Collaborative Research: Surface-Atmosphere Feedbacks and Holocene Climate Variations in Eastern North America: Linkages, Impacts, and Governing Mechanisms

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This award supports research to document the spatial and temporal modes of climate variation and land-cover change in eastern North America at millennial scales, assess the interactions between global forcings (orbital variations, trace gas concentrations) and regional controls (land-cover change, topography, lake effects) of climate and their relative effects on Holocene climate variability, and identify the critical mechanisms governing surface-atmosphere feedbacks. This research will utilize a Regional Climate Model (RegCM2) in combination with a new generation of land-cover reconstructions to detail the effect of Holocene surface-atmosphere feedbacks on atmospheric processes. Model results will be evaluated against millennially resolved climate reconstructions for eastern North America based upon multiple networks of climate proxy records. The dense networks of proxy records and the large and regionally varied changes in Holocene temperature, aridity, and land cover make eastern North America an excellent case study for the interplay between forcings external to the climate system and internal feedbacks in temperate regions. This research is important because climate variations during the Holocene were substantial, spatially variable, and spanned a wide range of frequencies and rates of change. Although these variations are in part forced by mechanisms external to the climate system, internal interactions among the atmosphere, oceans, and terrestrial biosphere are a critical source and modulator of climate variability. In particular, surface-atmosphere feedbacks are receiving increased scientific interest, due to recent demonstrations that such feedbacks exert a strong influence on Holocene and Recent climate processes at regional to global scales, with a magnitude comparable to orbital and greenhouse gas forcings. In summary, this project will advance our understanding of Holocene climate variability and the interactions between climate and vegetation dynamics, enhance the scientific infrastructure, build partnerships among institutions, and help support a new generation of climate scientists. All model and data syntheses produced during the course of this work will be stored at the World Data Center upon publication.