Collaborative Research:Volcanism in the Arctic SysTem (VAST): Geochronology and Climate Impacts

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This project integrates modeling and paleoenvironmental data to obtain a better understanding of the role of volcanism in the Arctic System, and to better utilize widespread tephra layers to date and synchronize paleoenvironmental records across the Arctic.The Arctic includes major centers of volcanism in the North Atlantic and the North Pacific sectors. Stratospheric aerosols derived from either Arctic or tropical volcanism alter the radiative balance of the Arctic, which in turn influences atmospheric circulation with global consequences. Reduced summer insolation can lead to substantial Arctic cooling of a few years' duration, but these perturbations may produce longer impacts if the system passes through a threshold condition, whereby strong positive feedbacks yield changes in the state of the Arctic System. New paleodata suggest that dramatic increases in terrestrial ice caps in Arctic Canada lasting several centuries occurred following two of the largest eruptions of the past millennium, during the transition into the Little Ice Age. Explosive Arctic volcanism can produce large volumes of source- and time-diagnostic tephra, with extensive distributions. These tephra layers provide time-synchronous marker horizons that constrain the geochronology of paleoenvironmental records and serve to precisely synchronize records derived from lacustrine, marine, and ice-sheet archives, thereby allowing a better assessment of leads and lags in the climate system.An international research team has been assembled to assess the impact of both Arctic and tropical eruptions on the Arctic System through climate modeling and to optimize the utility of tephras in paleoenvironmental studies throughout the North Atlantic Arctic. This represents the US contribution. Specific objectives of this effort include:- Establish a standardized geochemical inventory of Icelandic marker tephra erupted over the past 12,000 years, and develop criteria to differentiate Icelandic from North Pacific tephra.- Improve techniques to identify and extract microtephra from sedimentary archives.- Extend proximal-derived Icelandic tephra geochemical fingerprinting to microtephra in distal lacustrine, marine and Greenland ice-core archives.- Develop generalized maps of plume trajectories for most major Icelandic eruptions.- Evaluate the sensitivity of the Arctic System to high- and low-latitude eruptions through climate modeling and comparisons of model output to paleoenvironmental reconstructions.