Eugene S. Takle
© 2003
Paleoclimate studies rely on information other than measurements taken with meteorological instruments to reconstruct past climates. These so-called "proxy" data represent physical or biological conditions that relate to one or more climate conditions of the past. A key question to ask is what is a particular paleoclimate variable really measuring? Corals, for instance, are sensitive to both temperature and salinity, so a reconstruction of past temperatures from coral growth is not completely unambiguous. Biological indicators may adapt to a changing climate and so may respond differently today than, say, 100,000 years ago. Some indicators are relevant for only certain seasons. Global climate models can be used to relate various indicators across seasons and across the globe.
Reference
Trenberth, K. E., and B. L. Otto-Bliesner, 2003: Toward integrated reconstruction of past climates. Science, 300, 589-591.