Australia just had its wettest spring ever (September to November, in their upside-down way) setting a high mark in a record that began 111 years ago. Some parts of coastal Queensland had more than four feet (1200 mm) of rain. This has left the ground saturated with water, meaning that when more rain falls it no longer soaks in. Almost any rainfall can cause a flash flood under these conditions.
The flash flood that is now bearing down on Brisbane, threatening thousands of homes, unfortunately is not just any rainfall but an exceptional inundation by itself. That is why there is a wall of water almost 30 feet high fronting this flood.
Jeff Masters of the Weather Underground blog explains the exceptional weather this way.
The ocean waters surrounding Australia were the warmest on record during 2010, and these exceptionally warm waters allowed much higher amounts of water vapor to evaporate into the atmosphere, helping fuel the heavy rains. The record warm ocean temperatures were due to a combination of global warming and the moderate to strong La Niña event that has been in place since July. Queensland typically has its rainiest years when La Niña events occur, due to the much warmer than average ocean temperatures that occur along the coast.
Nineteen people have died in Queensland since December. An area the size of Germany and France together has been flooded. $5 billion dollars in damage has been done.
Maybe Australians, at least, are now ready to address climate change seriously. It’s not merely Pakistan, China or Russia facing the disaster this time. Maybe if the victims speak English ….
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