Is there any level on which a climate consensus can be said to exist? Only at the most obvious level, which is that everyone agrees that the climate changes. The realists know that the climate has always changed, drastically over millions of years of alternating Ice Ages and Warm Periods and within a narrower range over the warm last 12,000 years, with such periods as the Minoan Warm Period, the Roman Warming, the Medieval Warm Period, and the present warm period. The catastrophic man-made global warming alarmists claim that the climate was very stable prior to the Industrial Age, which just happens to have had its start at the end of the Little Ice Age according to the Climate Realists. But, since man became powerful and plentiful with the Industrial Age, the alarmists say that climate change now occurs mostly due to man.
Obama and legions of those who argue that mankind faces its greatest challenge in trying to prevent the catastrophe of man-made or anthropogenic global warming, like to claim that 97% of scientists agree with them. This claim is based on a completely bogus survey of published papers, with papers simply stating that there may be some human influence on climate being counted as part of a scientific consensus.
It is not noted that almost all climate research or other research with any implications about the climate at all is funded by governments, almost all of which will not fund research that is unfavorable to the thesis that man has warmed the planet badly since the start of the Industrial Age. If you are a scientist and you want further government funding for your research, you are likely to be rewarded if you find some way in which your results support the government-favored thesis of catastrophic anthropogenic global warming. If your results are contrary to that thesis, it will be fatal to further funding support to take note of that. You had best put another interpretation on your results. One of the most interesting observations is that retirement brings on a major change of viewpoint for many scientists. Those who supported the alarmist claims before retirement often oppose it afterwards. Those who were silent on the subject often come out against the alarmist thesis after retirement. This applies to many scientists who are not climate scientists themselves, but are experts in radiation such as infra-red, visible light, and ultra-violet light radiation. Just like climate scientists, it is harmful to their careers if they speak out against the so-called consensus the governments have tried so hard to create. NASA, Navy, Air Force, Army, EPA, NOAA, and university researchers in the sciences in the USA are all given good reason to be fearful about their careers if they speak up against the alarmist crusade. The government has worked ruthlessly hard to try to produce a “scientific consensus”, but has massively violated the scientific method in the process. The scientific method depends critically on independent thinking and on freedom of speech and press.
Most of the scientists said to be supporters of the catastrophic man-made global warming thesis can not provide a decent explanation of the physics which is supposed to cause the so-called greenhouse gases to cause a catastrophic level of warming. Most of those who attempt an explanation will initially try it by using an argument similar to that used in the IPCC reports from 2001 through 2014. This explanation of the science is based on a viewpoint provided in the following Earth energy budget:
The IPCC reports claim that solar radiation absorbed at the surface of the Earth causes the Earth's surface to emit about 2.3 times as much energy in the form of infra-red radiation as it absorbed from the sun. This seems plausible to them because they believe that a body will emit infra-red radiation at the bottom of the atmosphere and with water all over the surface just as the body would if it were isolated in space. This is not the case. Infra-red radiation is emitted from oscillating dipoles and they cannot emit all of their energy in the form of radiation when those same oscillating dipoles are dumping energy into the evaporation of water and losing energy via collisions with air molecules.
But having started off by neglecting the conservation of energy, the IPCC has to balance out the flow of energies, so they posit a huge back-radiation flow of energy from the so-called greenhouse gases in the atmosphere. This does not happen either. It violates electric field theory. It also fails because the mean free paths of the infra-red radiation that can be absorbed by water vapor, carbon dioxide, and methane gas are all very short. That means that these molecules absorb the infra-red energy they emit over a very short distance. In the lower half of the troposphere, the likelihood that the absorbed radiation in a greenhouse gas molecule will be re-emitted before it is transferred to non-radiating molecules in the infra-red range is very small. There is just too high a collision rate between molecules, so that radiation energy is almost immediately changed into molecular kinetic energy in non-radiating molecules. There is no way that the atmosphere as a whole can radiate a large quantity of infra-red radiation back to the Earth's surface in accordance with the IPCC viewpoint. The supposed back-radiation in the energy budget above is 1.93 times the solar radiation energy absorbed by the surface! What is more, though molecular infra-red radiation is isotropic, the catastrophic energy budgets all claim that the atmosphere radiates much more energy downward than out toward space. In the schematic of Fig. 1. the downward or back-radiation is 324 W/m2 from the atmosphere, while the radiation toward space from the atmosphere is only 195 W/m2 .
