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Post by icefisher on Jun 12, 2009 13:23:52 GMT
All of this detailed discussion of CO2 warming effects is a nice exercise, but the warming that is predicted in the upper atmosphere has completely failed to occur. The concept that a trace gas would drive the climate to any measurable degree borders on laughable. A crude approximation for the mean surface temperature of the earth is ~14 deg C (287K). By the Stefan Boltzmann Law, this temperature equates to an outgoing energy flux of ~386 w/m2. However, only ~235 w/m2 actually leaves the top of the atmosphere. If the concept is 'laughable', as you put it, you need to explain this discrepancy. Clouds
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Post by northsphinx on Jun 12, 2009 15:09:28 GMT
My opinion is that it is all about the clouds. Of total incoming radiation is about 365/1365 of the total solar spectrum absorbed in the atmosphere on a sunny day without clouds. en.wikipedia.org/wiki/File:Solar_Spectrum.pngSome absorbed by H2O vapor. But only about 1/4 is absorbed in the atmosphere. Remaining is just passing through in this wavelengths But with clouds is it common that only 1/10 reach the ground. Clouds make the difference, with a factor 10 at least. On the other way, emission out in space is temperature based, with a dip for CO2. Or is it? It is just temperature based. But depending from where it is originate "from" will there be dips. The emissions follows very much 280-290 K which is close to earth average surface temp or more specific the temperature of surface and most of the atmosphere vapor. Most of the vapor is low in the atmosphere and have a temperature close to earth temperature. Higher up in the atmosphere is there not vapor enough to absorb IR. And consequently no vapor to emmits heat either. CO2 is absorbing and emitting heat in the entire atmosphere because it is equally mixed in the atmosphere. The CO2 dip in earths emission spectrum is then just a marker of the coldest part of the atmosphere, because it is where the net absorption is. And here is it hardly no vapor. The temperature in this part of the troposphere is not depending of CO2 level. It is the other way around. The temperature here will set the CO2 window radiation level. Same thing for ozone. The dip correspond well to the temperature where most of the ozone is located. And by that mark the ozone window with that temperature where the ozone is located. But the heat is still going out. The outgoing heat is heavily depending on clouds. Differences far above factor 10 between min and max emission is common. Its all about the clouds. The amount of clouds is not temperature depending as AGW models insist. It is depending on temperature differences. Either in altitude or between air masses. Still clouds in wintertime far north and hardly no clouds in the deserts. It is the temperature difference in the atmosphere that drives the cloud formation and form our climate. If the higher altitude cools will there be more clouds and a cooler planet. More instable air will create a more local weather and air masses will more often mix in altitude instead of in larger cyclones and other large scale weather patterns. A colder atmosphere in higher altitudes will be equal to a more instable atmosphere which will reduce heat transports to higher latitudes. No need for the vapor to go 100 or 1000 km to condensate, when it can be condensate just a few 1000 meter up. Like in the tropics. The result is less latent heat transported to higher latitudes. And more clouds in the tropics that reduce total incoming heat to the earth. The result is global cooling. The atmosphere is cooled from above. The stratosphere decide the troposphere minimum temperature. Cooler stratosphere will cool our planet. Traditional science claim that the stratosphere is only heated by the ozone layer absorbing ultraviolet radiation from the sun. More recent is there much that shows that the stratosphere temperature follow the solar cycle. High activity leads to high temperatures. And a low solar activity cool the stratosphere and by that cool our climate by giving the fundament to a more instable atmosphere and more clouds. It is all about the clouds. The cloud formation is driven by temperature differences. All temperature differencen on our earth is driven by our sun. The altitude temperature which drive the cloud formation is driven of the solar activity. Here is the forcing that make the differance.
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Post by glc on Jun 12, 2009 19:43:06 GMT
Icefisher and Northsphinx:
I've been wondering whether or not to respond to your posts and have decided to give it a go. First let me say that clouds do play a part in the enhanced heating of the earth's surface but not in the way you both appear to think.
When calculating energy fluxes it's normal to deal with averages. It's true that the earth's atmosphere does receive ~1360 w/m2 but around 30% of this is reflected directly back into space and so plays no part in heating the surface or the atmosphere. This leaves about 960 w/m2. But only one point will receive this amount at any one time. The rest of the earth will either be in darkness, or will only receive a fraction (depending on the angle of incidence) of the 960 w/m2. In fact, the area of the earth which receives the full 960 w/m2 at any one time is equivalent to the X-sectional area of the earth (i.e. PI x R2), whereas the total surface of the earth can be represented as the surface of sphere (i.e 4 x PI x R2).
