Quote:
Originally Posted by t vago
I get a 0.07 % rise, so it looks like a decimal point is off.
Regardless, you can't just look at a percentage variation of solar irradiance without comparing it to the percentage rise in average global temperature.
So, we'll place the 0.6 C rise in the same percentage term as for the rise in solar irradiance. Taking the average global temperature on Earth, which is estimated to be 18 C, or 291.15 K, we get 0.6 / 291.15, or a 0.2% rise.
Now, take that 0.07% rise in solar irradiance, apply it to the Earth's atmosphere with all of its many mechanisms that are still poorly understood (even by pro-AGW climatologists), and you get a 0.2% rise in average global temperature.
Keep in mind that one of these poorly understood mechanisms is the ability of cosmic rays to influence cloud formation. Since clouds reflect sunlight back into space, that reflected sunlight cannot then cause greenhouse warming because it cannot hit the ground and warm it up. Solar output is known to partially shield the Earth from cosmic rays. So, if solar activity goes up, the Earth is a little more shielded from cosmic rays than before, and cloud formation drops. If cloud formation drops, more sunlight then is available to hit the Earth and heat up the atmosphere.
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Correlation does not imply causation. If that was true and there was a 5% increase in ice cream consumption as well as a 5% increase in homicides during the summer we would already be patting ourselves on the back for banning ice cream and eliminating homicide. Roughly speaking, the increase from solar irradiation is calculated by multiplying the increase in isolation by the Earth's albedo (How much of that stays in the atmosphere), which is ~.3-.35. Given the graph of solar irradiation you posted then we've seen a ~.3W/m^2 increase since 1900, and w/ a albedo of ~.33, then we'll trap an additional ~.1W/m^2, which happens to be what the
IPCC estimated. ~.1W/m^2 isn't enough to account for the increase in temperature, so we look at
other things that change the albedo of the planet (GHGs) and are large enough in size. Granted, science is still about theory. It could be that we really aren't causing this because our science is wrong and we just happened to have a natural rise in an undetectable substance that causes what we think GHGs cause, or maybe "God" or "Aliens" are doing something similar to "test" us. All we have to go on is what we think we know and that points to GHGs as the driver behind the change in albedo. Theories/Laws can be broken, but I wouldn't want to try to break the law of gravity by jumping off the empire state building, and I wouldn't try to prove physical chemistry is wrong by betting against GCC, especially when the
abatement for about half of our emissions is cost neutral.