The basic problem that greenhouse gas theory is trying to address is the fact that the surface temperature of the Earth is about 288K, while the radiative temperature with respect to space of the entire Earth including both surface and atmosphere is about 255K. Much of the radiation of infra-red into space is from altitudes in the atmosphere which are considerably cooler than the surface temperature, though some of the radiation is from the surface through the atmospheric window. Note that the temperature difference between 255K and 288K is 33K, which is attributed by the greenhouse gas theory to warming of the Earth by greenhouse gases. The viewpoint is one which is entirely dominated by a belief that by far the only significant transport of energy in the entire atmosphere is by means of radiation.
Interestingly enough, when the problems with the usual greenhouse gas viewpoint of man-made global warming featured in the IPCC reports and vaguely taught in the schools are pointed out, many of the scientists who hold that viewpoint will then begin arguing a second and very different theory of man-made global warming based on the effects of infra-red active gases. It seems not to register on them that one cannot claim a scientific consensus if there is no general agreement on the actual mechanism upon which an infra-red active molecule can warm the Earth. They have turned to a second and incompatible mechanism, yet they do not stop making the claim that they have a scientific consensus. Some of those who argue from the start for this second greenhouse gas theory are lukewarmers, who maintain that the warming effect is less than would be catastrophic, but still significant.
Examining Fig.1., one sees that 40 W/m2 of radiation from the surface is emitted through the atmospheric window directly into space without absorption in the atmosphere. Thus, of the total of about 235 W/m2 of infra-red radiation that the Earth emits into space, about 195 W/m2 is emitted from the atmosphere. We can calculate the effective temperature of this emission and from that find the effective altitude from which the emission from the atmosphere into space occurs. We have
P = 195 W/m2 = σ T4 = (5.6697 x 10-8 W/m2K4)(T)4
and we find that T = 242K. In the U.S. Standard Atmosphere Tables of 1976, this temperature is at an altitude just above 7000 meters. It is a higher altitude in the tropics.
The catastrophic man-made global warmers like to examine the case of a doubling of carbon dioxide in the atmosphere. Imaging such a doubling. The added carbon dioxide would absorb somewhat more of the radiation now emitted by water vapor into space, though water vapor emission would still be the main source of radiation into space. Water vapor is actually very low at altitudes of 7000m and above because the temperature there is way below the freezing point of water at 273.15K or 0C. Despite this, water vapor radiation emission will be greater than that from a doubled carbon dioxide concentration. The warming argument goes that radiation from lower altitude water vapor will be absorbed by carbon dioxide molecules and emitted by them into space at cooler temperatures since they are at higher altitudes. The cooler temperature of emission will mean that less energy is radiated into space, which results in warming the entire atmosphere. This ignores the fact that at these altitudes, some re-emission of absorbed radiation will occur without being distributed to non-radiating molecules since the gas molecule collision rate is now much lower than in the lower troposphere. The absorbing molecule is not in equilibrium with the surrounding air molecules. The argument makes a much greater mistake, as we will see.
Let us suppose for an estimate of the maximum effect that all of the emission from altitudes near 7000 m and all of the emission from water vapor molecules is captured by higher altitude carbon dioxide molecules. Instead of an emission temperature of about 242K, the carbon dioxide emission occurs at the lowest emission temperature from the tropopause beginning at about 11000 m in the U.S. Standard Atmosphere of 1976 or a higher altitude in the tropics. The tropopause temperature is about 217K. The stratosphere is above the tropopause and the temperature increases with altitude in the stratosphere. Let us calculate the power of emission possible by twice as many carbon dioxide molecules at the temperature of 217K:
P = σ T4 = 2 (5.6697 x 10-8 W/m2K4)(217)4 = 251 W/m2
It is clear that twice as many emitters at the lowest available temperature of 217K can emit more power than they can absorb despite the lower temperature. Yes, about 125 W/m2 will be emitted back to lower altitudes, but this energy will be quickly absorbed by other carbon dioxide or water vapor molecules and half will be emitted spaceward. A geometric series of powers of 0.5 quickly approaches 1 in terms of the number of absorptions and each absorption is occurring in very little time. In fact, these cooler carbon dioxide emitters are not going to emit more power than is transmitted to them by the predominantly warmer and lower altitude water vapor molecules, but they are not going to have any problem transmitting the 195 W/m2 into space. They will not cause the lower atmosphere to warm up.