The average solar insolation, therefore, is approximately 240 w/m2 (i.e. 1/4 of the direct solar energy). It's probably closer to the figure I wrote in the earler post, i.e. 235 w/m2, but we'll stick with 240 w/m2 for the sake of simplicity. So we have 240 w/m2 incoming radiation which, to maintain a stable climate, is balanced by 240 w/m2 outgoing (LW) radiation.
If the earth had no atmosphere, then the 240 w/m2 would would reach the earth, warm the surface and emit 240 w/m2 back to space. But, using the S-B Law, it's simple to calculate that the temperature required to emit 240 w/m2 is only 255K (or -18 deg C) yet the average temperature of the earth is ~33 deg warmer than this. The energy emitted by a body at this temperature is ~390 w/m2 (again using S-B).
Clearly the IR absorbing gases in the atmosphere are playing a significant part in maintaining a warm, habitable climate. Water Vapour is the dominant player, but CO2 contributes ~20% to the total warming. This varies between ~9% and ~26% depending on the humidity of the air. It's also thought, by some at least, that if there were less CO2 in the atmosphere there would be a lot less water vapour (warm air holds more water than cold air) and, conversely, there will be a lot more water vapour if there is more CO2 in the atmosphere. This is what's known as a positive feedback. But even with no feedback, doubling the amount of CO2 in the atmosphere is still likely to raise the earth's average temperature by ~1 deg C.
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Post by icefisher on Jun 12, 2009 20:36:50 GMT
Icefisher and Northsphinx: I've been wondering whether or not to respond to your posts and have decided to give it a go. First let me say that clouds do play a part in the enhanced heating of the earth's surface but not in the way you both appear to think. When calculating energy fluxes it's normal to deal with averages. It's true that the earth's atmosphere does receive ~1360 w/m2 but around 30% of this is reflected directly back into space and so plays no part in heating the surface or the atmosphere. This leaves about 960 w/m2. But only one point will receive this amount at any one time. The rest of the earth will either be in darkness, or will only receive a fraction (depending on the angle of incidence) of the 960 w/m2. In fact, the area of the earth which receives the full 960 w/m2 at any one time is equivalent to the X-sectional area of the earth (i.e. PI x R 2), whereas the total surface of the earth can be represented as the surface of sphere (i.e 4 x PI x R 2). The average solar insolation, therefore, is approximately 240 w/m2 (i.e. 1/4 of the direct solar energy). It's probably closer to the figure I wrote in the earler post, i.e. 235 w/m2, but we'll stick with 240 w/m2 for the sake of simplicity. So we have 240 w/m2 incoming radiation which, to maintain a stable climate, is balanced by 240 w/m2 outgoing (LW) radiation. If the earth had no atmosphere, then the 240 w/m2 would would reach the earth, warm the surface and emit 240 w/m2 back to space. But, using the S-B Law, it's simple to calculate that the temperature required to emit 240 w/m2 is only 255K (or -18 deg C) yet the average temperature of the earth is ~33 deg warmer than this. The energy emitted by a body at this temperature is ~390 w/m2 (again using S-B). Clearly the IR absorbing gases in the atmosphere are playing a significant part in maintaining a warm, habitable climate. Water Vapour is the dominant player, but CO2 contributes ~20% to the total warming. This varies between ~9% and ~26% depending on the humidity of the air. It's also thought, by some at least, that if there were less CO2 in the atmosphere there would be a lot less water vapour (warm air holds more water than cold air) and, conversely, there will be a lot more water vapour if there is more CO2 in the atmosphere. This is what's known as a positive feedback. But even with no feedback, doubling the amount of CO2 in the atmosphere is still likely to raise the earth's average temperature by ~1 deg C. Obviously clouds do a better job of absorbing IR than CO2 or water vapor. You just throw in a 30% for albedo like it is some kind of static given. The earth's albedo is changing all the time and there is no way to know what normal is unless what you do is figure what the GHG contribution is first and then fill in the 30% number. Looking at the cloud coverage numbers you have a 4.5% variation over the period of warming. The variance may be greater than that as clouds at differing levels and types are varying even more. Are you just going to discount the albedo and radiation effects of this kind of variance and go ahead and calculate your numbers?
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Post by glc on Jun 12, 2009 21:05:46 GMT
Obviously clouds do a better job of absorbing IR than CO2 or water vapor.
Possibly but the overall effect of clouds is mixed. Fewer clouds allow more solar insolation while more clouds absorb more IR. The net effect of clouds is probably cooling.
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Post by dmapel on Jun 12, 2009 22:30:11 GMT
glc: "The net effect of clouds is probably cooling."
That is correct.
I am still waiting for the responses to some questions I asked, that you said would be forthcoming.
