Does the Late Holocene Dry Period (2700 – 1800 cal yr BP) conform to a north/south dipole moisture gradient in the Great Basin?

Authors: Gregory Weisberg*, University of Nevada, Reno, Scott Mensing, Univeristy of Nevada, Reno, Theodore Dingemans, University of Nevada, Reno, Dave Rhode, Desert Research Institute, Douglas Kennett, Pennsylvania State University
Topics: Paleoenvironmental Change, Climatology and Meteorology
Keywords: paleoecology, Environmental reconstruction, paleoclimatology
Session Type: Paper
Day: 4/10/2018
Start / End Time: 2:40 PM / 4:20 PM
Room: Napoleon B2, Sheraton 3rd Floor
Presentation File: No File Uploaded


Persistent droughts of up to a century or longer during the Middle Holocene (ca. 7000 – 5000 cal yr BP) period and Medieval Climate Anomaly (ca. 1200 – 800 cal yr BP) have been documented through multiple proxy records in the western United States. Recently, a multi-century drought has been suggested falling within the late Holocene (ca 2700 – 1800 cal yr BP), called the Late Holocene Dry Period (LHDP). Modern climate modelling identifies a dry southwest/wet northwest dipole associated with the El Niño Southern Oscillation (La-Niña-like) ocean atmosphere dynamics that follows a boundary roughly along 40 N latitude in the west. Preliminary results suggest that the LHDP in the Great Basin was confined south of the 40N latitudes. The purpose of this study is to examine the geographic extent of the LHDP within the Great Basin, along a north south transect across the dipole to determine whether in the past this dipole pattern may have persisted for multiple centuries. A stable dipole would suggest a stable cold north Pacific (La-Niña-like conditions) for multiple centuries. We present preliminary pollen and sedimentary data from sites between 38 and 40 N latitude. The sites are each wet valley bottom sedge meadows fed by groundwater from alluvial runoff and springs.

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