Greenhouse warming – a refusal by some to analyse the science.

One thing that has annoyed me recently is the efforts of the so-called climate change skeptics. One of the rules of science is, nature is always right. You may have the most wonderful theory, but if nature disagrees, you are wrong. Evidence is key. The problem then is, the evidence has to be correctly interpreted and consistent with known physics.

An example that has annoyed me is the continued assertions that the temperatures have not risen significantly since 1990, and they produce graphs of temperatures taken at some place to prove their point. So, what is wrong with that? Well, for one thing, NASA has produced considerable evidence that temperatures have risen across the planet. Ha, the skeptics say, you have your figures, we have ours, so at worst it is unproven. The argument seems to be, our figures are no worse than yours. So, what is the problem here?

Actually, it is not really selected data. They are probably correct that their data is no worse. Their measurements may even be more accurate. The problem is that temperature is not the relevant measurement, but rather power flows are. If power in exceeds power out, since energy is conserved, something is heating. Prolonged measurements over the oceans during a period that is alleged to have had stable temperatures have shown (Lyman et al., 2010. Nature 465:334-337.) that between 1993 and 2008 there was an increase in the heat power delivered to the oceans of 0.64 w.m-2. A fifteen year period has to be sufficient to exclude random weather fluctuations during a “bad year”. The oceans were picked on because they are free of a number of other variables.

So, why were some temperatures not rising? There is more than one reason. One is that as you pump more heat into the atmosphere, there is more energy available, and that means that winds are stronger. In turn, that means better mixing of the air. Thus where I live has had some record cold temperatures, the reason being that stronger storms, etc, have transported more air from the Antarctic, and that is decidedly colder than the air normally about here. Of course, by moving colder air from the Antarctic, warmer air has gone in to replace it, and the Antarctic is warming. If it were only the air, that would not be a problem, in fact it might even be good because it would take more moisture over the Antarctic and deposit more snow, which works against sea-level rising, but unfortunately that is not the issue. Extra heat going into the oceans gets to work on the polar ice shelves, which melts them. There is another reason: as you melt ice, heat is absorbed but there is no temperature increase. You don’t believe me? Get a thermometer and put an ice/water mix on an element and heat. The thermometer will stay at 0 oC until the ice has gone, as long as the mixing is good. Melting ice absorbs heat, and unfortunately, the melting of polar ice is to some extent ameliorating the temperature increase.

Another claim that annoyed me was the observation that the upper troposphere was cooling, and this allegedly showed there was no global warming. That is just plain wrong. In the greenhouse mechanism, infrared radiation from the ground is absorbed by CO2. At this point, there is no change of temperature in the gas. The CO2 has become vibrationally excited, but that is all. Now, one of two things can happen. It can re-emit radiation in any direction, or it can collide with another gas molecule, in which case the vibrational energy may be converted to kinetic energy shared between the two molecules, and this does lead to heat. (Most of the atmospheric heat is actually from convection or water vapour condensation). However, the same works in reverse: collisions of molecules can excite vibrational states. If the new gas molecules can emit infrared, they have that option, but isolated oxygen and nitrogen cannot by themselves. Therefore, extra CO2 at the top of the troposphere actually cools it by radiating more heat to space, derived from collisions with other gas molecules, and that lowers the temperature of that part of the atmosphere. So, why does the planet warm? The extra CO2 at the bottom radiates energy back to Earth, and that excites the radiators there, and these radiate back to the atmosphere, but at the same rate they did before. The problem is, before they took heat from the environment and radiated it, thus cooling. Now that cooling is slowed because they are taking their energy in part from returning infrared radiation from the CO2 in the atmosphere. Thus the CO2 acts more like a blanket cast over the planet; technically it does not heat the planet, but it slows its cooling, which is the same effect.

What annoys me is that some seem to think that observing what the physics predicts is somehow evidence that the physics is wrong! Bizarre! You cannot prove a proposition is wrong by citing evidence required by the proposition.

The problem here is obvious: an urge to say what is convenient overcomes the need to do the proper thinking and properly analyze the evidence. Unfortunately, this urge will have some serious consequences.

I apologize to those who expected a post yesterday. I had an alternative post, an announcement, but unfortunately what I intended to announce did not happen!

 

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