End of the world scenarios
Donald Sensing surveys popular scientific literature and discovers various plausible explanations for catastrophes in the earth's past -- and dangers in the distant future. It turns out that on a planetary scale as well as on a personal, the real danger is often unsuspected. Science Daily, for example, cites a NASA study suggesting that methane released by non-anthropogenic "Global Warming" 55 million years ago (when there was no human civilization that we know of) released methane into the air causing the atmosphere to act like a giant fuel-air explosive.
Boom. Mass extinction came as a surprise to those it overtook. And then we are told that a massive hydrogen cloud is heading for earth, and that in 40 million years it will interact explosively with our galaxy. That in fact, "the leading edge of this cloud is already interacting with gas from our Galaxy," according to astronomers. Had the cloud come before man developed the technology to detect its arrival how could we know?
The first question that arises in connection with these observations is why the 'precautionary principle' beloved of environmentalists does not apply to all possible disasters, just some. After all, if the earth is doomed to encounter a hydrogen cloud in 40 million years, which is a short time in comparison to the life of the planet and its biosphere, isn't it time to accelerate our technological development so that we can develop the starships to get away? After all 40 million years may not be enough lead time, given the engineering challenges that must be faced to evacuate from the vastness of the threat. Admittedly extinction by hydrogen cloud is an unlikely, or at least incalculable danger. But the precautionary principle says that if some danger exists you have to prepare for it. My guess is the precautionary principle is always trumped by opportunism principle. Dangers which can't be used as opportunities to advance a political agenda are not covered by the precautionary principle. And therefore there won't be a UN Conference on Hydrogen Clouding any time soon.
But the second question is a little harder to deal with. How can we defend earth against unknown unknowns? Science is discovering new dangers all the time. Why only fifty years ago nobody heard of "Global Warming". Isn't it possible that Gaia may be done in by the peril we don't see coming? The limits to our knowledge guarantee that risk is irreducible. There are some precautions we can't take.
So maybe we should kick back, open a bottle of beer and be content with our measures for the day. "Sufficient unto the day is the evil thereof." Or does having that attitude make bigots of us or worse increase our carbon footprint?