Holman Jenkins: The Economic Uses of Al Gore - WSJ.com

In retrospect, a significant moment was the falling apart or debunking of two key attempts seemingly well-suited to clinch matters for a scientifically literate public. One, the famous hockey stick graph, which suggested the temperature rise of the past 100 years was unprecedentedly steep, was convincingly challenged. The other, a mining of the geological record to show past episodes of warming were sharply coupled with rising CO2 levels, fell victim to a closer look that revealed that past warmings had preceded rather than followed higher CO2 levels.

These episodes from a decade ago testified to one important thing: Even climate activists recognized a need for evidence from the real world. The endless invocation of computer models wasn't cutting it. Yet today the same circles are more dependent than ever on predictions made by models, whose forecasts lie far enough in the future that those who rely on them to make policy prescriptions are in no danger of being held accountable for their reliability.