Nerilie J. Abram et al., Recent intensification of tropical climate variability in the Indian Ocean

Letter abstract

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Nature Geoscience 1, 849–853 (2008)
Published online: 16 November 2008 | doi:10.1038/ngeo357

Recent intensification of tropical climate variability in the Indian Ocean

Nerilie J. Abram^1,2, Michael K. Gagan¹, Julia E. Cole³, Wahyoe S. Hantoro⁴ and Manfred Mudelsee⁵

The interplay of the El Niño Southern Oscillation, Asian monsoon and Indian Ocean Dipole (IOD)^{1, 2, 3} drives climatic extremes in and around the Indian Ocean. Historical^{4, 5} and proxy^{6, 7, 8, 9} records reveal changes in the behaviour of the El Niño Southern Oscillation and the Asian monsoon over recent decades^{10, 11, 12}. However, reliable instrumental records of the IOD cover only the past 50 years^{1, 3}, and there is no consensus on long-term variability of the IOD or its possible response to greenhouse gas forcing¹³. Here we use a suite of coral oxygen-isotope records to reconstruct a basin-wide index of IOD behaviour since AD 1846. Our record reveals an increase in the frequency and strength of IOD events during the twentieth century, which is associated with enhanced seasonal upwelling in the eastern Indian Ocean. Although the El Niño Southern Oscillation has historically influenced the variability of both the IOD and the Asian monsoon^{3, 8, 10}, we find that the recent intensification of the IOD coincides with the development of direct, positive IOD–monsoon feedbacks. We suggest that projected greenhouse warming may lead to a redistribution of rainfall across the Indian Ocean and a growing interdependence between the IOD and Asian monsoon precipitation variability.

1. Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia
2. British Antarctic Survey, Natural Environment Research Council, Cambridge CB3 0ET, UK
3. Department of Geosciences, University of Arizona, Tucson, AZ 85721, USA
4. Research and Development Center for Geotechnology, Indonesian Institute of Sciences (LIPI), Bandung 40135, Indonesia
5. Climate Risk Analysis, Schneiderberg 26, 30167 Hanover, Germany

Correspondence to: Nerilie J. Abram^1,2 e-mail: nabr@bas.ac.uk

Correspondence to: Michael K. Gagan¹ e-mail: Michael.Gagan@anu.edu.au

Link to abstract: http://www.nature.com/ngeo/journal/v1/n12/abs/ngeo357.html