[microgood]

If you believe that CO2 in the atmosphere traps heat, and you believe we can accurately measure the average temperature of the Earth, how do you know how much is due to natural variation and how much is human caused?

For that, they use computer models (there are about 140 of them), which are really evidence of nothing except personal bias. There is no way to tell the difference between natural and man made temperature changes.

[Robert A Cook PE]

Well, there are actually only 28 computer Global Circulation Models, run by 22 different government labs.

Problem is, NONE have been accurate over even 20 years of real world measurements. If ANY were correct, ONE would track real world measurements.
NONE DO.
ALL over-estimate future temperatures.