worst ever natural disaster?

Julia Gillard and Anna Bligh are calling these floods 'Australia's worst natural disaster.' Really? How do you measure disasters? Financial cost? Area affected? Lives lost?

Yes, this is bad. People have died and many have lost all of their possessions. The recovery will be very expensive and will take a long time. It will be messy and smelly and horrible. Farmers may never be able to get on their feet again.

But 2 years ago, 173 people died in the Victorian bushfires. 173. 400+ more were injured.

Who needs to rank disasters?