[Jim Noble]

Here is a record of periodic warming and cooling of the Earth's surface over the past 450 000 years.

You will notice nearly regular (and quite abrupt) shifts of 20 Farenheit degrees or more. Given such enormous fluctuations in the past, is it not more reasonable to believe that the present small observed variation arises out of poorly understood natural processes?

If your answer is "no", what's the null hypothesis? That the surface temperature should never vary, and that if it does there must be some anthropic cause?

That's the LEAST likely explanation for the observed data.

[Bigh4u2]

How do they determine the temperature differential?

Density?

[lectricpup]

To say nothing of periodic variations in solar output, and many other factors. CO2 is a very very small component of the atmosphere. Suggested reading: State of Fear by M. Crighton

[chemainus]

Hooray...an intelligent and educated man speaks the learned truth...and it is so refreshing to hear...kudos to you Jim Noble! Keep it up please.