Collaborative exploration of processes of decadal and multi-century variability under altered externally-forced climates. Final technical report for award no. DE-FG02-85ER60304

During the year February 1, 1998 to January 31, 1999, the authors accomplished the following: (1) the authors published their research results for paleoclimate modeling and the use of data to check the model results; (2) the authors participated in the BIOME 6000 project to produce paleovegetaion maps for 6000 and 21,000 years ago and published the results; (3) the authors continued their involvement in the PMIP(Paleoclimate Modeling Intercomparison Project) and contributed to an overview paper describing the 6 ka African monsoon response of 18 models and to a comparison of simulated biomes at 6 ka from ten models; (4) the authors contributed to the development of earth system component models and coupling strategies; (5) the authors explored a wide range of interactions among the earth's atmosphere, ocean and land surface in the context of past, present and future climates; (6) the authors developed and applied techniques for data-model comparisons; (7) the authors developed and used tools for model diagnostics and model intercomparisons; and (8) the authors began modeling ENSO variability during the last 20,000 years. By using data-constructed ''benchmarks'' for coupled models, the authors demonstrated that the deployment of models that include an increasingly wide spectrum of feedbacks leads to qualitative improvements in their ability to explain past climates. Models with these feedbacks should aid in predicting future climates