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Post by trbixler on Jun 12, 2009 22:43:21 GMT
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Post by icefisher on Jun 12, 2009 22:48:08 GMT
Obviously clouds do a better job of absorbing IR than CO2 or water vapor.Possibly but the overall effect of clouds is mixed. Fewer clouds allow more solar insolation while more clouds absorb more IR. The net effect of clouds is probably cooling. That depends on whether they are day clouds or night clouds
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Post by icefisher on Jun 12, 2009 22:52:04 GMT
glc: "The net effect of clouds is probably cooling." That is correct. I am still waiting for the responses to some questions I asked, that you said would be forthcoming. Good luck! When major gaps are presented in the AGW theory GLC just ignores them and immediately signs on to buy the bridge anyway.
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Post by glc on Jun 13, 2009 0:24:58 GMT
I am still waiting for the responses to some questions I asked, that you said would be forthcoming
Remind me.
UPDATE: I've checked on the other thread. I didn't respond to Peter Dietze's 'paper' so I suppose that's still oustanding. I also promised to put together some climate sensitivity figures which I believe are more realistic that Steve Milloy's. The final link was Jack Barrett's use of Pinatubo to calculate climate sensitivity.
There are 2 related, but separate, issues here, i.e.
1. the climate forcing 2. the temperature response to that forcing
Which of these issues would you like to address?
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Post by glc on Jun 13, 2009 0:27:41 GMT
That depends on whether they are day clouds or night clouds
I referred to the net effect. That is, the net effect of the warming and cooling effects.
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Post by dmapel on Jun 13, 2009 4:42:32 GMT
glc,
I appreciate your willingness, but on second thought it probably would not be productive to rehash those issues in detail. What I am really interested in, is your opinion on whether or not the alleged AGW is a serious problem that requires drastic action now.
You cited Barrett/Bellamy as a credible, informative source on climate science. I found it to be so. I previously posted excerpts from the website that I believe summarized the informed scientific opinions of the authors:
-IPCC climate sensitivity estimates are 4 times too large
-the global temperature anomaly change from a peak of +0.75?C in 1998, to -0.18?C in May 2008, makes the global temperature change of 0.7 ± 0.2?C over the 20th century seem of little significance
-there has been no significant temperature trend over the last 39 years
-there is no sign of continual upward warming from the burning of fossil fuels
-there has been some warming from fossil fuels but it's extent may never be discerned (according to physics it can't be zero)
-global temperature trend since 1998 is cooling
Unless they are way off base, we really don't have to sacrifice $$TRILLIONS$$ in economic growth in a feckless and phony attempt to reduce our carbon footprints to the equivalent of the neanderthal's. And consequently, there really is no point in scaring our children with BS Gorey horror stories.
Is there?
That's a loaded question. Please just give me your opinion/estimate on how much warming we can expect by 2100, and whatever justification and editorializing that you care to add.
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Post by northsphinx on Jun 13, 2009 8:45:42 GMT
The heat balance is the most basic math. And still a flaw.
Yes the solar constant is calculated against the earths projected area. And Yes the solar flux is always hitting the earth at a constant area. The energy flow to the earth is about constant but hardly average. Either is it on or off except for low solar angles. The cloud free atmosphere do not reflect or absorb more than this 365/1365. Bet the cloud in the sunny part may reduce the incoming with a factor 10. The average solar insolation it depending very much on cloud cover area and thickness. The albedo of clouds will reduce the incoming flux more than anything else. But it also affect outgoing flux. And the outgoing is depending where it is originated from. Satellite IR pictures of our earth show this. The picture show temperature of clouds. That is precisely what space see of earth. Cold clouds. And a large part of the outgoing flux is originated from the top of the clouds. Where temperature is in the range of 250-260K. Or even lower.
And in the part of earth without clouds why is they not colder? Like the earths desert areas.
But the heat balance calculation for a sunny cloudless windless desert is quite simple. I simplifies it little bit more Input is 12h from the sun with about 1000 w/m2 projected toward the sun Equals 12 kWh. In reality is it due to solar angles about 8 kWh maximum Outgoing is during 12 h with ground temperature that is 8 kWh/12 h = 666 w Since the outgoing during the day is already included in daily net in. Cant count outgoing twice.
That is 329 K as a theoretically maximum. Close to real observations. with just basic math.
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Post by glc on Jun 13, 2009 10:09:33 GMT
That's a loaded question. Please just give me your opinion/estimate on how much warming we can expect by 2100, and whatever justification and editorializing that you care to add.
