There seems to be a rash of trying to explain global warming by theories that either ignore, or flatly contradict, the science called “physics.”
Often they involve some mysterious “cycle” (usually a 60-odd year cycle) which is claimed to be “obvious” but doesn’t stand up to analytical scrutiny. This is suggested as a cause of the global warming that’s been observed over the last century or so — or at least, the cause of so much of it that it enables one to minimize the warming due to man-made greenhouse gases.
They may even attempt to suggest a physical relationship to some other so-called “cycle,” often the AMO or the PDO, which also fails the rigorous test for genuine periodicity. These models are built on the correlation-and-to-hell-with-causation principle. You might as well ascribe global warming to Leprechauns. The “physics” behind such a relationship is tenuous at best. Let’s face it people, temperature increase is heat, heat is energy, but there’s paltry reasoning about where the energy is coming from, and why it has decided to surface now.
Then there are the “natural variation” theories — those which imply that the globe’s warming is just “business as usual.” You have to ignore a helluva lot to believe this. Like the rapid, dramatic, and unprecedented decline of artic sea ice, the evidence from paleoclimate studies, the dwindling of most of the world’s glaciers, the breakup of ice shelves that existed for thousand of years, rise of sea level coincident with the industrial revolution, change in the timing of cherry blossoms in Japan, etc. etc. etc. etc. etc. You have to wear those blinders very tight, not to see that modern climate change is far from “business as usual.” And perhaps the most idiotic of the “natural variation” variants is the idea that global temperature is just a random walk. Such ideas are often mathematically subtle and fascinating, but seem to fail rigorous statistical testing, while suggesting them as the real explanation of global warming is an insult to physics.
In fact it’s astounding how much known physics has to be ignored. Carbon dioxide is a greenhouse gas, that’s no longer a matter of opinion. Sulphate aerosols cool the planet, we’ve seen it happen (from both factory emissions and volcanic eruptions), and we can model it with impressive accuracy. Solar changes have had a modest impact, and no recent trend, because solar changes have been modest, with no recent trend. And yes, Virginia, feedbacks really exist, like water-vapor feedback which is every bit as undeniable as CO2, while a notable increase in water vapor content has been observed.
I suggest there are two motives for the proliferation of such “theories.” One is the obvious: those who have an ideological objection to holding business responsible for its actions, will bend over backwards to convince themselves global warming is not real, or it’s not caused by man, or it’s not dangerous. The other is the natural tendency for smart people to play with numbers and ideas, find interesting relationships, then persuade themselves they’ve happened on a key insight. This often requires ignoring the existing literature of climate science — otherwise you’d know how much is already known, and how little (or none) your new “pet” theory adds to understanding.
Some (not tamino to be sure) would say this is how “crackpot” ideas are born. I have, however, decided to give a name to such theories: mathturbation.