Multidecadal drought and Holocene climate instability in the Rocky Mountains

Time series analysis of a diatom-inferred drought record suggests that Holocene hydroclimate of the northern Rocky Mountains has been characterized by oscillation between two mean climate states. The dominant climate state was initiated at the onset of the Holocene (ca. 11 ka); under this climate st...

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Bibliographic Details
Published in:Geology (Boulder) 2006-05, Vol.34 (5), p.409-412
Main Authors: Stone, Jeffery R, Fritz, Sherilyn C
Format: Article
Language:English
Subjects:
algae
Cenozoic
Climate change
cores
cycles
decadal variations
diatoms
Drought
Flathead County Montana
Foy Lake
Geological time
Holocene
lacustrine environment
lake sediments
late-glacial environment
microfossils
Montana
North America
paleoclimatology
paleoecology
paleolimnology
Plantae
Pleistocene
Quaternary
Quaternary geology
Rocky Mountains
sediments
statistical analysis
tephrochronology
time series analysis
U. S. Rocky Mountains
United States
upper Pleistocene
upper Weichselian
Weichselian
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Summary:Time series analysis of a diatom-inferred drought record suggests that Holocene hydroclimate of the northern Rocky Mountains has been characterized by oscillation between two mean climate states. The dominant climate state was initiated at the onset of the Holocene (ca. 11 ka); under this climate state, drought was strongly cyclic, recurring at frequencies that are similar to twentieth century multidecadal phase changes of the Pacific Decadal Oscillation. This pattern remained consistent throughout much of the mid-Holocene, continuing until ca. 4.5 ka. After this time the mean climate state changed, and drought recurrence became unstable; periods of cyclic drought alternated with periods of less predictable drought. The timing of this shift in climate was coincident with widespread severe drought in the mid-continent of North America. Overall, the strongest periodicity in severe drought occurred during the mid-Holocene, when temperatures in the northern Rocky Mountains were warmer than today.
ISSN:0091-7613
1943-2682
DOI:10.1130/G22225.1