Dialogue on AGW continued...

(Question): A theory is supported by data derived from repeatable experiments that result in the same conclusions.'

Some would suggest that since there is no 2nd Earth to run repeatable experiments on, then anthropogenic climate change can never be 'accepted'.

However, the theory that CO2 and other infrared-active gases do absorb and emit longwave radiation has been proven by lab experiments. Reduced outgoing LW radiation and increased downward LW radiation have been measured.

The effects of various natural forcings have been examined.

Is that approach sufficient?

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Owen
In short, no. The data that shows Co2 gasses absorb infrared light, and the determination it does so is good science. It is experimentally repeatable. However to take that determination and extrapolate it to global climate systems is hugely problematic. The global warming advocates refuse to admit that. There are other experimental results that reinforce the AGW theory. For example the experimental fact that CO2 measured in Hawaii is now 392 ppm, compared to 358.4 ppm 20 years ago.
This is good science. Various experiments verify that measurement repeatedly within appropriate margins of error. It is valid and is empirically supported to say atmospheric CO2 levels have increased over the past 20 years. The scientific methodology for both of these understandings is broadly accepted and repeatable. The error margins and conclusions have been accepted by peer review, and are not falsifiable.

The problem is when we erect complex theories around these conclusions. Erecting theories is fine, but to suggest that they are accepted without further study is disingenuous. The problem is multiplied by the way scrutiny is handled, the way questions are shouted down, the way that equally valid measurement is discounted. To say the science is settled on complex theory and anthropogenic global warming is established fact does irreparable damage to the discipline and seriously undermines scientific credibility.

No other field is as intolerant to criticism, skeptical questioning, and scrutiny of datum.