The isotopic composition of oxygen and hydrogen (δ 18 O, δD) in polar snow and ice can provide information on local or global temperature in the past, because there are some simple linear relationships between δ 18 O (or δD) and temperature. But there are many other factors that influence δ 18 O and δD in polar snow and ice, such as vapor sources and seasonal changes of precipitation, volcanic activities and solar activities. Some factors must be considered when temperature record would be reconstructed from δ 18 O (or δD) in snow and ice, which include spatial and temporal variations of precipitation, the temperature in the inversion layer and the processes of post deposition. Some linear relationships among δ 18 O, δD and temperature have been obtained for Greenland ice sheet, as δ 18 O=0.67T-13.7‰, for Antarctic ice sheet, as δD=6.04T-51‰, and there is a statistic relationship between δD and δ 18 O, as δD=8δ 18 O+10 on globe, based on analysis of data and modeling. Moreover, the deuterium excess d (or excess d) =δD-8δ 18 O in polar ice sheets is sensitive to the conditions of water moisture sources including sea surface temperature, relative humidity and surface wind. It has been found from research on excess d in Antarctic that water moisture of inland mainly comes from ocean area at lower latitudes and water moisture near the coast mainly from the local sea.
