New proxies in limnogeology to quantify Quaternary landscape change

Up to 65% of ice-free landscapes are predicted to be directly affected by climate change until the end of the century, a number that increases to 80% if also accounting for land use. This places great pressure on one of our most important resources – soils – particularly in densely populated areas and agricultural hotspots. Additionally, landscapes play a significant role in the global carbon cycle, and, thus, in the global climate system.

A comprehensive new approach to simultaneously study climatic, environmental, and anthropogenic controls on Quaternary landscape evolution has been developed in recent years. The research systematically applies traditional palaeo-climatic and -ecological (pollen) proxies along with a novel method to infer catchment erosion to temporally highly resolved and continuous lake sediment sequences. The new method, predominately applied to fluvial deposits in the past, is based on uranium isotope analyses and provides estimates of the time fine grained detritus (<63 µm) spends between comminution in a weathering horizon and final deposition in a sedimentary sink.

The applicability of the novel proxy is tested by fundamental research and demonstrated by the application to a sediment record from south-eastern Australia. The research provides crucial insights into the understanding of the novel (uranium isotope) proxy’s response to catchment and lake-internal geochemical processes and provides insights into a complex interplay between vegetation, climate, and catchment erosion in south-eastern Australia. It particularly highlights the need for research on Australia’s role as global terrestrial atmospheric CO2 sink in the geological past.