Scientists warn that the next colossal volcanic blast could hit within decades, yet governments still behave as if it’s science fiction.
Researchers tracking the world’s most dangerous volcanoes say the planet is edging toward another super-eruption, one on the scale of the 19th‑century disasters that rewrote climate and history. The difference this time: there are eight billion people, globalised food chains and a fragile, overheated climate, and almost no coherent plan for what happens when the sky turns dark for months.
The last time the sky went dark
In April 1815, Mount Tambora in Indonesia exploded with a force that dwarfed anything in modern memory. Ash soared into the atmosphere, circling the globe. More than 90,000 people died directly from lava flows, tsunamis and suffocating ash.
The blast hurled particles up to around 43 kilometres high. Those fine aerosols drifted across oceans and continents, eventually falling over Europe and North America. The result was a global temperature drop of at least 1°C.
The year that followed became known as “the year without a summer”. Frost hit New England in June. Crops failed in Europe. Food prices spiked, and famine spread from village to village. In some regions, disease followed hunger; cholera outbreaks surged along already stressed trade routes.
The Tambora eruption turned a local natural disaster into a worldwide food and climate shock long before globalisation and industrial farming.
That eruption happened when the global population was barely a billion. Today, the same scale of event would land on a far more crowded, interconnected and politically tense planet.
Scientists say the next one is a matter of time
Volcanologists class eruptions like Tambora as “super-eruptions” or “mega-colossal” events. They are rare on human timescales, but far from unique in Earth’s history. According to recent research led by the University of Geneva, the odds of such an eruption before 2100 are roughly one in six.
That is the kind of probability that would trigger emergency planning in finance or defence. In volcanology, it has barely stirred a policy response.
A one‑in‑six chance this century means super-eruptions belong in risk plans, not just disaster movies.
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Complicating everything is the state of the climate. The planet is already warmer by around 1.2°C compared with pre‑industrial times. That might sound like it would offset volcanic cooling, but the interaction is far from simple. A major eruption injects sulphur dioxide (SO₂) into the stratosphere, forming reflective aerosols that bounce sunlight back into space.
In a warmer, more energy-loaded atmosphere, that sudden shading could distort rainfall patterns even more violently. Monsoon belts over Africa and Asia, which support billions of people, are especially vulnerable.
From empty supermarket shelves to geopolitical shocks
The immediate dangers of a super-eruption are obvious: pyroclastic flows, ashfall, toxic gases. Yet for the vast majority of people on Earth, the threat would arrive more quietly, through food and prices rather than lava.
Global agriculture relies on stable growing seasons. If temperatures plunge by even 1°C for a couple of years and sunlight drops, yields of key crops like maize, wheat and rice can collapse. Past eruptions show this clearly.
- Shorter, colder growing seasons in temperate regions
- Weaker or shifted monsoons in tropical zones
- Increased risk of simultaneous harvest failures across continents
- Spikes in food prices and export bans
- Increased migration pressures from rural to urban areas and across borders
Insurance giant Lloyd’s of London has tried to put a price tag on such a scenario. One estimate suggests that an eruption comparable to Tambora could inflict economic losses of around €3.5 trillion in the first year alone, through destroyed infrastructure, disrupted trade routes and financial market turmoil.
The first true global recession triggered by geology, not banks, is a scenario that risk modellers now quietly discuss.
In regions already on edge politically, a sudden food crunch could push fragile states over the line. Aid systems designed for regional droughts could face simultaneous crises across multiple continents. Diplomats would be trying to negotiate grain shipments while their own capitals deal with power cuts and cold summers.
We’ve been here before, more than once
Tambora is only one chapter in a longer volcanic story. In 1257, another Indonesian volcano, Samalas, erupted with such force that many climatologists link it to the onset of the so‑called Little Ice Age. Over the following centuries, Europe and parts of Asia experienced cooler temperatures, advancing glaciers and repeated harvest failures.
Closer to the present, the 1991 eruption of Mount Pinatubo in the Philippines illustrates how even “smaller” events can shake the climate. Pinatubo sent about 15 million tonnes of SO₂ into the stratosphere. Global temperatures fell by around 0.5°C for several years.
