflected back so it never enters the system and therefore is not part of the budget that you are calculating. The experiments that you say have been done have assumed levels of radiation - it is simple enough to put a known IR source on the surface and actually confirm what you are claiming. But that would be physics not mathematical models and hypothesizing.
|
|
|
Post by icefisher on Aug 2, 2009 18:53:48 GMT
The main point is that an increase in greenhouse gases will reduce the amount of outgoing radiation Do you agree with this? I would like to see some evidence of how much. I don't know much about radiation but they say a good absorber is a good emitter. So replace a nitrogen molecule with a co2 molecule and you get more absorption and more emission. So you say 50% is emitted backdownwards to the surface. I say hogwash! If that were true then CO2 would play no role whatsoever in warming the atmosphere. The red dog is supposed to fill this role. CO2 capturing and reradiating is supposed to warm the mid to upper troposphere. It will do it more there because water vapor is going to block IR coming back and also carry it from the surface. Yet we don't see the evidence of the additional warming there. If radiation is emitted from a higher level - it will be emitted from a colder level. If it is emitted from a colder level the amount of energy emitted will be lower . This is a consequence of the Stefan Boltzmann Law (i.e. E is proportional to T 4). In order to maintain equilibrium (incoming=outgoing) the atmosphere must warm. How much depends on the increase in thickness of the abosrbing layer. Lets start in the upper atmosphere. Here the warming will be the greatest, because IR reemitted back at the surface is going to get sucked up by water vapor, clouds, and denser layers of CO2 and conduction from warm molecules to IR transparent molecules. What gets back to the surface could be quite minimal in relationship to what the alarmists claim. I don't think anybody disagrees that more gases in the atmosphere leads to a warmer planet but the amount of gas we are talking about is miniscule in relationship to our total atmosphere so the elevation effect you claim is going to be quite marginal. Now the elevation argument is a very strong one for a place like Venus or Mars where the vast majority of the atmospheres are CO2. Double their CO2 and it will get a lot warmer because then you are talking one heckuva a lot of additional CO2.
|
|
|
Post by radiant on Aug 2, 2009 19:16:55 GMT
I can see that the simplification that CO2 which is an absorber emitter as if by magic can remove energy from the atmosphere is naive and now i am thinking about it i suppose a none absorbing emitting atmosphere can be warmed by convection but at night it would cool very rapidly as would the earth.radiant Convection only operates in the lower atmosphere (the troposphere). Basically it just shifts energy around. The key to greenhouse warming is the incoming/outgoing balance at the top of the atmosphere. Averaged across it's surface the earth (and it's atmosphere), receives ~235 w/m2 from the sun. To maintain a stable temperature the earth must emit ~235 w/m2 back to space from the "top of the amosphere". It is only by radiation that this can be done. The surface can be cooled by latent heat, convection, etc but the earth, as a system, gets rid of the incoming ~235 w/m2 by radiation. A significant proportion of this outgoing radiation is emitted at higher altitudes by CO2. If CO2 concentrations increase then the outgoing radiation will be reduced. There will be an imbalance. To restore the balance the atmosphere will warm which (by Stefan -Bolzmann) will cause an increase in the energy emitted. I am not sure if i am rewriting the science of the atmosphere here or just getting confused convection takes hot air to a relatively small altitude where the air is thinner and very cold. Some of the energy radiates back to earth and some radiates to space. But whatever gets absorbed up there is not sufficient to majorly warm the clear air at relatively low altitudes of say 30000 feet And a green house prevents movement of air out of the green house and it preferentially retains low frequency radiations so that all radiations entering can only leave by low frequency radiation but a significant chunk of the work is done by physically preventing the warmed air from leaving the green house. The earth is very similar. The air at the immediate surface becomes very warm but air only slightly higher is colder by about 1.5 degrees per 1000 feet i think a chunk of that reduction might just be because there is less mass of air since by 18000 feet the pressure is about half. Away from the convection of the earth and the air warmed by convection it must be true that the atmosphere has a very poor ability to retain heat? It must be true that the bulk of the work of the green house effects of convection retention (because the atmosphere has no natural ability to rise very high even when warmed) and IR absorption happen very low in the atmosphere. At 30,000 feet apart from the odd penetrating thunder head it is exstremely cold as we all know. If there was significant absorption going on the air at altitude would not be cold since it is bathed in the enormous radiation of the sun all day long and yet still cold. I am not saying C02 has no effect but just wondering how much effect it does have.
