|
Post by nautonnier on Jul 13, 2009 18:03:19 GMT
I am not often here these days as I am working hard trying to reduce other people's carbon footprint However, I feel compelled to comment. There is a tendency to mix arguments here so can we go back to basic principles. The Earth is rotating around an axis which is at an angle to its elliptical orbit that puts the South pole closer to the Sun than the North pole in their respective summers. Each point on this rotating Earth has a period of time with line-of-sight to the Sun at varying angles providing varying insolation (Lambert's cosine law). Some points achieve insolation at varying angles on a daily basis others only on a seasonal basis. Those parts of the Earth and its atmosphere not with sight of the Sun lose heat without replacement those in sight of the Sun gain heat while losing heat. The inbound heat is mainly radiant energy. The outbound heat travels into and through the atmosphere by convection, conduction and radiation with the main transfer upward being convection and the hydrologic cycle below the tropopause and by radiation above the tropopause. The atmosphere varies in depth over the Earth indeed it is continually changing in depth much as the ocean only over much larger scales to the extent that TOA is really a meaningless or arbitrary concept. So when statements are made that talk of so many watts per square meter at "the TOA" as a single figure we know that this is close to meaningless mean However, mathematicians love these 'lets assume that the Earth is a point and that the atmosphere is an unresponsive slab', approaches as it makes their maths simpler. At some point this simple maths, unnoticed, passes the reductio ad absurdum boundary as it is now buried in maths and symbology rather than in conceptual thought. All the maths is based on simple well known physical laws of course so the outcome "must be correct" (sic). (How many times has that been asserted here?) So I think both Jim and glc are correct. Jim is looking at the problem at conceptual level and saying this is too complex to be modeled simply; especially with one side of the Earth facing the Sun and the other side of the Earth radiating to empty space, no agreement on what the energy inputs actually are, continual argument and uncertainties about energy flows within the atmosphere and the TOA continually changing with no precise empirical measures of any 'balance' or otherwise for validation. glc is looking at the simplistic model of an 'average' input of 242WM -2 (there's a nice lets-assume-the-input-is figure) on one side of a see-saw against an 'average' output of 240WM -2 on the other side saying as one is more than the other things will not be in balance until both sides are the same. QED. This is mathematician versus scientist versus engineer. Like two women arguing over the back fence - they will never agree as they are arguing from different premises. ( Sidney Smith)
|
|
|
Post by jimcripwell on Jul 13, 2009 19:42:12 GMT
First let me clear up a few points. CO2 is a greenhouse gas. The question is whether adding more CO2 to the atmosphere at current levels causes global temperatures to rise significantly, or indeed at all. Secondly, over the long term, the earth must be in radiative balance. However, on a shorter term basis, the claim is that the TOA is never in radiative balance; it is always trying to achieve radiative balance but never succeeds. In this sense both steve and nautonnier are correct. However, the distinction is not just academic.
As I understood the calculations which glc presented some weeks ago, the argument seemed to be that because the TOA was always in radiatve balance, therefore one only needed to consider radiation in calculating the effect of adding more CO2 to the atmosphere. If this is wrong, then I am on the wrong track.
Assuming this is right, then glc is wrong to claim that, because the TOA is in radiative balance over the long term, therefore it is always in balance, and therefore only radiation need be considered. If it is true that the TOA is never in radiatve balance, then in calculating the effect of adding more CO2 to the air, one needs to take into account the effects of conduction, convection and the latent heat of water. That is the point where glc and I disagree.
|
|
|
Post by glc on Jul 13, 2009 22:44:46 GMT
Assuming this is right, then glc is wrong to claim that, because the TOA is in radiative balance over the long term, therefore it is always in balance, and therefore only radiation need be considered. If it is true that the TOA is never in radiatve balance, then in calculating the effect of adding more CO2 to the air, one needs to take into account the effects of conduction, convection and the latent heat of water. That is the point where glc and I disagree.
Jim
Start by telling me why you think Convection, Conduction and Latent Heat are relevant here.
