From everything I’ve read (and I’ve read a fair amount), it seems that even if we stop all greenhouse emissions now, the complexity and sheer inertia of the planetary weather system will cause the average surface temperature of the planet to rise by 3-5 degrees C, according to the IPCC. Maybe that won’t be a tipping point, a watershed that’ll cause an irreversible runaway greenhouse effect capable of eventually turning Earth into a carbon (sorry) copy of Venus. Maybe not. But it’ll sure as hell cause rampant desertification, wholesale die-offs of sea life due to acidification, catastrophic rises in ocean levels -- and that’s not in some dim and murky distant future -- that’s in your lifetime, if you’re in your twenties. In other words, if you’re old enough to vote, you’re old enough to float.
That high-pitched whine you hear is Thomas Malthus spinning in his grave -- but not nearly fast enough, unfortunately, to provide the alternative energy we’ll need.
Accept for a few moments that global warming is a real, documented and imminent threat. That if we’re not past the point of no return already, we’re close enough to hear the death knells of most of the Third World. And that once the chaos begins, most of us will be too busy scavenging the ruins and fighting over canned goods bloated with botulism to give much thought to long term survival of the species.
And let’s say that some of us, at least, know when it’s time to scurry down the anchor chain and abandon a sinking ship.
"The earth is the cradle of humankind, but one cannot live in the cradle forever." -- Konstantin TsiolkovskyHeinlein said basically the same thing: “Earth is too small a basket for mankind to keep all its eggs in.” Even if we haven’t fouled our nest pretty much beyond saving, sooner or later we’re going to be pulverized by a killer asteroid, or fried up nice’n’crispy by the Yellowstone supervolcano, or ... well, pick any one of a hundred apocalypses, now or in the immediate future. And they don’t all have to be huge, epic, planetary scale disasters; lots of smaller ones will do just fine. Ever been in a major earthquake? I have. Ever been within spitting distance (not that it would have done much good) of a raging brushfire? I have. Ever been confronted by a roomful of brain-eating zombies? I have -- well, I’ve worked for network TV, which is pretty much the same thing. The point is, Tsiolkovsky's and Heinlein’s metaphors notwithstanding, the earth is a big, slow target. And one thing I learned in junior high school dodgeball is that it’s better to be small and light on your feet -- and, if you can manage it, in several places at once.
So let’s agree that the best way to survive is to diversify. To spread out. In short, to get some of us, at least, the hell out of Dodge.
The problem is, leaving the cradle is far easier said than done. We’ve got two obstacles that seem pretty much insurmountable.
The first is distance. The only world other than Earth that we’ve visited so far is the moon. And quite frankly, it’s the only one we’re likely to visit again in the near future. But, while it’s close enough to make round trips (semi) practical, it ain’t exactly a garden spot. Could we set up a permanent colony there? Frankly, I doubt it. We don’t even have people living full-time and raising families at the South Pole, which is Cancun compared to the moon. With temperature extremes that can go from -300 degrees F to 215 degrees F in a single step from sun to shade, an atmosphere less than one-trillionth that of Earth’s, and a comminuted layer of pulverized rock dust that, once through the airlock with you and inhaled, can give you a case of pneumoconiosis almost as fast as you can cough up blood ... the moon wouldn’t seem to be anybody’s first choice for extraterrestrial real estate.
Except that it is. Location, location, location, remember? The one thing we can count on is that the moon will always be about the same drive time. Which is a lot more than we can say about only other piece of prime location in the solar system -- Mars.
The problem is that, while the moon is tucked away, nice and snug, in orbit around the Earth, Mars and Earth both orbit the sun -- and Mars’ orbit is a lot more eccentric than ours. Bottom line is that Mars can be anywhere from 36 million miles to over 250 million miles from us. That’s a six-fold distance difference. In travel time it works out to anywhere from half a year to a year and a half, which makes booking rooms in advance a real bitch.
Trouble is, it’s the best alternative of all the planets. Mercury? Like the moon, only with a logarithmic sunblock scale. Venus? Like being at the bottom of a sea of molten lead; it makes Hell look hospitable. The outer worlds -- Jupiter, Saturn, Uranus, Neptune? They’re not called “gas giants” out of misplaced sophomoric frat-house humor; there’s no “there” there, even if they were close enough to be practical, which they aren’t. Some of the moons -- Titan, Europa, Ganymede -- are interesting from a lab-rat POV, but I wouldn’t count on the Land Rush starting for them anytime soon, either. And let’s not even bother mentioning Pluto.
So it looks like, for all its considerable drawbacks -- a long and varied travel time, temperatures that only look good compared to the moon, the lack of a magnetosphere which makes a tan sudden death -- Mars is it, even though the trip itself is, at optimum, still about twice as long as sailing around Cape Horn, without nearly as much deck time.
Except ... remember I said two obstacles?
Space is big -- there’s no getting around that. But as staggering and as complex as merely getting to another world is, there’s a much greater problem to be overcome once we’re there. One that makes cosmic rays, temperature extremes and lack of atmosphere look easy, indeed almost pleasant, by comparison. We can, after all, overcome all those problems, at least in theory, with terraforming techniques. It would take centuries, and require engineering on a cosmic scale -- playing planetary billiards with comets to create oceans, for example, or putting vast orbital mirrors up to magnify sunlight -- but all that could, theoretically, be done. Given a few hundred years of global restructuring, Mars could be given a breathable atmosphere, a decent climate -- everything except one thing.
In my next post I’ll discuss what that thing is.