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Hello and welcome back to the Extreme Weather Blog! Caroline here, and it has been an active week across the globe. We’ve seen extreme flooding in Saudi Arabia, snowfall in Seattle, and deadly storms producing tornadoes in Mississippi, Alabama and Louisiana. Although these are all undoubtedly extreme, I wanted to focus on the Mauna Loa volcano eruption in Hawaii.

What makes this volcano eruption so significant?

Mauna Loa is not just a volcano, it’s the largest active volcano in the world with the summit about 10.5 miles above the base. This the first eruption of Mauna Loa since 1984, so it’s been nearly 40 years since its been this active! In fact, since the last eruption, the Hawaiian population living near the volcano has more than doubled. An active volcano spewing lava can be highly dangerous; however, the folks from the USGS have said that the lava flows are currently not a threat to any communities downslope. Residents also had knowledge beforehand of the impending event as seismologists tracked an increase of earthquakes around the volcano prior to the eruption Sunday.

What does a volcano eruption do to our climate?

Volcanoes play an important role when it comes to climate. Although intuition might lead you to believe a molten lava eruption would raise our global temperature, it actually does the opposite! When a volcano erupts it emits a ton of ash, sulphur dioxide and aerosols into the atmosphere. These sulfate aerosols do not disperse easily and are so tiny that they can stay suspended in our atmosphere for up to three years. These aerosols in our upper atmosphere reflect sunlight back into space, reducing the solar radiation that reaches the surface, which cools us down.

In this video below you can see the sulphur dioxide release from Mauna Loa as it erupted. This plume will reflect sunlight away from earth, which will lead to a slight cooling. The magnitude of the cooling depends on how much volcanic ash, Sulphur Dioxide and aerosols was released.

Mount Pinatubo’s impact on climate:

Mount Pinatubo was one of the largest volcano eruptions of the 20th century, erupting on June 15, 1991, in the Philippines. This monstrous volcano emitted an enormous cloud of sulphur dioxide into the stratosphere which had global impacts for over three years! According to NASA the global temperature cooled by about 1°F for the first 15 months post-eruption. An important word here is global, it was not just in the Philippines that saw cooler temperatures, but instead the entire world felt the cooling impact from this eruption. One degree doesn’t sound like it would make a difference, and to us individually, it wouldn’t. However, even one degree of cooling can have enormous effects on overall climate patterns for months, even years at a time.

But don’t volcanoes release CO2 which warms our climate?

Yes! Volcanoes do release Carbon Dioxide which does act to warm our climate, however, the total CO2 emissions from all of the volcanoes combined in a year is less than a percent of human emissions. According to the USGS “The 1980 eruption of Mount St. Helens vented approximately 10 million tons of CO2 into the atmosphere in only nine hours. However, it currently takes humanity only 2.5 hours to put out the same amount.” For a more in-depth explanation on how volcanoes impact our global climate, check out this article from the USGS.

I’ll be back next week for another look at the wild weather across the globe!

Stay safe always,

Caroline