Commentary: Global Warming?

An article from the AP about global warming makes some interesting and strong claims. The article, based on a study from the National Academy of Sciences, claims that global warming is real and that it is caused by people. The report makes it sound like it's an open and shut case. Global warming exists, and we are the cause. Time for the Kyoto Protocol and other flawed and economically destructive policies, right? To quote Lee Corso, "Not so fast, my friend."

First, the claim that global warming is real can only be substantiated by direct temperature records for only the past 150 years. In that time, there does seem to be a sort of warming trend. )This, of course, ignores a dip in temperature observed during the 1970s.) Before about 1850, climatologists have to use indirect methods, such as looking at ice cores, tree rings, and lake sediments. Therein lies problem number one. Such indirect methods indicate some information about temperature, but because of the complex nature of this world, it is difficult to construct an accurate tempearture profile for the past. It is primarily guess work, and personal bias can easily affect such guesses. It's possible that this was the case.
However, I do not wish to deny the possibility that we're seeing global warming. Certainly, in the past 150 years, the average temperature of the lowest part of the atmosphere seems to have increased. So, the earth could be warming up. The data, though, are not as conclusive as the report (and article) make it seem.
Secondly, even if global warming exists, the evidence for human causes are unfounded scientifically. The best that scientists can do is point to a correlation between increased temperature and increase greenhouse gases. However, as any first-year statistics student will tell you, correlation does not mean causation. Is it a good idea to try to reduce "greenhouse gases?" Sure, it is a good idea, but to take desparate measures to limit greenhouse gases will only wind up doing greater economic damage than anything forecast by global warming.
So, in the end, we should take reasonable, economically feasible steps to limit any contribution that we may be making to global warming. Let's make sure, though, that we don't create an economic catastrophe in trying to prevent a possible environmental one.