UK may experience more cold winters

The amount of radiation emitted by the Sun varies naturally over time and over centuries. The scientists measured the magnetic field emanating from the Sun into space to quantify solar activity.

Using records of temperatures dating back to 1659, the study established a connection between lower solar activity and severe winters.

Between 1650 and 1700 there was a prolonged episode of low solar activity which coincided with more severe winters in the UK and continental Europe.

Mike Lockwood, Professor of Space Environment Physics in the Department of Metererology at the University, said: "The UK has experienced relatively mild winters in recent decades, but not this year. Also this year, the Sun fell to an activity level not seen for a century.

"The results relate to a seasonal (winter) and regional (Central England) temperature change and not a global effect. However the work does show how regional or local measurements can show a solar effect and highlights how important it is to avoid trying to make deductions about the global climate from what is seen in just one part of the world."

The paper published in IOP Publishing's Environmental Research Letters, says the cold weather trends during lower solar activity are consistent with solar influence on blocking events in the Eastern Atlantic. Blocking occurs when the warm jet stream from the west on its way to Northern Europe is blocked allowing north-easterly winds to arrive from the Arctic. Blocking episodes can persist for several weeks, leading to extended cold periods in winter.

Professor Lockwood says the trends do not guarantee colder winters but they do suggest that colder winters will become more frequent. He said: "If we look at the last period of very low solar activity at the end of the 17^th Century, we find the coldest winter on record in1684 but, for example, the very next year, when solar activity was still low, saw the third warmest winter in the entire 350-year record. The results do show however that there are a greater number of cold UK winters when solar activity is low."

The University of Reading worked in partnership with the Science and Technology Facilities Council Space Science and Technology Department at the Rutherford Appleton Laboratory in Oxfordshire, and the Max-Planck Institute for Solar System Research in Katlenburg-Lindau, Germany.