Mount Pinatubo exploded in 1991 with the force of roughly 3,000 Hiroshima bombs, and for the next year, global temperatures dropped by about 0.5 degrees Celsius. That’s half a degree that changed crop yields, altered monsoon patterns, and made meteorologists worldwide recalibrate their models—all because one mountain in the Philippines decided to exhale 20 million tons of sulfur dioxide into the stratosphere.
Here’s the thing about volcanic eruptions and climate: they’re not just dramatic spectacles for disaster movies. They’re nature’s own geoengineering experiments, conducted without permits or environmental impact statements.
When Sulfur Becomes the Atmosphere’s Unwanted Houseguest for Years
The 1815 eruption of Mount Tambora killed roughly 71,000 people directly. But the real horror show came the following year—1816, infamously known as “The Year Without a Summer.” Crops failed across Europe and North America. Snow fell in June in New England. Mary Shelley, stuck indoors at Lake Geneva during a miserably cold summer vacation, wrote Frankenstein. Volcanic ash doesn’t cause the cooling, though—that’s the plot twist nobody expects.
Sulfur dioxide is the villain.
When volcanoes punch through Earth’s crust, they inject sulfur dioxide high into the stratosphere, where it reacts with water vapor to form sulfuric acid aerosols. These microscopic droplets act like planetary sunscreen, reflecting sunlight back into space before it can warm the surface. The aerosols can linger for years, circling the globe on stratospheric winds, creating spectacular sunsets and agricultural disasters in equal measure. Wait—maybe that’s why volcanic eruptions have been linked to famines throughout history, from ancient Rome to medieval Europe.
El Chichón erupted in Mexico in 1982, and scientists initially underestimated its climate impact because the eruption wasn’t particularly large by volcanic standards. Turns out the sulfur content matters more than the explosion size—El Chichón released disproportionate amounts of sulfur, cooling the planet more than expected and teaching volcanologists a humbling lesson about prediction.
The Weird Part Where Volcanoes Might Actually Save Us From Ourselves
Some climate scientists have proposed mimicking volcanic eruptions deliberately—shooting sulfur particles into the stratosphere to cool the planet and buy time against climate change. It’s called solar geoengineering, and it’s either brilliantly pragmatic or terrifyingly hubristic, depending on who you ask. The idea isn’t new; it’s literally copied from what volcanoes do naturally, except with more PowerPoint presentations and international treaties involved.
But volcanic cooling is temporary—brutally, frustratingly temporary.
The aerosols fall out within a few years, and temperatures bounce back. Meanwhile, the carbon dioxide that volcanoes also emit? That sticks around for centuries. A single large eruption might cool things briefly, but over geological timescales, volcanic CO2 has warmed the planet significantly. The Siberian Traps eruptions 252 million years ago released enough carbon dioxide to trigger the Permian-Triassic extinction, which wiped out roughly 96% of marine species. That’s not a cooling event—that’s an apocalypse.
Iceland’s Laki eruption in 1783 created a toxic haze that drifted across Europe, killing crops and livestock. An estimated 6 million people died from the resulting famine. Benjamin Franklin, then living in France, correctly hypothesized that the “dry fog” and cold weather were connected to the Icelandic eruption—making him possibly the first person to document the climate effects of volcanism in real time, though he didn’t have the word “volcanology” in his vocabulary yet.
Modern eruptions still mess with climate, just less dramatically because we have better agriculture and supply chains. When Eyjafjallajökull erupted in 2010, it didn’t cool the planet noticeably, but it grounded 100,000 flights and stranded millions of travelers—proof that even modest eruptions can disrupt globel systems in unexpected ways. The ash itself poses risks to aircraft engines, turning into molten glass at high temperatures and coating turbine blades.
Krakatoa’s 1883 eruption was heard 3,000 miles away—the loudest sound in recorded history. The pressure wave circled Earth seven times. The sunsets afterward were so lurid and strange that artists painted them obsessively, and some historians think the blood-red skies in Edvard Munch’s “The Scream” were inspired by Krakatoa’s atmospheric effects. That’s culture shaped by chemistry, pigment choices influenced by sulfuric acid aerosols.
Volcanoes remind us that Earth’s climate has always been volatile, subject to forces we can’t control—mountains that decide, without consultation, to inject millions of tons of material into the atmosphere and change weather patterns for years. We’re currently doing something similar with fossil fuels, except slower and without the spectacular explosions. The difference is intent, or lack thereof. Volcanoes don’t care about Paris agreements or emission targts.
The next big one could happen tomorrow or in a thousand years, and we’d have maybe a few weeks’ warning at best.
