For twenty years, four thousand robotic floats have been quietly taking the ocean's pulse, collecting temperature and salinity readings never intended to reveal the great currents that govern European climate. Now, a team of researchers in Kiel has taught a machine learning algorithm to read those scattered measurements as a kind of hidden language, inferring the shape and strength of the Atlantic Meridional Overturning Circulation from data that was never designed for that purpose. It is a reminder that the most consequential discoveries sometimes come not from gathering new information, but