What is the function of oxygen isotopes in foraminifera for paleoclimatology?

The function of oxygen isotopes in foraminifera is primarily to track temperature changes over geological time. Foraminifera, which are microscopic marine organisms, have shells that incorporate oxygen isotopes from the seawater in which they live. The ratio of oxygen-18 to oxygen-16 in these shells can provide insights into past temperatures; warmer temperatures lead to a higher proportion of oxygen-16 being included in the shells, while cooler temperatures result in a higher proportion of oxygen-18.

By analyzing the oxygen isotope ratios in foraminiferal calcite from sediment cores, scientists can reconstruct historical climate data, providing a valuable record of how temperature has varied over millions of years. This method is a cornerstone of paleoclimatology, as it helps to infer the thermal conditions of the Earth during different geological periods. Therefore, the use of oxygen isotopes allows researchers to better understand how the Earth's climate system has changed over time and to predict future climate trends based on past data.