Global Warming Influences Volcanic Activity
I once thought volcanoes were one natural phenomenon human-induced climate change didn't impact, but I was wrong
Hiya!
So, my mom and I recently traveled to Hawaii to visit my aunt and cousin, the latter of which I hadn’t seen in over twenty years. It was a wonderful experience, both the long-overdue reunion and exploring the island for my first time ever. My cousin took me on a volcano hike where we galavanted across lava fields and climbed to the tippy top of a hidden caldera.
One night we all went to a park to see glowing red lava beneath the strikingly clear Milky Way — a sight I’ll never forget. But it also renewed my interest in volcanos, and I wondered about their role in climate change. After all, of all the natural phenomena global warming creates, volcanos seem to be the only ones uninfluenced by us humans. But it turns out my assumption was wrong.
Initial Curiosity
Extreme temperature swings, wildfires, hurricanes, floods, tornados, and more are awe-inspiring natural phenomena, to be sure — but these days, they’re also symptoms of human-caused global warming. And while standing there with my cousin, watching the lava glow, I thought perhaps volcanoes are one natural phenomenon safe from our influence.
After all, storms, fires, and floods occur with us on the planet’s surface. Whereas volcanoes seem a bit like icebergs in that much of their existence is beneath us and out of sight. Remember when we talked about the gigantic blobs near the center of Earth?
A friend once joked that choosing where to live in America means picking which natural disaster you want to risk surviving — fires in the west, hurricanes to the south and east, etc. — but volcanoes never crossed our mind as a climate-related risk.
Unlike hurricanes or wildfires, there isn’t a volcano season or any apparent connection between the planet’s surface activity and when a volcano erupts. But then I found research suggesting it’s more likely that volcanos and, to a degree, earthquakes are impacted by global warming, whether natural or human-produced.
Volcanoes and Global Warming
If there’s one thing I’ve learned from Hawaii and Iceland, it’s that volcanoes are to be respected and never trifled with — for they are everywhere on our planet and are responsible for creating over 80 percent of Earth’s surface.
Every continent, including Antarctica, have volcanoes with plenty along the ocean floors too. There are about 1,500 active volcanoes worldwide, of which 10 percent (161 in total) are within the United States.
Considering the raw and explosive power volcanos are capable of — and all the debris and gases within their eruptions — you might think volcanoes would intensify global warming, and you’re right. But… research shows that “human activities emit 60 or more times the amount of carbon dioxide released by volcanoes each year.”
Not only that, but volcanic eruptions have a cooling effect on the planet when temperatures rise and Earth reaches Hellscape environments. A volcano’s eruption helps cool the world down. Meaning, despite the blasts’ contents, they slow the heat rather than accelerate it because the plumes block the Sun’s light and heat from Earth’s surface.
I found two exciting studies that further examine this flip of perspective. That while volcanoes can contribute to global warming, the opposite is also true. Changes in the climate can influence volcanic activity.
Study One
In 2013, the journal Geology published a study by a team of experts at Geomar in Germany, which suggests sea level rises caused by rapidly melting continental glaciers eventually increase volcanic activity.
The team collected core samples from ocean floors off the coasts of South and Central America, showing the Earth’s climatic history over the last one million years. See, every now and then, Earth’s orbit shifts just enough to rapidly warm the planet, resulting in glaciers melting and rising sea levels — aka natural climate change.
The samples showed increased amounts of volcanic ash called tephra in the sediment after these periods of rapid warming. Interestingly, some areas showed more volcanic activity than others. For instance, places such as Costa Rica saw 5 to 10 times as much volcanic activity during rapidly rising sea levels compared to other times.
The team used a computer model to simulate the domino effect from warming temperatures to volcanic eruptions to understand why this happened. If you haven’t figured it out, it goes something like this.
Warming temperatures melt glaciers. The warmer it is, the faster the glaciers melt. Melting glaciers cause sea levels to rise — and again, the faster they melt, the quicker the oceans rise. And guess what? Water is heavy, and this added weight increases pressure on Earth’s crust along the ocean floor while decreasing stress on continents. It’s these shifts that appear to trigger volcanic activity.
