Australia: The Land Where Time Began

A biography of the Australian continent 

Climate Change and Variability on a Milankovitch scale - Its Impact on Monsoonal Australasia in the Late Quaternary

In this study the authors1 examined 4 pollen and charcoal records obtained from marine sediment coresdrilled around the northern perimeter of Australia to gain a regional picture of the climate change for the last 300 ka -100 ka, its patterns, causes and impacts. Primary chronological control was provided by radiocarbon dates and oxygen isotope records for the cores. An overall importance of Milankovitch frequencies showing clear glacial-interglacial cyclicity that is dominated by precipitation variation was found by spectral analysis of components of these cores. A 30 ka frequency is exhibited by some pollen grains and particles of charcoal, that is considered to reflect changes in El Niņo-Southern Oscillation (ENSO) variability, based on its relationship with the burning of biomass and the results from earlier modelling  A decline, that is frequently stepwise, is shown by pollen components of all records, in vegetation that is fire-sensitive and its replacement with vegetation that is more fire-tolerant. Some evidence indicates this trend is linked to an onset or a increase of ENSO activity, and possibly also to monsoonal activity variations from about 300 ka BP, possibly resulting from oceanic ocean circulation changes within the Indonesian region. The suthors1 suggest this trend may have been accelerated within the last 45 ka after the arrival of the ancestral indigenous people.

Sources & Further reading

  1. Kershaw, A. P., S. van der Kaars, and P. T. Moss. "Late Quaternary Milankovitch-Scale Climatic Change and Variability and Its Impact on Monsoonal Australasia." Mar. Geol. 201 (// 2003): 81-95.


Author: M. H. Monroe
Last updated  01/06/2013
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