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 to Europe.
“We’re talking about a lake the size of the UK emptying very quickly,” Bateman told Reuters by telephone. “We don’t know the exact period of time but we’re talking about a catastrophic flood.”
The finding has confirmed past theories about the likely cause of a sudden cooling period called the Younger Dryas when temperatures in Europe, similar to today’s, quickly returned to ice age conditions. The cooling lasted for about 1,400 years.
“Our research shows that if you put a large volume of fresh water into the North Atlantic in a very short space of time, this is what happens,” Bateman said. His team’s work is published in the latest issue of the journal Nature.
The Gulf Stream acts like a conveyer belt by bringing warm water from the tropics to Europe while cold salty water sinks to the depths in the far north. This “overturning” circulation draws in yet more warm water from the south.
Climate scientists fear rapid global warming could trigger a sharp increase in the amount of meltwater from Greenland. This surge in freshwater could trigger a tipping point that overwhelms the Gulf Stream, shutting it down and likely plunging Europe into another deep freeze.