The Wooster Tree Ring Lab is part of the international tree-ring community, that investigated the global extent and seasonal timing of the rapid increase in atmospheric 14C concentrations from the two largest cosmogenic events in 774 and 993 CE. The initiative named “COSMIC” is lead by Ulf Büntgen (Cambridge University), Lukas Wacker, and J. Diego Galván (Swiss Federal Research Institute WSL) and measured these two cosmogenic events in 44 of the world’s longest tree-ring chronologies. These events are now key marker years and a powerful dating tool. The study was published in Nature Communication and can be found here.