Final Report Summary - TRACE (Tephra constraints on rapid climatic events) Little has challenged our understanding of climate change more so than the abruptness with which large-scale shifts in temperature occurred during the last glacial period. Atmospheric temperature jumps occurring within decades over Greenland were closely matched by rapid changes in North Atlantic sea surface temperatures and major re-organisation of the deep ocean circulation. Although these climatic instabilities are well-documented in various proxy records, the causal mechanisms of such short-lived oscillations remain poorly understood, largely due to the dating uncertainties that prevent the integration of different archives. Synchronisation of palaeoclimatic records on a common timescale is inherently problematic, and unravelling the lead/lag responses (hence cause and effect) between the Earth's climate components is currently beyond our reach. TRACE - a 5-year project funded by the European Research Council - exploits the use of microscopic traces of volcanic events to precisely correlate the Greenland ice-cores with North Atlantic marine records. Our results demonstrate that invisible layers of volcanic ash can be traced over much wider geographical regions than previously thought and are used to constrain key time-intervals during the last glacial period. These precise correlations are used to assess the lead/lag responses between the ocean and atmosphere during rapid climatic transitions. In addition, a new catalogue of volcanic events is constructed based on microscopic ash deposits preserved within a range of ice and marine records from the North Atlantic region. Over 270 individual volcanic events have been identified giving new insight into the frequency and history of Icelandic volcanic events. Fifteen microscopic ash deposits originating from remote volcanoes in the Pacific Arc are also identified in Greenland and highlight the potential of using tephrochronology on a hemisphere-wide scale. These findings indicate that far-travelled ash clouds from North Pacific volcanoes have been underestimated in the past.
