T is for Temperature
In stable isotopes, there are lots of implications for the word ‘temperature.’ For one, we can use isotopes of oxygen, and oxygen plus carbon, to estimate the temperature at which an analyzed compound formed. Temperature could also refer to the temperature at which we react a sample during its analysis, whether it be room temperature or 1450 °C.
One of the original uses for the study of isotopes was to determine the past temperature of the ocean. A relationship between δ18O and water temperature was developed, and the shells of tiny, single-celled organisms were perfect for these analyses. Today, we have refined these methods, and have a much better understanding of the complexity of the relationship between δ18O and temperature.