Tropical cyclones have drastic socio-economic consequences in coastal regions. Accurately projecting their changes in a global warming context is a crucial challenge. This study by CLEX researchers and colleagues investigates future changes in South Pacific tropical cyclone activity using high-resolution atmospheric models.

In general, global climate model projections indicate fewer but more intense tropical cyclones in a warming climate. However, these coarse-resolution simulations suffer from long-standing biases in sea surface temperatures.

While most climate model studies correct for the present-day bias in sea surface temperatures, they do not consider the reliability of the future changes that occur for sea surface temperature in the models, which is done in this study.

The results following this additional correction show a strong reduction of the cyclogenesis (−55%) over the South Pacific basin. In contrast, no statistically significant change arises if this additional correction is not made.

The researchers found that this uncertainty in the future patterns of sea surface temperatures could strongly hamper the reliability of projections of South Pacific tropical cyclones. In addition, the researchers found that this strong reduction in tropical cyclone activity was caused by stronger vertical wind shear in response to a South Pacific Convergence Zone equatorward shift.

  • Paper: Dutheil, C., Lengaigne, M., Bador, M. et al. Impact of projected sea surface temperature biases on tropical cyclones projections in the South Pacific. Sci Rep10, 4838 (2020).