Boffins confirm sunspot-weather link
Sunspots still don’t account for climate change
A group of scientists led by German researcher Frank Sirocko of the Johannes Gutenberg University at Mainz has provided a long-term statistical study relating weather to the Sun’s 11-year cycle.
The study, carried out in conjunction with the Institute for Atmospheric and Climate Science in Zurich, Switzerland, used records of freezes in the Rhine dating back to 1780 to correlate conditions on the river to the sunspot cycle.
The researchers chose the Rhine because, as they put it, freezing is an “on-off” event for the major waterway. “Either there is ice or there is no ice,” the professor of Sedimentology and Paleoclimatology explained.
Because the Rhine was used for river transport from the early 19th century through to the 20th, cargo docks maintained records of freezing events, the researchers say. These documents showed that ten of the 14 documented freezes occurred during periods of low sunspot activity. Further statistical analysis suggests that a low sunspot period leads to a 99 percent chance of a cold winter in Central Europe.
Sirocko says the study provides the first “statistically robust evidence that the succession of cold winters during the last 230 years in Central Europe has a common cause”.
However, the research doesn’t invalidate carbon-driven warming. Co-author of the study Stephan Pfahl explains that the sunspot cycle “does not impact hemispherically averaged temperatures, but only leads to regional temperature anomalies”.
Rather, solar activity is merely added to the list of climate-impacting variables, Sirocko said. The same study also suggests that even the colder “low-sunspot” winters are growing warmer, with the researchers pointing out that the Rhine hasn’t frozen over since 1963 (in spite of record-setting cold winters in 2010 and 2011).
The study is published in Geophysical Research Letters, and the announcement from the American Geophysical Union is here. ®
Re: Correlation and Causation?
Yes there are: low sunspot activity means a weaker solar magnetic field, which leads to more cosmic rays penetrating the atmosphere, which leads to more ionized particles, which leads to more clouds (as ionized particles are condensation kernels which seed clouds), which leads to higher reflectance of the earth, which leads to lower temperatures. Quite a series of steps, but there is supporting evidence.
Statistically there have been many studies linking the Maunder Minimum to a "little ice age". I read a paper by Danish astronomers in about 1990, showing a 98% correlation between sunspot activity and temperature on earth over a period of about 150 years. Of course, this is correlation, not causation, but it is a very strong correlation indeed. Besides, I would hesitate yo suggest that temperatures on earth cause an increase in solar activity ;-).
Assuming the changes on the sun do not affect climate in any way is saying the main energy source of all earthly weather has no effect on the weather. However, saying the sun is the only cause behind climate change, and pollution has no effect at all is over-simplification as well.
Clearly what is needed here is a Sunspot Tax.
Re: “Either there’s ice or there’s no ice”
The Rhine is both large and fast so I suspect that either coherent icing remains quite minimal along the sides or progresses to a complete freeze-over, without stable states between these extremes. That was certainly the case with the Oder in the cold winter of 2005/2006 - although visible floating ice appeared in the river long before it froze over it remained navigable.