A new study has found that volcanic eruptions cut river flows worldwide by 10 percent, meaning a new method that would attack global warming could be a bad idea.
A new study has found that volcanic eruptions have a huge impact on water flows in major rivers, meaning that a scheme that would involve injecting reflective particles into the sky to fight Global Warming could backfire.
Researchers found that the Amazon, Nile, and Congo rivers saw their water volume decline by up to 10 percent through the 20th century due to volcanoes erupting, blasting millions of tons of debris into the atmosphere, according to an Agence France-Presse report.
The study, led by scientists at the University of Edinburgh, examined annual water flow in 50 rivers worldwide and looked at how major volcanic eruptions over that time period impacted water flows.
Specifically, they looked at the 1963 eruption of Agung, the 1982 eruption of El Chichon, and the 1991 eruption of Pinatubo. They were also able to compare eruptions in the 19th century for some rivers as well, since records go back quite far.
The findings were fairly alarming: a year or two after these massive eruptions that caused a sort of “sunscreen” effect in the atmosphere, there was a decrease in the flow of water in these rivers by as much as 10 percent.
It’s because volcanic eruptions have a major impact on total rainfall in the globe, as scientists had suspected, but had not been fully demonstrated until this study, at least in how it affects rivers. Because there is less sunlight due to the “sunscreen” effect from the volcanic debris, there is also less evaporation, and there is also a cooler surface temperature, which means the atmosphere can’t retain as much water.
What’s the big deal? This can have a big impact on agriculture, particularly in areas that depend on these rivers for their livelihoods. Much of the world population lives on a river, so a change of 10 percent is quite significant to them and their way of life.
However, not all areas saw a decrease in water flow after the volcanic eruptions. In some regions of South America and the southwestern United States, there was an increase, which is likely explained by variations in regional weather patterns rather than a contradiction of the trend.
This has major implications for the fight against Global Warming as well. Some have come up with geo-engineering schemes that would involve pumping reflective particles into the atmosphere to combat the effects of climate change. While this might have a cooling effect on the climate, it may also result in a tremendous change in river flow and rainfall, the study found. This could mean that the negative impacts of such meddling in the environment could outweigh the positives.
This doesn’t necessarily mean this is no longer a workable solution, but it does mean humans should exercise extreme caution before even attempting such a scheme, as the side effects may be extreme.
The findings were published in the journal Nature Geoscience.
The first eruption mentioned is the 1963 eruption of Mount Agung, which is located in Bali, Indonesia. This stratovolcano is the highest point on this island, which has become a popular tourist destination.
It erupted on Feb. 18 in 1963 as residents heard huge explosions and witnessed clouds rising from Mount Agung. Six days later, lava started to flow down the mountain and traveled a total of seven kilometers over 20 days. Another eruption followed March 17, blasting debris 10 kilometers into the air and causing huge pyroclastic flows, killing 1,500 people and flattening villages. Another 200 people died due to heavy rainfall after the eruption. Another eruption on May 16 resulted in the deaths of another 200 people from pyroclastic flows.
The El Chicon eruption happened in 1982, which is located at the southeastern end of Mexico near Guatemala. This eruption was the largest volcanic disaster in the history of modern Mexico. It blasted magma into the air and resulted in pyroclastic flows that spread out eight kilometers from the center of the volcano, destroying nine villages and killing 2,000 people. Up to 40 centimeters of ash covered the landscape, and it devastated crops of cocoa and banana, as well as wiping out cattle. It did a total of $132 million in damage in present-day U.S. dollars.
The third major eruption mentioned was that of Mount Pinatuba in 1991. This active straovolcano is located on the island of Luzon in the Philippines. Unlike most other volcanoes, this was a relatively inconspicuous mountain that was heavily eroded and wasn’t very easily seen, covered with a forest that was occupied by an indigenous people. It quickly came into the public eye in 1991 when it caused the second largest terrestrial eruption in the 20th century, second only to the 1912 eruption of Novarupta in Alaska. It also coincided with Typhoon Yunya to create a nasty mix of ash and rain. Fortunately, scientists had predicted that an eruption was coming and tens of thousands were evacuated, saving untold lives.
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