As the polar ice caps melt the sea levels are predicted to rise. My question is why? When you place an ice cube in a glass of water the water level rises, but if the ice cube is already there and then it melts the water level does not rise, due to the initial displacement of the water by the ice. Surely the same principle must be true of the ice caps. Why, therefore, are melting polar ice caps leading to a rise in sea levels?

If water could be pressurised, how low would the sea level be due to the pressurising weight of the overlying water?

DURING THE TIME UP TO SATS EXAMS THERE WAS A QUESTION ABOUT GLOBAL WARMING AND MELTING ICE CAPS.  IT SAID THAT AS THE CAPS SHRINK LEVELS WILL RISE BUT, I SAW IT AND THOUGHT FOR A BIT. ACCORDING TO ARCHIMEDES, THE LEVEL WOULD STAY THE SAME. THE CAPS WOULD MELT BUT, BECAUSE THEM MELTING WOULD RESULT IN LEVELS STAYING THE SAME WOULDN'T IT?  I TRIED THIS WITH A GLASS OF WATER AND AN ICE CUBE AND THE WATER DID NOT RISE. DOES ANYONE HAVE AN EXPLINATION OR IS IT JUST TOTAL RUBBISH?                                                                                                                                                                                                  Felix, 12 From Norwich

I read recently in an article that scientists measured a 3mm rise in the sea level. How is this done so precisely?