Earth is 15 years from a "mini ice age" that will cause bitterly cold winters during which rivers freeze over, scientists have predicted.

Solar researchers at the University of Northumbria have created a new model of the sun's activity which they claim produces "unprecedentedly accurate predictions".

They said fluid movements within the sun, thought to create 11-year cycles in the weather, will converge in such a way that temperatures will fall dramatically in the 2030s.

Solar activity will fall by 60 per cent as two waves of fluid "effectively cancel each other out", according to Professor Valentina Zharkova.

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In a presentation to the National Astronomy Meeting in Wales, she said the result would be similar to freezing conditions of the late 17th century. "[In the cycle between 2030 and 2040] the two waves exactly mirror each other - peaking at the same time but in opposite hemispheres of the sun," she said.

"Their interaction will be disruptive, or they will nearly cancel each other. We predict this will lead to the properties of a 'Maunder minimum'."

Maunder minimum, indicating low sunspot activity, was the name given to the period between 1645 and 1715 when Europe and North America experienced very cold winters.

In England during this "Little Ice Age", River Thames frost fairs were held. In the winter of 1683-84 the Thames froze over for seven weeks, making it "passable by foot", according to historical records.

Zharkova said scientists had known about one dynamo caused by convecting fluids deep within the sun, but her research appeared to have uncovered another. "We found magnetic wave components appearing in pairs, originating in two different layers in the sun's interior," she said.

"They both have a frequency of approximately 11 years, although this frequency is slightly different, and they are offset in time.

"Over the cycle, the waves fluctuate between the northern and southern hemispheres of the sun. Combining both waves together and comparing to real data for the current solar cycle, we found our predictions showed an accuracy of 97 per cent."

This had helped create a picture of what would happen in the 2030s.

"When the waves are approximately in phase, they can show strong interaction, or resonance, and we have strong solar activity. When there is full phase separation, we have conditions last seen during the Maunder minimum, 370 years ago."