Rainforest debris blocks a road after Cyclone Larry.

Climate change statistics – predicting extreme events

Reference: 07/84

A CSIRO course in Melbourne on Wednesday 9 May will focus on making reliable predictions about one-in-a-hundred year droughts, the frequency of future Cyclone Larrys and other extreme climate events that have economic impact.

9 May 2007

The course will be led by Dr Rick Katz who is visiting CSIRO from the US National Center for Atmospheric Research in Boulder, Colorado.

Dr Katz will teach course participants how to use new statistical tools he has developed to understand the climate events that cause most damage to property, loss of life and livelihood.

“How often will severe floods occur? Where will cyclones happen? How long will droughts last?” These are some of the questions that governments, infrastructure owners, farmers, and insurance companies want answered so they can plan for the potential economic impacts of climate change.

Statisticians can provide input to these questions drawing on rainfall distributions, cyclone intensities and other data collected by various agencies. The challenge is gathering enough data to get reliable results.

Dr Katz says that the problem with data about extremes is that there’s not much of it.

“As well as conducting the Melbourne course this week, Dr Katz will visit Perth next week for technical discussions with CSIRO researchers working on impacts of climate extremes.”

“Most data, by definition, is about average conditions,” he says.

“At the extremes, where events have low probability but high consequence, there isn’t much past data to work on. That means you need to make the best use of what little data you have to model and predict with the greatest reliability. Mistakes in forecasts can be expensive.”

The head of CSIRO’s Quantitative Risk Management group and course organiser, Dr Richard Jarrett, says the course’s aim is to share knowledge about the tools available to model extreme values so that Australia can be better prepared.

CSIRO statisticians and atmospheric researchers are co-ordinating Dr Katz’s Australian visit.
Katz is co-editor of the book: ‘The Economic Value of Climate and Weather Forecasts’ (Cambridge University Press, 2005) and has given recent presentations on modelling hurricane damage and determining if extreme weather events are becoming more common.

As well as conducting the Melbourne course this week, Dr Katz will visit Perth next week for technical discussions with CSIRO researchers working on impacts of climate extremes.