Regarding the basic (climate) physics there’s agreement. No one refutes the physical meaning of the greenhouse gas effect or that it warms the Earth surface, given the same insolation. Well, no one serious at least. But in some sense one must differentiate between the greenhouse effect and anthropogenic global warming, with the supposed effect of trace gases on temperature being the wedge between them.
But theoretical agreement aside, what really matters is empirical confirmation. As the defence attorney of the null hypothesis I’m putting forward the following case:
The Phanerozoic Eon
The Phanerozoic Eon is the current geologic eon in the geologic time scale, covering 541 million years to the present. Over this period there’s no correlation between co2 and temperature, as seen below.
Further, during the Ordovician period the planet plunged into the Andean/Saharan ice age, at a co2 level of 2240 ppm, that is, at a level 6 times the current level. Equally interesting, in the Permian period, the temperature rose sharply while co2 remained at a low level. At no time in history, high co2 levels induced a runaway climate with a catastrophic runaway warming. Quite the opposite, temperatures are remarkably stable.
Ice core data
It’s obvious from the ice core data that the climate is always changing and that the present temperature isn’t unique, even at substantially higher concentrations than the pre-industrial levels.
More importantly, but not as obvious, is that the dependent variable is co2 and the independent variable is temperature. That means that co2 lag temperature, i.e. first it gets warm than the co2 level rises – not the other way around.
The thermometer era
The above measurements of temperature are derived from various proxies. But since the average temperature has been accurately measured, from the end of the 19th-century, there have been periods of both warming and cooling while the concentration of co2 has been steadily rising. An example is 1940-70 where temperatures fell while co2 continued to rise; that is, negative correlation between the variables. Although controversial, another more up-to-date example is the 21th-century global warming hiatus, where temperatures have been essentially flat.
Antarctica has an avarage winter temperature of -60c. The very cold temperatures means that the air cannot hold water vapour. Hence, the atmosphere over antarctica is dominated by co2 making it the significant greenhouse gas.
However, both satellite and ground measurements show no warming at Antarctica over the past 40-50 years during which time the co2 level has increased with more than 70 ppm. According to the Planck response the change in concentration should imply a temperature increase with 0,29c.
Discrepancies in the predictions of the theory
First of all, and the most obvious, are the failures of the climate computer models. The climate models are more advanced do-overs of computer models used to forecast our daily weather. Almost every model overestimates the change in temperature, implying a structural flaw in the basic premises (the long term effect of greenhouse gases on the radiation budget). There are also more fundamental mathematical problems with the models (arbitrary start values, non-solvable differential equations, iterations far into the future etc.), and in the end they have no scientific value whatsoever.
Another prediction from the theoretical models is that the OLR at TOA will decrease, for which there is no observational confirmation. The data seem to indicate that the OLR is stable, or even that the OLR has increased slightly. According to Dr. Noor van Andel the OLR has increased over the past 62 years:
Finally, increased greenhouse gases are supposed to amplify the warming in the middle and upper troposphere, to a larger extent than the surface. The surface is then warmed from the back-radiation of the now warmer atmosphere. But that’s not supported by the observational data from which it is evident that the surface warming exceeds the warming of the atmosphere. If the data is correct, these are major blows to the AGW-theory.
This is not very flattering. But to be fair, the only firm conclusion from the empirics is that natural variability dominates any effect from co2. Nevertheless, it should be clear that the ”scientific consensus” is a gross overstatement and that the null hypothesis has not been proven rejected.
Or? I don’t know.