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Thread: How do I map an Earth after a significant sea level rise?

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    Help How do I map an Earth after a significant sea level rise?

    For a story, I am writing about a world in which the ice caps melted, raising the sea levels, and after which a nuclear winter caused most of the water to refreeze. Since water expands as it freezes, this would rise the levels even more. How can I go about determining where the water would go in terms of elevation? Do I have to do it all manually, pixel by pixel, or is there a way that I can use an elevation map and somehow tell the program how much I want the water to rise?

    I'm not even sure that this is possible, but I figured if anyone would know, it'd be the people here.

    C. of C.
    Last edited by Chum of Chance; 11-17-2014 at 08:13 AM.

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  3. #3
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    The freezing of seawater will not raise the sea level significantly. First of all, the seas do not freeze to the bottom, they freeze only to some depth that is fairly small relative to their depth. Secondly, floating ice displaces its weight, not its volume, so even the ice that freezes does not raise sea level.

    Thus you can simply look up the volume of the LAND ice on Greenland, Antarctica, and a few continental glaciers. Divide that by the surface area of the ocean, which you can also look up, and you have the additional sea level rise added by the melted land ice.

    To map this, take topo maps and find the contour matching the sea level rise you computed, trace that around all the continents, and you have a fairly good estimate of what the world will look like when the land ice has melted. Refreezing it will not change that significantly.

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    Administrator waldronate's Avatar
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    The usual effect of a nuclear winter is to allow snow to pile up on land, leading to an ice-age style situation, which will lower sea levels. There are many ways to get this information, including loading a digital elevation model into a piece of software (like, maybe, Wilbur or Fractal Terrains 3) and then changing the sea level.
    Last edited by waldronate; 04-04-2015 at 03:39 AM.

  5. #5
    Guild Grand Master Azélor's Avatar
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    Quote Originally Posted by gyldenstern View Post
    and even better, without limits: Flood Map: Water Level Elevation Map

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    Guild Expert johnvanvliet's Avatar
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    your assumptions are a bit off
    a "glaciation" would DROP the sealevel

    ice FLOATING!!! in the ocean will cause NO CHANGE
    but
    land locked ice WILL
    see
    http://www.giss.nasa.gov/research/briefs/gornitz_09/

    so making a world map for a HIGHER sealevel

    to start you can use my Global Earth DEM
    65536x32768 px.
    Earth topo map (RAW 16 bit short)
    https://googledrive.com/host/0B6ZYAd...g3Uk0/Ds15.zip

    the map is at a resolution of -- 182.044444444 pixels per degree
    Size 896,142,134 bytes -- 855Meg

    every tone in the 16 bit signed image is 0.5 Meters in height
    with CURRENT sealevel set to " 0 " zero
    ( Death Vally and Lake Assal and the Danakil Depression are all BELOW current sealevel )

    now this map is only good for a RISE in sealevel
    say a 200 M rise
    select the oceans and add 400
    and reset that to ZERO



    for a DROP in sealevel or rise
    --- a preview image


    from the Challenger Deep to MT Everest
    nasa has the "gebco_bathy.21601x10801.bin.gz --274Meg "
    http://mirrors.arsc.edu/nasa/topography/

    this RAW 16 bit signed
    MSB!!!!!!!!!!! integer!!!!!!!-- AKA BIG ENDIAN!!!!!!!

    this map is lowerres than mine above
    but it also includes UNDER WATER areas

    a slightly better dataset the "ETOPO1"
    http://www.ngdc.noaa.gov/mgg/global/global.html
    Last edited by johnvanvliet; 11-24-2014 at 03:58 AM.
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