Fair enough, I say. But there are two things that need to be said about this:
1. Yuk it up, Jon Stewart
2. If weather cannot be used as evidence, ever, except only over a historical period (decades? centuries?), then there is literally nothing that could happen to our climate in the short term that would be evidence against climate change theory. We could have 20 years of cooling, and scientists could say it is because of unexplained water vapor variations or unexpected solar minima, but it wouldn't contradict the general thinking on the upward trend, which is based on a historical record of supposedly reliable global temperature data.
As a result, global warming (as a trend) is not falsifiable by any sort of scientific experimentation. But that doesn't mean there is no debate worth having. There are still plenty of issues worth talking about: (1) the role of other substances (water vapor) in causing and perhaps preventing further warming; (2) the cost-benefit calculus concerning the value of carbon capture or geoengineering versus fossil fuel restrictions; (3) questions of "tipping point" science which indicates the existence of thresholds marking the irreversibilty of changes; and (4) what the actual results of warming will be, including whether there should be an assumption that all changes are inherently negative.
What the "global warming alarmists" have to understand is "humans are causing global warming" is not the end of the conversation, it's only the beginning. If they refuse to understand this, then they are just as willfully ignorant as the "global warming deniers."