Little has challenged our understanding of climate change more so than the abruptness with which large-scale shifts intemperatureoccurred during the last glacial period. Atmospheric temperature jumps of 8-16°C, occurring within decades over Greenland,were closelymatched by rapid changes in North Atlantic sea surface temperatures. Though these climatic instabilities arewell-documented in variousproxy records, the causal mechanisms of such short-lived oscillations remain poorly understood. Two hypotheses have beenproposed:one relating to the behaviour of the ocean circulation and the other to the dynamics of the atmosphere. Testing thesehypotheses,however, is severely hampered by dating uncertainties that prevent the integration of proxy records on common timescales.As a resultunravelling the lead/lag responses (hence cause and effect) between the Earth’s climate components is currently beyond ourreach.TRACE will exploit a powerful new approach whereby microscopic traces of volcanic events are employed to preciselycorrelate proxyrecords from the North Atlantic region to assess the phasing relationships between the atmosphere and the ocean duringthese rapidclimatic events. Volcanic layers have the unique advantage of representing fixed time-lines between different proxy records.Thiscorrelation tool has experienced a considerable step-change in recent years, with invisible layers of volcanic ash traced overmuch widergeographical regions than previously thought. What is more, recent work has identified new, previously unknown eruptions -several ofwhich coincide with the rapid climatic jumps imprinted in the proxy records. Thus tephra isochrones represent (perhaps theonly)independent constraints for resolving past events on decadal timescales.