1. Alter Earth's orbital path around the sun.
2. Change the synthesis of plants in the ocean. The bulk of the planet is water after all.
Obviously, neither of these things are going to happen.
1. Every body in the universe has some finite temperature.
2. Every body in the universe radiates some of its energy away, continually, as electro-magnetic radiation, aka light, of whatever frequency. The hotter the body, the higher the energy of the light and the shorter its frequency.
3. By one of the great laws of physics, the light energy radiated away by a body generally goes as the fourth power of its absolute temperature (degrees Kelvin). This is strictly the case for a so-called "black" body, with minor corrections for "lighter" (in color, i.e. more white) ones.
4. The energy radiating away happens continually. It is a transfer of energy away from the body per unit time. The physical term for a flow of energy per unit time is "power".
5. As energy is radiated away, less is left within the original body, whose average energy per unit mass therefore declines. Which is synonomous with the body becoming cooler, i.e. the absolute temperature falling.
6. Therefore, every body in the universe declines in temperature continually, if left by itself. Energy is something that -naturally- "spreads out". In physical terminology, a system state with light photons scattered over enourmous distances in all directions, with a cool body left in the middle, is higher in entropy (less "ordered") than one with a hot body in the middle and no scattered photons. Natural systems left to themselves progress from the more ordered (center-hot) state to the less ordered (scattered light, cool) state.
7. Notice that entropy increase does -not- mean things get continually hotter. On the contrary, entropy increase leads to energy getting more spread out in space, more "even", thus cooler at the hot points (warm bodies), and warmer in the empty reaches of outer space (spread photons).
8. To maintain any given body at the -same- finite temperature, something must replace the energy being continually radiated outward as light. We say, a continually operating -power source- is necessary merely to -maintain- a given finite temperature. Energy per unit time is needed to hold temperature -steady-.
9. For temperature to increase -temporarily-, all that is necessary is for there to be greater energy per unit mass within the body in question. But a higher temperature also means an increased rate of radiation outward. This is thus a "restoring" force.
10. So, one-off inputs of energy lead to -temporary- rises in temperature, an increased rate of re-radiation, which reduces the energy to its previous level. The long run mean temperature cannot be changed by any one-time energy input.
11. To bring about an -sustained- increase in the mean temperature of a body, therefore, requires a -new- continually operating -power source-. A source of energy per unit time. Natural entropy increase does not bring this about. Energy input does not bring this about. Only energy per unit time, and more of it than before, brings it about. Some energy per unit time is needed just to -maintain- the -old- temperature, which would fall without such an ongoing source. A larger, more powerful ongoing "income" of energy is necessary for the temperature to stay higher.
12. If anyone thinks any of the above is complicated or difficult to follow or counter-intuitive, simply turn on an electric stove burner, maximum setting. It heats up, and glows red-hot. Now turn off the power. It does not get continually hotter with the power source removed. It does not maintain the same temperature. The temperature rapidly falls as energy is radiated away (which you can feel warming your hand several inches away). When you set the power at "5", the burner heats to some level and then stops getting warmer, once the rate of re-radiation equals the power you have supplied. To increase the temperature further, you must supply more power, say 8, and do so continually. You have seen this many times and it is fully in line with your common sense, the only tricky thing is what the various physical terms used to describe aspects of the process, mean.
13. Now consider the whole earth. What is its power supply, that is can maintain (let alone increase) its present mean temperature? There are actually a number of components, but by far the most important is incident sunlight. There is a small additional amount of energy provided by radiactive decay processes throughout the earth, particularly from trace uranium in the crust and mantle. The inside of the earth is getting slightly cooler over time, which "transports" a slight additional energy term to the surface layers. There are tiny amounts of incident starlight and incoming particles, cosmic rays, etc.
14. There are three additional aspects of the earth system that are important for its mean temperature. First is the geometry of the system. The earth is approximately a sphere and it rotates. The area receiving light from the sun is smaller than the area continually re-radiating. Only half the earth is in sunlight, noon is only a line, etc. The energy received per unit of re-radiating area is only 1/4th what it would be if the earth were bathed in sunlight from all sides.
15. The second is the albedo of the earth, its "color" or reflectivity. The earth is not entirely "black", and some portion of the sunlight reaching it is not absorbed and converted to heat energy, but is instead re-radiated immediately without spending time as heat. This makes a minor reduction in the sunlight power term.
16. And the third is the presence of the atmosphere, and the famous "greenhouse effect". Which has to do with energy transfer within the atmosphere. Basically, the atmosphere is more "opaque" or "dark" to infrared wavelength light ("heat" rays, like those you feel from a fireplace with glass doors closed) heading outward, than to the mostly visible wavelength light (plus some ultraviolet) heading inward. Light energy can make more than one "round trip" between surface and sky, which increases the total power -at the surface-.
