Indian Ocean Dipole Research at RSES

Ocean-atmosphere interactions in the tropical Indo-Pacific Warm Pool are fundamental drivers of the global meridional Hadley and zonal Walker circulations. Recent research indicates that changes in sea surface temperatures and atmospheric convection in this region play important roles in modulating global climate on interannual, decadal, millennial, and even glacial-interglacial time-scales. Knowing the natural bounds of past ocean-atmosphere variability in the Warm Pool region will enhance our ability to predict the climate in the future.

Current Research projects

The Indian Ocean Dipole, Australasian drought, and the great-earthquake cycle: Long-term perspectives for improved prediction

This project will provide a unique opportunity to answer questions that are central to Australia's ability to predict and adapt to climate change, crippling droughts, and devastating tsunamis generated by great submarine earthquakes.

The recently discovered Indian Ocean Dipole is now recognised as a climate system of international importance because of its effect on rainfall in Indonesia, Australia, Asia, and East Africa (Saji et al. 1999; Webster et al. 1999). Resolving the debate about how the Dipole and ENSO climate systems interact, and how they respond to different background climates, is essential for understanding the nature of drought in southern Australasia.

The expanding coral palaeoclimatology program at RSES, ANU aims to produce novel findings in the area of tropical palaeoclimatology and global change research (Gagan et al. 1998, 2000; Hendy et al. 2002; Abram et al. 2003, 2007; Correge et al. 2004). The group will work with an international team to build on advances made in the microanalysis of stable-isotopes and trace elements in recently discovered corals from the Mentawai Islands, Sumatra, in western Indonesia.

The Mentawai corals are perfectly located to quantify the range of IOD variability over the last 7,000 years, during times when Earth's climate was different from the present day. These records will be crucial for answering the vexing question; will the Indonesian-Australian region be one of society's “winners” or “losers” in the regional redistribution of future rainfall?

Monsoon extremes, environmental shifts, and catastrophic volcanic eruptions: Quantifying impacts on the early human history of southern Australasia

In Australasia, three key components of Earth's climate system (the Indo-Pacific Warm Pool, El Niño-Southern Oscillation, and Australasian monsoon) coincide with a human history of incredible antiquity and surprising diversity (Morwood et al. 1998, 2004, 2005; Brown et al. 2004). Understanding the potential role of these major climate systems in influencing human dispersal in southern Australasia is now urgent, given the remarkable discovery of a new dwarf hominin species ( Homo floresiensis) on the island of Flores, in southeastern Indonesia (Brown et al., 2004; Morwood et al., 2004, 2005). The great adaptability of the ‘Hobbit' is indicated by its apparent isolated existence for tens of millennia (until ~18-12,000 years ago) while modern Homo sapiens dispersed across Indonesia to colonise northern Australia around 60-50,000 years ago.

The potential role environmental shifts in the surprisingly recent extinction of the Hobbit is a particularly intriguing question. group research will focus on the essential task of reconstructing the history of monsoon rainfall extremes, abrupt climate shifts, and catastrophic volcanic eruptions over the past 150,000 years. It is likely that the records produced will identify, for the first time, important climatic turning points that influenced human history in southeastern Indonesia.

Recent advances in geochronology and the microanalysis of stable-isotope ratios ( ¹⁸ O/ ¹⁶ O, ¹³ C/ ¹² C) and elemental concentrations (e.g. Sr, Mg, P, Ba) in carbonate cave formations (speleothems) have opened a new era in tropical palaeoclimatology and global change research (Ayliffe et al., 1998, Wang et al. 2001, Zhao et al. 2003, Drysdale et al. 2004, Yuan et al. 2004, Treble et al., 2003, 2005). We will apply these geochemical techniques to speleothems from Flores. During a caving expedition to Flores in August 2006, our team discovered a wealth of material suitable for this research near the Hobbit occupation site in western Flores (see photos). A major expedition is scheduled for 2007 to collect speleothems from these, and neighboring sites.