Spot the rain

Researchers have spotted a pattern in the floods that hit parts of Africa - they tend to occur in the year preceding a peak in sunspot activity. Writing in the journal of Geophysical Research, Curt Stager from Paul Smith's College, New York and his colleagues looked at one hundred years of rainfall data and water level records from Lakes Victoria, Tanganyika and Naivasha, which showed that rainfall peaks occurred in the year immediately before the 11-year sunspot peak. The next peak is expected in 2011-2012, meaning that if the relationship holds true, as it has done throughout the 20th century, then rainfall should peak again in 2010. The researchers suspect that the increased solar energy associated with sunspots leads to increase heating of both the land and sea, which promotes moisture evaporation and precipitation. It could also be linked to El Nino, which increase rainfall in east Africa. The finding may help authorities to better plan their resource allocations to tackle the problems commonly associated with heavy rainfall, chiefly flooding, erosion and disease, particularly water-bourne illnesses and malaria. "When you think of climate troubles in Africa, it's usually about drought," says Stager. "You don't often think of the opposite situation. Too much rain can create just as many problems."