Original URL: http://www.theregister.co.uk/2012/01/02/cyclones_to_get_worse/

Fewer, stronger cyclones in greenhouse Oz, says CSIRO

Heading southwards as well

By Richard Chirgwin

Posted in Science, 2nd January 2012 22:00 GMT

So far, Australia’s 2011/12 cyclone season seems unusually benign so far, but local climate boffins don’t expect things to stay that way.

According to Dr Debbie Abbs, a scientist working for the joint CSIRO-Bureau of Meteorology Centre for Australian Weather and Climate Research, the consensus emerging in Australia is that climate change will lead to fewer, but more destructive cyclones.

Dr Abbs also believes that cyclone activity could move as much as 100 Km southwards over the course of the next century, exposing regions that aren’t geared up to deal with cyclones (for example, building codes in areas like Darwin are substantially different to non-cyclone cities).

While Dr Abbs’ work focused on the impact on Western Australia, which is a partner in the research, she says the results hold true Australia-wide.

In this CSIRO podcast, Dr Abbs notes that the CAWCR research has refined the older assumption that climate change would lead simply to an increase in cyclone activity. That model, she says, focuses on the impact of greater energy stored in the sea, in a warmer Earth.

Taken in isolation, the warmer sea surface drives more energy into cyclone formation. However, Dr Abbs explains, the greater energy in the entire climate system will also lead to changes in wind speed and direction (wind shear) at different heights; along with changes in temperature and humidity.

“There’s a greater likelihood, or greater risk, that the cyclones that do form will form in the category three, four and five level,” Dr Abbs says.

And those cyclones are likely to be larger in the future: “Our research is showing that they are changing in size. We’re finding larger cyclones, and that’s cause for concern because it’s the size of cyclones that affects the destruction from waves and storm surge.” ®