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Delvo
2007-Sep-30, 12:12 PM
Eventually, the sun is supposed to swell so much that the Earth might end up inside it, or the Earth might still remain barely outside it but would at least lose its water and atmosphere. But is the heat enough to melt most of its solids, or even vaporize them, or would it just end up like a big Mercury? If it remains solid or liquid once inside the sun, how far would it sink and how long would that take?

And what about before that...

Is it far enough in the future that the Earth would have radiatively cooled off first, before heating up again?

Would the tectonic plates still be moving? How far could the continents have moved by then?

Aren't we losing atmosphere anyway, and how long would it take for that to be gone (and for the surface water to go with it) without any changes in the sun?

Ronald Brak
2007-Sep-30, 01:53 PM
Aparently 1-3 billion years before surface water is gone.

eburacum45
2007-Sep-30, 03:05 PM
The Sun, like all main sequence stars, is heating up very slowly and will continue to do so before it becomes a red giant.
So the Earth will heat up too, and lose all its water in a runaway moist greenhouse state, which will then turn into a dry greenhouse state like Venus, if there is time before the red giant phase (and I think there is). The dry Earth will probably not have plate tectonics, as they seem to rely on water to work.

But there are at least two stages to go through before that; global warming might affect the earth for a few thousand years; not permanently, as fossil fuel will run out soon enough.
And the long term trend for CO2 content in the atmosphere is down, so once anthropocentric CO2 has run out the Earth will start getting colder, probably resulting in an ice age that lasts a few miillion years at least.

Ronald Brak
2007-Sep-30, 03:17 PM
And the long term trend for CO2 content in the atmosphere is down, so once anthropocentric CO2 has run out the Earth will start getting colder, probably resulting in an ice age that lasts a few miillion years at least.

Without AGW we would expect the earth to continue to cycle between glacial and interglacial periods but it has been suggested that if warming results in the earth losing its current icecaps that could switch the earth to a warmer equilbrium that will prevent glaciation. I'm afraid I don't know how likely this is. It sounds a little odd because the continents would still pretty much be where they are now, but I think it might have something to do with large parts of Antartica now being under sea level due to the weight of the ice.

Michael Noonan
2007-Sep-30, 03:58 PM
So the Earth will heat up too, and lose all its water in a runaway moist greenhouse state, which will then turn into a dry greenhouse state like Venus, if there is time before the red giant phase (and I think there is). The dry Earth will probably not have plate tectonics, as they seem to rely on water to work.


If we had problems with rising oceans could some of the excess water be pumped inland to extend the plate tectonic activity?

When it comes to survival on an island seawater is not drinkable but if you can dig down a bit back from the beach then the water may have enough filtering by the sand to be drinkable. Even pumping salt water to inland catchments already high in salt may add water overall and be filtered enough at a distance to be drinkable.

When concentrated enough the water could be pumped to drying ponds to extract the salt. Then if a cover was used any water caught would be kept unsalted and in wet times the salt held in the sands may 'push back into the catchment to do a second salt reclamation.

Delvo
2007-Sep-30, 06:33 PM
Here's a few more I meant to include but didn't recall when posting at first...

How long would it take for the moon to be lost? Or would something else like the sun boiling off all of our fluids or swallowing us whole come first, while the moon is only something like 2-3 times as far away as it is now?

And would the absence or reduction of the moon's influence have any effect on Earth other than oceanic tides and maybe some warming (due to the "bulge" wandering around the planet with the tidal cycle)? How long will a day be in 1, 2, 3, 4, 5, and so on billion years? Would the axis's tilt increase or decrease?

Also, how long would it take after mountain-building was done for there to be no (good, biologically useful) soil left because there's no source of new rocks from which to replace physically or chemically eroded/lost soil with fresh soil (freshly eroded rock)? Given how close Australia already is, it seems like it would be pretty quick on the scale we're talking about (billions of years).

What about solar flares? When the sun grows, the Earth will be closer to its surface, so how soon will those start hitting us? (This would be before the sun actually swallows us, or even if it doesn't swallow us at all.)

"Global warming" as we know it today isn't really related to these things...

Michael Noonan
2007-Oct-01, 12:20 AM
One thing for certain if we have enough time and can prepare for change early there are quite a few options.

I have a number of radical ideas (including some ATM reasons for considering a heavier close orbit planet to the sun that I won't go into).

But if given the resources is it possible to have a two moon system?

This means somehow getting the earth to a more distant orbit and using both the moon and Mars as satellites of the earth. Not an option as yet, but when one considers the rapid advancement of technology over just the last 100 years perhaps the doing could be left in abeyance.

The question then becomes like some of the larger planets could the earth support a two moon system?