Also have you read Steve's post.
|
|
|
Post by jimcripwell on Jul 14, 2009 16:03:48 GMT
glc writes "Start by telling me why you think Convection, Conduction and Latent Heat are relevant here. "
I will, but first some background. When I first heard of AGW and radiative forcing some 6 years ago, it was obvious that with current technology, it is impossible to measure how much global temperatures rise as more CO2 is added to the atmosphere from current levels. As my mentor, Sir Gordon Sutherland, and other professors hammered into my head in my freshman year at college, if you cannot measure it, it is not physics and it is not science. Add to that, a realization that the earth's climate is so complex, that no-one understands it. When someone presents a simple "back of the envelope" calculation to show how much global temperatures rise when you add more CO2 to the atmosphere, I simply dont believe them.
So when I see a simple calculation, such as you do, claiming it "proves" that doubling CO2 causes global temperatures to rise 1 C, my whole instinct shouts that there is something wrong with the calculations. Over the years, I have found my instinct to be right more often than it is wrong. What was wrong with your calculations I could not work out.
The clue came when it was pointed out the the TOA is never in radiaitive balance, which is part of your assumptions. Initially, I failed to realize that there is a time constant involved. Over a long length of time, the TOA is in radiative balance, but this time is measured in years, maybe decades. For the purpose of your calculations, the TOA is rarely in radiative balance. It is manly trying to restore radiative balance.
Now my understanding of your calculations was that, because the TOA is in radiative balance, therefore one only needs to consider radiation in doing the calculations. However, it follows that if the TOA is not in radiative balance, then the conditions there are governed, in part, by what is going on in the rest of the atmosphere. Some or all of the other atmospheric effects, e.g conduction, convection and the latent heat of water, control the conditions at the TOA. I dont know which these are, but it does not matter, The assumption that you can calculate what is going on only considering radiation is simply wrong.
Now if enough people guess what is happening in the atmosphere, someone is likely to be correct. But that is not science. I believe your calculations are fundamentally flawed.
I hope I have answered your question .
|
|
|
Post by steve on Jul 14, 2009 17:40:37 GMT
Jim,
If you increase the amount of CO2 in the atmosphere, then the amount of radiation into space will (all things being equal) reduce. The TOA balance will be lost. That's Myrhe for you.
To regain the balance, you have to change the atmosphere so that it radiates more energy into space.
If you increased the temperature of the atmosphere, then this would increase the amount of radiation to space.
or:
If you could reduce the amount of some clouds (the ones that keep heat in) and increase the amounts of others (the ones that reflect away sunlight) you could regain balance without changing the surface temperature much.
If you could make the atmosphere drier, you could regain balance without changing the surface temperature much (because you've reduced an important greenhouse gas)
If you could increase the amount of ice in mid-latitude and tropical glaciers you could regain balance without changing the surface temperature much (if the ice reflects away more sunlight).
And there are many other configurations of the earth which would retain a similar surface temperature while retaining the energy balance after doubling CO2.
But which configuration is most likely?
|
|
|
Post by glc on Jul 14, 2009 19:31:19 GMT
The clue came when it was pointed out the the TOA is never in radiaitive balance, which is part of your assumptions.
Wrong. This isn't one of 'my' assumptions. As far as the change in RF is concerned there are no assumptions. As far as warming or cooling is concerned the only assumption is that the the earth (and it's atmosphere) will obey a basic fundamental law of thermodynamics, i.e.
If there is a change in the balance between incoming and outgoing radiation then the temperature of the system will change.
The incoming radiation comes from the sun. The outgoing radiation is emitted from the TOA.
If incoming=outgoing we have stability. If incoming > outgoing the earth warms. If incoming < outgoing the earth cools.
If CO2 is added to the atmosphere the amount of outgoing radiation is reduced. The climate system will warm. The warmer atmosphere will emit more energy in proportion to the 4th power of the temperature (Stefan-Boltzmann Law). Eventually the outgoing radiation will balance the incoming radiation and temperatures will stabilise.
Yes there are other factors other than CO2 which may change the incoming/outgoing balance, but this is just another separate forcing. As far as the calculation of RF due to increased CO2, the equations are robust. No assumptions need to be made despite your continual repetition to the contrary.
Conduction, Convection and Latent Heat are, to all intents and purposes, irrelevant in this context.
Incoming Energy comes from the Sun. Outgoing Radiation is emitted from the TOA by RADIATION.
