The primary focus of my research is on understanding the past behavior of tropical monsoons, working on a variety of timescales from seasonal variability to tens of thousands of years. I investigate not only how the rainfall amount has changed in one place, but the regional spatial relationships to determine which parts of the climate system interact to produce these changes. Additionally I am interested in the impacts of climatic changes on the local environment - the flora, fauna and humans. To accomplish these goals, I use stalagmites as a paleoclimate archive, using a multi-proxy approach to investigate past climates and their impact on the vegetation and hydrology above the cave.
The context that surrounds paleoclimate records reveal the impacts and consequences of a changing climate. Paleoclimatology is often at its best not to its own ends, but when it is answering questions posed by other disciplines such as archaeologists and anthropologists, opening the way for interdisciplinary research. My collaborations with colleagues in archaeological and anthropological disciplines have uncovered climatic driving forces behind major events in mammalian evolution, adaptation and extinction. My recent work in Madagascar involves caves that act as fossil graveyards. These caves are widely studied by anthropologists interested in the development and extinction of subfossil lemur groups. Our results demonstrated that a major vegetative disturbance in northwestern Madagascar at 900CE occurred during the wettest period of the last 2000 years, and therefore climatic changes are unlikely to have been the cause. This result puts the focus onto human agency and the impacts of slash and burn agriculture in both the vegetative change and faunal extinction. Elsewhere, I have worked on human evolution problems. Stalagmites for my PhD came from Liang Luar cave on the island of Flores, just 800m from the Liang Bua cave, where the diminutive hominin Homo floresiensis was found. Our 92,000-year record of Flores’ paleoclimate has helped put H. floresiensis into its climatic and environmental context, and revealed new insights into the cause of its disappearance.
My future research agenda will examine monsoon systems in northern Madagascar and the Dominican Republic, and expand my research out of the tropics into semi-arid regions, constraining the timing, severity and duration of droughts in south-east Australia and southern Madagascar.
I'm lucky enough to work in some of the most beautiful parts of the world and collaborate with great scientists on a variety of different projects. Here are a few of my field areas and current projects.
My postdoctoral work is conducted in Madagascar in two contrasting field areas: the grassy Anjohibe in the northwest, and the desert of Tsimanampesotse in the south-west. I work alongside Stephen Burns at the University of Massachusetts Amherst and we collaborate with Laurie Godfrey, an expert in lemur anthropology at UMass. Our record of past climate and vegetation gives environmental context to the evolution, lives and extinction of the Madagascan megafauna.
I did my Ph.D. at The Australian National University in Canberra under the guidance of Mike Gagan. My primary work was on the island of Flores, working to extend the Liang Luar stalagmite stable isotope record backwards through time, and discover what was going on in Flores around the time of the extinction of the dwarf hominim, Homo floresiensis. I also worked on detecting volcanic eruptions in stalagmites using elemental sulphur concentration, and on the "life-cycle" of stalagmites - investigating the rates at which stalagmites are created and destroyed on the island on Sulawesi.
Careys Cave in Wee Jasper is a show cave in New South Wales, Australia. With my colleague Mo Walczak, now at Oregon State University, we're looking into the record of past droughts in the Murray-Darling Basin, Australia's breadbasket. Stalagmites from Careys Cave contain a record of the frequency, strength and duration of droughts in an area which yeilds few high-resolution paleoclimate archives. This new information will help the resilience of this key agricultural region in the face of modern climate change.
I work with the X-ray fluorescence facility at UMass and previously with the ITRAX facility at the Australian Nuclear Science and Technology Organisation to develop the use of XRF core scanning as a new tool for measuring trace element ratios in stalagmites. Rapid, non-destructive analysis of trace elements will help open up well understood but underutilized proxies in helping to constrain changing karst hydrology.
EASTERN EQUATORIAL PACIFIC
For my Masters project, I worked on deep sea sediment cores from ODP site 846. With Ros Rickaby and Michael Hermoso at Oxford University, and later with Sarah Bonham and Alan Haywood at the University of Leeds we investigated ENSO climate variability in the Pliocene using foraminifera, coccolithophores and the HadCM3 climate model.
With my colleagues we have more field areas under development. I've recently started work on a stalagmite from Peru, using trace elements to see if local rainfall on the eastern flanks of the Andes is related to overall convection over the Amazon basin.
I also have grants pending for some exciting new fieldwork in the Caribbean.