LONDON, Oct. 10 (UPI) -- Recent nasty winters in the United States and northern Europe may be partly caused by changes in ultraviolet radiation from the sun, researchers say.
Fluctuations in the amount of ultraviolet light reaching the Earth could change winter weather patterns across the Northern Hemisphere, a climate simulation run by the British Met Office showed.
There has long been anecdotal evidence linking low solar activity, such as the number and frequency of sunspots, and cold European winters, ScienceNews.org reported.
From 2004 to 2007, during low points of the last solar activity cycle, scientists at the Met Office recorded a significant drop-off in the amount of ultraviolet radiation coming from the sun.
"I thought, if that's true, that's going to do something interesting to the climate system," climate modeler Adam Scaife said.
The scientists fed the data on the decline into their climate model, and found with ultraviolet radiation falling, parts of the upper atmosphere cooled more than usual, allowing cold weather to form over northern Europe and the United States.
"We hope this will open the door to improving ultralong-range predictions," Scaife said, and that researchers hope to start incorporating solar variability into long-term weather predictions.
"It's changing the odds of what kind of winter you're going to get by a significant amount."