Younger Dryas
Examples of older Younger Dryas-like events have been reported from the ends (called terminations) of older glacial periods. Temperature-sensitive lipids, long chain alkenones, found in lake and marine sediments, are well-regarded as a powerful paleothermometer for the quantitative reconstruction of past continental climates. The application of alkenone paleothermometers to high-resolution paleotemperature reconstructions of older glacial terminations have found that very similar, Younger Dryas-like paleoclimatic oscillations occurred during Terminations II and IV. If so, the Younger Dryas is not the unique paleoclimatic event, in terms of size, extent, and rapidity, as it is often regarded to be. Furthermore, paleoclimatologists and Quaternary geologists reported finding what they characterized as well-expressed Younger Dryas events in the Chinese δ records of Termination III in stalagmites from high-altitude caves in Shennongjia area, Hubei Province, China. Various paleoclimatic records from ice cores, deep-sea sediments, speleothems, continental paleobotanical data, and loesses show similar abrupt climate events, which are consistent with Younger Dryas events, during the terminations of the last four glacial periods (see Dansgaard–Oeschger event). They argue that Younger Dryas events might be an intrinsic feature of deglaciations that occur at the end of glacial periods.