The data show warming since we came out of a little ice age a few hundred years ago. Fine.OK, let's use your data........![]()
The data also show CO2 rising over the last couple hundred years. Fine.
The CAGW hypothesis is that the correlation of these observations is not coincidence, and more specifically is due to human activity. That's a reasonable hypothesis, although it ignores established data showing that historical CO2 lagged warming and was thus likely a result of warming, rather than the other way around.
But then the wheels really come off. Testing the hypothesis required building models of the climate that consider how human-made CO2 might affect future climate. These models have to use an estimate of the positive feedback associated with CO2. Even the alarmists agree that CO2 alone won't have a significant impact. It's the positive feedback – warmer oceans means more moisture in the air, which means still more greenhouse effect – that raises temperatures so alarmingly. I believe most of the models used feedback factors of 2-5, even though the true value is unknown and could be zero or even negative.
These models failed miserably over the last 20 years. The null hypothesis that the elevated CO2 in our atmosphere will have no effect, cannot be ruled out.
Where are the data that conclusively tie current temperatures with elevated, manmade CO2? Not just correlation, but causality.

