The Dutch Met Office (et al.) figured out that if world average sea levels should rise by 1 metre, water levels in the North Sea will rise (i) by 1.2m if the ice melt occurred in Antarctica, (ii) by 40 centimetres if the ice melt occurred in Greenland. Why? Ocean currents and rising earth crusts. Interesting stuff, but the question, of course, is: are these likely scenarios?