Volcanic eruptions reduce the flow of water in world’s rivers due to the amount of volcanic ash and fine particles released in the atmosphere.
This is the conclusion of a new study published in the Nature Geosciences journal, authored by Gabriele Hegerl and Carly Iles of the University of Edinburgh. While it has been scientifically proven that volcanic eruptions affect rainfall across the globe, there have been no studies to link the fine particles and ash released in the atmosphere to the decrease in water volume in rivers.
Volcanic eruptions are a disruptive natural force. The ash spurted out remains trapped in the atmosphere over a period of years, blocking sunlight. In turn, as the atmosphere becomes laden with fine particles, it also cools down. This leads to reduced volumes of rainfall and as such, reduced water volumes in the world’s rivers.
According to Carley Iles:
“It was known that volcanic eruptions affect global rainfall, but it was unclear to what extent this translated into changes in river flow”.
The scientific team set out to study how volcanic eruptions reduce the flow of water in world’s rivers. Data on water flow gathered annually on 50 rivers around the globe was subject to analysis. Once introduced in computer models including data on volcanic eruptions, the research team could determine the impacts of the latter on the world’s rivers.
For instance, some of the greatest volcanic eruptions were taken into account. These included the eruption of El Chichon, Mexico in 1982, of Agung, Indonesia in 1963 or of Pinatubo, Philippines in 1991.
Unsurprisingly, the effects of volcanic eruption are not homogenous across regions. In the tropics the research team found that the flow of water was affected for an average period of two years following a volcanic eruption. Two of the world’s largest rivers, the Nile and the Amazon, were estimated to decrease in volume by approximately 10 percent after a volcano erupts.
In the sub-tropical regions, a reverse process was observed. In some regions of South America, as well as Southwestern U.S., water flow in rivers increased as a result of volcanic eruptions as circulation patterns in the atmosphere were disrupted in other regions.
Why is river water volume so important?
The world’s rivers are a crucial source of clean drinking water. The Amazon is estimated to be the main source of clean drinking water for over 20 million people. The Nile might even surpass this stunning number.
As volcanic eruptions reduce the flow of water, this might have serious impacts on global water availability. Millions of communities could see their access to clean drinking water cut and conflicts arising. Water used in agricultural irrigation, in households and for human and animal use increased the pressure on global water availability.
This study not only establishes the link between volcanic eruptions and water flow in the world’s rivers, but also argues against geo-engineering as a means to fight global warming. The solution, researchers say, lies somewhere else.
Geo-engineering means that the Earth’s atmosphere and climate are artificially modified. For instance, replicating a volcanic eruption in the sense that sulfate aerosols are being injected artificially in the atmosphere to deflect sunlight and keeping the atmosphere has adverse impacts on river volume and global water availability.
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