Increased Indian Ocean-North Atlantic Ocean warming chain under greenhouse warming

Over the past half century, both the Indian Ocean and the North Atlantic Ocean exhibit strong warming trends like a global mean surface temperature. In this study, the authors show that not only an increase of greenhouse gases, but also atmospheric teleconnections boost the observed warming trends. Over the past half a century, both the Indian Ocean (IO) and the North Atlantic Ocean (NA) exhibit strong warming trends like a global mean surface temperature (SST). Here, we show that not only simply as a result of increased greenhouse gases, but the IO-NA interaction through atmospheric teleconnection boosts up their warming trends. Climate model simulations demonstrate that the IO warming increases the NA SST by enhancing the longwave radiation through atmospheric teleconnection, subsequently, the warmer NA SST-induced atmospheric teleconnection leads to IO warming by reducing evaporative cooling with weakened surface winds. This two-way interaction (i.e., IO-NA warming chain) acts as positive feedback that reinforces warming over both ocean basins. The Pacific Ocean is partly involved in this warming chain as a modulator in an interdecadal timescale. These results highlight the importance of understanding ocean-basin interactions that may provide a more accurate future projection of warming.

Automated summary

The warming trends in the Indian Ocean and the North Atlantic Ocean are not only a result of increased greenhouse gases, but also influenced by atmospheric teleconnections. This study demonstrates that the interaction between these two ocean basins through atmospheric teleconnection reinforces their warming trends, creating a positive feedback mechanism. The Pacific Ocean also plays a role in modulating this warming chain. These findings highlight the importance of understanding ocean-basin interactions for more accurate future warming projections.