Paleotemperature for the North American Continent Derived from Noble Gases Dissolved in Groundwater

The derivation of terrestrial paleotemperatures is complicated because there are few indicators of climate that are solely related to temperature. As a result there are discrepencies between estimates based on different methods. Furthermore, there is a serious difference between temperatures estimated for the marine and terrestrial tropics during the last glaciation. This proposal presents a novel approach to reconstruct paleotemperatures in terrestrial environments. It is based on the known temperature dependence of the solubility of noble gases in water. By sampling 20,000 year old water in two aquifers, the PIs will be able to estimate past temperatures by determining their noble gas concentration. This research is important because the new method is based on sound chemical principles and it will help to resolve important discrepencies between other estimates of glacial surface temperatures.