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Tree rings reveal unmatched 2nd century drought in the Colorado River Basin

June 9, 2022

The ongoing 22 year drought in the Upper Colorado River Basin (UCRB) has been extremely severe, even in the context of the longest available tree-ring reconstruction of annual flow at Lees Ferry, Arizona, dating back to 762 CE. While many southwestern drought assessments have been limited to the past 1200 years, longer paleorecords of moisture variability do exist for the UCRB. Here, gridded drought-atlas data in the UCRB domain along with naturalized streamflow data from the instrumental period (1906–2021) are used in a K nearest neighbor (KNN) nonparametric algorithm to develop a streamflow reconstruction for the Lees Ferry gage starting in 1 CE. The reconstruction reveals a 2nd century drought unmatched in severity by the current drought or by well-documented medieval period droughts in the UCRB. Although data are sparse, analysis of individual long tree ring records and other paleoclimatic data also support the occurrence of an exceptional 2nd century drought.

Publication Year 2022
Title Tree rings reveal unmatched 2nd century drought in the Colorado River Basin
DOI 10.1029/2022GL098781
Authors Subhrendu Gangopadhyay, Connie Woodhouse, Gregory J. McCabe, Cody C. Routson, David Meko
Publication Type Article
Publication Subtype Journal Article
Series Title Geophysical Research Letters
Index ID 70236280
Record Source USGS Publications Warehouse
USGS Organization WMA - Integrated Modeling and Prediction Division