Extreme events in the Indian Ocean : marine heatwaves, cyclones, and tsunamis
Résumé
In this chapter, we review the current knowledge on high-impact oceanic extremes in the Indian Ocean, namely, marine heatwaves (MHWs), tropical cyclones (TCs), and tsunamis. MHWs and TCs are both modulated by Indo-Pacific climate variability, in particular, the El Niño-Southern Oscillation and the Indian Ocean Dipole. Anthropogenic warming has resulted in more frequent MHWs over the past two decades, a tendency very likely to increase further. Because of their stochastic nature, it is difficult to confidently attribute the declines in TC numbers, observed over large parts of the Indian Ocean except for the Arabian Sea, to climate change. Future projections consistently suggest fewer TCs in the southern Indian Ocean but also more intense TCs with more extreme precipitation at the basin scale. Subduction of the Indian and Australian plates underneath the Eurasian plate creates hotspots for earthquakes in the Indian Ocean that generate tsunamis, devastating bordering countries. Monitoring, predictions, and early warning systems are crucial to mitigate the impacts of marine extremes.