THE CASE AGAINST ANTHROPOGENIC GLOBAL WARMING ... Click here
What they will tell you is quite true up to a point ....
They will explain in detail how carbon dioxide molecules "trap" infra-red (IR) radiation from the surface and get warmed. They may not mention that they cool again (sometimes less than they warmed, but not always) when they emit "back radiation" a very small fraction of a second later.
They will demonstrate that measurements confirm the existence of Longwave Downward Radiation, that is, radiation in the infra-red spectrum. ("Longwave" sounds more impressive than low energy.) Then they will explain how these measurements fit with the models, which have been designed so that they do fit, but which may not necessarily correctly predict the outcome if carbon dioxide levels doubled.
Then they will explain that the surfaces of the Earth and the oceans absorb this low energy radiation and convert it to heat, even though such surfaces are themselves emitting more radiation. Finally, they will conclude somewhat laconically, "Thus warming happens."
But the surface cannot absorb the IR radiation that returns from the atmosphere ....
The above statement is confirmed by this experiment, and also in an excellent book Slaying the Sky Dragon which you can order here by mail from the US. It is billed on the back cover as ...
“the world's first and only full volume refutation of the greenhouse gas theory of man-made global warming ... destined to be the benchmark for future generations of climate researchers ... Eight leading international experts methodically expose how willful fakery and outright incompetence were hidden within the politicized realm of government climatology. ... Step-by-step the reader is shown why the so-called greenhouse effect cannot possibly exist in nature. By deft statistical analysis the cornerstones of climate equations – incorrectly calculated by an incredible factor of three - are exposed, then shattered. This volume is a scientific tour de force and the gamechanger for international environmental policymakers as well as being a joy to read for hard-pressed taxpayers everywhere.”
When incoming radiation meets a surface two very different processes can occur, depending upon whether the frequency of the radiation is above or below a certain "cut off" value. That radiation which is above the cut off will be absorbed and the coherent radiation is converted to incoherent thermal energy, thus "warming" the surface. However, incoming low energy radiation with frequency below the cut off will not be absorbed and thus will not cause any warming. Proponents of the so-called atmospheric "greenhouse effect" have incorrectly assumed (without any empirical evidence) that the low energy "back radiation" from the atmosphere can warm the surface. But it cannot because its frequency will always be below the cut off value. Professor Claes Johnson explains all this here.
Incoming radiation with an attenuated Planck spectrum does in fact carry temperature information, not in the amplitude but in the cut-off (Wien's Law.) The temperature can only be determined from the amplitude if the attenuation factor is known, this factor depending upon the distance and the angle subtended by, for example, the Sun. The important result coming from this (and proved in this book) is that the temperature of outgoing radiation can only be less than or equal to the temperature of incoming radiation. This is the reason why the spectrum of high energy incoming (direct) solar radiation absorbed by the Earth does not overlap the spectrum of outgoing low energy IR radiation.
The above may be observed by considering the internal mirrors on the walls of a vacuum flask filled with hot coffee. These mirrors reflect IR radiation back into the coffee. They slow the rate of cooling, but they do not warm the coffee one iota. Likewise, a mirror reflecting radiation back at the radiating bar of an electric radiator does not cause the bar to be heated more. Any such process would be creating energy.
Now, when a GHG molecule captures and re-radiates some small "package" of radiation, then the outgoing radiation must have a temperature less than or equal to the incoming radiation. So, when any of this radiation gets back to Earth, its temperature cannot be greater than that of the radiation being emitted by the Earth, and so IT WILL NOT BE ABSORBED. In a sense, the "stronger" radiation coming out of the surface will "push" away the lower energy back radiation.
In the atmosphere, when radiation is captured it is usually re-emitted where the temperature of the atmosphere is warm enough. This creates a scattering effect.
Now, because the scattering is in all directions, very little radiation continues in exactly the same direction as the incoming radiation. This is why, when an instrument in space is pointed towards Earth the measurements appear to imply that carbon dioxide is blocking radiation because of the missing spectral lines. In truth, the radiation has just been scattered in all other directions, so next to none appears to have travelled in a straight line from the surface.
Hence, in a nutshell, infra-red radiation that has been initially emitted by the Earth is then in effect deflected all around the atmosphere AS WELL AS BY THE SURFACE but all the time there is an “open window” above, through which some (and eventually all) will escape to space. It really doesn't matter if it "bounces" off the surface or just other molecules. It's like a pool table (without pockets) with one end removed: the balls bounce around and all end up on the floor. The open end of the table represents space, and the other end Earth's surface.
The scattering process slows the rate at which the energy gets to space, yes by a few seconds perhaps. But it does not lead to a “traffic jam” type of build up that would cause an increase in surface temperature. Molecules are not like cars which keep at a minimum distance from each other, hopefully, and thus bank up on a motorway when, for example, they have to merge into one lane. And there are no traffic lights up there causing complete stops.
The most significant thing that causes a delay is, however, simply the fact that thermal energy from direct high energy solar radiation received in sunlight hours penetrates the oceans and land surfaces and thus retains some energy for a few hours into the night and, in the case of the oceans most noticeably, for a few months from summer to winter. The atmosphere itself also retains thermal energy, mostly in water vapour, oxygen and nitrogen molecules of course, so we don't have a situation as on the Moon where temperatures vary from about 100 deg.C in the day to even less than -150 deg.C at night. But all this has been happening on Earth for billions of years.
Yes, there can be natural small build ups (and declines) in the total energy stored from one year to the next, and these will lead to variations in net radiative flux at the top of the atmosphere (TOA), usually between about plus and minus 0.5% of total incoming insolation. But these are virtually all caused by natural processes which can involve variations in cloud cover and especially variations in pressure. These are the areas in which research funds should be invested.
