Who claimed that solar variance turns off known physics? Remember, no one is claiming that there is only one factor that sets the earth temperature. It’s well established that GHC does modulate temperature, but there is no evidence that increases in CO2 really do lead to the kind of temperature rises observed.
OK, so you accept that the physics of the greenhouse gases is there—will you start to accept the rest of the science?
Now you are arguing the specific physics and number of “climate sensitivity” and to go further you have to do quantitative science. This is what professionals have spent decades working on.
This number is around what the vast majority of scientists who work on this think it is, and you get to the current consensus, which is mostly reflected in IPCC.
Now you have to show quantitatively that solar variance explains the current observations. Here is what current science says: It does not, on its own. Adding in GHGs does, and, most importantly GHG influence is going to increase strongly with time over the next 100 years.
The Sun & cosmic rays will do what they do.
It is true that there remains scientific uncertainty in the role of cosmic rays, but not enough to believe that the basic picture is broken.
Remember, the Ice ages came and went without man’s help!
Right. And if you work the numbers you find that the change in solar insolation from orbital forcing is not sufficient to explain the variation in climate, and so you have to look for feedforwards and feedbacks, and these are greenhouse gases and ice albedo. And sure enough the greenhouse gases DO change quite strongly with temperature (meaning that there is a feedforward amplification thanks to GHG).
The paleological record shows the physics of the greenhouse effect and changes thereof is valid both then, and now.
The emissivity of the greenhouse gases is not changed very much whether humans or natural phenomena released them (modulo small changes from isotopic composition balance affecting their mass and perhaps mixing to a small degree).
Nevertheless there is a final point. Even if there existed enough climate feedbacks to make the “sensitivity” be ZERO (which nobody serious believes), this also means that the patterns of the climate might change quite significantly from where they are now, because of all the effects necessary to maintain the temperature change at zero, and usually that’s a bad thing.
For instance, suppose you imagine that the ocean will absorb nearly all the CO2 and clouds will do the rest with albedo.
This still can significantly change weather patterns to be in a situation which is unprecedented over the last 600,000 years or so.
Is this a good thing? Human activities and agriculture and domesticated plant species are adapted to current conditions. Acidification of oceans would probably be really bad for food chains—and this is starting already.
In sum, significant global climate alteration (which is the inevitable consequence of doubling greenhouse gases in a geologically tiny amount of time) will occur even if you imagine all sorts of feedbacks. Solar influence will add random noise, increasing the risk of the high-side turning really bad.
