Picture: Atlantic ocean sun. Credit: Guillaume Bassem (Unsplash)

The ocean transports vast amounts of heat around the planet, helping to regulate regional climates and keep them habitable. Along with the atmospheric circulation, the ocean moves heat from the warm tropical regions toward the cold polar regions. How this heat transport may change in the future remains a first-order question in climate science.

In this study, we introduce a rigorous framework that relates the ocean’s Equator-to-pole heat transport to the processes that change the temperature of seawater. These processes include both heat exchanges with the atmosphere and turbulent mixing within the ocean.

By applying this framework to a numerical model of the ocean’s circulation the researchers show that solar heating of surface waters in the tropical Indian and Pacific oceans, along with turbulent mixing that moves this heat into the colder deep-reaching Atlantic meridional overturning circulation, play a crucial role in shaping oceanic heat transport pathways.

This role, often overlooked in traditional studies of the ocean’s deep overturning circulation, highlights the need to study these tropical regions in more detail in the context of both natural and anthropogenic climate variability.