PALEOCLIMATE: Taking the Temperature of Past Ocean Surfaces.

Accurate reconstructions of past climatic conditions on Earth are important for modeling future climate change. Researchers use climate "proxies" from deep-sea sediments, corals, or ice cores to reconstruct these past climatic conditions, but as Nürnberg explains in this Perspective, different techniques often give different answers. A relatively new technique, Mg/Ca paleothermometry, is a particularly promising tool, especially in conjunction with oxygen isotope measurements on the same planktonic foraminiferal specimens. The power of this method is exemplified by the study by Lea et al.