>Man is changing the environment, and I think there is quite a lot to worry about. As to the physics of your question:
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>Let's assume you have a floating ice-block, made from a million kg. (= a million liters) of water. As floating ice, it will still have a mass of a million kg., and therefore, it will displace exactly a million kg. (liters) of water. Therefore, it makes no difference whatsoever, in the water level, if it is floating as ice, or melted.
>

But that million kg of ice would not = 1 million litres. 1 kg of WATER takes up 1 Litre of space, AT ROOM TEMPERATURE or thereabouts. Ice expands (have you ever left a soda bottle in your freezer, to quickly cool it down, but forgotten about it?!). So 1m Kg of ice DISPLACES more than 1 m litres of seawater. So, as it melts, it displaces less till, as water itself, it NOW only "displaces" 1 m litres of seawater.