Volcanic Crater Research

Studies of deposits in a Queensland volcanic crater emphasise the role of the tropical Pacific in forcing global climate change, according to a team of international researchers including Monash University's Professor Peter Kershaw.

Results from the study of a sediment core from Lynch's Crater on the Atherton Tableland in north-east Queensland, question the traditional view that changes in the North Atlantic region have dictated global climate variation, said Professor Kershaw, of Monash's School of Geography and Environmental Science. The international research team he was part of included Dr Chris Turney of Queen's University in Belfast, former Monash PhD researcher Dr Patrick Moss, Dr Steve Clemens of Brown University in the US, Dr Nick Branch of London University, and Dr Keith Fifield of the Australian National University.

The study has produced a detailed, well-dated record of climatic variability inferred from changes in pollen composition, charcoal abundance and degree of decomposition in organic matter detected in the sediment core, over the last 50,000 years.

Professor Kershaw said the inferred climate record suggests that the El Niño-Southern Oscillation (ENSO) phenomenon, that involves periodic shifts in sea surface temperature across the Pacific Ocean with the warm El Niño phase bringing drought to Australia, operated throughout the last glacial period that terminated about 10,000 years ago, but that the frequency of El Niño events varied on 1,500 and 11,000 year timescales.

"Time series analysis showed that times of high El Niño frequency, or dry periods in Australia, were in phase with periods of warming in the glaciated North Atlantic region which, at times, resulted in rapid ice cap melting and disruption of the ocean circulation," Professor Kershaw said.

"As there is no known mechanism for the rapid transfer of a climate signal from the North Atlantic to northeast Queensland, it is considered that Pacific ENSO, through atmospheric teleconnections, has been an important driver of northern hemisphere climatic variation. This hypothesis questions the traditionally accepted view that changes in the North Atlantic region have exercised the fundamental control over global climate variation and emphasises the role of the tropical Pacific in forcing global climate change. Understanding the causes of rapid climate change has major implications for predicting the timing and nature of dramatic, abrupt climate events in the future".

Grants obtained for future research on Lynch's Crater would support further drilling, intensive dating and high resolution analysis of microfossils and geochemistry to unlock more of the secrets contained in this natural archive.