No abstract

A dendroclimatic reconstruction based on tree ring chronologies from the Gulf of Alaska (GOA) explains 50% of the variance in annual Lake Erie levels. Temperature‐sensitive ring‐width series from the GOA are strongly and negatively correlated with annual lake levels, reflecting the Pacific North American (PNA) teleconnection pattern. Phases of the PNA are linked to variable circulation patterns that provide moisture to the Lake Erie basin, determining lake levels. The reconstruction extends back 265 years and shows that annual lake levels were high during the mid 1700s, the mid to late 1800s and the late 1900s. Relative low stands occurred during the late 1700s and early 1900s. The highest lake levels in the reconstruction are found over the past few decades, as seen in the observed record. Multidecadal‐scale fluctuations in the Lake Erie reconstruction underscore the importance of Pacific Decadal Variability in determining levels in the Great Lakes.

The abundance of sedimentary organic material from two lakes was used to infer past Holocene storminess on Adak Island where frequent storms generate abundant rainfall and extensive cloud cover. Andrew and Heart Lakes are located 10 km apart; their contrasting physical characteristics cause the sedimentary organic matter to respond differently to storms. Their records were synchronized using correlated tephra beds. Sedimentation rates increased between 4.0 and 3.5 ka in both lakes. Over the instrumental period, Andrew Lake biogenic-silica content (BSi) is most strongly correlated with winter sunlight availability, which influences photosynthetic production, and river input, which influences the dilution of BSi by mineral matter. Heart Lake BSi is likely affected by wind-driven remobilization of sediment, as suggested by correlations among BSi, the North Pacific Index, and winter storminess. The results indicate relatively stormy conditions from 9.6 to 4.0 ka, followed by drying between 4.0 and 2.7 ka, with the driest conditions from 2.7 to 1.5 ka. The stormiest period was between AD 500 and 1200, then drying from 1150 to 1500 and more variable until 1850. This record of Holocene storminess fills a major gap at the center of action for North Pacific wintertime climate.