Now my understanding of your calculations was that, because the TOA is in radiative balance, therefore one only needs to consider radiation in doing the calculations.
Your understanding is faulty. I'm not sure how many times I need to say this. We only need to consider radiation because it is only by radiation that the climate system cools.
|
|
|
Post by magellan on Jul 15, 2009 1:59:58 GMT
The clue came when it was pointed out the the TOA is never in radiaitive balance, which is part of your assumptions.Wrong. This isn't one of 'my' assumptions. As far as the change in RF is concerned there are no assumptions. As far as warming or cooling is concerned the only assumption is that the the earth (and it's atmosphere) will obey a basic fundamental law of thermodynamics, i.e. If there is a change in the balance between incoming and outgoing radiation then the temperature of the system will change. The incoming radiation comes from the sun. The outgoing radiation is emitted from the TOA. If incoming=outgoing we have stability. If incoming > outgoing the earth warms. If incoming < outgoing the earth cools. If CO2 is added to the atmosphere the amount of outgoing radiation is reduced. The climate system will warm. The warmer atmosphere will emit more energy in proportion to the 4th power of the temperature (Stefan-Boltzmann Law). Eventually the outgoing radiation will balance the incoming radiation and temperatures will stabilise. Yes there are other factors other than CO2 which may change the incoming/outgoing balance, but this is just another separate forcing. As far as the calculation of RF due to increased CO2, the equations are robust. No assumptions need to be made despite your continual repetition to the contrary. Conduction, Convection and Latent Heat are, to all intents and purposes, irrelevant in this context. Incoming Energy comes from the Sun. Outgoing Radiation is emitted from the TOA by RADIATION. Now my understanding of your calculations was that, because the TOA is in radiative balance, therefore one only needs to consider radiation in doing the calculations. Your understanding is faulty. I'm not sure how many times I need to say this. We only need to consider radiation because it is only by radiation that the climate system cools. Yes there are other factors other than CO2..... Do you really think so? Like maybe....clouds, or.....the sun? Or how about the oceans? But then, the surface is warming faster and at an accelerating pace (hmm) compared to the troposphere, although neither are moving upward. No problem, just pretend nobody said it should be the other way around, right? Nonetheless, the crux of your conundrum still exists: Where is the missing heat? Surely the fact that 90% of surface warming is due to the oceans and not "greenhouse" gases can't have anything to do with climate shifts, can they? It appears if Tsonis may have been on to something www.uwm.edu/~aatsonis/2007GL030288.pdfwww.wisn.com/weather/18935841/detail.htmlWhat matters is how the system behaves in reality, not by assuming CO2 levels going up will necessarily cause the globe to warm. This earth is not a static system which you infer that it is. Your entire argument since day one is: CO2 goes up, temperatures therefore must as well. Was it the chicken or the egg? Must chemical laws be obeyed? folk.uio.no/tomvs/esef/esef4.htmwww.youtube.com/watch?v=-g-c_WbJWAQ
|
|
|
Post by glc on Jul 15, 2009 7:54:21 GMT
Do you really think so? Like maybe....clouds, or.....the sun? Or how about the oceans? But then, the surface is warming faster and at an accelerating pace (hmm) compared to the troposphere, although neither are moving upward. No problem, just pretend nobody said it should be the other way around, right?
Nobody said all the warming was due to CO2. Adding CO2 to the atmosphere will reduce the amount of outgoing IR to space. Now it's perfectly possible that changes in insolation or internal variability will offset the 'energy out' change due to CO2. But unless the natural changes are permanent then eventually a CO2 signal will emerge.
Believe it or not, I know about clouds...oceans.... and the sun but these factors tend to shift in cycles and if they shift in a certain direction which offsets the CO2 effect then there is a chance they will shift back the other way which will amplify the effect. I think there was some some amplification of the CO2 effect between ~1975 and ~2000. Your argument here seems to be that we don't need to consider CO2 because something at some point in timwe may offset it's effect.
Nonetheless, the crux of your conundrum still exists: Where is the missing heat?
There is no conundrum. It's you who appears to require that warming takes place year on year. There has been warming over the last ~30 years of which some, at least, is probably due to increased concentrations of CO2.
