The late Pliocene (3.3 to 3.0 million years ago) was the most recent interval in Earth’s history when global temperatures were within the range of warming predicted for the 21st century. During this period, atmospheric carbon dioxide concentrations last reached 400 parts per million, a value we now have surpassed. Taylor-Silva and Riesselman  document presence and extent of sea ice as well as a major southward migration of the Antarctic polar front during a single interglacial period (3.17 to 3.15 million years ago) within the late Pliocene, using information from diatoms, unicellular algae which form a siliceous skeleton. Global reconstructions and climate models suggest that summer sea surface temperatures were an average of more than two degrees warmer relative to the present day. The results suggest that this interglacial period is a crucial interval to test ice sheet stability in the context of anthropogenic warming.
Citation: Taylor-Silva, B. I., & Riesselman, C. R. . Polar frontal migration in the warm late Pliocene: Diatom evidence from the Wilkes Land margin, East Antarctica. Paleoceanography and Paleoclimatology, 33. https://doi.org/10.1002/2017PA003225
—Ellen Thomas, Editor in Chief, Paleoceanography and Paleoclimatology