There is nothing in last century's temperature data which has not happened somewhere in the past due to natural causes. The increase of about 0.5 deg.C between 1970 and 2000 was mirrored from 1910 to 1940, for example. It can be shown with physics that even just a 1.5% change in cloud cover could have explained it all, and this could have something to do with variations in cosmic rays caused by variations in solar activity. This is but only one suggestion of many which could have caused (perhaps in combination) everything that has been observed. Whether you consider it significant or not, I suggest the obvious reduction in the temperature gradient for moving 17 year trends up to the present is indicative of a clear cut trend towards lower rates of warming, if not cooling, in the near future.
Older physics textbooks say that oxygen and nitrogen molecules do not emit very much radiation at atmospheric temperatures. This appears to be incorrect, because radiation can be emitted whenever molecules collide. The observed spectrum of downward radiation is equivalent to that of a blackbody radiating at a temperature found just above the measuring instrument. Thus all the "backradiation" supposedly coming from carbon dioxide is in fact primarily from ordinary air molecules, mostly nitrogen and oxygen. It is hard to believe that the IPCC was not made aware of the observed spectral distribution, because this in itself demolishes the hypothesis of a greenhouse effect.
Furthermore, the satellite measurements comparing inbound and outbound radiation do not show a difference which can be proven to have a statistically significant correlation with thermal energy content in the Earth system, because there are so many other factors for which insufficient data is available for proper climate analysis. These include the effects of winds sweeping warm air towards the poles, cloud cover and aerosol distributions, humidity, salinity, vegetation, soil moisture, snow and ice distribution and the proportions of atmospheric gases. Above all, variations in the "break out" temperature for the temperature gradient from the core will lead to apparent discrepancies between calculated total energy and net radiation. The 60-year cycle is controlled by Jupiter and Saturn which have a resonance cycle of about 59.6 years. As discussed on the Home page, no one can be absolutely certain of the reason for the correlation of climate with this cycle, but the "information" from the planets must be "transmitted" to Earth by magnetic field changes and/or changes in the acceleration due to gravitational forces. The latter seems the more probable, and the actual variation in heating may be due to variations in the energy created by friction in the outer crust caused by solid Earth tides. For more detail on this please see the Home page. But more recent work published by Knox and Douglass in November, 2010 (see Summary) shows otherwise and they conclude that the oceans have been cooling since 2003, which is in keeping with NASA data. A comment is often made that the measured heat flow from the crust is insignificant. Pollack has analysed measurements of this and come up with a mean of 87 mW/sq m, though it is not clear to me exactly how he compensated for evaporation both on land and oceans, or for the conduction/convection process. In general, we would not expect much radiation when the temperature of the adjacent air is very similar in an equilibrium state: when temperatures are exactly the same there is no net heat flow at all. This is quite different from viewing the Earth as a blackbody from space. All the heat coming out from the core could certainly vary in long term cycles. This could explain any variation in net radiation which could be due to the underlying 934 year cycle (and other natural factors such as variations in cloud cover) rather than to the build up of carbon dioxide. The heat flow from the core has, at least since animal life started on Earth, maintained the temperature of the land and oceans at a "base" temperature something like that we would observe on a calm winter night an hour or so before sunrise. This is at least more than 250 degrees above what it would now be in the absence of such heat. Solar insolation during the day warms mostly on a daily basis, but with some storage of thermal energy as summer is approaching, and loss of that energy as winter approaches in that hemisphere. See more detailed explanation here. The only issue is whether there is or is not a build up of thermal energy in the oceans from one year to the next. Indeed we do find an accumulation between 1961 and 2003 (according to this IPCC plot) and that is in keeping with the temperature records. In general, we would expect such a build up of thermal energy in the oceans when temperature records have shown increases for a few years, because heat is distributed about 90% in the oceans and sea ice, 6% on land (and other ice) and 4% in the atmosphere. But this suggests that temperature records should be weighted by the energy in the oceans compared with the land (90:6), rather than by the relative surface area of oceans (~ 70%) and land (~ 30%.) Furthermore, if we can assume reasonable correlation between ocean thermal energy levels and mean sea surface temperatures, then this suggests that NASA "sea surface" temperatures could be the best available guide to what is really happening with world temperatures. The good news is that it now appears that the mean of these for 2011 will be less than the mean for 2003, implying a slight heat loss in that eight (8) year period. (See the last plot at the foot of the page and keep watching "Sea Surface" here!) However, note that the Trenberth and Fasullo plot above still shows an increase of about 0.3 W/sq m in 2009, but at least that is less than half the average annual increase of about 0.64 W/sq m for 1993-2008, But even these figures have been refuted by Knox and Douglass who produced the lower plot indicating cooling since 2003, in keeping with the NASA data. This paper is particularly relevant and all should read at least the Discussion and Summary. Thus we have compelling evidence that the global warming of last century is starting to become cooling at the very time when carbon dioxide levels are continuing their upward climb. Knox and Douglass explain that, assuming there really is no missing energy, the models have predicted excessive positive net radiation into the Earth, whereas the data indicates the result should have been slightly negative. All the carbon dioxide is having no effect. The period since 2003 has been very informative because (as can be predicted from the cycles discussed on the Home page) we have experienced fairly stable temperatures. Knox and Douglass found that, after correcting for errors in earlier measurements, ocean thermal energy has in fact been declining slightly, in accord with sea surface temperature data recorded by NASA,. (Here is a review relating to this issue.) So, the above shows that we have no scientifically valid theory or models which can accurately predict net radiation - or net energy changes in the oceans. Nor do we have any statistically significant empirical evidence to establish a correlation between rates of global warming and total carbon dioxide levels. Temperature trends have gone from positive gradients to negative gradients since early 2003, but the models have shown quite the opposite. How can the world trust such models?