Supervolcanoes and Volcanic Winter

Science · Volcanoes & Earthquakes · ages 12-13

Name ______________________ Date ____________

Which of these is an example of a supervolcano caldera?
- Yellowstone
- Mount St. Helens
- Mount Vesuvius
What makes a supereruption different from an ordinary volcanic eruption?
- It happens only underwater
- It ejects more than 1,000 cubic kilometers of material
- It only produces lava, never ash
Sulfur dioxide released by an eruption can turn into droplets that reflect sunlight.
Circle one: True False
Ravi says the planet cooled a little for a couple of years after Mount Pinatubo's 1991 eruption. What actually caused that cooling?
- Ash blocking out the sun for years
- Sulfate aerosols from sulfur dioxide scattering sunlight
- A drop in ocean currents
When an eruption sends enough sulfur dioxide into the stratosphere, why can it cause a volcanic winter?
- Less sunlight reaches the ground
- The gas directly freezes the air
- The gas replaces oxygen in the atmosphere
A large ordinary eruption releases about 1 cubic kilometer of ash. Toba released about 2,800 cubic kilometers. About how many times bigger was Toba's eruption?
Answer: ______________
Kofi claims that every volcanic eruption cools the planet for years afterward. Is Kofi right?
- No, volcanic winters only happen during ice ages
- Yes, all eruptions cool the planet for years
- No. Long-lasting cooling depends on enough sulfur dioxide reaching the stratosphere
The Toba catastrophe theory suggests that Toba's eruption about 74,000 years ago might have done what?
- Nearly wiped out early human populations
- Created the first ice age on Earth
- Caused every volcano on Earth to erupt at once

Answer key

For grown-ups. Fold this page away before handing over the rest.

Supervolcanoes and Volcanic Winter W1-mt_Am_iTzHjoe-s1

Yellowstone · Yellowstone sits inside a huge caldera left by a past supervolcano eruption. Toba, in Indonesia, is another example.
It ejects more than 1,000 cubic kilometers of material · A supereruption ejects more than 1,000 cubic kilometers of material in one eruption.
True · Sulfur dioxide converts into sulfate aerosols in the stratosphere, and those droplets scatter sunlight away from Earth.
Sulfate aerosols from sulfur dioxide scattering sunlight · The cooling came from sulfate aerosols high in the stratosphere, not from ash, which falls out much faster.
Less sunlight reaches the ground · Sulfate aerosols scatter sunlight back into space, so less energy reaches the ground and temperatures drop.
2800 · 2,800 cubic kilometers divided by 1 cubic kilometer is 2,800 times bigger.
No. Long-lasting cooling depends on enough sulfur dioxide reaching the stratosphere · Most eruptions have little global cooling effect. Enough sulfur dioxide must reach the stratosphere and form sulfate droplets that scatter sunlight for the cooling described here.
Nearly wiped out early human populations · The theory proposes that the eruption's volcanic winter put severe strain on early human populations, though scientists still debate how big the effect really was.