RELATION BETWEEN LONG-TERM TRENDS OF O-18 ISOTOPE COMPOSITION OF PRECIPITATION AND CLIMATE

Stable isotope ratios of oxygen (O-18/O-16) and hydrogen (D/H) in water have long been considered powerful indicators of paleoclimate. However, quantitative interpretation of isotope variations in terms of climate changes is hampered by a limited understanding of physical processes controlling the global isotope behavior. Analysis was conducted of time series of O-18 content (deltaO-18) of monthly precipitation and surface air temperature available through the International Atomic Energy Agency-World Meteorological Organization global network, "Isotopes in Precipitation." This study indicates that long-term changes of isotopic composition of precipitation over mid- and high-latitude regions during the past three decades closely followed long-term changes of surface air temperature with the average deltaO-18-temperature coefficient around 0.6 per mil per degree Celsius.