The Pliocene Epoch is the focus of scientific interest as a period of sustained global warmth, with a continental configuration similar to modern. Studies suggest that the Pliocene was warmer and largely wetter, at least in the subtropics, than today, which contrasts with most long-term climate model simulations. We hypothesize that the hydro-climate of western NA was, in addition to global warmth, dictated by changes in the Pacific surface sea temperature (SST) gradient either: a weaker zonal gradient in SST between the western and eastern equatorial Pacific, or a weaker equator-to-pole temperature gradient between the tropics and the mid-latitudes 

During the Pliocene in WNA, large perennial lakes existed for 0.1 – 1 million years in basins to the east of the Cascades, Klamath Mountains and the Sierra Nevada, spanning seven degrees of latitude. Data from these basins will compliment the SST reconstructions from global sites spanning the last 5Ma and investigate the large-scale hydrological cycle controls associated with both global warming and cooling. We propose to acquire new drilled cores from four of these basins and request funds to organize an ICDP workshop in Minneapolis, MN, USA in 2020, to extend the research objectives, refine the drilling and site survey plan, and broaden the science team working in PLIOWEST.

Keywords: North America, USA, Hydroclimate, Northern Hemisphere, Paleoclimate, Paleolakes, Pliocene