This proposal seeks 50% matching funds to acquire two new mass spectrometers. The need to add two new mass spectrometers is urgent for three reasons. First, in the next year Ohio State University will acquire at least 1500 meters of additional ice core from three newly funded (NSF, NOAA and NASA) drilling projects: on Dasoupu in the southern Himalaya of China, on Sajama in Bolivia, and on Graham Bell Island in the high Russian Arctic. The number of samples to be measured to produce high temporal resolution records (e.g., annual where possible) will greatly exceed the capability of the 7-year old obsolete mass spectrometer. Secondly, substantially more environmental information (e.g., estimates of relative humidity and indications of moisture source changes) can be gleaned from ice core samples if the deuterium/hydrogen ratio ((D) is measured in combination with (18(. Thirdly, at this time all known tropical glaciers and ice caps are retreating in response to the recent warming which is particularly evident in the middle troposphere between (30o of the equator and soon there will be a major push to recover these endangered archives. The Ohio State University Core Research Group has the demonstrated ability to retrieve cores from remote and harsh environments, to extract a spectrum of paleoclimatic information, and publish the results in major peer-reviewed journals. As discussed in the proposal, the Ohio state University isotopic results have contributed to the emerging view that the tropics were much colder during the Last Glacial Stage than previously thought and strongly suggest a recent warming at high elevations, particularly in the tropics. The proposal mass spectrometers will enable the Ohio State University Ice Core Research Program to make even stronger contributions to the understanding of the Earth's climate system.