The energy in/out balance must change if we add more CO2 the the atmosphere. Emission spectra graphs show us that CO2 plays a significant role in the emission of earth's energy to space. Look at those plots. See the distinctive CO2 funnel. This shows that energy at CO2 absorption wavelengths is emitted to space at higher levels of the atmosphere. CO2 is significant here.
But what about the warming - or the lack of warming, if you prefer?
Unlike Steve or Socold, I think climate sensitivity is lower than that given by the general consensus. I reckon no more than ~1.5 deg per 2xCO2. Since we've probably had ~0.5 deg of that, this means we can expect an average rate of warming of ~0.1 deg per decade for the rest of this century. This can be easily offset by ENSO events. In particular we had a huge El NIno in 1998, which was way above trend, and then, in 2008, we had a La Nina. It's not surprising that the 10 year trend stalled during that period.
There will not a consistent year on year or even decade on decade warming trend. To suggest there should be is ridiculous and runs totally contrary to your argument that there are other factors which contribute to climate change.
|
|
|
Post by steve on Jul 15, 2009 9:52:35 GMT
Unlike Steve or Socold, I think climate sensitivity is lower than that given by the general consensus. I reckon no more than ~1.5 deg per 2xCO2. I'm not sure what I think the sensitivity is. The evidence that points to a higher sensitivity than 1.5C is, I would say, sufficiently strong to suggest that action to reduce greenhouse gas levels now would be prudent. As this is off-topic, I won't say more here.
|
|
|
Post by glc on Jul 15, 2009 12:49:37 GMT
I'm not sure what I think the sensitivity is. The evidence that points to a higher sensitivity than 1.5C is, I would say, sufficiently strong to suggest that action to reduce greenhouse gas levels now would be prudent. As this is off-topic, I won't say more here.
Steve
You're right. It is a separate debate. It might be interesting to move on to it at some point but, for now, trying to convince other posters here that the basic theory is sound is all I can cope with at the moment.
Strange really - since Lindzen, Spencer, Michaels et al all subscribe to the theory - I'm a bit surprised it's so difficult trying to get it across.
|
|
|
Post by jimcripwell on Jul 15, 2009 17:54:01 GMT
glc writes "You're right. It is a separate debate. It might be interesting to move on to it at some point but, for now, trying to convince other posters here that the basic theory is sound is all I can cope with at the moment."
There is no use trying to convince me. I seem to have a rather peculiar and old fashioned view of what theory in physics is useful for. So far as I am concerned, theoretical physics has the job of devising new and interesting experiments. When these experiments are performed, and we get the hard experimental data, which validates, or otherwise, the theory, we make real progress.
The idea that you can take a system as complex as the earth's atmosphere, and with a few equations prove anything at all, is to me ludicrous. There is no experimental data that shows that when you add x amount of CO2 to the atmosphere at current concentrations, this causes the temperature to rise y degrees. When you can uses your equations to devise such an experiment, I will be very interested. Otherwise, IMHO, your theory and equations prove absolutely nothing.
|
|
|
Post by glc on Jul 15, 2009 19:01:46 GMT
The idea that you can take a system as complex as the earth's atmosphere, and with a few equations prove anything at all, is to me ludicrous.
It's ludicrous to me that you think the earth loses heat by cconvection at the TOA.
There is no experimental data that shows that when you add x amount of CO2 to the atmosphere at current concentrations,
There is plenty of experimental data which shows the amount of IR transmission/absorption through an atmosphere with varying amounts of CO2. These experiments provide very strong support for the validity of the IR transmission equations. <i> ....Otherwise, IMHO, your theory and equations prove absolutely nothing. </i> It's not my theory or my equations. Perhaps you should take up your complaint with Richard Lindzen or Roy Spencer or Jack Barrett. They all subscribe to the basic theory. If you think they are wrong you need to explain why, but I suspect the problem lies with your understanding.
|
|
|
Post by glc on Jul 15, 2009 19:04:46 GMT
The idea that you can take a system as complex as the earth's atmosphere, and with a few equations prove anything at all, is to me ludicrous.
It's ludicrous to me that you think the earth loses heat by cconvection at the TOA.
