Predicting global changes with a bang

Kiwi scientists have found a clever way to investigate how climate change impacts in Antarctica will touch the rest of the world.

A University of Otago-led team is working at the Priestley Glacier, 400km from Scott Base. Getting a clearer idea of what several degrees of global warming might mean for the frozen continent — and the 60m of global sea-level rise it holds — has become increasingly urgent.

“In both Antarctica and Greenland ice flows from the land to the sea, and an increase in the rate of flow of ice from the land to the sea will cause global sea levels to rise,” said the study’s leader, Professor David Prior. “What is less certain is the rate of sealevel change that will occur in the next few decades.”

Understanding how ice flow would respond to the changing climate was vital. A big driver of ice flow is ice deformation – which happens on the edges of the fast-moving Priestley Glacier, where it meets slowmoving ice at what’s called the shear margin.

“We will treat the Priestley Glacier shear zone as a natural experiment to calibrate how ice might speed up as the world gets warmer,” he said.

The team are producing seismic waves to image the large-scale structure of the rapidly shearing ice at the glacier’s edge. They record these lowfrequency sound waves via seismometers.

“We detonate explosives at each of about 10 locations to generate seismic waves that pass through the shearing ice before being recorded on our seismometer array,” Prior said.

By combining this data with laboratory work, they could put together an extrapolation describing ice flow behaviour — which could be used in ice sheet modelling.