Long-term records of cyclic droughts are valuable for understanding future changes in hydrologic patterns and constraining climate models. A 3,300-year long record of δ18O and δ13C values from endogenic carbonate from Foy Lake, Montana is used to infer such droughts during the early Holocene. From 10.8 to 9.6 kyr BP, δ18O and δ13C values are low, indicating a period dominated by a cooler, less evaporative climate. Both records exhibit strong cyclicity in the ~200 yr range, which is inferred to be a solar cycle. A dramatic shift towards a warmer, drier climate occurs after 9.6 kyr BP in a step pattern, dramatic in the δ13C record. Warming occurs after the transition. Stochastic cyclicity dominates with weaker, but statistically significant, periodicities ranging from 40-70 yrs. These are believed to be an expression of the Atlantic Multidecadal Oscillation. This larger synoptic climate signal may be important to the overall Pacific Northwest climate.
|School:||California State University, Long Beach|
|School Location:||United States -- California|
|Source:||MAI 52/04M(E), Masters Abstracts International|
|Subjects:||Geology, Meteorology, Paleoclimate Science, Limnology|
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