17. The present earth mean temperature is around 290 degrees kelvin. If the earth did not rotate, the hot side would be much hotter. If there were no atmosphere, the whole thing would be much cooler -at the surface-. It is -40 degrees up at the altitude jet airlines fly, for instance.
18. The dominant component of greenhouse effect, the warming provided by the existence of the atmosphere, is due to water vapor. Water vapor accounts for well over 95% of all greenhouse warming. If we didn't have any of it, if there were no water vapor in the sky, the surface would be frozen solid, as cold as the upper atmosphere is today.
19. 70% of the earth's atmosphere is nitrogen, 20% or so is oxygen, and the water vapor that provides most of the greenhouse warming effect is no more than a few percent of the atmosphere. The portion of the light spectrum (colors) sensitive to water vapor is "saturated", meaning the sky is nearly "black from below" in those frequencies. So small changes in water vapor concentration have little effect on total greenhouse effect.
20. Everything else in the atmosphere is a "trace gas", present in very small quantities. CO2, for instance, is less than 1% of the atomsphere. When we consider the greenhouse effect of trace gases, it must be clearly understood what a peripheral role they play in mean temperature. The dominant factor is sunlight, then rotation, then having an atmosphere at all, particularly one effectively saturated with water vapor. Way down the list comes whatever marginal greenhouse power -at the surface- may be provided by the trace components of the atmosphere.
21. Now, what factors in all of the above can change over time? Sunlight can change over time, either from changes in total solar output, or changes in distance from the sun weighted by time spent at that distance. The "color" of the earth (its "albedo") can change over time, though only marginally, within pretty narrow limits. And the composition of the atmosphere can change over time, particularly the trace elements, because they are tiny quantities to begin with so larger changes in them are possible.
22. Remember the law discussed in item 3. To increase the mean temperature 1-2% in degrees kelvin (2.9-5.8 C) and keep it there, a continually operating power source is needed, that is 1.01^4 times to 1.02^4 times the size of the previous one, or 4-8.25% higher. The typical scare prediction of a 5 C mean temperature increase therefore requires 7% higher power, henceforth and forever. 23. Direct observation of solar output shows that mean solar energy output varies by on the order of 1% over time scales as short as 15 years. These variations correlate with sunspot activity - the sun is hotter overall when sunspot activity is high.
24. The total power per square meter from sunlight is estimated at around 1370 watts. But these things are usually tracked in terms of earth area or re-radiating area, which as mentioned above is 4 times larger, so around 342 watts is the sunlight figure, adjusted in effect of rotational cooling.
25. The UN estimate for greenhouse effect from CO2 is on the order of 1-2 watts per square meter. When CO2 concentration is projected to double, this would add roughly 1-2 watts additional to the total power, therefore. The total power is much higher than the sunlight alone (else it would be -40 C at the surface, as it is at the edge of space), so we are talking about +1-2 to an existing 700-800. Some allege additional power terms from other elements besides CO2, similar in size. In rough orders of magnitude, that gives possible changes from 0.1% to 1% in the total power.
26. Changes of 0.1% to 1% in the total power term can only lead to sustained changes in earth mean temperature of 1.01^.25 to 1.001^.25, or 0.07 to 0.7 degrees C. It is also noteworthy that changes of that size are the same order of magnitude, or one order of magnitude smaller, than observed solar variation.
27. Detailed records from the past century show mean temperature changes on the order of 0.5 C. Exactly in line with the scale of variation predicted by the above physical analysis. Meanwhile, temperature measurements by deep ocean or by satellite data show either no measureable change over the last 40 or so years (satellite), or changes 1/10 to 1/100 the above scale (ocean).
28. The actual predictions of global warming theorists have consistently been 3-6 C, most commonly 5 C, ever since the theory was first advanced more than 100 years ago, when little was known about any of these processes, and even the basic physics behind it all was quite new. Science develops, new data is gathered, the theory changes, but the prediction does not move in response to any of it. This is not usually a sign of a good prediction in science. It is usually a sign of jiggling the theory to save the prediction, instead of the other way around.
29. When first proposed, the 5 C warming prediction was supposed to occur due to doubling the atmospheric concentration of CO2 alone. This was hypothesized as the cause of ice ages. Historical data on ice ages tended to show 5 C overall mean temperature changes, and scientists were looking for a possible cause of those changes. That CO2 could cause greenhouse effect was a deduction from recent physics at the time. No direct measurements of the scale of power effect from CO2 greenhouse were available. As already noted, the UN and global warming theorist's own estimates of CO2 power are far too low to actually cause temperature changes that large.
