The arguments for man-made global warming remind me of the argument that eating eggs causes heart disease.
The proponents of anti-carbon measures like carbon taxes or CO2 emissions caps chide those opposed for being unscientific. Judy Weiss of the “Citizens Climate Lobby” argues that “scientists are curious” whereas “deniers and 'climate skeptics' cherry-pick data to disprove warming.” What data? Well, that the world hasn't seemed to be warming much in the last 15 years.
It seems obvious to carbon-cappers that urgent action is needed. The story, they explain, is simple: so much energy reaches the Earth each day from the sun: some is reflected into space, some is retained in near the Earth's surface. Carbon dioxide retains heat better than oxygen or nitrogen (the main components of air). If the proportion of carbon dioxide in the atmosphere increases, heat retention will increase: end of story. If we don't notice any heating, it must just be because we aren't being open-minded enough. It must be there, and it must be bad—and more regulation must be the cure.
Now, back to eggs. For many years, it was thought that eating cholesterol (which eggs have lots of) caused elevated blood cholesterol and thus caused heart disease and death. When consistent evidence was not found that cholesterol-eaters had higher mortality, this did not deter the “scientific” advocates of low-cholesterol diets. The story, they explained, was simple: you are what you eat.
But it turns out that eaten cholesterol does not consistently impact “serum” cholesterol in the blood. Go figure: the anti-egg policy had neglected to account for digestion and the effects of nutrition.
When carbon-cappers reaffirm their faith that carbon emissions must be bad, regardless of surface temperatures and actual weather patterns, could they be making the same kind of mistake the anti-egg dietitians were making? That is, using a simple, but false, story in place of solid evidence.
The climate is complex: cloud patterns, ice formations, human construction, plant growth, and solar activity are just a few of the many contributing factors. The story behind the man-made warming hypothesis is not unreasonable. But it isn't the primary evidence.
In studying the effects of diet, we should look to life expectancy. When thinking about global warming, we should look to, well, global warming. And when we think what to do about changes in climate, there is no cause to panic as long as life remains good on Earth. The global warming hypothesis is, in the end, a hypothesis about warming. That's the evidence that has to be assessed before enacting draconian public policy measures that can make life on Earth demonstrably bad.