What's keeping James Hansen up at night?

In a post last week you'll recall I pointed out a story about a top government scientist who is openly criticizing President Bush for his failure to address global warming. Dr. James Hansen admitted he was risking his career by speaking out. What has him so alarmed?

Well, there are a number of things that when added up make Hansen's extraordinary move more understandable. First, take a look at this Pentagon report on the possible catastrophic effects of a sudden, rapid cooling in climate, the kind illustrated by the recent movie, The Day After Tomorrow. (The cooling would result from the collapse of the Gulf Stream which would ironically be caused by global warming. To understand how this would work, go here.) While the movie portrayed the change occurring over just a week for dramatic effect, the Pentagon report, which preceded the movie's release, outlines a scenario that would take place over 10 years and yet be wildly disruptive. A sudden cooling could lead to decreased harvests creating food shortages, mass migrations to warmer regions, long droughts with accompanying water shortages, and pressure on energy resources as dropping temperatures led to more energy consumption. Resource wars might become commonplace. The writers of the report say the scenario is only "plausible," not likely, and that they are trying to "imagine the unthinkable."

But, there are other urgent signs as well. There has been a sudden jump in carbon dioxide levels in the atmosphere. If carbon dioxide, which is a major greenhouse gas, continues to build up at this rate, it could lead to runaway, self-reinforcing global warming. And, there's this warning from German scientists working for a government advisory panel.

All of this doesn't mean a catastrophe is either imminent or certain. But, it does point to some very troubling possibilities. As I discussed in a post about the possibility of peak oil production, when we are faced with uncertain, but possibly catastrophic events, we would be wise to take out some insurance. We often take out insurance against risks that are quite unlikely, such as a house fire. But, we do it when the consequences of some rare or even theoretical event are especially severe.

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