Saturday, August 6, 2011

Climate change likened to an imminent asteroid impact

From Peter Kelemen via WAMC, Northeast Public Radio, comes a thought experiment that illustrates the ethics of making decisions about climate change: A large meteorite impact 65 million years ago probably wiped out the dinosaurs. This episode may be relevant episode as we consider scientific evidence of climate change.

What if astronomers today were to discover a similar object, which most agree has a 90% chance or more of hitting earth but that the extent of damage is less clear? If missiles are built and launched in ten years, we could deflect it, for $50 trillion nearly a whole year of earth's economic output. If we wait, the meteorite will become more difficult to deflect, and the cost will rise dramatically. Some politicians shrug it off and propose to take the hit -that is, if it happens - and deal with the consequences. After all, people are smarter than dinosaurs. To stimulate action, a few astronomers exaggerate their predictions. In turn, scientists are accused of a conspiracy to garner grant money and fame. An international conference is convened.

This parallels the situation facing climate scientists and policy makers. The great majority of climate scientists have a high degree of confidence that the climate is changing, and we are driving it. Though the specific consequences are uncertain, we know that carbon dioxide is a greenhouse gas; its concentration in the air is the highest in human history; and its rate of increase is unprecedented in the geologic record. Do scientific uncertainty and political debate mean that no action should be taken?

No. Some possible outcomes have disastrous consequences. I'd recommend getting to work on the missiles, right away. The longer we delay, the higher will be the cost of limiting or reducing atmospheric carbon dioxide. As with the meteorite, there may be a point of no return. The cost may be high now, but it may become astronomical in the future.

NASA illustration of the KT-impact 65 million years ago

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