Deep freeze

Scientists have speculated that global warming might cause an ocean current called the Atlantic Conveyor to slow, bringing less life-giving warm surface water to Northern Europe.

According to the theory, rising air temperatures cause ice caps to melt, making the water less salty and therefore less dense so it can't sink and flow back south.

For the first time, there is possible evidence of this phenomenon.

While measurements in 1981 and 1992 had shown little change, those in 1998 and 2004 had shown a major shift, with less of the warming Gulf Stream getting up to Greenland and less of the cold, deep returning current coming back.

Scientists are of course stressing that this is not conclusive, and further observations need to be made.

What if this is happening, though? How much of Northern Europe will become uninhabitable? Will weather around the world be affected? Where will people go to flee the cold?