Abstract ATM-9523584 Bartlein, Patrick J. University of Oregon Title: Testing Earth System Models with Paleoenvironmental Observations (TEMPO) This award supports a project under the Earth System History (ESH) Program of the USGCRP. The objective of this award is to improve the ability of models to simulate large changes in the earth system and to understand the interactions and feedbacks among components of the system. The earth's climate system with its vegetation, lakes, wetlands, and oceans has changed dramatically in the past, and the data about these large changes provide "ground truth" for testing the accuracy of the earth system models. The research team will develop an integrated equilibrium biosphere model, a lake/continental-hydrology model, and coupling procedures to link these models off-line to atmospheric general circulation models and an ocean general circulation model. A regional fine-mesh climate model will also be used for studying earth system changes in regions of complex topography. With these coupled models, it will be possible to explore a wide variety of potential earth system feedbacks including: a) atmosphere-biosphere interactions associated with boreal forest replacing tundra, or tropical savannah replacing desert; b) atmosphere/land-surface-hydrology interactions associated with increases or decreases in the area extend of lakes and wetlands; atmosphere/ocean/terrestrial- vegetation interactions associated with changes in Arctic sea-ice, the North Atlantic thermohaline circulation, and coastal and equatorial upwelling. Global paleovegetation and lake status data sets will be compiled for 6000 and 21,000 years ago, and these data sets will be used along with data for ocean circulation and from the previous intergalcial to make comparisons with the coupled earth system models.