Reconstructing 2000 years of hydrological change in Africa - implications for future climate scenarios

Climate change in the 21st Century and beyond is very likely to cause the highest rates of warming in equatorial regions (IPCC, 2013), therefore increasing the vulnerability of communities due to pressure on water resources. Having previously travelled to Ghana and recently met the Ugandan government's Minister for water (IAH Ineson Lecture, October 2017), I have witnessed and understand the barrier to development that a lack of clean water presents. Research into the response of African crater lakes to past climates and therefore possible response to projected change has the potential to aid decision-making to manage the response to future climate changes more effective. The positive impact of this research upon eastern African communities in the future really excites me. Paleoclimate reconstructions have captured my imagination because understanding past climate is proving to be key in understanding and modelling the future. Studying isotope sciences and marine microfossils as part of my degree has highlighted the huge amount of information about the past that is recorded by these. I am excited by the prospect of undertaking fieldwork in Uganda, visiting the crater lake itself to better understand the environment, and then using the cores and multiple analysis techniques to turn the samples into data that can be analysed to piece together a history of a lake's hydrological system and how that has changed. The capability of modelling systems to simulate the future is hugely important in understanding anthropogenic climate change and its impact, and I am excited to try to use these to better understand future hydrology in Uganda, and to develop my own skills in proxy-system modelling. This will be helped by calibrating the sediment core data to modern sediment data collected using sediment traps, and monitoring of rainfall and lake waters. The water and modern sediment will be analysed to work out how the isotope signal is preserved in the sediments, aiding both modelling and core data interpretation. I believe it would be effective to develop the project with a multiproxy approach, time permitting, as this would allow for a broader understanding of hydrological and other environmental changes over the 2,000 year period. Investigating multiple parameters in the lacustrine environments adds strength to interpretations as some changes may only be reflected by certain proxies. Oxygen-18 isotope analysis of bulk carbonates obtained from the core can be used to infer a hydroclimate history of the lake, which could be aided by diatom abundance and species counts from samples along the core. Sedimentary logging of the core would also allow a more holistic overview of changes in environmental conditions that the lake had experienced over the course of its history. Pollen content within the core may be able to give insight on other aspects of lake and catchment environmental change over the 2,000 year period, as different vegetation species have different responses to environmental and hydrological change and can themselves impact hydrology.