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Recent intensification of tropical climate variability in the Indian Ocean


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. Historical4,5 and proxy6,7,8,9 records reveal changes in the behaviour of the El Niño Southern Oscillation and the Asian monsoon over recent decades10,11,12. However, reliable instrumental records of the IOD cover only the past 50 years1,3, 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 monsoon3,8,10, 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.

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Figure 1: IOD climate anomalies.
Figure 2: Coral reconstruction of the DMI.
Figure 3: Twentieth-century intensification of the IOD.


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We thank B. Suwargadi, D. Prayudi, I. Suprianto, K. Glenn, T. Watanabe, H. Scott-Gagan, K. Sieh and the Indonesian Institute of Sciences (LIPI) for logistical support and technical assistance with fieldwork, which was carried out under LIPI Research Permit numbers 3551/I/KS/1999 and 2889/II/KS/2001. We also thank H. Scott-Gagan and J. Cali for laboratory assistance. C. Charles and M. Pfeiffer are thanked for providing published coral data. This study was supported by an Australian Postgraduate Award and RSES Jaeger Scholarship to N.J.A., and an Australian Research Council grant (DP0663227) to M.K.G. and W.S.H.

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Authors and Affiliations



N.J.A. was responsible for coral geochemical analysis and interpretation of the records. M.K.G. was Chief Investigator and the Australian Institutional Counterpart for the ARC project. J.E.C. provided the spectral analysis. W.S.H. was Partner Investigator and the Indonesian Institutional Counterpart for the ARC project. M.M. assisted in statistical analysis. N.J.A., M.K.G. and J.E.C. wrote the paper.

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Correspondence to Nerilie J. Abram or Michael K. Gagan.

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Abram, N., Gagan, M., Cole, J. et al. Recent intensification of tropical climate variability in the Indian Ocean. Nature Geosci 1, 849–853 (2008).

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