Studies of the Relationship between the Climatic Tempera- tures and the D/H and 13C/12C Ratios in Trees, with PossibleApplications for Retrieval of the Earth's Past Climates

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This award supports a project designed to establish the relationship between environmental temperature and the Deuterium/Hydrogen (D/H) ratio in unexchangeable hydrogen in cellulose extracted from trees from locations covering a wide range of climatic conditions. The project will ascertain to what degree factors other than temperature affect the Deuterium/Hydrogen (D/H) ratio. Among these might be humidity, growth history, the nature of the root system and its relationship to the source water used by the trees, and generally the relationship between the D/H ratio in cellulose and the hydrology of the area. The collecting sites are located in Oregon, California, and Manitoba, Canada. The resolution of these factors will allow the retrieval of climatic information from many trees from different locations. The Deuterium/Hydrogen records currently indicate unexpectedly that the rate of global warming is greater in the 19th century than in the 20th century. This is contrary to what is expected if global warming were directly related to the increase in atmospheric C02. The confirmation of this result is critical to our understanding of the role that C02 plays in affecting the earth's climate.