I though I had given my opinion/estimate. I reckon that by doubling the CO2 in the atmosphere we will raise the global temperature by about 1 deg C (in total). This is pretty much what Barrett says and also what Richard Lindzen says. This is what h e wrote on WUWT a few weeks ago:
For example, if one simply doubles the amount of CO2 in the atmosphere, the temperature increase is about 1°C.
This is the calculated increase which is due solely to the presence of the extra CO2. The main argument centres on the magnitude (and sign) of any feedback. As Lindzen points out in the WUWT post, observations tend to suggest that feedback is low.
So what does a 1 deg rise mean?
It shouldn't be a problem particularly as we've already had about 0.5 deg so far.
Doesn't the temperature trend since the mid-1970s suggest a higher temperature rise?
The trend since the mid-1970s has been ~0.16 deg per decade which implies a rise of 1.5 to 2 deg. But I reckon the recent trend has been amplified by natural factors such as ocean oscillations (e.g. PDO, AMO, etc). This is similar to what happened in the 1910-1945 period when there was also a strong warming period despite the relatively low CO2 levels.
Will we continue to see a steady uptrend then?
No. The underlying CO2 signal is only around 0.05 to 0.07 deg per decade. This could easily be offset by natural factors (see above). If we get a cool PDO/AMO/etc phase, temperatures could easily go sideways for 10 - possibly 20 years. The are other shorter term ocean fluctuations which can affect the short term trends.
Does the current 'flat' trend mean we have entered a long term cool phase.
Possibly - but it's a bit early to tell. Any trend of less than 10 years up to the end of 2008 is heavily influenced by the 2007/08 La Nina. The trend since 1998 is down - but the trend from 1999 is up. This is simply due to the strong El Nino in 1997/98 which was over in 1999. Why do I (glc) appear to come under "attack" from sceptics when my overall position is one of scepticism.
First point to remember here is that a genuine sceptic should be sceptical about all theories associated with AGW not just the ones that suit his/her personal agenda. When I first starting posting on this blog I was critical of many of the claims and predictions of imminent global cooling that were being bandied about. Most of these were based on the Sun's deep minimum and it's supposed role in global climate fluctuations. I think the evidence of a solar/climate link is sketchy to say the least and, even if there is some mechanism by which the sun causes the climate to vary, I can't see it happening for several decades.
Many so-called sceptics are hoping desperately for the knock out blow that will stop the AGWers dead in their tracks. It might be an attractive thought, but it almost certainly won't happen like that, and the danger is that when the big cooling predictions fail to hit the buffers the sceptic side loses a bit more credibility.
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Post by glc on Jun 13, 2009 12:06:02 GMT
Northsphinx
I'm not totally sure what your point is.
1. Do you agree that ~240 w/m2 LW radiation is emitted to space from the earth's atmosphere (and surface). 2. Do you also agree that this gives us a broadly stable climate on earth.
If you agree to both (1) and (2) then you must also accept that the average solar insolation hitting the earth is ~240 w/m2 because
(i) If Incoming Solar = Outgoing LW - we have 'stable' temperatures (ii) If Incoming Solar > Outgoing LW - we have warming (iii) If Incoming Solar < Outgoing LW - we have cooling
Now if the earth's average surface temperature is ~15 deg (i.e. 288K) then the surface is emitting ~390 w/m2. This clearly shows that something, which has nothing to do with the distribution of sunlight on the earth's surface, is happening between the surface and the "top of the atmosphere".
You keep mentioning clouds. But the incoming ~240 w/m2 solar insolation has already accounted for the reflectance of clouds. This is the energy which goes towards heating the earth and the atmosphere. Clouds do contribute to the greenhouse effect as we know from their warming effects on a winter's night.
You say
And the outgoing is depending where it is originated from. Satellite IR pictures of our earth show this. The picture show temperature of clouds. That is precisely what space see of earth. Cold clouds. And a large part of the outgoing flux is originated from the top of the clouds. Where temperature is in the range of 250-260K. Or even lower.
What "outgoing" are you referring to? There is the direct reflectance but there is also LW emission. There is a difference. Also
And in the part of earth without clouds why is they not colder? Like the earths desert areas.
Deserts are warm by day and cool quickly at night. But I'm sure you knew that. If you're trying to tell me that clouds prevent the siun's energy reaching the earth - I know that. I also know that some parts of the earth will be receiving a lot more than ~240 w/m2 (during the day at least) and others a lot less, but none of this changes the fact that
An average of around 240 w/m2 comes in and an average of around 240 w/m2 goes out. The fact that the surface emits an average of around 390 w/m2 is almost certainly due to the presence of greenhoues gases in the atmosphere. If anyone has a more convincing explanation then I'll be glad to hear it.
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