"There are some fears that warming in the Northern Hemisphere, particularly around the Greenland ice sheet, might cause quite a bit of meltwater to come into the North Atlantic Ocean," he said.
"That might change the salinity of the water there and stop what's called 'the great conveyor belt of the oceans' forming deep water that releases an enormous amount of heat that keeps Europe out of an ice age, essentially.
"So if global warming does stop this circulation from occurring, then we could potentially have a new ice age in Europe."
He says that finding lends support to a theory that heat will accumulate in the Southern Hemisphere if there is cooling in the north.