El Niño–Southern Oscillation
The 2010-2011 Queensland floods were caused by a La Niña event which brought very heavy rain to the east coast of Australia. Other big floods in Australia have also happened during a La Niña, 1916, 1917, 1950, 1954-1956, and 1973-1975. The cost of the 2010-2011 Queensland floods has been worked out to A$30 billion.