James Stewart

Like Topor, the crater left by the Toba super eruption is now occupied by a large lake. But whereas the New Zealand event 26,000 years ago ejected a little over 1,000 cubic kilometers of material, the Toba super eruption 50,000 years earlier involved at least twice the amounts and perhaps many times more.

And in case you're having trouble imagining what a thousand cubic kilometers looks like, try to picture a cube of rock and ash as tall as Mount Everest. And you still won't quite be there. Everest is a little under nine kilometers tall, but you're in the ballpark. And it wasn't just rock ash that was ejected from Toba in that gargantuan eruption.

And in case you're having trouble imagining what a thousand cubic kilometers looks like, try to picture a cube of rock and ash as tall as Mount Everest. And you still won't quite be there. Everest is a little under nine kilometers tall, but you're in the ballpark. And it wasn't just rock ash that was ejected from Toba in that gargantuan eruption.

And in case you're having trouble imagining what a thousand cubic kilometers looks like, try to picture a cube of rock and ash as tall as Mount Everest. And you still won't quite be there. Everest is a little under nine kilometers tall, but you're in the ballpark. And it wasn't just rock ash that was ejected from Toba in that gargantuan eruption.

All magma has various gases dissolved in it, such as hydrogen sulphide, sulphur dioxide, carbon dioxide and water vapour. In fact, it's the behaviour of these gases that determines how explosive an eruption is. As the magma moves up through the volcano's plumbing system to be erupted as lava, the pressure decreases and the gases come out of solution.

All magma has various gases dissolved in it, such as hydrogen sulphide, sulphur dioxide, carbon dioxide and water vapour. In fact, it's the behaviour of these gases that determines how explosive an eruption is. As the magma moves up through the volcano's plumbing system to be erupted as lava, the pressure decreases and the gases come out of solution.

All magma has various gases dissolved in it, such as hydrogen sulphide, sulphur dioxide, carbon dioxide and water vapour. In fact, it's the behaviour of these gases that determines how explosive an eruption is. As the magma moves up through the volcano's plumbing system to be erupted as lava, the pressure decreases and the gases come out of solution.

If the magma is runny, like that which feeds the volcanoes on Hawaii, the gases can bubble up and escape. But when the magma is thick and viscous, as is the case at Toba and other super volcanoes, it's much harder for the gases to get out. Now when the pressure drops, the gases explode suddenly, like a shaken bottle of lemonade when the lid is removed.

If the magma is runny, like that which feeds the volcanoes on Hawaii, the gases can bubble up and escape. But when the magma is thick and viscous, as is the case at Toba and other super volcanoes, it's much harder for the gases to get out. Now when the pressure drops, the gases explode suddenly, like a shaken bottle of lemonade when the lid is removed.

If the magma is runny, like that which feeds the volcanoes on Hawaii, the gases can bubble up and escape. But when the magma is thick and viscous, as is the case at Toba and other super volcanoes, it's much harder for the gases to get out. Now when the pressure drops, the gases explode suddenly, like a shaken bottle of lemonade when the lid is removed.

These blast the lava into pieces as fine as ash and as large as boulders. So these gases are responsible for pulverizing some of the erupted material into particles, small enough to linger in the atmosphere for years, shading the planet and lowering temperatures. But sulfur dioxide makes the problem even worse.

These blast the lava into pieces as fine as ash and as large as boulders. So these gases are responsible for pulverizing some of the erupted material into particles, small enough to linger in the atmosphere for years, shading the planet and lowering temperatures. But sulfur dioxide makes the problem even worse.

These blast the lava into pieces as fine as ash and as large as boulders. So these gases are responsible for pulverizing some of the erupted material into particles, small enough to linger in the atmosphere for years, shading the planet and lowering temperatures. But sulfur dioxide makes the problem even worse.

When it reaches the atmosphere, this gas reacts with oxygen and water to form tiny droplets of sulfuric acid and other aerosols. These aerosols can remain in the stratosphere for as long as a decade, reflecting sunlight back into space and plunging the Earth into a so-called volcanic winter. The super eruption of Toba 74,000 years ago released huge quantities of sulfur dioxide.

When it reaches the atmosphere, this gas reacts with oxygen and water to form tiny droplets of sulfuric acid and other aerosols. These aerosols can remain in the stratosphere for as long as a decade, reflecting sunlight back into space and plunging the Earth into a so-called volcanic winter. The super eruption of Toba 74,000 years ago released huge quantities of sulfur dioxide.

When it reaches the atmosphere, this gas reacts with oxygen and water to form tiny droplets of sulfuric acid and other aerosols. These aerosols can remain in the stratosphere for as long as a decade, reflecting sunlight back into space and plunging the Earth into a so-called volcanic winter. The super eruption of Toba 74,000 years ago released huge quantities of sulfur dioxide.

Although it's difficult to distinguish volcanic effects from background climate cycles, scientists have found evidence that the eruption was followed by a century-long period of cooling. It has also been proposed, based on archaeological and genetic data, that the climatic effect of the Toba super eruption caused our species to pass through a genetic bottleneck.

Although it's difficult to distinguish volcanic effects from background climate cycles, scientists have found evidence that the eruption was followed by a century-long period of cooling. It has also been proposed, based on archaeological and genetic data, that the climatic effect of the Toba super eruption caused our species to pass through a genetic bottleneck.

Although it's difficult to distinguish volcanic effects from background climate cycles, scientists have found evidence that the eruption was followed by a century-long period of cooling. It has also been proposed, based on archaeological and genetic data, that the climatic effect of the Toba super eruption caused our species to pass through a genetic bottleneck.

The global population might have dwindled to just a few thousand. This so-called Toba catastrophe hypothesis is contested. Some scientists doubt that the climatic effect of the Toba eruption was large enough to induce a global multi-year volcanic winter. And some question the severity of the population crash that supposedly coincided with it.