North American Cordillera 1600 Year Snowpack Reconstructions Pederson, G.T.; Gray, S.T.; Woodhouse, C.A.; Betancourt, J.L.; Fagre, D.B.; Littell, J.S.; Watson, E.; Luckman, B.H.; Graumlich, L.J. Pederson, G.T. Gray, S.T. Woodhouse, C.A. Betancourt, J.L. Fagre, D.B. Littell, J.S. Watson, E. Luckman, B.H. Graumlich, L.J. Other Hydroclimate Reconstruction drought earth science/paleoclimate/climate reconstructions|tree ring (age,null,null,year Common Era,null,climate reconstructions|tree ring,null,null,N,null) earth science/paleoclimate/instrumental (snow water equivalent,null,null,standard deviation unit,Apr,instrumental,null,null,N,April 1 SWE) earth science/paleoclimate/climate reconstructions|tree ring (snow water equivalent,ring width,null,standard deviation unit,Apr,climate reconstructions|tree ring,composited|smoothed,null,N,April 1; 20 year cubic smoothing spline (50% frequency cut-off)) earth science/paleoclimate/climate reconstructions|tree ring (snow water equivalent,ring width,null,standard deviation unit,Apr,climate reconstructions|tree ring,composited,null,N,"composite April 1 SWE reconstruction built using ""standard"" chronologies (i.e. autocorrelation preserved), and extended using successively longer versions of the reconstrution that have had their mean and variance scaled to equal the ""best"" reconstruction") earth science/paleoclimate/tree ring (age,null,null,year Common Era,null,tree ring,null,null,N,null) earth science/paleoclimate/tree ring (total ring width,null,null,millimeter,null,tree ring,null,null,N,units are 0.01 mm if end-of-series marker is 999 and 0.001 mm if end-of-series marker is -9999) earth science/paleoclimate/climate reconstructions|tree ring (snow water equivalent,ring width,null,standard deviation unit,Apr,climate reconstructions|tree ring,composited|smoothed,null,N,April 1; 50 year cubic smoothing spline (50% frequency cut-off)) earth science/paleoclimate/reconstructions (North American Cordillera>LATITUDE 44.5>LONGITUDE -111) 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 that is 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 United States. STUDY NOTES: 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 NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Pederson, G.T. Investigator : Gray, S.T. Investigator : Woodhouse, C.A. Investigator : Betancourt, J.L. Investigator : Fagre, D.B. Investigator : Littell, J.S. Investigator : Watson, E. Investigator : Luckman, B.H. Investigator : Graumlich, L.J. 2011-06-09 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/11205 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/readme-cordillera2011swe.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera-north2011swe.xls https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera-south2011swe.xls https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera2011swe-suppl.xls https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera2011rwl.zip https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/readme-cordillera2011swe.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera-north2011swe.xls https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera-south2011swe.xls https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera2011swe-suppl.xls https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera2011rwl.zip English https://www.ncdc.noaa.gov/paleo/study/11205 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/readme-cordillera2011swe.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera-north2011swe.xls https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera-south2011swe.xls https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera2011swe-suppl.xls https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/northamerica/cordillera2011rwl.zip Gregory T. Pederson, Stephen T. Gray, Connie A. Woodhouse, Julio L. Betancourt, Daniel B. Fagre, Jeremy S. Littell, Emma Watson, Brian H. Luckman, Lisa J. Graumlich2011The unusual nature of recent snowpack declines in the North American CordilleraScience3336040332-33510.1126/science.1201570http://science.sciencemag.org/content/333/6040/332 START YEAR: 369 AD * END YEAR: 2009 AD -117 36 -105 49