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AlexSchacher
08-17-2014, 06:13 PM
I'm not sure if this is in the right forum section, as I'm not posting a map in this post but more just asking for resources and opinions on a world-map idea.

As ive been thinking about my geofictional world, Ive come up with an interesting idea for a post-apocolyptic era which drastically changes the world. A drastic event happens where a very large meteor strikes the planet, and somehow (I realize this part doesn't make any scientific sense but Im willing to overlook that) a large majority of the worlds moisture escapes the atmosphere. 90% of the worlds oceans basically vanish. This event kills a large majority of life on the planet, but some humans do manage to survive through it. There is a "dark age" after the cataclysm that covers the world in dark clouds for several years. Once the clouds disperse, the majority of the world is covered in arid desert (from a lack of moisture and global heating) with some remaining seas scattered about the size of the black or caspian sea. Around some of these seas (depending on lattitude) would be small but somewhat lush regions of land, due to the nearby water. Assuming the water from the sea evaporates and is only able to travel a short distance before raining, creating rivers feeding back to its sea, this would give the surrounding areas fresh water and ability for life to thrive.

This was my idea, but I have absolutely no idea how sensible it is. This is a fantasy world, so the cataclysm part doesnt need to make a huge amount of sense (in my opinion) but if the earth was drained of most of its water, what would the climate be like? Is most of the world covered in arid desert but with a few temperate lush lands around small seas even plausible? The new "seas" would be at a very low altitude, and most seas are much lower than the majority of the surrounding desert. Does this make any sense, since the higher altitude, the colder it gets? What about ice on the highest altitudes and polar caps? I would prefer if there wasnt any ice left on the world, making the sealands the only place to escape the desert (makes for interesting story elements and conflicts).

Again, this is all fantasy. But I am trying to make it seem atleast somewhat plausible. Anyone have any thoughts on this?

66715

happywanderer
08-17-2014, 07:17 PM
I would look to mars as the extreme example. All the water would be concentrated near the poles and would only be liquid during certain periods of time. And the ice caps would likely be much smaller. Underground aquafers are an option though. But I'd imagine anything breaking to the surface would quickly evaporate.

I'd also imagine that the coloration would differ significantly from that of Mars. Less red-brown and more grey.

Azelor
08-17-2014, 08:22 PM
Interesting, without water the difference between winter and summer would be huge, well over 100 Celsius in some places. Siberia already experience these extreme Verkhoyansk - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Verkhoyansk)
The equator would have the least extreme of the climates because the difference in sunlight (between summer and winter) is the smallest. And the poles will have the largest difference (not if they are still covered by ice).
Water prevent these extreme but the only place left with large amount of water is in the North Pacific. Other body of water would have a small impact on their surroundings.
Pushing in that direction, the water would evaporate completely from smaller lakes but would definitely fall back in winter or before as the cold air can't keep all that moisture.
Summer will most likely be a season with no rain at all for maybe 3-4 months. But humidity could be moderately high at some places. Hot air carries more humidity than cold air, and since the temperature are high, rainfall could be scarce and small. The moisture fall back in the autumn (some kind of rain season). Arrived at winter, the air is completely dry, drier than summer so don't expect snowfalls. Spring is like autumn but with much less precipitations.

Will the ice melt? as I said the difference in temperature could be immense : Antarctica, Greenland and all other places would melt eventually. The surrounding temperature would be over the freezing point in the summer but very cold in winter, So it would freeze back and forth. Slowly the landscape would change. ALSO, much all of the water on the planet could freeze during winter. Not completely, but ice sheets could form on the surface.

Winds: If the difference in temperature between the ice caps and the surrounding is large enough it could trigger some violent conditions. At least for the couple of years following the cataclysm.
High temperature differences create more active weather. The tornado corridor is a good example of this as hot air meet cold air. It creates a really destructive force. On the opposite, the horses latitudes are really calm because it's an area with hot air surrounded by relatively hot air = almost no winds.

So the general wind pattern could look like:
summer: the continents (highlands) are always colder that the ocean bed because they are at a higher altitude. This mean it's a high pressure area compared to the sea. Winds will move toward the sea.
Winter: it's the same thing
The only place where it's different is probably in the North Pacific region.
But even there, the winds might be weak for the reason explained above.

Deserts: Antarctica is the biggest desert on Earth and I doubt anyone would want to live there, especially with the possible violent weather.

***All of this is considering that the axial tilt of Earth is still the same after the impact. If not, it could have some major impact.

waldronate
08-17-2014, 08:43 PM
You'd get a pretty awful greenhouse effect and likely drop in oxygen levels due to the exposure of Methane clathrate (http://en.wikipedia.org/wiki/Methane_clathrate) and the large amounts of unoxidized sediments on the ocean floor. I wouldn't expect much in the way of a multicellular biosphere after an event like this...

Messinian salinity crisis - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Messinian_salinity_crisis) may also be of interest, although you'd be less likely to get evaporate deposits of the water were simply magicked away. I am of the opinion that any impact large enough to drive away the oceans would pretty much sterilize the surface of the planet for a few hundred million years...