Picture (above): Maldives. Credit: Asad Photo (Pexels).

Indian Ocean surface waters have warmed more than the tropical Atlantic or Pacific over the last 60 years. In contrast, the amount of heat stored in the upper 700m of the Indian Ocean did not exhibit strong increases between 1960 and 2000, which is counter to temperature trends in other ocean regions across the globe. Only since the year 2000 was rapid warming down to 700m observed for the Indian Ocean.

Using ocean model simulations, this study demonstrates that the unusual behaviour of Indian Ocean temperatures over the past 60 years was mainly due to wind conditions. Two different pathways highlight how winds can impact the upper-ocean temperature structure in the Indian Ocean, either through the atmosphere or via an oceanic connection from the Pacific. The wind trends during 1960-2000 counteracted additional heat input into the Indian Ocean due to an overall warming climate.

These long-term changes in the Indian Ocean temperature structure affect regional climate in the surrounding countries, meaning they are important for predicting how the Indian Ocean will respond in the near future to a warming climate.

  • Paper: Ummenhofer, C. C., Ryan, S., England, M. H., Scheinert, M., Wagner, P., Biastoch, A., & Böning, C. W. (2020). Late 20th century Indian Ocean heat content gain masked by wind forcing. Geophysical Research Letters, 47, e2020GL088692. https://doi.org/10.1029/2020GL088692