COLLABORATIVE RESEARCH - Earth-Life Transitions: Integrated Data-Model Analysis of CO2-Climate-Vegetation Feedbacks in a Dynamic Paleo-Icehouse

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COLLABORATIVE RESEARCH :Integrated Data-Model Analysis of CO2-Climate-Vegetation Feedbacks in a Dynamic Paleo-IcehousebyIsabel Montanez, Univ. California, Davis EAR-1338281Christopher Poulsen, Univ. Michigan, EAR-1338200Joseph White, Baylor University, EAR-1338247Michael Hren, Univ. Conneticutt, EAR-1338256ABSTRACTOverview: Vegetation-CO¬2-climate feedbacks have been shown to be an important component of the climate system, capable of perturbing atmospheric circulation, continental surface temperatures, and hydrological cycling on regional- to global-scales. Recent work indicates that vegetation-climate feedbacks likely had the potential to push the late Paleozoic climate system between glacial and interglacial states and to strongly modify the climate regime within these states. The details of the nature, time-scales, and potential impact of these feedbacks remain elusive. This multi-disciplinary project, driven by three interlinked hypotheses, addresses these shortcomings and analyzes the roles of CO2- and orbital-forcing and vegetation-climate feedbacks in promoting glacial-interglacial transitions on eccentricity- to multi-million year time-scales: - The response of vegetation to primarily CO2-driven glacial-interglacial transitions depended on the timing, magnitude and duration of CO2 forcing and whether critical ecological thresholds were reached.- Tropical vegetation, by way of physiological forcing, impacted low-latitude climate and water & C cycling- Vegetation-climate feedbacks - on a global-scale - amplified radiatively forced glacial-interglacial transitions through changes in direct surface forcing and terrestrial C & N cycling.These hypotheses are being tested through integrated empirical, experimental and multi-scale modeling approaches across a spectrum of time- (10 to 1,000,000 yr) and spatial-scales (leaf-to-canopy-to-global climate system). Climate-CO2-vegetation feedbacks, including the role of plant physiological forcing of climate will be assessed through a two-stage modeling effort that will first reformulate a terrestrial biosphere model (BIOME-BGC) using the empirical and experimental results coupled with modeling sensitivity experiments to define plant functional traits for late Paleozoic PFTs. In the second stage, we will incorporate these PFT traits into NCAR's fully coupled Community Earth System Model and use this version to investigate glacial-interglacial dynamics.Intellectual Merit: This research will generate the first high-resolution, high-precision reconstruction of atmospheric CO2 during the LPIA, which when incorporated into the climate modeling will provide insight into the evolution of earth system processes, including the terrestrial biosphere, in an icehouse under changing CO2 levels relevant to our long-term future. This study will be the first modification of terrestrial biosphere models to account for paleo-PFT traits and investigation of paleovegetation-climate feedbacks thus providing an improved understanding of the potential of non-angiosperm plants to influence hydrologic and C cycling through physiological forcing. Broader Impacts: Cross-disciplinary training and mentoring will occur through in-residence internships for the Ph.D. students. Underrepresented students to Earth and environmental sciences will be integrated through a range of summer and academic year internships and programs at the collaborating institutions. This study will contribute directly to a Carboniferous exhibit planned for the Paleontological Halls of the National Museum of Natural History, Smithsonian Institution. All data generated by this study will be archived and shared via publications, and web-accessible tools.