Pliocene El Niño
Three million years ago, when greenhouse gas concentrations were last as high as they are now and global temperatures were about 3ºC higher than today, the western US was a vastly different landscape with giant lake systems dominating the now-dry desert basins. Observations of these wetter-than-modern Pliocene conditions are seemingly at odds with future projections of how the hydrologic cycle will respond to current greenhouse gas forcing: dry areas such as the southwest US should become drier with increasing global temperatures. Using a combination of stable isotope measurements from well-preserved Pliocene soils and modern observations of stable isotopes in precipitation, we are investigating whether or not these wet conditions were a product of El Niño-like conditions in the tropical Pacific. This project is in collaboration with Dr. Jeff Welker of the University of Alaska, Anchorage. See our most recent paper in Climate of the Past (Winnick et al., 2013).