National Public Radio: Sydney Levitus works in an ordinary government office building in the ordinary town of Silver Spring, Md. But his work frequently transports him — at least figuratively — back to the helms of ships that plied the seas many decades ago. He’s looking at temperature readings from the ship’s logbooks. “The data are priceless because you can’t go back in time, obviously,” Levitus says. And scientists would dearly like to know how the temperature of the seas has changed since …