Could a huge volcano trigger a new ice age?

Morgan Jones, 26, is studying supervolcanoes and climate change

People think geology is about rocks and microscopes, but it's the history of the earth. I was inspired by a great geology teacher at Esher College in Surrey, and got interested in volcanoes during my BSc in geology at Edinburgh. I did my dissertation on volcanic rocks in Greenland, which was fascinating. That's one of the joys of geology; going into the field and looking at the evidence in front of you.

For my PhD, I'm looking at supervolcanoes and their role in changing global climate conditions, with funding from the Natural Environment Research Council. In the St Helens eruption in 1980, the volume of magma that came out of the earth was one cubic kilometre; in a supervolcano, the volume is 1,000 cubic kilometres or more.

Supervolcanic eruptions happen around once every 50,000 years. The last big one was Toba, Sumatra, about 74,000 years ago. I've no idea when the next will be; if I knew that, I'd be rich.

One effect of a large eruption is that sulphuric acid and other volcanic gases can stay suspended in the stratosphere for 10 years. This affects radiation levels, scattering sunlight and allowing less radiation to reach the earth's surface.

An eruption produces ash, which buries vegetation. I'm using a computer model of the earth's atmosphere, designed by the Met Office, to simulate the ash blanket that would follow an eruption of Yellowstone, a supervolcano in America. Everywhere from California to Mississippi to Seattle would be covered in ash. The blanket can act like an ice sheet, reflecting radiation and causing surface cooling. It also kills vegetation, so the land cools. While it hasn't been proven, supervolcano eruptions could act as a catalyst for climate change. This is my research: could an eruption trigger an icehouse climate?

The Toba eruption was close to the onset of a glacial event, so it may have been a catalyst for the climate to change from a greenhouse to an icehouse regime.

When I tell people what I'm doing, they either say: "Oh cool, volcanoes!" or "You're doing what?" I like explaining. Ultimately I'd like to teach, possibly AS-level geology.