Reconstruction of past climates from stable isotope records of palaeo-precipitation preserved in continental archives

Abstract

The potential of stable isotope ratios (H-2/H-1 and O-18/O-16) of water as a modern tool for palaeoclimatic reconstructions on continents is reviewed. Examples of stable isotope records of palaeo-precipitation preserved in various continental archives (polar ice sheets, mid-and low latitude glaciers, lacustrine deposits, groundwater) are presented, and the methodology of their interpretation in terms of climatic changes is briefly discussed. To interpret quantitatively the isotope records preserved in continental archives, the response of the isotopic composition of precipitation to long-term fluctuations of key climatic parameters (temperature, precipitation amount, relative humidity) over the given area should be known. Further, the transfer functions relating the climate-induced changes of the isotopic composition of precipitation to the isotope record preserved in the given archive should be established. Since the isotopic composition of precipitation has been monitored only for the past three decades, alternatives ways of assessing the long-term climatic sensitivity of the isotopic signature of precipitation are being investigated. The isotope composition of precipitation should be viewed not only as a powerful proxy climatic indicator but also as an additional hydrometeorological parameter which should be explored as a diagnostic tool for the modelling of climate-induced changes in the water cycle, both on a regional and a global scale.