SINGAPORE (Reuters) - Scientists say they have found the trigger of a sharp cooling 13,000 years ago that plunged Europe into a mini ice age.

Mark Bateman from the University of Sheffield in England said a catastrophic flood unleashed from a giant North American lake dumped large amounts of freshwater into the Arctic Ocean.

This led to the shutting down of the Gulf Stream ocean circulation pattern that brings warmth ..
Mega-Flood Triggered Cooling 13,000 Years Ago: Scientists - ABC News

Ice sheet melt identified as trigger of Big Freeze