|
|
|
Post by nautonnier on Aug 2, 2009 20:08:31 GMT
I can see that the simplification that CO2 which is an absorber emitter as if by magic can remove energy from the atmosphere is naive and now i am thinking about it i suppose a none absorbing emitting atmosphere can be warmed by convection but at night it would cool very rapidly as would the earth.radiant Convection only operates in the lower atmosphere (the troposphere). Basically it just shifts energy around. The key to greenhouse warming is the incoming/outgoing balance at the top of the atmosphere. Averaged across it's surface the earth (and it's atmosphere), receives ~235 w/m2 from the sun. To maintain a stable temperature the earth must emit ~235 w/m2 back to space from the "top of the amosphere". It is only by radiation that this can be done. The surface can be cooled by latent heat, convection, etc but the earth, as a system, gets rid of the incoming ~235 w/m2 by radiation. A significant proportion of this outgoing radiation is emitted at higher altitudes by CO2. If CO2 concentrations increase then the outgoing radiation will be reduced. There will be an imbalance. To restore the balance the atmosphere will warm which (by Stefan -Bolzmann) will cause an increase in the energy emitted. I am not sure if i am rewriting the science of the atmosphere here or just getting confused convection takes hot air to a relatively small altitude where the air is thinner and very cold. Some of the energy radiates back to earth and some radiates to space. But whatever gets absorbed up there is not sufficient to majorly warm the clear air at relatively low altitudes of say 30000 feet And a green house prevents movement of air out of the green house and it preferentially retains low frequency radiations so that all radiations entering can only leave by low frequency radiation but a significant chunk of the work is done by physically preventing the warmed air from leaving the green house. The earth is very similar. The air at the immediate surface becomes very warm but air only slightly higher is colder by about 1.5 degrees per 1000 feet i think a chunk of that reduction might just be because there is less mass of air since by 18000 feet the pressure is about half. Away from the convection of the earth and the air warmed by convection it must be true that the atmosphere has a very poor ability to retain heat? It must be true that the bulk of the work of the green house effects of convection retention (because the atmosphere has no natural ability to rise very high even when warmed) and IR absorption happen very low in the atmosphere. At 30,000 feet apart from the odd penetrating thunder head it is exstremely cold as we all know. If there was significant absorption going on the air at altitude would not be cold since it is bathed in the enormous radiation of the sun all day long and yet still cold. I am not saying C02 has no effect but just wondering how much effect it does have. In actual fact the tropopause varies in 'height' dependent on latitude. In the tropics it can be as high as 50,000ft. There is (as you would expect ) considerable discussion on this and many papers now accept what they call a Tropical Tropopause Layer : "A growing body of observations and theoretical considerations suggests that the transition from the troposphere to the stratosphere is gradual, rather than a relatively sharp discontinuity at the tropopause. In the tropics, it has been suggested that a tropical tropopause layer (TTL) spans the transition region from the convectively dominated overturning circulation of the Hadley cell to the region of slow upwelling (primarily wave-driven) of the lower stratospheric Brewer-Dobson circulation."www.atmosp.physics.utoronto.ca/SPARC/News25/tropical.html
|
|
|
Post by glc on Aug 2, 2009 20:34:38 GMT
You are avoiding the issue by oversimplification. I do not see a black and white issue that you see. I see a system that can respond by bypassing much of the ghg (a point you acknowledge as 'having some truth in it'). I also see a system that can increase its albedo reflecting away much of the input energy.
What do you mean by "can respond". Lots of things "can" happen but unless you can show that there will be a change in the trend of other processes then we assume, for the moment, they remain constant. We are interested in what happens when we change one variable, i.e. CO2 concentration. This will change the amount of IR transmission through the atmosphere. Nothing else matters at this point. We're simply analysing the effect of doubling the level of CO2 in the atmosphere while all other factors remain constant. This leads to a change in forcing of ~4 w/m2 and an increase in temperature of ~1 deg C. If you disagree with this then you are also disagreeing with Richard Lindzen and most other leading sceptical scientists.
Now you may want to argue that, say, cloudiness will increase and the effect will be to dampen the warming. Fine - but that is a feedback. Lindzen happens to think that any feedback is low and possibly negative. In other words he believes that net warming may be less than 1 deg. Others think differently. But feedback is a separate discussion.
|
|
|
Post by kiwistonewall on Aug 2, 2009 21:27:18 GMT
By the way folks, the ice (Jaxa) is doing exactly what I said it would, sharply stopping its dive & levelling off to about 6 million sq kms.
Nothing unexpected - the thinner ice near Siberia will melt out, but the massively thick ice (as shown by photos from the Catlin expedition) will hold out. The Canadian side is cold, the ice is thick.
