Global Warming and Sea levels 

 One of the major concerns of global warming (enhanced or not) is the raising sea levels do to the increase in temperature.  The volume expansion of a substance is:

But it is important that volume change will only appear at the surface (you really can't expand in any other direction right) 

The additional, and often ignored, effect of global warming and raising water levels is the desalination  of ocean water.  The increase of fresh water into the ocean and the expansion of that water starts a run-away desalination of ocean water.  When desalination of ocean water starts to occur, then the ocean currents slow down and the amount of carbon in the atmosphere starts to increase (ocean currents are the largest "lungs" on the planet removing more carbon dioxide then all of the rain forests combined).  Increasing the carbon level in the atmosphere increases temperature and this whole mess gets worse