> Better to have tried and failed, than to have
> sat around watching ‘Leave it to Beaver’

It’s a matter of choosing priorities. If you live in a safe neighborhood you are unlikely to spend a good deal of your money on 3 meter tall electrified fence and armed guards just because there is a remote chance that the neighborhood turns rough.

You are right that distance itself is not such a great guarantee of safety any more, and certainly a self-contained air supply is hard to quarantine, but so what? Better to have tried and failed, than to have sat around watching ‘Leave it to Beaver’ reruns while the house burns down.

Thousands of years? Thousands? Are you kiding? Let’s just consider 2 thousand years. Year 3AD, the most advanced civilization – Roman Empire. What was the largest concern then? Invasions of barbarian tribes from the north and east, slave uprisings, plague and other deseases from lack of sanitation. Suppose some roman scientist figured out that in 2 thousand years all city streets would be filled with human waste 6" deep and proposed drastic economic measures to make people sh*t less. Would it have any impact on our life now? Can you honestly say that you can imagine what humans are going to be like in 200 years, save 2 thousand? Taking current trends and then linerly projecting them to the future is exactly the short term thinking you referred to.

In late 60s Soviet scientists discovered that Caspian sea was drying up. In 70s and 80s USSR expended significant effort trying to stop shrinking of the sea. A dike was build to cut off one of the gulfs (Kara Bogaz Gol? sp.). Then all of a sudden in late 80s sea spontaneously started to fill up again. The general opinion now is that drying-filling of Caspian is a naturally occuring cycle.

> As for new technology allowing us to ensure our
> survival without the need for colonizing other
> worlds, I doubt our ability to defend against
> engineered killer viruses will be able to keep
> pace with our ability to create them. As long
> as we’re all here on Earth, I think we’re all
> vulnerable.

America was discovered by Europeans in late 15th century. By travelling to America you would be pretty much safe from any Old World epidemics because travel was long and difficult. By late 19th century travel was easy, by late 20th – trivial. Distance was no longer a protection. Same goes for your idea of other world colonization as a security measure against terrorism. In a historically short time distance will be no protection at all. Colonization will happen only if there is an economic need for it.

As for new technology allowing us to ensure our survival without the need for colonizing other worlds, I doubt our ability to defend against engineered killer viruses will be able to keep pace with our ability to create them. As long as we’re all here on Earth, I think we’re all vulnerable.

And I would say it’s an example of fear mongering completely out of control :-). Venus is what, 0.7au to Sun? Which means it gets 1/(0.7^2) = about two times more solar radiation per unit area than Earth. Look at Mars. Its atmosphere is made predominantly out of CO2, a greenhouse gas. But it’s 1.5au from Sun, i.e. gets 2 times less radiation per unit area than Earth. Tell me, why isn’t the greenhouse effect out of control on Mars? Could it be due to distance to Sun?

Life *started* on Earth when its atmosphere was like that on Mars or Venus.

> When you can’t grow food anymore, due to
> extreme, non-sporadic temperatures

Yes, economic trouble on a grand scale. But your original comment was about making Earth uninhabitable. "Economic trouble" and "uninhabitable planet". See the difference?

Same goes for your other comments. Economic difficulty != extinction of all life. Be a responsible journalist, measure your words :-)

> But I think the
> only way to "really" be safe is to colonize
> other worlds.

When we gain the ability to colonize other worlds, we most likely won’t need it. I am pretty sure both economic and security needs will be addressed by other means.

As for near-term colonization of planets, colonize Antarctics first. It has a lot milder environmental conditions than any planet in solar system save for Earth; trip to Antarctics is a lot cheper than even a trip to the Moon :-)

As for how a greenhouse effect could make Earth uninhabitable, Venus is certainly an example of what can happen to a planet if a greenhouse effect goes completely out of control. When you can’t grow food anymore, due to extreme, non-sporadic temperatures and a lack of fresh water, we’re all in trouble. And the destruction of the ozone layer could certainly lead to massive sterility problems, as well as blindness and many other health problems. Such problems would affect the animal kingdom more than humans, which would upset our planet’s ecological systems, which would inevitably affect us too.

I do agree that in 100 years, we “might” have the technology to better ensure our survival. But I think the only way to “really” be safe is to colonize other worlds.

I agree though, the most viable and obvious solution would be to spread out as much
as possible.

Even a fully independent, self sufficient orbital station or two would help against many of the
mentioned threats. It is not a truly long term solution though. If those stations are
all that is left after an ‘extinction level event’, it would place humanity that much closer
to true extinction, since the room for error on a station (even a very advanced one) is far
narrower than on a planet.

This just day dreaming, but I often wondered if there might not be some ancient, benevolent
alien race keeping watch over us. Flicking rocks out of their collision paths,
deflecting/absorbing the occasional gamma ray burst, converting the odd invasion armada into antimatter, and sometimes even prevent specific humans from doing something really dumb like pushing big red buttons…

The most likely extinction level event would be  rapid climate changes – a slow killer but no less deadly. Imagine the Earth turning into something resembling Mars or Venus in an relatively short period of time.
Humanity might survive such an event and learn something from it, but it would take a serious toll.

GRB or planet killing asteroids are external events and it seems too distant and unreal for your average Joe who goes to work everyday.
It would be a long while before we can do anything to prevent either of those things anyway, especially GRB. You try and convince the government to build billion dollar orbital weapons platforms with the purpose of shooting at rocks. A short sighted military might get a few platforms going, but their sights would be pointing down, not up.

Far more depressing to me would be if we cause our own destruction with a virus or that creepy nano-goo.

An invasion by malevolent aliens, as unlikely as it sounds, would be extremely depressing to say the least. Humanity won’t stand a chance in hell. We probably won’t even see them coming and it will all be over before we can figure out what’s happening. Slaves you say? Who would need a human slave if you can build interplanetary armadas?

Anyway, at the very least, humanity should get a self contained moon base going! Soon!

However, dealing with planet-level problems is not enough. It’s a dangerous universe. In addition to what was mentioned, a nearby supernova could sterilize us with radiation…or after a very long time cover the planet with debris. We could sweep through an interstellar dust cloud with nasty results. Something might miss Earth but irritate the Sun enough to cause us danger. Something that got blasted up to relativistic speeds could zip past and bathe us with radiation along with a gravitational shake. And we are ignorant of many things yet.