That drop was measurable in satellite data and weather records. It slightly slowed the warming trend of the early 1990s and altered rainfall patterns worldwide. The episode still shapes debates over geoengineering, because it offered a real-world demonstration of how aerosols can cool the planet.
Volcanic eruptions double as accidental climate experiments, showing both the power and the side effects of sun‑blocking aerosols.
Climate change may be nudging volcanoes too
The relationship between volcanoes and climate runs in both directions. While eruptions can cool the planet temporarily, a warming world can in turn affect volcanic systems. As glaciers and ice caps melt, the weight pressing down on the crust decreases. That pressure change can alter how magma accumulates and rises.
Evidence from Iceland and other high‑latitude regions suggests that deglaciation has coincided with periods of increased volcanic activity in the past. Researchers are now watching carefully to see if today’s rapid ice loss triggers similar responses.
No one is claiming that climate change will suddenly switch on a line of new supervolcanoes. The deeper point is that Earth systems are linked in ways societies rarely factor into planning. A hotter atmosphere, shifting rainfall, melting ice and restless magma are not separate stories.
What preparation actually looks like
Unlike an asteroid strike, a large eruption often gives some warning. Magma movement tends to trigger small earthquakes, ground deformation and gas emissions. That creates a window, sometimes weeks or months long, to act—if people are ready.
Volcanologists argue for a layered approach to preparation:
- Dense networks of seismometers and GPS stations around known supervolcanoes
- Permanent satellite monitoring of ground uplift and gas plumes
- Pre‑agreed evacuation routes and shelter plans for local populations
- Strategic food and fuel reserves sized for multi‑year global disruption
- Stress tests of financial systems and supply chains against a multi‑year “volcanic winter”
Some high‑risk areas, such as parts of Indonesia and the Yellowstone region in the US, are now heavily instrumented. Yet early-warning hardware is only one part of resilience. Political leaders would need the courage to order mass evacuations and rationing on the basis of scientific probabilities, not certainty.
The technology to see a super-eruption coming is advancing; the political will to act on those warnings is lagging far behind.
Key terms that shape the debate
Two scientific ideas often surface in these discussions and are worth unpacking.
Stratosphere: This is the layer of the atmosphere above the troposphere, starting roughly 10 to 15 kilometres up. When volcanic gases reach this region, they can stay aloft for months or years, spreading around the planet and reflecting sunlight. Weather systems do not easily wash them out, which is why their cooling impact can last.
Volcanic explosivity index (VEI): This scale ranks eruptions from 0 to 8 based on how much material they eject and how high the column of ash rises. Pinatubo reached VEI 6. Tambora was VEI 7. The very largest events, such as some ancient eruptions at Yellowstone and Toba, hit VEI 8 and can change climate for decades.
How a super-eruption scenario could unfold
Risk analysts sometimes run “day‑by‑day” scenarios to stress-test systems. One simplified storyline, based loosely on Tambora and Pinatubo data, looks like this:
| Phase | Timeframe | Main impacts |
|---|---|---|
| Unrest | Weeks to months | Earthquake swarms, ground uplift, local evacuations debated, markets barely react. |
| Main eruption | Hours to days | Massive ash column, regional air traffic halted, emergency broadcasts, first casualties. |
| Global spread | Weeks | Aerosols reach stratosphere, sunsets redden worldwide, first temperature anomalies recorded. |
| Volcanic winter | 1–3 years | Crops fail in multiple regions, food prices soar, supply chains strain, governments impose export controls. |
| Long tail | 3–10 years | Recovery of climate patterns, debt overhang, migration patterns reshaped, infrastructure rebuilding. |
None of this is fixed fate. Early decisions—such as releasing food reserves quickly, coordinating trade rather than hoarding, and supporting farmers with seeds better suited to cooler seasons—could soften the blow significantly.
Yet those decisions will not happen on the fly during a maelstrom of ash and rumours. They require rehearsals, clear chains of command and public communication that treats volcanic risk with the same seriousness as pandemics or financial crises.
The next super-eruption will test not just the strength of our buildings, but the flexibility of our politics and the honesty of our risk calculations.