Long-Term Hydroclimatic Change in the U.S. Rocky Mountain Region: Implications for Ecosystems and Water Resources

Persistent Link:
http://hdl.handle.net/10150/194302
Title:
Long-Term Hydroclimatic Change in the U.S. Rocky Mountain Region: Implications for Ecosystems and Water Resources
Author:
Pederson, Gregory Thomas
Issue Date:
2010
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Both natural and anthropogenic climate change are driven by forcings that interact and result in hydroclimatic changes that alter ecosystems and natural resources at different temporal and spatial scales. Accordingly, changes within regions (i.e. individual points to large watersheds) may differ from patterns observed at sub-continental to global scales, thus necessitating the generation of point- to region-specific, cross-scale hydroclimatic data to elucidate important drivers of observed changes, and provide information at scales relevant to resource managers. Herein, we use the Northern U.S. Rocky Mountains as a study region to explore 1) the covariability between observed hydrologic and climatic changes, 2) the nature of changes occurring at the scale of days to decades, and 3) the ocean-atmosphere teleconnections operating at continental- to hemispheric-scales underlying the observed regional patterns of hydroclimatic variability. We then expand the scope of study to include the entire central North American Cordillera to investigate changes in winter precipitation (i.e. snowpack) spanning the last millennia+, with a focus on the spatial and temporal coherence of events from the medieval climatic anomaly to present. To accomplish this we utilize the full suite of hydroclimatic observational records in conjunction with proxy records of snowpack derived from a distributed network of tree-ring chronologies.Results from observational records in the Northern Rockies show important changes have occurred in the frequency and means of biophysically important temperature thresholds, and that recent changes appear greater in magnitude at the mid- to high-elevations. These changes, coupled with interannual- to interdecadal-scale moisture variability driven by ocean-atmosphere teleconnections, are shown to be strong controls on the timing and amount of regional snowpack and streamflow. Across the cordillera, tree-ring based records of snowpack show that before 1950, the region exhibited substantial inter-basin variability in snowpack, even during prolonged droughts and pluvials, marked by a predominant north-south dipole associated with Pacific variability. Snowpack was unusually low in the Northern Rocky Mountains for much of the 20th century and over the entire cordillera since the 1980s; heralding a new era of snowpack declines entrained across all major headwaters in western North America.
Type:
text; Electronic Dissertation
Keywords:
Climate Change; Paleoclimate; Snow Water Equivalent; Streamflow; Tree-Rings; Water Resources
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Natural Resources; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Graumlich, Lisa J.
Committee Chair:
Graumlich, Lisa J.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleLong-Term Hydroclimatic Change in the U.S. Rocky Mountain Region: Implications for Ecosystems and Water Resourcesen_US
dc.creatorPederson, Gregory Thomasen_US
dc.contributor.authorPederson, Gregory Thomasen_US
dc.date.issued2010en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractBoth natural and anthropogenic climate change are driven by forcings that interact and result in hydroclimatic changes that alter ecosystems and natural resources at different temporal and spatial scales. Accordingly, changes within regions (i.e. individual points to large watersheds) may differ from patterns observed at sub-continental to global scales, thus necessitating the generation of point- to region-specific, cross-scale hydroclimatic data to elucidate important drivers of observed changes, and provide information at scales relevant to resource managers. Herein, we use the Northern U.S. Rocky Mountains as a study region to explore 1) the covariability between observed hydrologic and climatic changes, 2) the nature of changes occurring at the scale of days to decades, and 3) the ocean-atmosphere teleconnections operating at continental- to hemispheric-scales underlying the observed regional patterns of hydroclimatic variability. We then expand the scope of study to include the entire central North American Cordillera to investigate changes in winter precipitation (i.e. snowpack) spanning the last millennia+, with a focus on the spatial and temporal coherence of events from the medieval climatic anomaly to present. To accomplish this we utilize the full suite of hydroclimatic observational records in conjunction with proxy records of snowpack derived from a distributed network of tree-ring chronologies.Results from observational records in the Northern Rockies show important changes have occurred in the frequency and means of biophysically important temperature thresholds, and that recent changes appear greater in magnitude at the mid- to high-elevations. These changes, coupled with interannual- to interdecadal-scale moisture variability driven by ocean-atmosphere teleconnections, are shown to be strong controls on the timing and amount of regional snowpack and streamflow. Across the cordillera, tree-ring based records of snowpack show that before 1950, the region exhibited substantial inter-basin variability in snowpack, even during prolonged droughts and pluvials, marked by a predominant north-south dipole associated with Pacific variability. Snowpack was unusually low in the Northern Rocky Mountains for much of the 20th century and over the entire cordillera since the 1980s; heralding a new era of snowpack declines entrained across all major headwaters in western North America.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectClimate Changeen_US
dc.subjectPaleoclimateen_US
dc.subjectSnow Water Equivalenten_US
dc.subjectStreamflowen_US
dc.subjectTree-Ringsen_US
dc.subjectWater Resourcesen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineNatural Resourcesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorGraumlich, Lisa J.en_US
dc.contributor.chairGraumlich, Lisa J.en_US
dc.contributor.committeememberGray, Stephen T.en_US
dc.contributor.committeememberWoodhouse, Connie A.en_US
dc.contributor.committeememberBetancourt, Julio L.en_US
dc.contributor.committeememberFagre, Daniel B.en_US
dc.identifier.proquest11135en_US
dc.identifier.oclc752260993en_US
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