Volcanic eruptions can significantly alter river flow rates

New Scientist : Volcanoes can release large amounts of aerosol particles into the stratosphere. That can significantly alter rainfall, but the extent and impact of the change is still unclear. To get a better picture of the effects, Carly Iles and Gabriele Hegerl of the University of Edinburgh in the UK looked at historical flow volumes for 50 major rivers around the world. They found that for two years after major eruptions, rivers experienced significant changes in flow rate. In wet, tropical areas such as the Amazon, Nile, and Congo, river flow rates decreased by up to 10% of their average flow. In drier, subtropical regions, the river flows increased by as much as 25%. This difference emphasizes the potent effects of volcanic aerosols: By blocking sunlight, they allow less heat to reach the atmosphere, which alters circulation patterns and the distribution of rainfall.