Reconstructing Indian Ocean climate variability during the Pliocene

Indian Ocean Climate influences the safety and the food, water, energy and financial security of over two billion people. Models do not simulate the Indian Ocean well, causing difficulties in future projection. The project will use models to reconstruct Indian Ocean climate during warm periods of the geologic past and evaluate performance with data-model comparison.

We will run simulations that support the next phase of the Paleoclimate Modelling Intercomparison Project, timed to support the upcoming IPCC report.

The Indo-Pacific Warm Pool (IPWP) supports deep atmospheric convection and plays a major role in the modern global hydrological cycle. Over the last 50-years, the IPWP has warmed and expanded rapidly alongside an increase in tropical upper ocean heat content. Warm, fresh waters flow unidirectionally from the Pacific to Indian Ocean through the shallow and tectonically complex Indonesian gateway.

The transport of water helps to modulate the heat and freshwater balances of both oceans as well as the Atlantic through a coupled link with the Agulhas Current.

We will focus on the Pliocene, the last period that the atmospheric CO2 concentrations were comparable to present. During the Pliocene, tectonic changes impacted the restrictiveness of the Indonesian Gateway. This restrictiveness and the mean climate state have implications for the oceanic heat content and the strength of the connection between ocean basins.

This project will quantify tropical upper ocean heat content and IPWP heat content during intervals of distinct mean climates and Indonesian Gateway openness. We will also consider the volume transport through the Agulhas Current, compensatory mechanisms and the climate impacts of modification.