The Hijacking of this thread by conjecture, and naming this or that scientist thinking this or that I see has continued. Arrhenius's Victorian & discredited Science has been reborn by the greenies, along with Cow horns filled with manure in the full moon.
Time to get real & do science - not quoting authorities of long ago - that WAS the dark ages. It matters not a whit what x or y says when they are outside their specialty. They are just quoting other authorities and their opinions are irrelevant.
This was the state of Science in the dark ages - where authority ruled. Also the state of Science on Trantor in the decline of the Galactic empire. (Which was Asimov's placing the decline of the Roman empire into a fictional future setting ;D)
When people "think" about the problem, and quote authorities, we no longer have Science - but the inquisition. (Which was used to preserve Platonic science as much as the authority of Rome)
|
|
|
Post by bluecon on Aug 2, 2009 21:48:26 GMT
The NW Passage is all plugged up with ice and the sailboats are stuck in Tuktoyaktuk. Uni-Bremen showing the Southern Route of the NW Passage. iup.physik.uni-bremen.de:8084/nwp/nwp05.pngiup.physik.uni-bremen.de:8084/nwp/nwp06.pngThere is more than one sailboat in Tuk waiting for the ice to clear. www.aroundtheamericas.org/At this point it is very unlikely these sailboats will go through. (unless they follow an icebreaker) Reminds of the fellows that attempted to prove AGW by kayaking to the North Pole. July is the warmest month in the Arctic and now the temps will begin to drop off. Many years the melt ends in mid August.
|
|
|
Post by neilhamp on Aug 3, 2009 0:45:05 GMT
Thanks Kiwi and bluecon. At last we are back on topic!
|
|
|
Post by socold on Aug 3, 2009 0:58:40 GMT
I've been waiting for it to get back on topic again so I could post this. Anyone remember this graph? Or this one? Just noticed they hadn't been posted in a while so thought I would put them up.
|
|
|
Post by bluecon on Aug 3, 2009 1:05:03 GMT
This link is to an Arctic map with the temperatures. Cold on the Russian side now. Alert was down to zero last night and again today. Winter coming early? www.athropolis.com/map2.htm
|
|
|
Post by icefisher on Aug 3, 2009 2:46:49 GMT
Nothing else matters at this point. We're simply analysing the effect of doubling the level of CO2 in the atmosphere while all other factors remain constant. This leads to a change in forcing of ~4 w/m2 and an increase in temperature of ~1 deg C. If you disagree with this then you are also disagreeing with Richard Lindzen and most other leading sceptical scientists. LOL! While all other factors remain constant? Now thats a kneeslapper! If CO2 has an effect on other factors it certainly doesn't wait until its doubled then unleash it like a dam breaking. I could care less who you say I am disagreeing with, no way are those folks as messed up on this as you are. But I am going to just assume you are misreading them. I don't particularly object to your theoretical universe other than to note its entirely theoretical and has next to a zero chance of coming out with the same result in the real world.
|
|
|
Post by radiant on Aug 3, 2009 4:10:57 GMT
the ice (Jaxa) is doing exactly what I said it would Nothing unexpected The Hijacking of this thread by conjecture, has continued. It matters not a whit what x or y says when they are outside their specialty. They are just quoting other authorities and their opinions are irrelevant. If we rely on the Jaxa authorities at this point in time there is not much more ice than in the last two years and it is only the beginning of August. However i can add that the Finnish authorities say Finland had a below average June and July and my own thermometer shows August has begun very cool so far. ;D
|
|
|
Post by glc on Aug 3, 2009 7:50:07 GMT
LOL! While all other factors remain constant? Now thats a kneeslapper!
No-one says they will remain constant but at the moment you have no way of knowing which way things will go. This is the point I'm making. The effect on the other factors may produce more warming - or it may reduce the warming. This is what the debate is about. It is not whether more CO2 results in warming - we know it does.
If CO2 has an effect on other factors it certainly doesn't wait until its doubled then unleash it like a dam breaking. I could care less who you say I am disagreeing with, no way are those folks as messed up on this as you are
I repeat you don't know what the effect is. It is still the subject of much research and even more speculation, though a good number of scientists seem convinced feedback will be positive (i.e. warming will be more than 1 deg)
|
|
|
Post by radiant on Aug 3, 2009 7:57:29 GMT
It is not whether more CO2 results in warming - we know it does. All you can say is that physics supports the theory that more C02 is likely to increase warming. But you cannot say we know it does increase warming because we dont know that. We cannot know it because we cannot do the experiment to prove it. At this stage it is about probabilities and guess work versus observation of a very limited set of historic data
|
|