Daniel Watson*
Due to significant climatic and biological changes that contributed to the development of our present climate, the late Miocene is a fascinating historical period for paleo climatologists. Tracers that were used to reconstruct previous temperatures revealed a significant cooling of the world's surface waters; however, it is uncertain how much of this cooling occurred in the tropics and how much of it was caused by atmospheric Carbon Dioxide (CO2). Based on the temperature-dependent ratio of magnesium to calcium found in fossil zooplankton shells, we propose a new reconstruction of sea surface temperatures from the eastern equatorial Indian Ocean (Foraminifera). Our findings show a cooling (3.2°C) that is higher than earlier predictions of the tropical ocean cooling (1°C–2.5°C). We ran simulations to better understand how atmospheric CO2 is causing this cooling.
