Scientists have found new evidence that the solar sunspot cycle has influenced the Earth’s climate in the recent past.
Sirocko and his colleagues found that between 1780 and 1963, the Rhine froze in multiple places fourteen different times. The sheer size of the river means it takes extremely cold temperatures to freeze over making freezing episodes a good proxy for very cold winters in the region, Sirocko said.
Mapping the freezing episodes against the solar activity’s 11-year cycle — a cycle of the Sun’s varying magnetic strength and thus total radiation output — Sirocko and his colleagues determined that ten of the fourteen freezes occurred during years when the Sun had minimal sunspots. Using statistical methods, the scientists calculated that there is a 99 percent chance that extremely cold Central European winters and low solar activity are inherently linked.
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