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Ocean levels dropped by five millimetres between March 2010 and May 2011 as La Niña conditions — cooler surface waters in the eastern equatorial Pacific Ocean — contributed to heavier than normal precipitation over land.

Global mean sea level has been rising by roughly 3 millimetres per year over much of the past 18 years. But when Carmen Boening at the Jet Propulsion Laboratory in Pasadena, California, and her colleagues analysed satellite-altimeter data, they detected an overall drop in sea level that coincided with the onset of La Niña in 2010. Another set of satellite data confirms a decrease in ocean mass during the same period and suggests a parallel increase in terrestrial water storage, mainly over Australia, the northern part of South America, and southeast Asia.

The 2010–11 La Niña was one of the strongest in eight decades, but sea levels recovered and had increased beyond their pre-La Niña levels by early 2012.

Geophys. Res. Lett. http://dx.doi.org/10.1029/2012GL053055 (2012)