The study didn’t explain, but it seems to me that if the ocean floors are forced to bear the weight of more water, then the magma chambers in Earth’s crust would presumably be squeezed as they bend or shift to accommodate the pressure. In this case, the chamber’s contents — magma and/or gasses — would be forced to relocate, ultimately leading to an eruption or at least venting at the surface.
The study did find that when it comes to the intensity of volcanic activity, the speed of the melting mattered more than the total amount of melting that occurred. Geophysicist and co-author of the study Marion Jegen explains in an article by LifeScience that the periods of faster melting predicted more intense volcanic eruptions.
Although the team focused on natural changes in the climate over the last million years, they can’t say if the same effects would occur for human-induced global warming.
In my opinion, why the glaciers melt—whether it’s our fault or a natural occurrence — doesn’t matter. What matters is the speed at which it raises sea levels. So if human-induced global warming melts the glaciers at an accelerated rate (which it is), then I don’t see how it wouldn’t have the same results the experts found in their study.
Study Two
Research from Cambridge, in the United Kingdom, published a paper in 2021 in the journal nature communications suggests climate change makes volcanic activity “far more devastating.” Remember, if the climate shifts and cools too quickly… well, welcome another Ice Age.
The researchers found additional information confirming the cooling effect of volcanoes in tree rings. In an article about the study, Dr. Thomas Aubry from Cambridge’s Department of Geography stated,
“[W]e can also see the cooling effect of volcanoes going back two thousand years from the information contained in tree rings.”
But they wanted to determine whether a warming climate could affect the cooling effects of volcanic eruptions. They found that, indeed, warmer temperatures cause plumes from eruptions to rise higher and spread faster across the globe.
The researchers predict a layer of Earth’s atmosphere called the tropopause will increase — the layer between Earth’s lowest level ( called the troposphere) and the stratosphere. This widening of the tropopause, in turn, would make it harder for volcanic plumes to reach the stratosphere. And as a result of that, aerosols from the plumes wash out into precipitation within weeks, making the effects of the eruptions more localized and less disastrous.
In fact, they found that such effects cause the plumes from once or twice-a-century eruptions to result in a cooling effect amplified by 15 percent. Meanwhile, in high-warming situations, the effects of more moderate explosions, such as those that occur yearly, are reduced by 75 percent.
In a university release about the study, a lecturer in Climate Modeling named Dr. Anja Schmidt explains:
“The effects of climate change and some of the feedback loops it can cause are becoming more obvious now. But the climate system is complex: getting a grasp of all these feedback loops is critical to understanding our planet and making accurate climate projections.
Due to more frequent and more intense wildfires, as well as other extreme events, the composition of the upper atmosphere is changing in front of our eyes, and so is our understanding of the consequences of these changes.”
Perspective Shift
Nature sure is teaching us a lot of lessons. We’re learning of mistakes we’ve made — and continue to make— and the intricate web of our planetary system is slowly revealing itself to us as we discover more connections. Volcanoes are a significant part of that web and shouldn’t be forgotten or neglected regarding climate models. The absolute last thing we need is for our rising oceans to set off a mega explosion.
Like Manua Loa, the planet’s largest active volcano, which happens to make up 51 percent of Hawaii island— the Big Island — and has recently become restless. Mere days after returning home from our trip, my aunt and cousin received a volcano alert warning of Manua Loa’s increased activity.
My stance regarding the relationship between volcanoes and global warming has dramatically changed since before diving down this rabbit hole. After learning all of this, and more that I’ll share on Monday in Curious Life, it’s clear to me now that volcanoes are indirectly impacted by human influence. In fact, volcanoes just may be the most dangerous and volatile repercussions we face in the coming years, considering the severity of the heat waves headed our way.
We can find ways to fire or hurricane-proof our homes, but how does one prepare for the ramifications of high volcanic activity? Oof, I don’t want to think about it. Still, behind my “what-if” fears is Awe. Both at the power and magnitude of volcanoes and our influence as a species. One person may not appear to make much of a difference, but all of us together literally alter the course of Nature, and by default, all of Life itself.
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