Sunspot activity may be linked to rainfall - climate-change - 05 November 2008 - New Scientist Environment

THE sun is nearly 150 million kilometres away, but it seems to have Earth's rivers on a leash. The flow of a huge South American river - and thus the rainfall that feeds it - appears to rise and fall with the number of sunspots.

Though scientists reject the climate sceptics' assertion that the sun's activity can explain global warming, many have wondered whether it can affect rainfall. No one has been able to test this, though, as it has proved difficult to collate rainfall measurements over long timescales and areas large enough to rule out local variations.

Pablo Mauas of the University of Buenos Aires in Argentina and his colleagues decided to take a different tack by studying the 4000-kilometre-long Paraná river in South America. It has the fourth-largest streamflow in the world and so acts as an indirect indicator of rainfall right across the continent....