AGU: Link found between cold European winters and solar activity

Temperature could be related to the big heater thingy in the sky? Nah…

Scientists have long suspected that the Sun’s 11-year cycle influences climate of certain regions on Earth. Yet records of average, seasonal temperatures do not date back far enough to confirm any patterns. Now, armed with a unique proxy, an international team of researchers show that unusually cold winters in Central Europe are related to low solar activity – when sunspot numbers are minimal. The freezing of Germany’s largest river, the Rhine, is the key.

Although the Earth’s surface overall continues to warm, the new analysis has revealed a correlation between periods of low activity of the Sun and of some cooling – on a limited, regional scale in Central Europe, along the Rhine.

“The advantage with studying the Rhine is because it’s a very simple measurement,” said Frank Sirocko lead author of a paper on the study and professor of Sedimentology and Paleoclimatology at the Institute of Geosciences of Johannes Gutenberg University in Mainz, Germany. “Freezing is special in that it’s like an on-off mode. Either there is ice or there is no ice.”

From the early 19th through mid-20th centuries, riverboat men used the Rhine for cargo transport. And so docks along the river have annual records of when ice clogged the waterway and stymied shipping. The scientists used these easily-accessible documents, as well as additional historical accounts, to determine the number of freezing episodes since 1780.

Sirocko and his colleagues found that between 1780 and 1963, the Rhine froze in multiple places 14 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 around 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.

“We provide, for the first time, statistically robust evidence that the succession of cold winters during the last 230 years in Central Europe has a common cause,” Sirocko said.

With the new paper, Sirocko and his colleagues have added to the research linking solar variability with climate, said Thomas Crowley, Director of the Scottish Alliance for Geoscience, Environment, and Society, who was not involved with the study.

“There is some suspension of belief in this link,” Crowley said, “and this study tilts the argument more towards thinking there really is something to this link. If you have more statistical evidence to support this explanation, one is more likely to say it’s true.”

The study, conducted by researchers at Johannes Gutenberg and the Institute for Atmospheric and Climate Science in Zurich, Switzerland, is set to be published August 25 in Geophysical Research Letters, a journal of the American Geophysical Union.

EurekAlert

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4 Responses to AGU: Link found between cold European winters and solar activity

  1. This is what we get for relying on an unregulated fusion reactor 96 billion miles away for temperature control!

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