Falsifiability is required by the scientific method, and it refers to the ability to run experiments that would confirm or disprove (falsify) a hypothesis. AGW was non-falsifiable because there was no practical experiment that anyone could run that would prove or disprove that global warming -- when it happens -- is caused by humans.
The climate alarmists frequently use computer models to "prove" that their assertions are true, and then extrapolate wildly to invariably catastrophic conclusions. However, computer models are not experiments at all, but buggy self-fulfilling prophecies with circular dependencies.
When real scientists attempt to reveal the truth (just like Galileo and Copernicus in the olden days), they are shunned, de-funded, un-published, and called "outliers". Thank you Dr. Easterbrook, for your courage to speak out.
Dr. Easterbrook offers real scientific data at his website - you can find it here.