Understanding our environmental history is one of the most urgent research tasks facing humanity. Despite the necessity of improving our understanding of global environmental trends, our knowledge of environmental conditions in the period AD 400 – 1000 is very limited compared to that for the years post AD 1200. Yet very recent advances in regard to obtaining scientific natural proxy data and the ability to locate and analyse a significant corpus of historical European documents offer the prospect of an invaluable insight into the climate of the early medieval era.At the heart of the current proposal is the conviction that a medieval historian with expertise in working with Europe’s annals and chronicles, working among colleagues with a strong engagement with medieval social history, can compile accurate environmental data from the documentary sources for the period AD 400 - 1000. Prior to the eleventh-century the volume of available contemporary sources in Europe is known to decrease significantly and this has deterred historical climatologists from tackling such an early period. But this does not mean that relevant information is not available. Using modern historical source criticism to indicate the prospective reliability of the information obtained from the documents, the results obtained by the two years of research will be put into a database in a form that will allow statistically valid comparison with scientific environmental natural ‘proxy’ data.The goal of this research proposal, however, is not just to compile an innovative database of early medieval environmental information, but to use the comparison with the scientific proxy data to provide answers to very fundamental and ‘high level’ questions such as whether there was a Medieval Warm Period? Or: what were the societal consequences of abrupt climatic changes and extreme weather events? And perhaps most important of all: how anomalous is the recent large-scale phase of climate warming.