During the Pliocene (approximately 4 million to 3 million years ago), tectonic activity led to the formation of a number of small islands in the Indonesian Archipelago. This protruding land restricted the Indonesian Throughflow (ITF), a current that carries warm, fresh, tropical Pacific water through the island chain and feeds the Leeuwin Current. On the basis of their shell-based reconstruction, the authors identify a strong divergence between the temperature of the Leeuwin Current and the nearby tropical Indian Ocean since about 3.3 million years ago. The finding of a relative cooling of the coastal Leeuwin Current was indicative of a weakened ITF rather than other regional changes. Colder waters flowing along the Australian shore would have reduced the amount of precipitation making its way inland, allowing tectonic activity in Indonesia to change the climate of the land down under.
Paleoceanography, doi: 10.1029/2010PA001949, 2011
Title: Pliocene Indonesian Throughflow and Leeuwin Current dynamics: Implications for Indian Ocean polar heat flux
Authors: Cyrus Karas: Leibniz Institute of Marine Sciences (IFM-GEOMAR), University of Kiel, Kiel, Germany; and Goethe-University Frankfurt, Frankfurt am Main, Germany;
Dirk Nrnberg: Leibniz Institute of Marine Sciences (IFM-GEOMAR), University of Kiel, Kiel, Germany;
Ralf Tiedemann: Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany;
|Contact: Maria-Jos Vias|
American Geophysical Union