When the end of the world comes around, will it end in fire or ice? We are late for an ice age and if it came around would we all freeze to death? Or will our ozone layer finally give way and will the sun burn us to a crisp? How much longer do we REALLY have left? Could we be so smart that we could escape to another planet?
Don’t worry about the ozone. If it was all gone we could still easily survive on Earth. The worst we have to fear is sunburn. Our genetic engineering facility could probably produce crops and polinators resistant to U-V light, which could be spread around the globe in less than a year.
Also, don’t worry about global warming. It will never make the Earth uninhabitable.
And an ice age is not a problem either. Such large temperature changes are, as far as we know, very slow to develop. Again, we could easily survive in the worst of Earth’s ice ages in history.
Probably the most likely end is in fire, after the impact of a large asteroid. We may be smart enough to avoid this by detecting the asteroid in time and diverting it from its course. No one knows what the likelihood of Earth being struck by a world-ending asteroid is, but it is certainly not zero. One of the leading theories of the history of Mars is that it used to be much more like Earth, but it was struck by a world-ending asteroid that gutted its core.
Currently we are not smart enough to escape to another planet. We can barely manage a mission to Mars, and the lander would not be able to land a significant number of people. Anything outside of Mars is impossible with our current technology.
No one knows what advances research into subatomic and relativistic physics may yield. All indications are that the speed of light is an absolute ceiling. This means that there are few stars that can be reached in less that a couple of decades. Any extra-solar journeys are likely far in the future. We don’t even know of a single planet that is habitable other than the Earth. Before we go anywhere we need at least a destination.
I would say fire when the sun goes red giant on us, then ice after the sun cools into a dead core. By ice I mean extreme coldness as all of the water of Earth would be boiled off after the sun expands. Heck, maybe Ed Wood was right and we will develop solarinite which will turn our planet into a crisp.
There is another option - dry. The earth could loose all it’s water somehow.
Some say the world will end in fire,
Some say in ice.
From what I’ve tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To know that for destruction ice
Is also great
And would suffice.
I can’t believe I’m the first one to post this 
from:
http://www.space.com/scienceastronomy/solarsystem/death_of_earth_000224.html
goes in to this very subject.
I came to the thread hoping to do just that. Beat me to it.
If, in five billion years, we lack the technology to move or protect the Earth somehow, I will be severely disappointed.
Chances are in 5 billion years human kind will have evolved into something else or become extinct anyways.
I believe humanity has only been around for about 5-7 million years.
Given that we had about an inch of snow accumulate on the 18th of May this year, I half wonder if the people saying we’re headed for another ice age are on to something…
Slurpees. The world will end in a deluge of cherry-flavored Slurpee.
An oldie:
A retiring Phys Chem professor was setting his last exam, for a graduate course in statistical thermodynamics. Being a bit bored with it all, and with a well kept and wry sense of humor, he set a single question on the sheet:
Is Hell endothermic or exothermic? Support your answer with a proof.
He had little idea what to expect, or how to grade the results, but decided to reward any student who was able to come up with a reasonable reply to his query. One “A” was awarded.
Most of the students wrote proofs of their beliefs using Boyle’s Law or some variant. The top student however wrote the following:
First, we postulate that if souls exist, they must have some mass. If
they do, then a mole of souls can also have a mass. So, at what rate
are souls moving into Hell and at what rate are the souls leaving?
I think that we can safely assume that once a soul gets to hell, it
will not leave. Therefore no souls are leaving.
As for souls entering hell, lets look at the different religions that
exist in the world today. Some of these religions state that if you
are not a member of their religion, you will go to hell. Since there
are more than one of these religions and people do not belong to more
than one religion, we can project that all souls go to hell.
With birth and death rates as they are, we can expect the number of
souls in hell to increase exponentially.
Now, we look at the rate of change of volume in hell. Boyle's Law
states that in order for the temperature and pressure in hell to stay
the same, the ratio of the mass of souls and volume needs to stay
constant. There are two possible conditions.
One, if hell is expanding at a slower rate than the rate at which
souls enter hell, then the temperature and pressure in hell will
increase exponentially until all hell breaks loose.
Conversely, if hell is expanding at a rate faster than the increase of
souls in hell, than the temperature and pressure will drop until hell
freezes over, condition two.
We can solve this with the 1990 postulation of Theresa LeClair, the
girl who lived across the hall from me in first year residence. Since
I have still not been successful in obtaining sexual relations with
her, condition two above has not been met, and thus it can be
concluded that condition one is true, and hell is exothermic.