Abstract

Professor Christine Lane: Timing is everything. Using tephra to explore past climate and environmental change.

Understanding the spatial and temporal variability of climate forcing as well as human and palaeoenvironmental responses to change, relies upon comparison of data from widespread terrestrial, glacial and marine archives. Building accurate, precise and independent chronologies for palaeoclimate, palaeoenvironmental and archaeological records is essential; however this remains a major challenge in many environments and often prevents the valid comparison of detailed palaeo-proxy records. In the Cambridge Tephra Lab we are using far-travelled volcanic ash tie-lines to tackle these issues and to address interdisciplinary research questions. This talk will focus on on-going investigations into the presence of visible and non-visible (crypto-) tephra layers within lacustrine palaeoenvironmental records of the last _{150 ka BP from across East Africa. With this approach we are revealing the potential to (i) precisely correlate, and therefore robustly compare, palaeoclimate archives from across and beyond tropical Africa within a regional tephrostratigraphic framework; (ii) provide chronologies for individual lake sediment palaeoclimate records, in particular beyond the limits of radiocarbon dating; (iii) increase our knowledge of the history of Late Quaternary explosive volcanism in East Africa; and (iv) explore the environmental impacts of major volcanic eruptions, which are believed to have had global climate effects.}

Professor Ulf Büntgen: A tree-ring perspective on climate and history.

In this talk, I will focus on novel tree ring-based, proxy evidence of the European Alps and the Russian Altai-Sayan Mountains in Inner Eurasia. While stressing data-inherent and methodological-induced limitations of the existing high-resolution, summer temperature reconstructions, I will emphasize their spatiotemporal coherency and ability to link past climate variability with human history. Large-scale peopolitical and socio-cultural transformations during the Late Antique Little Ice Age between 536 and 660 CE (LALIA), the sudden withdrawal of the Mongols from the Hungarian Plain in 1242 CE, and the unprecedented rate and magnitude of dispersal and virulence of the Black Death from 1347 CE onwards, will be used as key examples of how climatic and environmental changes have, directly and/or indirectly, affected historical societies. Finally, I will prioritize future, interdisciplinary research avenues towards a better understanding of natural climate variations and its forcing agents, as well as the associated ecosystem responses and societal consequences throughout much of the late Holocene.