Though the world's oceans have been steadily rising at a rate of 3.2 mm per year for decades now, NASA scientists reported last year that the global sea level had actually dropped sharply between early 2010 and summer 2011, by about half a centimeter in total. However, a new study now shows that, as predicted, the global mean sea level has recovered from its drop and is once again rising.
"The water the ocean 'lost' was compensated for rather quickly," said Carmen Boening, lead author of the study and ocean/atmosphere researcher at NASA's Jet Propulsion Laboratory (JPL). "The newest data clearly indicate that the drop in 2010-11 was only temporary."
The paper, published recently in the journal Geophysical Research, shows that the "pothole" on the road to rising sea levels was caused by a strong La Nina event that began in late 2010. La Nina is a periodic Pacific Ocean climate phenomenon, and the counterpart to El Nino. The paper shows that the event changed rainfall patterns all over Earth, moving a huge volume of water from the ocean to land. In particular, rainfall in Australia, Northern South America, and Southeast Asia was heavy.
"In 2011, we detected a lot of water that was temporarily stored over land, causing severe flooding in some regions," said Felix Landerer, co-author of the study and research scientist at JPL. "In 2012, we have seen much of this water find its way back into the ocean."
(Image courtesy NASA/JPL-Caltech/CNES)