Talk Title: Volcanic influences on the Climate of the Common Era

Spatiotemporal climate reconstructions from high resolution proxies offer opportunities to examine patterns of climate anomalies in both time and space and use these to diagnose causal mechanisms linked to radiative forcing and internal modes of ocean-atmosphere variability.  Here, we use new reconstructions of Common Era temperatures to investigate the response of the climate system to volcanic eruptions. Our tree-ring reconstructions of Northern Hemisphere summer temperatures shows coherent, broad-scale cooling associated with large tropical and high latitude volcanic eruptions. Cooling persists in some cases for 2 or more years following eruptions and different eruptions reveal different magnitudes and spatial patterns that are not clearly associated with the estimated radiative forcing. Our coral-based reconstruction of tropical sea surface temperatures shows cooling of the western Pacific and Indian Ocean in response to well-dated tropical eruptions but no statistically significant response in the eastern tropical Pacific, suggesting a reduction in the tropical Pacific temperature gradient but not a consistent nor canonical El Nino pattern. Climate models simulate an overall larger cooling in the western Pacific and Indian Ocean than the reconstructions and produce a variety of anomalies in the eastern Pacific. New spatiotemporal climate reconstructions can provide useful benchmarks for comparing proxy reconstructions with model simulations and may help identify the origins and sources of disagreement.  Data assimilation approaches provide new opportunities for global multivariate field reconstructions, but an understanding of the contributions from diverse proxies in time and space remains critical.