evidence: Global sea levels have been ticking steadily higher by about an eighth of an inch (3.2 millimeters) each year since scientists began measuring them two decades ago. That’s why Carmen Boening, a research scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, was so shocked in 2010 and 2011, when she saw a quarter-inch (five-millimeter) drop in sea level – a sudden reversal of the trend. [...] Scientists will continue learning more about the ocean’s intricacies, correcting assumptions and revising old estimates. But Willis warns against losing sight of the strong global trend toward rising sea levels.