The ice that melts in Antarctica and in Greenland as a result of global warming will redistribute into the oceans of the world.  This will involve redistribution of many gigatonnes of mass from the polar regions (close to the earth's axis) to the average latitude of the earth's oceans (further from the earth's axis). This means that to conserve angular momentum the earth should reduce its spin rate.  Has this occurred and if so what is the magnitude of the effect; A - Now - and B - when all the polar ice has melted?

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?

 Glaciers flow across landscapes carrying boulders and debris e.t.c. Until recently I always assumed they travelled downhill, but I hear they can carry boulders uphill. How is this gravity defying feat possible?

Ian Jones, Solihull, UK

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