Proxy Data. Because climate involves long-term patterns, climate researchers often seek data about what the climate was like thousands or millions of years ago. But such data are difficult to find (ice cores provide one source of actual prehistoric climate data). Researchers may therefore use other kinds of data that tell them about something related to climate. Non-climate data analyzed for clues to climate is called proxy data. For example, information about the past strength of ocean currents might be gained by studying fossil microorganisms deposited in sediments—the ages, types, and distributions of these organisms could reflect the nature of the currents that existed at the time they were deposited.