What Is Epsilon?

[hatrack]

EDIT

One of the members of the commission which investigated the disaster was physicist Richard Feynman. In one of his biographies (sic) he tells an interesting story. My memory is imperfect, but it goes something like this. At one point he was meeting with a NASA manager and some engineers. He asked them point-blank, what’s the probability of mission success for a launch? The manager replied something like “certainty.” Feynman protested that no it wasn’t. The probability of success is 1 minus epsilon. What’s epsilon?

He even let them submit their estimates by “secret ballot,” writing them on a slip of paper, but it was immediately obvious whose guess was whose. The engineers gave failure probabilities around 1 out of 100, or even as optimistic as 1 out of 400, but the manager’s estimated failure probability was 1 out of 100,000. 1 out of 100,000! At those odds, you could launch a shuttle every day for 300 years and expect only one mission failure. Feynman’s wasn’t the only bullshit meter flashing red.

He also tells of an interesting discussion with the range safety officer, who had to decide whether or not to include a self-destruct mechanism. About 1 out of 25 solid-rocket launches had failed, but the shuttle was better-than-average rocket technology so he estimated the chance of catastrophic failure at about 1 out of 100, optimistically, which would indeed require the inclusion of a self-destruct mechanism. Management balked at this figure — so the range safety officer altered his estimate to conform with management wishes, then attached a self-destruct mechanism anyway.

We’re seeing the same exact thing happen with the global warming “debate.” Fossil-fuel shills, conservative politicians and pundits, and misguided and ill-informed bloggers are telling us “No problem, don’t do anything. Keep burning fossil fuels, impose no restrictions, no costs. Drill baby drill!” My bullshit meter is flashing red. So here’s your chance to answer the question: What’s epsilon? I moderate this blog with a heavy hand, but for this post I’ll allow anyone to submit an estimate. That does not mean you get to proselytize. Don’t give us your reasons for thinking climate sensitivity estimates are too high, or it’s all the sun, or it’s galactic cosmic rays or sheep albedo, or launch into a diatribe about emails from the climate research unit — attempts to argue why are not the point of this post, and indulging in same will get you sent to the trash-bin. The prohibition against proselytizing goes both ways — don’t give us your reasons for insisting climate sensitivity is high, or it’s not the sun or cosmic rays, or a diatribe about the character assassination of honest climate scientists.

EDIT

http://tamino.wordpress.com/2012/01/04/what-is-epsilon/

[kristopher]

1. Good application of that story.

With a business as usual scenario stipulated I put the chance of disaster (with disaster defined as a major global extinction event) at 95%.

I do not think we will continue with BAU.

[Saving Hawaii]

2. We're already continuing with business as usual.

Every time we break ground on a new coal power plant, we're locking ourselves into business as usual for the next few decades. Every time we approve another big oil pipeline, we're locking ourselves into business as usual for the next few decades. Oh sure we can start to make the transition today, but all these expensive investments in infrastructure are going to be used until they're obsolete.