Australia's Two-Year Flood Event Made Sea Levels Drop

By: Sean Breslin

Published: August 22,2013

 

 

 

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This aerial image shows major roads submerged by the Brisbane River as flood waters devastate much of Brisbane on Jan. 13, 2011. (Torsten Blackwood/AFP/Getty Images)

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Since the start of the 20th century, sea-level rise has been on a steady incline across the planet. However, in 2010 and 2011, it rained so hard in Australia that sea levels fell all over the globe.
New research by the National Center for Atmospheric Research concluded the perfect combination of events occurred over Australia during those two years, yielding a temporary softening of sea-level rise. Because the continent doesn't allow rainwater to seep back into oceans as quickly as other landmasses, persistent rainfall not only slowed the rising seas, but reversed the trend until the flooding slowly receded, according to an AtmosNews report.
(MORE: Where Have All the Tornadoes Gone?)
The article explains the cause of this rare event to be a combination of two climate modes that came together at an exact location to cause a massive flooding event. La Nina, a periodic cooling of sea surface temperatures in the Eastern Pacific, pushed moisture west toward Australia, while the Southern Annular Mode pulled moisture into the continent's interior to create a worst-case scenario for the continent.
It was one of the two most devastating flood events in the country's history, according to Australian Geographic.
"The 2010-11 Australian floods were the most expensive natural disaster in that country's history, costing over $7 billion," said Weather Underground meteorologist Dr. Jeff Masters.
On a chart of the mean sea level rise over the last two decades, the Australian floods had a visible, albeit temporary, impact on the trend:

Credits CLS/Cnes/Legos

The world's seas are rising approximately three millimeters per year, but for 18 months in 2010 and 2011, sea levels fell by seven millimeters, according to a National Science Foundation story. Australia received nearly a foot of rain more than average during the two-year event.
It was one of the wettest periods in recorded history for Australia, proving even the smallest continent can have a pronounced effect on sea levels.