Volcanic Eruptions And Rainfall

By Victoria Clare

Posted October 26, 2020

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Y: Do you remember the last time it rained here, Don? It seems like it’s been ages.

D: There hasn’t been a volcano eruption recently that I missed, right?

Y: Are you ignoring my question, or are volcanos and rainfall somehow related?

D: I wouldn’t ignore you! Scientists have noticed that global precipitation tends to drop after a volcanic eruption, but they haven’t known all the factors that can influence this effect. Now, thanks to a new study, a group of researchers thinks the missing link is El Niño, the weather pattern we normally see every 2 to 7 years. After looking at several climate model simulations, they found that most models had El Niño showing up the year after a volcanic eruption. El Niño comes with weakened trade winds and warmer sea surface temperatures in the tropical Pacific, and causes all kinds of extreme weather conditions all around the globe, including a drop in precipitation. This reduced rainfall is especially noticeable in the global monsoon regions, which include Southeast Asia, India, South Africa, Australia, and the northern part of South America.

Y: Good to know in case a volcano erupts anytime soon.

D: Not only that. There’s been some talk of using geoengineering to fight global warming—essentially mimicking the global cooling effects of a volcano explosion by releasing sulfur dioxide, the main component of volcanic ash, into the atmosphere. Knowing the side-effects of volcanic explosions is one of the many things that would be helpful before we even begin to think about trying something like that.

Y: Messing with rain patterns isn’t something I’d really want to try, personally.

Volcanic eruptions may be connected to the El Nino effect. (Petr Novak, Wikimedia Commons)

Scientists have noticed that global precipitation tends to drop after a volcanic eruption, but they haven't known all the factors that can influence this effect.

Now, thanks to a new study, a group of researchers thinks the missing link is El Niño, the weather pattern we normally see every 2 to 7 years. After looking at several climate model simulations, they found that most models had El Niño showing up the year after a volcanic eruption.

El Niño comes with weakened trade winds and warmer sea surface temperatures in the tropical Pacific, and causes all kinds of extreme weather conditions all around the globe, including a drop in precipitation. This reduced rainfall is especially noticeable in the global monsoon regions, which include Southeast Asia, India, South Africa, Australia, and the northern part of South America.

There’s been some talk of using geoengineering to fight global warming—essentially mimicking the global cooling effects of a volcano explosion by releasing sulfur dioxide, the main component of volcanic ash, into the atmosphere. Knowing the side-effects of volcanic explosions is one of the many things that would be helpful before we even begin to think about trying something like that.