PIs promise to establish the sea level rise associated with warm Pliocene high stands. This is critical to our understanding of the cryosphere during a time that has been suggested by many to be similar in some respects to conditions expected by the end of this century.
In this grant, we investigated warm climates of the Pliocene, a time about 3 million years ago. Atmospheric carbon dioxide was similar to that in 2014 (400 parts per million) and global climates were 2°C warmer, yet previously published reports were that sea level was 35 m above present. This would require loss of not only Greenland and West Antarctic ice sheets, but also a substantial portion of the East Antarctic ice sheets. We show that sea level during the Pliocene peaked at 20±10 m, suggesting that at most small loss of the East Antarctic ice sheets. New stable isotope and trace metal data generated under this grant, also strongly support these lower sea-level estimates, with the best estimate of 17 m suggesting only loss of 5 m of the 52 m (~10%) sea-level equivalent stored in Antarctica. This suggests that the equilibrium state for a 400 ppm world is with loss of Greenland and West Antarctic ice sheets and the most sensitive parts of the East Antarctic ice sheet. This has profound implications for the future of Earth’s climate on the 100’s of year scale. We published a paper in Geology, submitted one to Science, and are about to submit another paper to Science about these results. We supported a post-doctoral scholar, Stella Woodard and partially supported several graduate students.
