More and longer droughts but also periods of heavy rain are likely, according to research from the Australian National University.
Weather in Australia tends to oscillate between two phenomena in the Pacific Ocean: La Nina and El Nino.
The first often means above average rainfall. And the second often means lower average rainfall plus warmer temperatures and more fires.
The researchers at the ANU and two universities in the United States conclude that both La Nina and El Nino could come to last longer, over several years.
"The circulation of the atmosphere over the Pacific Ocean has changed," researcher Georgy Falster said. "This means in the future we could see longer La Nina or El Nino events as the atmospheric flow above the Pacific Ocean switches more slowly between La Nina and El Nino phases.
"That could exacerbate the associated risks of drought, fire, rains and floods."
The changes in the Pacific and the atmosphere above it mean that in the future El Nino and La Nina events could each last longer, perhaps for two to three years.
"After Australia saw severe flooding and rainfall from a rare three-year La Nina event, our research has found that one of the key drivers of these events is changing, with slightly slower transitions between La Nina and El Nino events," Dr Falster said.
The study's co-author Sloan Coats from the University of Hawai'i said "the tropical Pacific has an outsized influence on global climate".
"What happens in the tropical Pacific doesn't stay in the tropical Pacific - it impacts vast stretches of the world," Bronwen Konecky from Washington University in St Louis said.
"Ultimately, we know planet Earth is warming and that warming is caused by human-induced greenhouse gases. To plan and adapt for the impacts of climate change, we need to improve our knowledge of climate systems across the board," the ANU's Dr Falster said.
