I'm thinking of creating a world in which sea levels have risen by around 200 metres, leading the Earth's surface to look something like this, minus the ice:

enter image description here

Obviously, a 200 metre rise is enormous, and probably not even feasible with man-made global warming alone. What could cause such a dramatic rise in sea levels, in under a few million years? Additionally, does anyone know how much of an increase in global temperature this would entail?

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    $\begingroup$ @StarfishPrime Yes - rather I mean what would cause the melting of all the ice. $\endgroup$
    – SealBoi
    Feb 16, 2020 at 14:32
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    $\begingroup$ @Halfthawed Well, the globe has to warm of course, but even the worst-case predictions for man-made sea level rise do not exceed 60 metres. For 200, there would have to be a partially naturalistic explanation I think. $\endgroup$
    – SealBoi
    Feb 16, 2020 at 14:53
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    $\begingroup$ Many ideas here: worldbuilding.stackexchange.com/questions/115597/… $\endgroup$
    – Willk
    Feb 16, 2020 at 15:05
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    $\begingroup$ Check out Clive Cussler's The Rising Sea. In it, he states that the quantity of water trapped within the earth's crust far exceeds that on the surface. (I have no idea if that is true, but he made it sound plausible in this light fiction) In his story, undersea mining accidentally punctured a pressurized pocket of water leading to rapid sea level rises and changes in ocean salinity. $\endgroup$ Feb 16, 2020 at 15:20
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    $\begingroup$ @jamesqf Well the problem is that there isn't enough ice on the planet to raise sea levels by more than 70 metres. $\endgroup$
    – SealBoi
    Feb 16, 2020 at 18:36


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