North American Cordillera 1600 Year Snowpack Reconstructions 
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               World Data Center for Paleoclimatology, Boulder 
                                  and 
                     NOAA Paleoclimatology Program 
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NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! 


NAME OF DATA SET: 
North American Cordillera 1600 Year Snowpack Reconstructions 
LAST UPDATE: 8/17/2011 (File name changes and updates for 6 tree ring 
             data files.  See Description section for details) 
             6/2011 (Original receipt by WDC Paleo) 
CONTRIBUTORS: Pederson, G.T., S.T. Gray, C.A. Woodhouse, J.L. Betancourt, 
D.B. Fagre, J.S. Littell, E. Watson, B.H. Luckman, and L.J. Graumlich.
IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2011-080 


WDC PALEO CONTRIBUTION SERIES CITATION: 
Pederson, G.T., et al.  2011. 
North American Cordillera 1600 Year Snowpack Reconstructions. 
IGBP PAGES/World Data Center for Paleoclimatology 
Data Contribution Series # 2011-080. 
NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. 


ORIGINAL REFERENCE: 
Pederson, G.T., S.T. Gray, C.A. Woodhouse, J.L. Betancourt, D.B. Fagre, 
J.S. Littell, E. Watson, B.H. Luckman, and L.J. Graumlich. 2011. 
The unusual nature of recent snowpack declines in the North American Cordillera. 
Science, Vol. 333, no. 6040, pp. 332-335, 15 July 2011. 
DOI: 10.1126/science.1201570  
Published Online June 9 2011 

ABSTRACT: 
In western North America snowpack has declined in recent decades, 
and further losses are projected through the 21st century. 
Here we evaluate the uniqueness of recent declines using snowpack 
reconstructions from 66 tree-ring chronologies in key runoff generating 
areas of the Colorado, Columbia and Missouri River drainages.
Over the past millennium, late-20th century snowpack reductions are 
almost unprecedented in magnitude across the northern Rocky Mountains, 
and in their north-south synchrony across the cordillera. Both the snowpack
declines and their synchrony result from unparalleled springtime warming 
due to positive reinforcement of the anthropogenic warming by decadal 
variability. The increasing role of warming on large-scale snowpack
variability and trends foreshadows fundamental impacts on streamflow 
and water supplies across the western USA. 


GEOGRAPHIC REGION: Western North America  
PERIOD OF RECORD: 369 - 2009 AD

FUNDING SOURCES: 
US Geological Survey (USGS) Western Mountain Initiative, 
US National Science Foundation (NSF) grants GSS-0620793 
and DEB-0734277.  C.A.W. was supported by NSF (grants 980931 
and 9729571), USGS Earth Surface Dynamics Program, and the 
Denver Water Board.  J.S.L was supported by the Joint Institute 
for the Study of the Atmosphere and Ocean (JISAO) under US 
National Oceanic and Atmospheric Administration (NOAA) 
Cooperative Agreement NA17RJ1232 (contribution 1856), 
and NOAA Climate Program Office Sector Applications Research 
Program (grant NA07OAR4310371). B.H.L was supported by the 
Natural Sciences and Engineering Research Council of Canada
(grant 8847).



DESCRIPTION: 
Tree-ring based reconstructions of annual snow water equivalent (SWE) 
contained in drainage basins of the North American Cordillera for the 
last 1600 years.  Reconstructions data are available in two 
Excel data files for the Northern and Southern Cordillera: 
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera-north2011swe.xls 
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera-south2011swe.xls 

Supplementary Tables containing site locations, formulas, and statistics are available in a separate 
Excel file: 
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera2011swe-suppl.xls

The 66 tree ring width data sets utilized in this study are listed in Table S3, and are available 
in the International Tree Ring Data Bank:
http://www.ncdc.noaa.gov/paleo/treering.html 
and in a ZIP archive file for this study: 
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera2011rwl.zip 


 
File name changes and location updates for tree ring data files, 8/17/2011: 
File co642.rwl (Anderson Ridge East) renamed wy042.rwl 
File co643.rwl (Boulder Lake) renamed wy043.rwl 
File co645.rwl (Fremont Lake) renamed wy045.rwl 
File nm588.rwl (Beef Basin) renamed ut529.rwl, and Lat-Long corrected 
File nm589.rwl (Harmon Canyon) renamed ut530.rwl, and Lat-Long corrected 
Lat-Long corrected for co644.rwl 
Species corrected for co650.rwl (PSME to PIED) 

No ring width data or climate reconstructions were affected.