A 545Year Drought Reconstruction for Central Oregon
OCTOBER 2, 2017
... it shows just how variable climate has been in the past, this time in Oregon:
ABSTRACT Using a 545-year ponderosa pine ( Pinus ponderosa ) tree-ring chronology, we examine the drought history of central Oregon to: (1) determine the relationship among drought, ENSO (El Niñ o/Southern Oscillation), and the PDO (Pacific Decadal Oscillation), and (2) compare the climatic sensitivity of ponderosa pine and western juniper ( Juniperus occidentalis ) to determine their suitability as interchangeable climate proxies. Our climatic reconstruction explained 35% of the variance in historical Palmer’s Drought Severity Index (PDSI) values and revealed severe drought periods during the 1480s, 1630s, 1700s, and 1930s. The most sustained drought period in our reconstruction occurred during the 1930s, with the most severe single drought year occurring in 1489. We found a significant ( p < .01) but weak relationship between our ponderosa pine chronology and ENSO and the PDO, explaining 9% and 12% of the variation respectively. Both ponderosa pine and western juniper record periods of severe regional drought, but western juniper is more sensitive to regional and seasonal climatic variations, whereas ponderosa pine is more responsive to temperature change. These differences suggest that their substitutability as climate proxies https://www.researchgate.net/public...ear_Drought_Reconstruction_for_Central_Oregon
All a bit dry! But the graphs tell the real story:
Fig. 4. Reconstructed Palmer’s Drought Severity Index (PDSI), 1455– 2000. Grey line is reconstruction; black line is 8-year moving average of reconstruction. Note pronounced periods of drought during the decades of 1480, 1620, 1700, and 1930.
It would appear that Oregon’s climate was actually much more volatile in earlier centuries, both in terms of wetness and dryness.
