PetroStrat, United Kingdom

The last major transition in Earth's history, from a world with unipolar to bipolar ice, occurred between the Pliocene and Pleistocene epochs. Yet a variety of challenges associated with most previous methods of determining Earth's surface temperatures results in a paucity of estimates constraining the evolution of this critical climatic variable through this transition. Here, we review the alkenone organic proxy, which allows for the rapid, independent, characterization of past sea-surface temperature, as well as the construction of qualitative records of past ocean productivity. We discuss the development, calibration and implementation of the alkenone method for the study of palaeoclimate problems and identify the limitations as well as some of the important considerations for its application. We specifically explore the use of these proxies to study Plio-Pleistocene climate, briefly summarizing the insights that the application of the alkenone method has provided about the Plio-Pleistocene transition. We conclude with an optimistic view of the potential use of these proxies to greatly augment our understanding of past climates.