How Will Climate Change Impact Volcanic Eruptions? Wafact

Understanding how volcano activity may change over time is particularly important as climate change continues to have direct and indirect effects on how volcanoes behave.

“Governments use past experience to forecast what might happen next,” explains Jonathan Fink, volcanologist and director of PSU’s Digital City Testbed Center and author of a new study analyzing the relationships between society, climate and volcanoes.

About 500 active volcanoes presently exist on the Earth’s surface, of which around 50 erupt each year, and more than 800 million people are living within 100 kilometers (60 miles) of an active volcano. But as modern society is “heading into uncharted territory” as today’s climate change has been “unprecedented” over the past 24,000 years, many concepts adopted by policymakers and scientists to deal with volcano-related hazards will quickly become outdated.

Fink and Idowu “Jola” Ajibade, associate professor of Geography, argue that climate change can impact volcanic disasters in two ways. In the first scenario, another climate-related event will happen during a volcano-related event, adding to the disaster. In the second scenario, climate change will directly trigger a volcanic eruption.

The growing frequency of climate change–related hazards such as wildfires, floods, landslides, and drought increases the chances that they will coincide in space and time with volcanic eruptions. The combined effects of two or more disasters happening at once are much harder to predict or mitigate than an eruption alone.

The researchers looked at the Pacific Northwest, a region that has the largest variety of potential natural and man-made disasters in North America, which have only increased in frequency and overlap in the last 20 years.

The region is crossed by a 1,300 kilometers (800 miles) long chain of Cascades volcanoes, which extends from northern California to southern British Columbia. During the past 4,000 years, periods of volcanic rest, lasting from a few decades to centuries, were suddenly interrupted by eruptive activity at various volcanoes. The most recent eruption at Mount St. Helens vividly demonstrated the power and impacts that those volcanoes can unleash when they do erupt.

In the last few decades, average temperatures have risen in the Cascades and droughts, heat waves and wildfires have become more common. A survey published in 2020 shows how wildfires are steadily increasing in their severity and size over the past 100 years, with seven of the largest fires occurring since 2003.

“This region is characterized by volcanic eruptions of different scales and types, catastrophic subduction zone earthquakes, mega-wildfires that can wipe out cities, wildfire smoke events that can make our air unbreathable, tsunamis that can drown coastal communities, landslides that can shut down transportation corridors, floods that can inundate cities, and heat dome events that can kill thousands of individuals.”

An eruption happening during an extended period of drought or severe wildfire season would likely put more pressure on rescue efforts and recovery agencies.

In addition, recent discoveries suggest that climate change can also directly affect volcanic eruptions.

“Sea level rise, glacial melting, aquifer depletion, and mountain erosion can all affect the likelihood and frequency of volcanic eruptions,” Fink explains.

A study published in 2022 showed a link between volcanic activity and the retreat of the Cordilleran Ice Sheet, which once covered large portions of western North America, during times of rapid climate warming. A study of Iceland’s volcanic systems showed a similar pattern. Volcanoes experienced a period of heightened activity when the ice cap covering the island disappeared. The average eruption rates were found to be up to 100 times higher after the ice melted. Scientists now think that ice cover to volcanoes is like a cork in a champagne bottle. Remove the icy cork and boom, the eruptions begin.

Also, sea levels can influence the likelihood of volcanic eruptions. Studying the past eruptions of the island of Santorini in the Aegean Sea, the authors of a study published in 2021 showed that volcanic activity was directly linked to variations of the water levels. Rising sea levels could displace an estimated 267 million people worldwide, forcing them to settle in areas at higher risk of volcanic hazards.

“These kinds of ‘cascading’ or ‘compound’ disasters pose large challenges for public officials and for university faculty trying to train future volcano scientists,” the authors conclude.

“Rather than focusing exclusively on one aspect of volcanology, such as volcanic gasses, volcanic earthquakes, or lava flows, future volcano scientists will need to know at least a little bit about a great many more fields, including social science, public health, and communication.”

The study “Future impacts of climate-induced compound disasters on volcano hazard assessment” was published in the Bulletin of Volcanology (2023). Interview-based material provided by Katy Swordfisk for the Portland State University.

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