HIGH RESOLUTION ICE CORE RECORDS OF LATE HOLOCENE VOLCANISM: CURRENT AND FUTURE CONTRIBUTIONS FROM THE GREENLAND PARCA CORES

Anthropogenic climate forcing on a global scale has necessitated efforts to differentiate the contributions of natural forcing mechanisms from those attributable to human activities of the past two centuries. One natural cause of short-term climate change is the perturbation of the Earth's radiation balance by volcanic gases emitted into the stratosphere where they may remain for several years affecting surface temperatures and modifying both atmospheric and oceanic circulation patterns. Ice cores have been used to establish the history of explosive volcanism and to quantify the sulfate emissions attributable to specific eruptions for inclusion in climate models. Only a few such histories have been annually dated using multiple seasonally varying constituents and the emissions estimates are not always based on high resolution sulfate analyses. Precise dating is critical for robust comparisons with other histories. Questions have been raised regarding the quantity and timing of material delivered to the polar ice sheets and how much reliance can be placed upon a reconstruction from a single core. Knowledge of transport time and the relationship between the quantity of sulfur gases emitted and the sulfate deposited is critical if the full potential of ice cores for volcanic reconstruction and climate modeling constraints is to be realized. A suite of spatially distributed, multi-century cores has been collected under NASA's Program for Arctic Regional Climate Assessment (PARCA) and these provide an excellent archive of volcanic emissions reaching Greenland. The Greenland PARCA cores have been accurately dated and the ongoing chemical analyses are providing new volcanic histories that complement the limited records that exist. The PARCA cores promise richly detailed histories of excess sulfate (EXS) emissions from both known and yet to be identified volcanic eruptions. The high temporal resolution of these ice core volcanic records will help resolve timing issues and their broad spatial distribution will provide a more representative estimate of the EXS flux associated with a specific eruption.