Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Stone, J. R. Articles by Fritz, S. C. Search for Related Content GeoRef GeoRef Citation

Multidecadal drought and Holocene climate instability in the Rocky Mountains

¹ Department of Geosciences, University of Nebraska–Lincoln, 214 Bessey Hall, Lincoln, Nebraska 68588, USA

Time series analysis of a diatom-inferred drought record suggests that Holocene hydroclimateof the northern Rocky Mountains has been characterized by oscillation betweentwo mean climate states. The dominant climate state was initiated at the onset ofthe Holocene (ca. 11 ka); under this climate state, drought was strongly cyclic, recurringat frequencies that are similar to twentieth century multidecadal phase changes of thePacific 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, anddrought recurrence became unstable; periods of cyclic drought alternated with periods ofless predictable drought. The timing of this shift in climate was coincident with widespreadsevere drought in the mid-continent of North America. Overall, the strongest periodicityin severe drought occurred during the mid-Holocene, when temperatures in the northernRocky Mountains were warmer than today.

Key Words: drought • diatoms • Holocene • climate variability • Pacific Decadal Oscillation