Since the late 1990s, the study of stalagmite geochemistry has delivered new insights into past sea level, rainfall patterns and permafrost melting. In this seminar, Professor Henderson will review this work, focussing on recent stalagmite paleoclimate research at Oxford.
Abstract
Future temperature increase is most often quoted as the measure of climate change, but other changes will have more direct impact on natural ecosystems and human societies. Rising sea level; changing rainfall patterns; melting of huge areas of northern hemisphere permafrost. Such changes occur slowly and have not been directly observed by humans. They involve a complex array of physical and biogeochemical feedbacks and are difficult to predict with climate models. Study of pre-instrumental paleoclimate can help understand the response of these important components of the climate system during periods of change, and help in accurate prediction of the future. Much paleoclimate work has focused on marine sediments and ice-cores, but since the late 1990s, significant insight has been gained from study of the geochemistry of stalagmites. The talk will overview key aspects of this work, and focus on recent stalagmite paleoclimate research at Oxford. Particular foci will be on work to assess the response of Siberian permafrost to temperature change of the last 3 million years; and on reconstruction of the South East Asian Monsoon during the Holocene and abrupt climate change, both of which have implications for prediction of future change. The talk will also touch on the use of cave records to assess sea-level change, and the interaction between human evolution and aridity in northern Africa.
Biography
Professor Gideon Henderson FRS is a British geochemist focusing on low temperature geochemistry, and on improving understanding of the mechanisms driving climate change. In his own words: “I develop and refine geochemical proxies to understand the history of the past environment. These include radioactive isotopes to study rates of processes such as ocean circulation, and stable-isotopes to understand variables such as past rainfall or weathering.”He runs a leading lab dating the history of sea level and of high-resolution climate records in stalagmites and collaborating with ocean modellers to better understand and apply paleoclimate proxies. The unifying goal of this work is to use paleoclimate to better understand the processes controlling climate change.He also works on modern ocean chemistry as it links to peleoclimate to further study the proxies used for paleoclimate and because the oceans play such a critical role in driving climate via the carbon cycle. Further research interests include the oceanic cycling of critical nutrients such as iron; the sensitivity of future ocean carbon uptake; and the potential and pitfalls of schemes to geoengineeer carbon dioxide removal.Gideon is Head of Department of Earth Sciences at Oxford, and a member of the Oxford Martin School, The Oxford Climate Network, and University College.