81 metres - remember that figure. It's how high the sea level could reach above it's present level if there was massive global warnming.
Where does all that water come from? It's the Ice trapped on land (mainly in Greenland and in Antartica, but also in Glaciers) and a small amount of expansion of water in the sea as it warms.
Ice floating on water does not count (it has already affected the sea level - drop an ice cube in a glass. The level goes up when it goes in but should stay steady as it melts).
Each set will contribute different amounts - Greenland is about 6.5 metres of rise, but the vast bulk is trapped in Antartica. It is here temperatures will have the most drastic effect. West Antartica is already showing signs of a slow melt (Total rise 8.5 metres if it all goes). East Antartica is still cold and it is here that the bulk of the worlds frozen water is - a massive 65 Metres of sea rise.
The remainder is made up from expansion of existing water as it warms and other ice (Snow and Glaciers).
My place will be on the beach at about 30 Metres - not likely to happen for generations sadly so 'll have to keep taking my boats down the hill.
It can go the other way - at one point the sea was 120 Metres below it's present level.