Britain could be in for a big freeze, with the climate ending up more like central Canada, say scientists studying the world's oceans.
They have found evidence that the flow of cold water from the Arctic has decreased by 20% since 1950.
If the trend continues, the supply of warm water to northern Europe will decline, bringing a big chill.
The last time this happened, in the 11th to the 18th Century, northern Europe entered the Little Ice Age.
Such climate variations are thought to be caused by changes to a belt of water that moves heat and cold around the world, the global conveyor belt.
'Key' decade
The new research was presented at the British Association Science Festival in Glasgow.
In a research paper, Sarah Hughes of the FRS Marine Laboratory in Aberdeen, Scotland, said: "It seems that in the past the conveyor belt has stopped and started, sometimes as quickly as within one or two years.
"When it stops, northern Europe is cooled by about 5 C and we get a climate similar to that of northern Canada."
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