Rights: The University of Waikato Published 21 June 2007

Dr Mike Williams from NIWA explains how the thickness of icebergs can be measured and why it is hard to do this after an iceberg has calved off the Antarctic ice sheet.

## Transcript

DR MIKE WILLIAMS
One of the biggest problems we have is getting the thickness of ice. An iceberg moves too much for us to be able to measure how thick it is, and how high it is. But something like an ice shelf, we can do that. Because it’s fixed in position, you can get enough repeat measurements that you can get rid of the errors that are associated with each measurement, and - and work out how high an ice shelf is.

The most accurate method we have is to drill a hole through it and use a tape measure. And then, because we know an ice shelf is floating, we can then do a little bit of maths and work out how thick it is. So that means we have a really good idea of how thick an iceberg is when it first calved off an ice shelf, but you get to this point and you decide, well, it’s pretty much anyone’s guess how thick it is.

Acknowledgement:
Zee Evans, National Science Foundation (USA)