WERC Seminar and INE Pubinar are joining forces this week! Please note the special time and place of this talk: 3:30-4:30pm @ the UAF Pub
The strength of the wintertime Aleutian Low pressure system (AL) in the North Pacific affects the severity of drought in the Western US and the size of salmon runs in Alaska. Unfortunately, our long-term understanding of how the AL interacts with global climate has been limited by the fact that most paleoclimate indicators are blind to cold season conditions. In this talk, I will present a 500-year winter-sensitive record of the AL based on the architecture, wood morphology, and ring widths of sub-alpine trees growing along remote reaches of the Northeast Pacific coast. Results show that, similar to its behavior in the last century, the AL shifted between strong and weak phases every few decades back to at least AD 1500. The most striking feature of this record is that the duration of these strong-weak regimes suddenly became 2-3x longer ca. AD 1700, a change that was accompanied by stormier conditions in Southeast Alaska. This discovery warrants further investigation because a similar change in AL regime duration in the future could impact the year-to-year availability of AL-affected resources that society now relies on. I will close the talk by using this new winter climate record to discuss how changing seasonality affected the timing and extent of Little Ice Age glacier advances in Coastal Alaska.