Recent flooding in Queensland, Australia, as shown here in 2011, was so severe that it lowered global sea levels briefly. (Source: Government of Australia)
The complexity of the global warming/climate change debate is not something that can easily be discussed in simple or binary terms. As sea waters rise, the politics and economics that take over the debate on climate change often fails to give a clear picture, and when science is unable to provide that clear picture, they are blamed for causing hysteria and disrupting human progress. The debate took on a very interesting wrinkle today: Government scientists in America discovered that floods that greatly affected Australia in 2010 and 2011 briefly halted and lowered sea levels for more than a year, before continuing to rise apace.
The American scientists, working for the National Science Foundation and in conjunction with NASA and other organizations, were monitoring the global sea levels through the use of satellites and sea-based equipment. Prior to 2010, the world's oceans were rising at a rate of just about 3 millimeters per year. This has led to projections by many in science of the seas rising by about 13 inches by 2050, flooding many areas around the world.
However, an odd quirk happened, in that the global sea levels actually stopped rising, and even dropped considerably by 7 millimeters, from 2010 to 2011. Given the current trends, the National Science Foundation scientist were astounded and tried to figure out the reasons, finally pinpointing it at the floods that ravaged eastern and central Australia in that time period, killing dozens and causing billions of dollars in damage.
During that time, a series of meteorological events played hand-in-hand with each other to create the chain reaction necessary to produce the mass flooding that affected Australia. One was the weather phenomenon known as La Nina, which cools the waters of the Pacific, pushed moisture towards Australia. While this is not unusual for this weather event, what blew up the situation was a climate pattern called the Southern Annular Mode, which further brought moisture into central Australia, including the normally arid Outback.
Australian map detailing flooding that occurred in 2010. (Source: Government of Australia)
Combining La Nina and the Southern Annular Mode with unusually increased moisture from the Indian Ocean, and all these circumstances led to torrential rains that covered Queensland, Victoria, and parts of the Outback. Because of the shape of Australia, however, much of the rainwater did not return to the oceans initially, but stayed in the ground, or filled Australia's largest basin, Lake Eyre basin, turning it once again into an actual lake. This led to the decline in sea levels.
However, while the decline was good respite, scientists warned that the respite was brief. Following 2011, sea levels have risen at an above average rate, in this case about 10 millimeters. The long term impacts of this dip in sea levels is uncertain, but it does not change the pessimistic outlook on climate change among scientists. Furthermore, it remains to be seen if flooding this year will have as great an impact.