Developing a 3.5-million-year benchmark record of Indian Ocean Dipole variability

The Indian Ocean Dipole (IOD) is the primary mode of interannual sea surface temperature variability (SST) in the tropical Indian Ocean. The climatic effects of the IOD are diverse and geographically widespread. Extreme flood events in eastern Africa, weakened summer monsoon intensity over India and Southeast Asia, and severe droughts in Australia are among the most significant societal consequences of IOD variability. These extreme climate events caused by the IOD are predicted to become more common as greenhouse gas emissions increase. However, despite its significance, surprisingly little is known about IOD variability during the geological past, which would allow for a better assessment of its sensitivity to atmospheric CO2 level changes in the future. This study presents the first insights into the spatio-temporal complexity of the IOD over the past 3.5 million years. We utilize geochemical proxy data (XRF core scanning, stable oxygen, and carbon isotopes, as well as Mg/Ca paleothermometry of planktonic foraminifera) derived from Site ODP 709, situated in the western equatorial Indian Ocean - a critical region for IOD forcing.