I've been following this for a couple of years...and quite honestly, its very alarming. There is only 1/4 of the normal amout of water sinking under the greenland shelf. This site is very good at explaining whats going on:
http://www.whoi.edu/institutes/occi/currenttopics/climatechange_wef.html
Basicly, when you get too much fresh water in the northern atlantic it does not sink as quickly since freshwater is less dense than saltwater. Ice traps the water leaving the salt. More ice=more salt Less ice=Less salt.
Freshwater can also "cap" the heat given off by the denser saltwater below...again, causing it to sink more slowly. Problem here is if the water does not sink...the warm waters flowing north to replace it... dont. How this would affect the hurricane season? I have no idea, but it would not take a huge leap to think that the oceans have to transfer heat to the northern lattitudes somehow. If you have a gulfstream thats not doing enough of it...hurricanes are the other way oceans transferr heat, so you would see more of them (I know this WAY more complicated)