There is no experimental data that shows that when you add x amount of CO2 to the atmosphere at current concentrations,
There is plenty of experimental data which shows the amount of IR transmission/absorption through an atmosphere with varying amounts of CO2. These experiments provide very strong support for the validity of the IR transmission equations. ....Otherwise, IMHO, your theory and equations prove absolutely nothing.
It's not my theory or my equations. Perhaps you should take up your complaint with Richard Lindzen or Roy Spencer or Jack Barrett or, more recently, Steve McIntyre. They all subscribe to the basic theory. If you think they are wrong you need to explain why, but I suspect the problem lies with your understanding.
|
|
|
Post by icefisher on Jul 15, 2009 19:10:55 GMT
The idea that you can take a system as complex as the earth's atmosphere, and with a few equations prove anything at all, is to me ludicrous. There is no experimental data that shows that when you add x amount of CO2 to the atmosphere at current concentrations, this causes the temperature to rise y degrees. When you can uses your equations to devise such an experiment, I will be very interested. Otherwise, IMHO, your theory and equations prove absolutely nothing. Right on. These UK types still don't understand. The tradition in this country is the bumpkin with the very strange religious beliefs lifting his middle finger at the King's taxmen. Net result is what is on your dinner plate. Bottom line is if you can't get people to voluntarily buy it . . . .it probably isn't worth buying. . . .I am all set to install a solar array on my house. . . .just that nobody has yet offered me one at the right price. As we have traveled down this risky path of Steve's. . . .about two thirds of the 4.5C top end warming from doubling CO2 has fallen into the valley of an ocean oscillation. Whats next? Will we lose another 2/3rds to the recovery from the LIA? Mankind's progress has been amazing. Naysayers and luddites and Al Gore with his catastrophic sand pile is nothing more than the guy with the longbeard standing on a soap box selling his own despair and the end of the world. Give him a shave, a haircut, a new suit of clothes and you have. . . .Al Gore. As time goes on we are likely to harness nuclear fusion which has promise of bringing us, yet again, a cleaner source of energy. Yep oil is a cleaner source of energy. The world would indeed be a dirty polluted place if we were all still grouped around campfires.
|
|
|
Post by nautonnier on Jul 15, 2009 19:40:56 GMT
Jim, If you increase the amount of CO2 in the atmosphere, then the amount of radiation into space will (all things being equal) reduce. The TOA balance will be lost. That's Myrhe for you. To regain the balance, you have to change the atmosphere so that it radiates more energy into space. If you increased the temperature of the atmosphere, then this would increase the amount of radiation to space. or: If you could reduce the amount of some clouds (the ones that keep heat in) and increase the amounts of others (the ones that reflect away sunlight) you could regain balance without changing the surface temperature much. If you could make the atmosphere drier, you could regain balance without changing the surface temperature much (because you've reduced an important greenhouse gas) If you could increase the amount of ice in mid-latitude and tropical glaciers you could regain balance without changing the surface temperature much (if the ice reflects away more sunlight). And there are many other configurations of the earth which would retain a similar surface temperature while retaining the energy balance after doubling CO2. But which configuration is most likely? "If you increase the amount of CO2 in the atmosphere, then the amount of radiation into space will (all things being equal) reduce. The TOA balance will be lost. That's Myrhe for you."Steve the problem that Jim is pointing out is that all things are NOT equal. Not only that but no-one knows for sure what ALL THINGS are either. There are some clouds in the tropics (where it matters) that have shown negative forcings of more than 100 watts/meter 2. This would reduce the inbound radiation and resolve the balance problem in another way other than increasing radiation out. The clouds are there due to CONVECTION that occurs in the tropics when the surface is warmer than usual. As such they are a negative feedback to the warming. As I have said before the AGW theory has tunnel vision and only uses radiation and the Stefan Boltzmann equation and (claimed) CO 2 absorption. Its like always looking at only one end of the see-saw. Even when it pointed out that such things as the weight at the other end of the see-saw and the momentum of the movement matter - AGW proponents continue to disregard them and point at the one end of the see-saw. As JimG has pointed out - convection and the hydrologic cycle carry huge quantities of heat to the tropopause past most of the CO 2 in the denser layers of the atmosphere and, as a side effect of this convection, clouds form that reflect an unexpectedly high amount of incoming radiation back out to space. This negative feedback can restore the radiative budget/balance.
|
|