Toowoomba floods 'made worse' by warm oceans
THE DEADLY floods that devastated Toowoomba, Oakey and Grantham were exacerbated by warming oceans, according to new research published in Geophysical Research Letters.
The study is one of the first to show how ocean warming can impact a heavy rainfall event.
In the summer of 2010/2011, Australia was surrounded by extremely warm sea surface temperatures, particularly in the eastern Indian Ocean, western Pacific warm pool region - to the north and east of Papua New Guinea - and the Coral Sea, the study claims.
Warm water increases the amount of moisture in the atmosphere and can intensify rain-producing circulation conditions.
In 2010/11 more moisture was brought onshore along Australia's east coast.
Stronger rising motion over the northeast resulted in higher rainfall, making it more likely for Australia to suffer extreme rainfall conditions during this strong La Niña
The research showed that due to warmer sea surface temperatures, Australia was three times as likely to more rain during a strong La Niña event.
"The sea surface temperatures around Australia during 2010/2011 were on average 0.5°C warmer than they were 60 years ago," lead author and Woods Hole Oceanographic Institution oceanographer Caroline Ummenhofer said.
The research team modeled atmospheric general circulation with 2010/2011 ocean conditions with and without long-term warming.
The study found that additional ocean warming enhances onshore moisture transport onto Australia.
The researchers say their findings highlight the role of long-term ocean warming for modifying rain-producing atmospheric circulation conditions, increasing the likelihood of extreme precipitation for Australia during future La Niña events.