ABSTRACT Rastetter 9711626 Most integrated assessments of climate change do not consider the effects of the deposition of atmospheric compounds on ecosystem biogeochemistry. This project will study these effects in conjunction with the responses of terrestrial ecosystems to changes in atmospheric chemistry and climate and to incorporate these responses into an integrated assessment framework. The work will emphasize the effects of nitrate deposition and of ozone and sulfur dioxide exposure on global ecosystems. The MBL Terrestrial Ecosystem Model (TEM) coupled to the MIT Coupled Chemistry-Climate Model(CCM). TEM will be improved to include the influence of nitrate inputs and pollutant exposure on ecosystem function. TEM and CCM will enable predictions relevant to future economic viability of forests and their uptake of CO2. Because it is expected that the future effects on ecosystems will be sensitive to the relative mix of CO2, NOx, SO2 and CO emissions, predictions of anthropogenic emissions from the MIT model for global and regional economic development (EPPA) will be used as input to the CCM and TEM. The integrated effects and feedbacks of human activity, atmospheric composition, climate, and ecosystem change will be studied using the MIT Global System Model for Integrated Assessment of which TEM, CCM and EPPA are coupled component submodels. Using sensitivity studies, it is expected that the results of this work will help set priorities for future research on the effects of atmospheric deposition on ecosystems.