30. The present scientific explanation of ice ages is not a CO2 greenhouse hypothesis. It is instead an orbital variation hypothesis. Briefly, the earth can absorb more solar radiation on average when its orbit around the sun is more eccentric (elliptical) than it does when it is less (more circular). The reason being, the earth moves more slowly at the far end of the ellipse. More of its total energy is gravitional potential, less is kinetic, at the far point. It thus spends more time lingering at colder, farther point, comparatively less at the closer, warmer one.
31. The eccentricity of the earth's orbit can change over time. Angular momentum can be exchanged between the earth-sun orbit, and the earth's rotation, as the angle of the earth's spin-axis to the orbital plane shifts. It is like the physics of a spinning top. The orbital variation ice age hypothesis can explain changes of several percent in the average solar radiation the earth would receive, over the right time scales - tens of thousands of years.
32. The 5 C prediction is based on a parallel to ice age scale changes, in the other direction. But CO2 greenhouse changes do not cause ice ages. Past ice ages are "over-explained" by greenhouse theories and models. Meanwhile, direct measurement of the power available from trace gas greenhouse changes are the wrong order of magnitude for the 5 C prediction.
33. No observational data contradict the idea that greenhouse gas variation can only account for mean temperature changes on the order 0.1 C to 1 C, as suggested by physical "power budget" analysis.
34. Global warming theorists, confronted by these facts, have stubbornly refused to change their 3-5 C temperature change predictions.
35. Global warming theorists, confronted by these facts, cannot produce a power budget that explains -what- the supposed new continually operating power source needed to sustain a 3-5 C temperature increase, is supposed to be.
36. Instead, they wave their hands and chase "epicycles". They allege - merely allege - all sorts of hypothetical linkages between the small power terms they can get from trace greenhouse gases, and every other process they can think of that might effect mean temperature. Such as changes in cloud cover, water vapor, planetary albedo. They need, in other words, some giant "amplifier" hidden in some hitherto unknown part of the system, to "boost" the tiny power term sound physics can see, and what they need to save their precious scare-monger prediction.
37. Every allegation specific enough to have a number put on it, upon examination is the wrong magnitude, in the wrong direction, or both. They said it was clouds. Physicists looked. They found tiny changes in cloud cover, on the order of 1%, over time scales of decades, and in the wrong direction. It was doubted whether clouds were net coolers or net warmers. Physicists looked. They found a total surface power effect on the order of 13 watts for all clouds. 1% variations in 13 watts produce changes of .13 watts, two orders of magnitude too small. The story is the same with alleged albedo effects (from reduced snow cover e.g.).
38. Meanwhile, the hypothesis of a hidden 10-fold power amplifier has insurmountable conceptual difficulties. Because variations as large as those causes by trade greenhouse gases are impacting on the system continually. Solar variation over sunspot cycles are as large. Regional weather variations are orders of magnitude larger. Why don't these other variations touch off the amplifier effect, whatever it is? Why only CO2 greenhouse?
39. The amplifier hypothesis thus makes an additional prediction that can be tested directly. It predicts widely fluctuating mean temperature, and "runaway" temperature change processes, in both directions. If this were in fact the case, the earth would long since have shifted to frozen or to boiling. It hasn't.
40. Instead, long term past data shows temperature variations on the order of 0.5 C changes in a century, 1-2 Cchanges over millenia, and 3-5 C changes over ten thousand years. Which suggest (1) that the total power in the surface system is tightly bounded, varying only a few % overall, (2) comparative large changes in power require long periods of time, (3) power terms either vary slowly, or vary randomly with a small standard deviation, on the order of 1% per century at most.
Everything else has been an "epicycle hunt". Meaning, an attempt by those committed to a theory to find ways it may still prove right, by alleging all of its missing deficiencies are due to less than total understanding of the most obscure, random, and complicated processes they can imagine linked to their model. They then insist that their prediction is right, that it "comes out of their models", and wave their hands at the mass of not-yet exhausted complexity over there, in the epicycle de jour.
The parismonius alternate theory is that variations in trace greenhouse gases can account for mean temperature variations of tenths of a degree C, but not of ones on the scale of 5 C. This fits the known physics and the known facts, on every front. The only thing it doesn't fit is the outdated scare mongering prediction of 5 C temperature changes.
It also fits common sense. Because the existence of the atmosphere at all is only the third largest factor in earth mean temperature. And trace greenhouse gases are changes to less than 1% of the atmosphere. Changes in tiny portions of subsidiary causes very rarely lead to wholesale changes in the effect.
They can only do so in remarkably unstable systems. But all of the evidence - above all, the fact that we are still here - says earth mean temperature is broadly stable. All long time-scale exceptions to that statement (ice ages e.g.) are already accounted for by other processes (orbital variation e.g., also solar minimums and maximums).
I hope this is interesting...