They have found that the salinity of the ocean around Antarctica is decreasing, which will impact the rate at which water sinks. This is the same problem that scientists worry about in the North Atlantic thermohaline circulation (the North Atlantic Conveyor) which has been proven to have caused snaps into ice age conditions.
On the other side of the globe, researchers have found that the Canadian Arctic Ice Sheet has lost 90% of its size since 1900.(2) What is left has broken into three giant pieces, and it is feared that the remaining ice shelf will disintegrate within the next few years.
1) Ocean salinity evidence of climate change: researchers, 4/17/08
2) Ward Hunt Ice Shelf, Largest In Northern Hemisphere, Has Fractured Into Three Main Pieces, 4/16/08