We're concerned with glaciers melting because sea levels will rise and flood coastal cities. Could we survive this? Maybe. Imagine higher sea walls, buildings that float, or everyone just moves to the Midwest. We might figure it out.
But at the 2025 Goldschmidt Conference in Prague, researchers from the University of Wisconsin warned a second concern awaits us when the ice melts away: what lies underneath. When the glaciers disappear, it's not just dirt that's left behind. Beneath the ice sheets of Antarctica, Russia, New Zealand, and North America are dormant volcanos. And we're not talking about a few. The scope is much bigger. Enough to impact the entire planet. There are no less than 245 potentially active volcanoes under the ice, about to see the light of day.
When glaciers melt, significant populations will suddenly find themselves dangerously close to these ancient volcanoes. According to a 2020 study "Global mapping of future glaciovolcanism" (not the most exciting title, but researchers aren't going for clicks), 20,000 people live within 3 miles of a glacierized volcano (meaning it's currently covered by ice). 160 million people live within 60 miles of one. Is 60 miles far enough to be safe? The short answer is no. The 2022 eruption of Hunga Tonga--Hunga Haʻapai, an undersea volcano, extended for 162 miles and sent a pillar of ash 12 miles into the air. If that's not terrifying enough, NASA was kind enough to point out Hunga Tonga released energy equivalent to 100 Hiroshima-sized bombs. That's from one volcano. With the glaciers gone, we'd be left with 245 volcanoes.
Just because the volcanoes are free of ice cover, does that necessarily mean they'll be active? This is the question that prompted the University of Wisconsin study. Researchers studied six volcanoes in southern Chile that -- during the ice age -- were covered in ice. Using argon dating and crystal analysis, they learned how the Patagonian Ice Sheet's retreat influenced these volcanoes, all of which are active today.
The Wisconsin researchers found during the last Ice Age (around 26,000 years ago), ice cover tamped down the volume of eruptions on the surface, causing a giant reservoir of magma to accumulate miles below. When the ice sheet melted, pressure grew inside this reservoir and was eventually released. In other words, the weight of glaciers exerted a downward force on the Earth's crust. When the ice retreated, magma expanded, leading to explosive eruptions.
So not only are these newly revealed volcanos likely to be active, it's the disappearing ice that actually triggers the activity. According to one of the study's authors, "the key requirement for increased explosivity is initially having a very thick glacial coverage over a magma chamber, and the trigger point is when these glaciers start to retreat, releasing pressure -- which is currently happening."
If moving inland might save us from rising oceans, there's no easy solution if the ground erupts in ash and molten lava and carbon dioxide. Hundreds of volcanoes suddenly erupting would trigger a global-scale environmental and humanitarian catastrophe.
Vast quantities of volcanic gases would be released. Sulfur dioxide would cloud the upper atmosphere, turning it into a reflective haze. These aerosols would block sunlight, reducing surface temperatures worldwide--a phenomenon known as volcanic winter. Global temperatures could plunge by several degrees for months or even years. Crops would fail on a massive scale. Photosynthesis would slow, growing seasons would shorten, and famine would follow.
Volcanic ash--microscopic shards of glass and pulverized rock--would be thrown into the atmosphere and carried by global winds, blanketing entire regions. Whole populations would suffer respiratory damage and air travel would be forced to stop, with plane engines choking on airborne ash.
Rivers of lava would consume cities and forests, transforming the ground into molten rock surface. Being alive during this era of toxic air and burning ground would mean surviving compete civil unrest and the breakdown of society. Ultimately it all leads to a frequent topic in these posts -- mass extinction, similar to the Permian event 252 million years ago, which was also triggered by -- you guessed it -- massive volcanic activity.
Apparently we should raise our level of concern about the world's glaciers melting. Because when they're gone it will bring Hell on Earth.