When Will the Floods in Australia Stop?

Flash flooding recently overwhelmed the Australian city of Toowoomba, where rushing waters killed 16 people in a town that is home to about 130,000 on Jan. 11.

The disaster in Toowoomba, about 60 miles (95 kilometers) west of the state capital, Brisbane, was the latest in the ongoing flooding that has killed 20 people and affected more than 200,000 in the state of Queensland since December. As the heavy rains continue to fall and the death toll in Queensland rises, many want to know when the flooding in Australia will end.

"This monsoonal system is in decline and will decay in a relatively short period," said Greg Holland, a senior scientist and severe weather expert at the University Corporation of Atmospheric Research (UCAR) in Boulder, Colo. "There may be follow-up systems, but we shall have to wait and see."

Kevin Trenberth, a climatologist with the National Center for Atmospheric Research (NCAR) in Boulder, Colo., told OurAmazingPlanet that "the worst is probably over." Yet even after the rains stop, other factors will cause the water to stick around, Holland said.

Make it rain

The flooding in Toowoomba and in many Australian cities has been described as an "inland tsunami," according to many news reports. These intense floods were caused by a massive monsoon due to this year's unusually strong La Niña — which is perhaps the strongest ever recorded.

"All of this is fueled by the very high sea-surface temperatures in the region," Trenberth said.

La Niña is the opposite phase of El Niño, or a cooling in the central and eastern tropical Pacific Ocean. La Niñas create stronger than normal trade winds that push warm water from the tropics into the western Pacific. The waters around Australia are now the warmest ever measured. As this warm ocean water evaporates, moisture fills the atmosphere and fuels intense storms.

The record ocean temperatures have some scientists drawing a link between climate change and the flooding in Australia.

"I think people will end up concluding that at least some of the intensity of the monsoon in Queensland can be attributed to climate change," Matthew England, of the Climate Change Research Center at the University of New South Wales in Sydney, told Reuters.

The oft-repeated line is that no one storm or event can be linked directly to climate change, but Holland said, "There is also undoubtedly a contribution from global warming."

Wet cycle

Even after the rains stop, the floodwaters will not disappear overnight. Water in southeast Queensland will drain to the sea, but the water in north-central Queensland will likely head southwest, and could take up to six months to move down through the center of the continent, Holland said.

The water that hangs around will become a massive, hot, inland sea that will create moist air and drive intense local rains similar to what happened in Toowoomba.

Lake Eyre, which sits below sea level in the south-center of the country, may become filled with draining floodwater. This is good news for the plants and animals around the lake, Holland said, but the water will also provide more moisture for future rains in southeast Australia.

"So you can see there is a long cycle that has commenced and will last for many months yet," Holland said.

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Reach OurAmazingPlanet staff writer Brett Israel at bisrael@techmedianetwork.com. Follow him on Twitter @btisrael.

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Brett Israel was a staff writer for Live Science with a focus on environmental issues. He holds a bachelor’s degree in biochemistry and molecular biology from The University of Georgia, a master’s degree in journalism from New York University, and has studied doctorate-level biochemistry at Emory University.